Technical articles provided by the French Section, host

Transcription

Technical
Articles
dedicated to france, host Country of PIANC’s AGA 2013
125
126
LES BARRAGES DE L’OISE:
MODES CONSTRUCTIfS
DAMS ON ThE RIVER OISE:
CONSTRUCTION PRINCIPLES
FRéDéRIC AURY
EMCC (Vinci Construction France)
Siège de Rungis
E-mail: [email protected]
PATRICK AMATHIEU
(EMCC (Vinci construction France), Agence de
Villeneuve Le Roi
KEY WORDS: construction par phases, batar-
deau, palplanches, butonnage, câble de garde
MOTS-CLES: step-by-step construction, cofferdam, sheet piles, shoring, ship impact protection
cable
1. INTRODUCTION
Le programme interrégional d’aménagement de
l’Oise, dont VNF assure la maîtrise d’ouvrage, avait
pour objet de moderniser les ouvrages de navi-
gation situés entre Compiègne et la confluence
avec la Seine, soit 100 km de rivière navigable.
Il prévoit principalement le remplacement des 7
barrages manuels de l’Oise par des ouvrages mécanisés (cf. Figure 1), l’aménagement de passeà-poissons au droit de ces ouvrages, ainsi que la
modernisation des 14 écluses de l’Oise.
Les barrages de Venette et de Boran-sur-Oise sont
les deux derniers barrages manuels à avoir été reconstruits sur les sept barrages de l’Oise navigable, après la mise en service des barrages de Creil
(2004), l’Isle-Adam (2007), Pontoise (2008), Verberie (2008) et Sarron (2009).
Figure 1: Aménagement de l’Oise
127
Entièrement automatisés, les nouveaux barrages
de l’Oise assurent une régulation efficace et sûre
du plan d’eau, indispensable à la navigation et
au développement du transport fluvial. Ils améliorent également les conditions d’exploitation et
de maintenance des ouvrages et ils contribuent à
fiabiliser l’alimentation en eau potable.
Enfin, en période de crues, ils permettent une gestion précise, rapide et synchronisée des manœuvres afin d’assurer l’effacement des barrages et ne
pas créer d’obstacle à l’écoulement des crues.
cote de la retenue normale amont à une valeur
constante mais ajustable à 5 cm prêt, selon les besoins de la navigation.
Le barrage de l’Isle Adam est constitué de 2 passes
principales, d’un pertuis et d’une passe à poisson.
Comme tous les autres barrages, il est implanté
à l’amont de l’ancien barrage, là où la hauteur
d’eau est maximum, de l’ordre de 5,00 m. Le barrage de Pontoise est constitué simplement de 2
passes navigables et d’une passe à poissons.
Les sept barrages de l’Oise ont fait l’objet d’un
avant-projet unique qui garantit une homogénéité
de conception propre à faciliter la maintenance.
Les barrages à clapets ainsi conçus sont mécanisés et automatisés, permettent une manœuvre
simple, sécurisée, rapide et synchronisée.
Figure 3: Barrage de Venette
Le principe de fonctionnement d’un barrage à
clapets est le suivant (cf. Figure 4):
Figure 2: Exemple de passe à poissons
Dès leur conception, les sept barrages de l’Oise
ont été équipés de passes à poissons (cf. Figure
2: ouvrage permettant aux poissons migrateurs de
remonter les cours d’eau) afin de rétablir la continuité piscicole.
Dans chacune des passes, un volet métallique:
le clapet, pivote sur une semelle en béton armé,
c’est-à-dire le radier. Les clapets sont actionnés par
des vérins. Commandés de manière automatique,
ces clapets assurent une régulation du plan d’eau
en maintenant une hauteur d’eau constante en
amont du barrage, hors période de crues.
Lors des crues, le clapet est couché en fond de
radier et le barrage est alors dit ‘effacé’ afin de ne
pas créer d’obstacle à l’écoulement des crues.
L’entreprise EMCC a participé en 2005 et 2006 à
la reconstruction des barrages de Pontoise et de
l’Isle Adam, les plus proches de la confluence.
2. Description générale
des barrages
Les nouveaux barrages sont généralement constitués de trois passes hydrauliques dont deux principales et une plus réduite, appelée pertuis ; cette
dernière passe n’étant pas systématique pour les
sept barrages. Le débouché linéaire hydraulique
de chaque passe est de 33,00 m pour les passes
principales et de l’ordre de 12,00 m pour le pertuis
(cf. Figure 3).
La bouchure du barrage est obtenue à l’aide de
3 clapets dont l’axe de rotation est parallèle au
barrage actuel, et qui permettront de réguler la
128
Figure 4: Principe de fonctionnement d’un
barrage à clapets
3. PHASAGE DES TRAVAUX
Les travaux prévus pour les barrages de l’Isle Adam
et de Pontoise ont été réalisés en trois phases distinctes entrecoupées d’une période hivernale (minovembre à mi-avril) à risque de crues pendant
laquelle les travaux en rivière ont été interrompus.
En première phase: conception et mise en place
du câble de garde lorsqu’il est prévu, puis réalisation du génie civil de la première passe navigable
de rive droite et pose du clapet correspondant,
celui-ci devant pouvoir être manœuvrable par
l’entreprise à la demande du maître d’ouvrage à
tout moment une fois posé.
En deuxième phase: réalisation du génie civil
de la deuxième passe navigable et du pertuis
(lorsqu’il existe), pose des clapets correspondants
et de leurs organes de manœuvre, mise en place
des équipements de commande, de contrôle et
de supervision, réalisation de la passerelle.
En troisième et dernière phase: démontage
des équipements et superstructures du barrage
actuel, démolition de ses piles et de ses culées, finitions, remise en état des lieux et repli du chantier
après mise en service du nouveau barrage.
4. MODE D’EXECUTION
DES BARRAGES
La présence permanente de l’eau de la rivière
impose un mode de réalisation adapté avec des
travaux réalisés par phases distinctes.
Durant ces phases, l’ouvrage est construit dans
la rivière, à sec et à l’abri d’ouvrages provisoires
appelés batardeaux et constitués d’une enceinte
étanche en palplanches (cf. Figure 5 à la page
suivant).
Compte tenu de la nature des sols et de la hauteur
d’eau à soutenir, les palplanches ont des modules
standards, voire assez faibles, généralement de
type PU 12 à PU18 et de 12/13,00 m de longueur.
Elles sont foncées de 7,00 à 8,00 m dans les alluvions puis dans la craie à l’aide d’un vibrofonceur
puis d’un marteau hydraulique.
Une fois la cote des palplanches atteinte, un terrassement est réalisé sous eau pour mettre à nu
l’assise saine qui servira de fondation au barrage.
Un béton de rattrapage entre le sol en place et le
radier est mis en œuvre sous eau (béton immergé).
Néanmoins, la seule épaisseur de gros béton ne
suffit pas à la reprise des efforts de soulèvement
dus aux sous-pressions, notamment en phase de
chantier, lorsque que la ‘boîte’ est vide. Cette
sujétion conduit à la mise en œuvre d’éléments
d’ancrage.
Ces ancrages sont constitués de pieux H de 7/8 m
de longueur environ enfichés dans le sol.
Une fois ces pieux et le bouchon en béton effectués, un dispositif de butonnage vient ceinturer
l’ensemble en tête de rideau afin de créer un appui de rive aux palplanches.
Lorsque tout ce dispositif construit sous l’eau est en
place (palplanches, ancrages verticaux, gros béton, cadre de butonnage), l’enceinte peut être
vidée en toute sécurité.
Le génie civil et les équipements du barrage sont
construits à sec (cf. Figure 6).
Figure 6: Construction du génie civil et mise en place des équipements à sec
129
Figure 5: Cinématique de construction d’un barrage sur l’Oise
130
5. LES CABLES DE GARDE
5.1. Le système NAVISTOP®
EMCC a mis au point un système de protection
des barrages contre les chocs de corps flottants,
dont les bateaux, il y a plus de 25 ans. Ce procédé
breveté s’appelle NAVISTOP®.
C’est ce système qui a été mis en œuvre sur les
barrages de L’Isle Adam et de Pontoise dans le
cadre des marchés de reconstruction des barrages de l’Oise.
21 barrages sont équipés aujourd’hui en France et
en Belgique de ce dispositif.
Le système NAVISTOP® est constitué d’un câble
en aramide (fibres synthétiques) tendu en travers
de la voie d’eau, qui permet d’absorber l’énergie
cinétique incidente du corps flottant ou bateau
venant s’engager dans le câble en trainant sur le
fond un ensemble de corps-morts et de chaînes
(cf. Figures 7 et 8).
Le dispositif NAVISTOP® est composé par :
• Un câble de retenue en aramide
• Deux coffres d’extrémité (et éventuellement
des flotteurs intermédiaires)
• Des amarres fusibles avec tensionneur intégré
• De chaînes et corps-mort trainés sur le fond.
Figure 7: Dispositif NAVISTOP® , vue en plan
Figure 8: Dispositif NAVISTOP® , vue en perspective
131
Le principe de fonctionnement est le suivant (cf.
Figures 9 et 10):
Le bateau A dérivant heurte le câble de garde B
mettant en tension le dispositif jusqu’à provoquer
la rupture des fusibles d’amarrage C.
Les coffres flottants D maintiennent le câble de
garde B hors d’eau. Ils entraînent dans leur sillage
la chaîne pendeur E sur lesquelles sont accrochés
les corps-morts F et les lignes de chaînes de traine
G.
Les chaines pendeurs E, les corps-morts F, et les
lignes de chaine de traine G sont trainés sur le
fond de la rivière et absorbent l’énergie cinétique
du navire en perdition ainsi qu’aux efforts du courant sur un navire A perpendiculaire au courant.
Les fusibles C sont définis de manière à céder bien
avant les limites de capacité des tensionneurs.
Ainsi, en cas de déclenchement du dispositif, les
tensionneurs restent dans leur plage de fonctionnement normale, et peuvent être réemployés lors
de la remise en place du dispositif.
Figure 9
Figure 10
132
5.2. Méthode de dimensionnement
• Calcul de la distance B (cf. figure 12):
5.2.1. Description de la méthode
Les calculs sont réalisés par itérations à l’aide d’un
tableur Excel. Une itération correspond à un pas
de déplacement constant du bateau égal à la
distance de freinage disponible sur le nombre de
discrétisations souhaité. Connaissant la vitesse initiale du bateau, on utilise la définition de l’énergie
cinétique pour calculer son énergie. Puis, à
chaque itération on calcule la nouvelle énergie
du bateau en soustrayant les pertes dues aux frottements des masses:
Figure 12
Nous avons alors :
La connaissance du Ei nous permet de trouver la
vitesse du bateau au pas i. Lorsque sa vitesse devient nulle, nous notons la distance de freinage.
5.2.2. Calcul des distances, angles
et positions
• Calcul des angles α et δ:
On considère la chaîne pendeur comme un système de barres avec F la force de frottements
du corps-mort et des chaînes de traine (cf. Figure
13):
• Déplacement du convoi (bord avant gauche):
• Distance de mise en tension (cf. Figure 11):
Figure 13
En faisant l’équilibre global suivant l’horizontale
nous obtenons:
Or par géométrie:
Figure 11
Soit:
Nous avons alors :
et:
Ce qui nous permet d’obtenir la valeur de α, puis
la valeur de δ.
133
• Système en tension:
5.2.3. Calcul des forces mises en jeu
Le dispositif est en tension lorsque :
• Calcul de l’énergie cinétique du convoi:
• Calcul de la position du coffre :
Cm est le coefficient de masse ajoutée qui sert à
prendre en compte l’eau qui se déplace avec le
convoi.
On commence par calculer la position du coffre à
la mise en tension en s’appuyant:
Si le système n’est pas en tension, on utilise la connaissance des positions initiale jusqu’à la mise en
tension. Puis la position du coffre est le prorata de
l’avancement du convoi entre sa position initiale
et sa position à la mise en tension. C’est-à-dire :
Par itérations successives, on évalue, avec Ec0 =
Ecini:
Le signe de la contribution des forces hydrodynamiques dépend du signe de la vitesse relative
du convoi par rapport au courant.
• Force hydrodynamique sur le convoi:
Si le système est en tension, on suppose que le coffre se déplace du pas i au pas i+1 selon la direction du câble au pas i+1 (cf. Figure 14).
Avec CD le coefficient de trainée qui dépend de
la forme du bateau. Pour un parallélépipède rectangle on prendra CD=2.
• Force de frottement du corps-mort et des chaînes
de traine:
On prend en compte la contribution des frottements et de la cohésion du sol:
On en déduit :
Figure 14
On calcule:
On en déduit:
• Calcul de la position du corps-mort:
Le corps mort est dans l’alignement du convoi et
du coffre. On en déduit:
134
• Tension dans le câble de retenue:
Selon le schéma 3 elle vaut:
• Tension maximale dans les chaînes pendeur:
• Effort sur le bateau:
5.3. Les principales hypothèses:
Les principales hypothèses nécessaires au dimensionnement sont les suivantes:
• Les caractéristiques du navire (4 à 5.000 tonnes)
• La vitesse du courant (environ 2 m/s)
• Les niveaux d’eau de fonctionnement (5 à 10,00 m)
• Les caractéristiques de frottement du sol constituant le fond de rivière (tgj avec j = 25 à 35 °)
• L’espace disponible pour arrêter le navire (de
l’ordre de 100 m).
6. CONCLUSION
Les chantiers de reconstruction des barrages de
l’Oise a nécessité, pour leur protection, de batardeaux.
Les batardeaux, réalisés en palplanches, limitent
le gabarit hydraulique de la rivière et gênent le
passage des crues c’est pourquoi les travaux ont
été réalisés en dehors des périodes de crues potentielles, d’avril à novembre.
Dans ces conditions, les délais globaux à prendre en compte pour la construction des barrages
n’ont pu être inférieurs à 2 ans.
Des moyens nautiques (pontons, bateaux remorqueurs-pousseurs, barges, etc.) ont été nécessaires
pour construire les batardeaux en palplanches
ainsi que pour mettre en place les équipements,
en particulier les clapets.
Sous forme de cadres assemblant profilés H et
tubes circulaires, les systèmes de renfort et de butonnage des palplanches ont été conçus pour assurer le passage du matériel et des équipements
afin de ne pas modifier la structure des batardeaux
en cours de chantier.
Les travaux étant réalisés en maintenant la navigation sur l’Oise, le travail à l’abri de batardeaux
a nécessité la mise ne place de systèmes de protection contre les erreurs de navigation ou les ‘bateaux fous’.
Le choix s’est porté sur la mise en place de câbles
de garde. La conception du système a été laissée à l’initiative de l’entreprise. EMCC a proposé
son système breveté et éprouvé depuis plus de 25
ans sur les rivières françaises et belges: le système
NAVISTOP®.
7. REFERENCES
- Site internet du service navigation de la Seine
- Archives EMCC sur les barrages de l’Isle Adam
et de Pontoise
- Publications internes EMCC sur le système NAVISTOP®
SUMMARY
The river Oise development plan, of which VNF is
the owner, aimed at modernising the navigational constructions and structures located between
Compiègne and the confluence with the river
Seine. Amongst others, the replacement of 7 dams
was planned for new expected traffic, in particular with the new Canal Seine Nord Europe.
EMCC worked in 2005 and 2006 on the reconstruction of the dams of Pontoise and l’Isle Adam, the
closest to the confluence. These dams are mobile
dams for water level regulation in the upstream
reach. They consist of two main sections, one secondary section with smaller width and a fish way.
The new dams are established upstream of the old
ones, where the water depth is maximum (about
5 m).
Because the river flow cannot be stopped completely, works must be realised with a specific
methodology, with distinct stages taking into ac-
count a 6 months winter interruption period (from
November to April) for flash-flood risks. During these
different steps, the dam is built on the river bed,
inside temporary enclosures called ‘cofferdams’,
creating a dry work environment. At each stage,
only a part of the river is blocked by the cofferdam
so that a continuous river flow is maintained during
the works and navigation is not stopped.
Water tightness is a key issue in this type of works.
Lateral water tightness is realised by means of steel
sheet pile walls, and the bottom of the cofferdam
is concreted underwater. This bottom concrete
slab is anchored by means of driven piles in order
to counterbalance bottom water pressure.
To protect the zone of dams during the works as
well as in the course of exploitation against the
floating objects and the ‘crazy’ boats, a specific
device of ‘stop boat’ is planned in the upstream
of dams.
135
RESUME
Le programme d’aménagement de l’Oise, dont
VNF a assuré la maîtrise d’ouvrage, avait pour objectif de moderniser les ouvrages de navigation
situés entre Compiègne et la confluence avec la
Seine. Il prévoyait, entre autre le remplacement
de 7 barrages en perspective des nouveaux trafics
attendus avec le nouveau Canal Seine-Nord Europe.
Durant ces phases, l’ouvrage est construit dans la
rivière, à sec et à l’abri d’ouvrages provisoires appelés batardeaux. Les phases distinctes ont pour
but de laisser la rivière s’écouler par une partie du
lit pendant que l’on exécute les travaux de l’autre
partie. Le trafic fluvial ainsi que les captages
d’eau peuvent ainsi être maintenus pendant les
travaux.
EMCC a participé en 2005 et 2006 à la reconstruction des barrages de Pontoise et de l’Isle Adam, les
plus proches de la confluence. Il s’agit de barrages mobiles destinés à réguler le niveau d’eau du
bief amont. Ces barrages, constitués de 2 passes
principales, d’un pertuis et d’une passe à poisson
sont implantés à l’amont des anciens barrages, là
où la hauteur d’eau est maximum, de l’ordre de
5,00 m.
La proximité immédiate de l’eau rend primordiaux
les problèmes d’étanchéité. L’étanchéité latérale est assurée par la réalisation d’une ceinture
étanche en palplanches métalliques et la perméabilité du sol à l’intérieur du batardeau est quasiment annulée à l’aide d’un béton immergé. Pour
une étanchéité totale, les sous-pressions sont bloquées par un réseau d’ancrage en pieux battus.
La présence permanente de l’eau de la rivière impose un mode de réalisation adapté avec des
travaux réalisés par phases distinctes entrecoupées d’une période d’interruption hivernale de 6
mois (de novembre à avril) à fort risque de crues.
Afin de protéger la zone des barrages durant les
travaux ainsi qu’en cours d’exploitation contre les
objets flottants et les bateaux ‘fous’, un dispositif
spécifique d’arrêt du type ‘câble de garde’ est
prévu à l’amont des barrages.
ZUSAMMENFASSUNG
Der Entwicklungsplan von VNF für den Fluss Oise hat
zum Ziel, die Bauwerke für die Schifffahrt, die zwischen Compiegne und der Mündung in die Seine
liegen, zu modernisieren. Unter anderem wurde
für das zusätzlich erwartete Verkehrsaufkommen,
insbesondere im Zusammenhang mit dem neuen
Kanal Seine-Nordeuropa, vorgesehen, sieben
Dämme zu ersetzen.
EMCC arbeitete in den Jahren 2005 und 2006 an
der Deichsanierung von Pontoise und l’Isle Adam,
die dem Zusammenfluss am nächsten liegen. Bei
diesen Deichbauwerken handelt es sich um bewegliche Dämme für die Regulierung des Wasserstandes im oberen Flussabschnitt. Sie bestehen
aus zwei Haupt- und einem Nebenabschnitt mit
geringerer Breite und einem Fischpass. Die neuen
Dämme werden oberhalb der alten Dämme errichtet, wo die größte Wassertiefe herrscht (ca. 5
m).
Da die Flussströmung nicht komplett gestoppt
werden kann, müssen die Arbeiten mit einer besonderen Methode durchgeführt werden, die für plötzlich auftretende Fluten unterschiedliche Schritte
136
vorsieht, unter Berücksichtigung einer 6-monatigen Unterbrechungszeit im Winter (von November
bis April). Während dieser verschiedenen Schritte
wird der eigentliche Damm innerhalb eines temporären Fangedamms, einem sogenannten Kofferdamms (‚cofferdam’) im Flussbett errichtet, was
für eine trockene Arbeitsumgebung sorgt. In jeder
Bauphase wird nur ein Teil des Flusses durch den
Kofferdamm abgesperrt, sodass eine kontinuierliche Flussströmung aufrecht erhalten wird und die
Schifffahrt nicht eingestellt werden muss.
Wasserdichtigkeit nimmt eine Schlüsselposition bei
dieser Art von Arbeiten ein. Die seitliche Wasserdichtigkeit wird mittels Spundwänden erzielt und
der Boden des Kofferdamms wird unter Wasser betoniert. Die Betonplatte wird mittels Rammpfählen
verankert, um den Grundwasserdruck auszugleichen.
Um die Dammzonen während der Arbeiten sowie
im Verlauf der Abgrabung gegen schwimmende
Gegenstände und Fahrzeuganprall zu schützen,
ist eine spezielle Vorrichtung eines ‚Bootstopps’ in
den oberen Bereichen der Dämme geplant.
RESTORATION Of ThE LOIRE ESTUARY:
ThE RESULTS Of 20 YEARS Of STUDIES
RESTAURATION DE L’ESTUAIRE DE LA LOIRE:
LES RéSULTATS DE 20 ANNéES D’éTUDES
PIERRE BONA
BERNARD PRUD’HOMME LACROIX
Groupement d’Intérêt Public (GIP) Loire Estuaire
22, rue de la tour d’Auvergne
44000 Nantes
France
Tel: +33 (0)2 51 72 93 67
SéBASTIEN LEDOUX
LUCIE THIEBOT
ARTELIA
8, Avenue des Thébaudières
44815 Saint-Herblain
France
Tel: +33 (0)2 2809 1849
RégIS WALTHER
LUC HAMM
ARTELIA
6, rue de Lorraine
38130 Echirolles
France
Tel: +33 (0)4 7633 4000
KEY WORDS: mud flat, ecological engineering, 3-D
modelling, monitoring network, working with nature
MOTS-CLES: vasière, génie écologique, modélisation 3D, réseau de mesures, œuvrer avec la
nature
1. INTRODUCTION
The Loire is one of the three major estuaries on the
French Atlantic seaboard. Over the past 200 years
it has undergone major development with a view
to improving its navigability and making it safe for
shipping. The bed has been deepened, intertidal
zones and secondary branches haven filled in to
allow the tide to propagate further and ships to
sail upstream as far as the port of Nantes, over 50
km from the river’s mouth.
These projects have considerably modified the
hydro-sedimentary dynamics of the estuary, leading in particular to a fall of several metres in lowwater levels and greater saline intrusion. The phenomenon of fine sediment being trapped in the
137
form of a maximum turbidity zone and fluid mud
has also been amplified due to asymmetric tidal
propagation accentuated by morphological
changes in the estuary, and especially the considerable depths in the shipping channel in the
downstream section.
This disturbance of the river’s hydro-sedimentary
behaviour has created problems in several areas:
• anoxic conditions have had an effect on the living environment
• side branches of the river have become
clogged
• it is difficult to manage water offtake for agricultural and industrial uses
• there has been an impact on the landscape in
urban areas, etc.
Because of this, the various stakeholders launched
an ambitious study and monitoring programme in
the 1990s as part of the ‘Plan Loire Grandeur Nature’ development plan, which has been supervised since 2000 by the ‘Groupement d’Intérêt
Public Loire Estuaire’ [GIP LE, 2006]. The aim of this
programme was to improve the knowledge about
the estuary system, to define an agreed set of objectives for improving the functioning of the estuary and to investigate restoration scenarios.
The ‘predictive modelling’ studies undertaken between 1995 and 2000 provided an initial assessment of the situation and examined proactive
intervention scenarios that led to the decision to
study a hydraulic solution involving the construction of a tidal barrier.
The ‘downstream predictive studies’ carried out
between 2000 and 2006 provided a large number
of field data and enabled a 3-D hydro-sedimentary model of the estuary to be built. They looked
in greater detail at the ‘tidal barrier’ scenario and
various alternative types of intervention in the
context of a comprehensive ‘morphological’ restoration scenario for the estuary. These were then
evaluated [GIP LE, 2007] and it was decided to
optimise the comprehensive scenario and launch
an initial experimental phase.
These two points were included in the 2007-2013
pre-operational programme to restore the estuarine section of the Loire downstream of Nantes
[GIP LE, 2008], which is currently nearing completion. This is a sustainable development project using the concept of ‘Working with Nature’ advocated by PIANC. It is based on objectives shared by
the main stakeholders in the estuary area defined
with a view to readjusting the balance between its
main functions: economic activities, environment,
urban development and amenities. It also involves
consultation with users and local players in drawing up projects. Finally, it takes into account the
effects of global warming.
138
This paper first recalls the main characteristics of
the estuary and then the objectives and overall
approach adopted in the studies. It then discusses
the 2007-2013 pre-operational programme and
ends with a presentation of the results obtained
from the two comprehensive scenarios studied in
greater detail, i.e. changes that will occur in the
estuary by 2040 if nothing is done, and the morphological restoration scenario.
2. MAIN CHARACTERISTICS
OF THE LOIRE ESTUARY
Running for 1,000 km, the Loire is the longest river
in France. It has a catchment area of 117,000 km2
and flows into the Atlantic Ocean at Saint-Nazaire. The tidal range at the river’s mouth reaches 5
m and tides run upstream as far as Ancenis, more
than 90 km above Saint-Nazaire. Nantes, the largest city on the river, is 55 km upstream. The river’s
discharge varies considerably from 100 m3/s during
low-flow periods to 6,000 m3/s during major floods
(the reference historic flood of 1910 reached 6,400
m3/s), with an average of 850 m3/s. The estuary is
also subject to high tides and severe storms. Water
quality in the estuary is considered to be relatively
poor, with saline intrusion running beyond Nantes,
70 km upstream of Saint-Nazaire, and a large maximum turbidity zone that can reach as much as 0.8
to 1 million tonnes of suspended mud.
The successive development projects implemented over the past 100 years or more have considerably modified the morphology of the estuary,
as can be seen from the situations in 1870 (Fig. 1),
1947 (Fig. 2) and 2002 (Fig. 3).
Fig. 1: Situation of the estuary in 1870
(distances in metres)
3. OBJECTIVES OF THE
COMPREHENSIVE STUDY
APPROACH
3.1. Objectives
(distances in metres)
The objectives originally defined in 1998 were reevaluated in 2005 and redefined in the context of
the Water Framework Directive (WFD) insofar as
this relates to the transitional water bodies formed
by estuaries. The WFD aims primarily to determine
the ecological condition of water bodies not simply on the basis of chemical criteria but by incorporating criteria linked to the living environment
and morphological condition of rivers. It aims to
achieve good ecological status by fixed dates
(2015, 2021, 2027, etc.), or at least good potential
for highly modified water bodies such as the Loire
estuary, determined by appropriate ‘good status’
indicators.
In the current state of discussion and work to define
such indicators for estuaries, the approach developed by the WFD emphasises the importance of
criteria such as fish resources, benthic resources,
the extent of mud flats in particular in mesohaline
areas, the size and position of maximum turbidity
zones and the extent of anoxic crises (cf. BEEST
programme).
Fig. 4: Historic changes in high and low water
levels in the estuary between 1903 and 2002
These projects began upstream and involved creating a single inland navigation channel between
Paimbœuf and Nantes dredged to -5 m CM (the
marine chart datum (CM) corresponds more or
less to the lowest water level at Saint-Nazaire)
and extracting large quantities of sand (90 million
m3) from the low-water bed of the river upstream
of Nantes between 1915 and 1993. In the 1980s
a deep-water port was built downstream on the
right bank between Saint-Nazaire and Paimbœuf
and an outer access channel was deepened to
-12.5 m CM as far as Paimbœuf (Fig. 3). All these
works transformed the original wide estuary with
its multiple channels into a narrow one with a
single channel. A double-channel system is still
visible, however, between Paimbœuf and the
ocean, though there is little exchange between
the branches, which behave independently. One
of the consequences of these works has been to
lower the low water levels in the estuary. At Nantes, 52 km from Saint-Nazaire, the drop between
1903 and 2002 was more than 4 m (see Fig. 4).
It should also be pointed out that the programme
of measures defined by the river basin committee
with a view to improving the status of the estuary water body is based on the restoration programme. It is thus possible to distinguish:
1.Objectives directly linked to the good ecological status of the water body, which are governed primarily by the size of the maximum turbidity zone and the distance it travels:
• Improvement in water quality for the needs of
drinking supplies, industry and agriculture.
• Maintenance/improvement of biological resources in the estuary through its function as
a nursery for flatfish and transition area for fish,
which is governed by oxygenation of the water, etc.
• Maintenance of fisheries and the resultant
farming activities.
2. Objectives relating to environmental maintenance or restoration:
•Improvement of nursery functions for flatfish
and as a stopping place for wintering birds;
these depend on the mud flats.
•Improvement of spawning functions further
upstream.
139
3.More general objectives connected with the
social and urban functions of the estuary, including improved relations between urban areas and the river, the visual appearance of the
river and the development of water and river
usage.
Finally, restoration was conditional upon a number of factors:
• changing port functions: development downstream, prospects for reducing draughts in
the Nantes channel;
• the need not to aggravate flooding, in particular in the Nantes urban area.
3.2. Investigation of Solutions
3.2.1. Hydraulic Regulation of the Estuary by a
Tidal Barrier
The solutions tested at the time with regard to the
estuary were consolidated into different scenarios.
The so-called ‘disconnection’ scenario appeared
to be the one that provided the best response to
the objectives defined, and in particular for raising low-water levels at Nantes by 3 m. This scenario was based on the construction of a gated
flow-regulation structure situated downstream of
Nantes at kilometre point 38, to reduce the oscillating volume of water that propagates upstream
as far as the city. The principle of this structure was
to create a reservoir at low tide, which would then
disappear at high tide and during floods. The fact
that it reduced the oscillating volume of water
would have a favourable impact on the retreat of
the saline wedge and turbidity.
The principles for operating the structure, the preferred location at the Martinière site and very general geometrical aspects were defined in predictive modelling studies between 1995 and 2000. In
2000, at the end of this process, the stakeholders
adopted the principle of taking this scenario fur-
ther by examining its feasibility and impacts, and
also expressed their desire to seek an ‘alternative’
scenario owing to its high cost and non-progressive character.
3.2.2. Progressive Restoration: the Morphological Scenario
Various consultants (Delft Hydraulics, HR Wallingford, expert committee, etc.) were involved in the
exploratory phase between 2004 and 2005. This revealed that it was possible to develop an alternative to the tidal barrier scenario, focused more on
modifying the sedimentary dynamics of the estuary by combining measures to adapt its geometry
and the progressive restoration of environments
with important biological functions. This change in
the approach to restoration was initiated by Delft
Hydraulics and the European expert committee
mobilised at the time by the GIP Loire Estuaire. It
was based on consideration of the asymmetric
nature of tidal propagation in the estuary and on
improved knowledge of its functioning.
This type of approach represented a real alternative to the tidal barrier scenario and in this respect
it provided encouraging results. Even so, it did not
fulfil all the objectives, in particular with regard to
raising the low-water level by 3 m at Nantes. The
studies carried out in 2005 and 2006 aimed to give
concrete expression to this type of intervention by
identifying realistic solutions.
Two solutions were proposed (see Fig. 5 below):
• The creation of intertidal mud flats, located upstream of Paimbœuf. These would ‘store’ flood
tides penetrating into the estuary. The other advantage of this type of operation is ecological:
environments that had receded considerably
during the past century would be recreated.
• Raising the bed in the Nantes channel, which is
now deeper than necessary for shipping.
Fig. 5: The two solutions that now constitute the morphological restoration scenario for the estuary
140
3.3. Use of a 3-D-Model for the Hydro-Sedimentary Evaluation
Since the studies began in 1995, numerical modelling has been an important means of analysing
field data, understanding the physical processes
occurring in the estuary and exploring the various
solutions proposed during the successive studies.
An important step forward was taken in 2006 with
the setting up of a first version of a comprehensive three-dimensional hydro-sedimentary model
capable of reproducing the major vertical stratification that influences the current fields, salinity
and turbidity in the estuary, along with the deposition, erosion and consolidation processes affecting mud at the bottom of the river, which can be
several metres thick. This model was calibrated using a considerable amount of data obtained from
field surveys conducted by the GIP LE between
2000 and 2004. It showed in particular that the
morphological changes observed in the sandy
bed of the river could not by themselves explain
the 3.5 m drop in low-water levels at Nantes. There
would also have to be a major reduction in bed
friction resulting from a layer of fluid mud several
tens of centimetres thick. Consequently, any simulation of the various solutions would have to combine calculations of both the water surface curves
and the dynamics of the mud layer [Walther et al.,
2007 ; Walther et Hamm, 2008].
This first version of the model provided an initial vision of the estuary’s functioning in the current situation, based on a trend scenario involving no outside intervention. It was then used to explore the
impact of different solutions and thereby define a
morphological restoration scenario.
A second version of the model was then developed in 2008-2009. This included the following improvements: integration of areas subject to submersion by tides between Nantes and the sea,
refinement of the strategy for defining the vertical
grid, improvement of friction maps, taking into
account the presence or absence of fluid mud
on the estuary bed, improvement of the vertical
turbulence model to represent saline and turbid
stratification more accurately and improvement
of parameter definition for all the mud erosion,
deposition and consolidation laws. Two important
new results were obtained with this model:
• On the one hand, by developing and validating new parameters for the vertical turbulence
model, it was possible to reproduce more precisely the saline intrusion episodes observed
particularly at low water during neap tides, as
measured by the permanent SYVEL continuous monitoring network operated by the GIP LE
since 2007 [Walther et al., 2009];
• On the other hand, by improving the empirical
model of deposit consolidation and erodibility
and defining parameters for mud floc fall velocity by including the local turbulence produced
by flow depending on shear stress, it was possible to reproduce the dynamics of the maximum
turbidity zone/fluid mud system over a period of
a year more accurately [Walther et al., 2012].
Fig. 6 shows a comparison between in situ monitoring of the position of the fluid mud in the inland channel and the numerical simulation for
the year 2007 covering the entire estuary.
4. THE 2007-2013 PREOPERATIONAL PROGRAMME
4.1. Overview
The study approach introduced by the GIP LE for
this pre-operational programme includes various
components aimed at answering the many questions of operational feasibility not addressed by
conventional engineering practice:
Fig. 6: Left: measurement of the position of fluid mud depending on discharge in the Loire.
Right: result obtained by numerical modelling
141
• Evaluation of the effectiveness of different solutions with regard to estuarine systems involving
complex processes that depend in addition on
climate change.
• The permanence of the works and the resultant
changes in morphological balances.
• The ecological effects of such operations.
• The different uses of the sites (agriculture, hunting, hydraulic management, ecological functions, etc.).
• Its feasibility from the technical and legal standpoints, but also in terms of the operational backing of a project of general interest.
The study approach included two types of analysis
in order to address these questions:
• Re-evaluation and refinement of the comprehensive morphological scenario defined in 2006
and of the trend scenario without any intervention up to the year 2040, based on knowledge
gained since 2006 and in particular on improved
hydro-sedimentary modelling tools and better
knowledge of hydro-climatic changes, in order
to confirm or rule out the need to act and the
relevance of the solutions, and also to examine
questions of long-term feasibility.
• Examination of the feasibility of the proposed solutions. With regard to the mud flats, the procedure was taken to an advanced level of definition in order to measure and identify all aspects
of the operation’s feasibility.
The study strategy pursued since 2008 is based on
the various components described below.
4.2. Definition of Baseline Situations and
Acquisition of Data Required for the Project
Investment in this area aimed to improve knowledge in various fields: the physical operation of the
mud flats, by monitoring their sedimentary dynamics; characterisation of ecological functions associated with the mud flats (birds, benthos, fish, etc.)
via data acquisition and processing; knowledge
of the physical operation of the estuary (sediment
inflows, sediment behaviour, etc.). The aim was to
obtain reference information in order to guide the
design of the works, enable them to be evaluated
and refine the tools used. It was also necessary to
obtain information on the study area governing
the feasibility of an experimental mud flat. This involved detailed characterisation of habitats liable
to be affected and an analysis of materials likely
to be disturbed during the works.
4.3. Development and Application of
Evaluation Tools
As part of this programme, in 2008 and 2009 the
GIP LE reused the hydro-sedimentary model developed in the framework of the previous pro142
gramme, as it was necessary to have a sufficiently
reliable study and evaluation tool that would reduce the uncertainties surrounding these fields
and could be used predictively.
Similarly, the model of the Loire estuary’s ecological functions developed by the GIP LE was used
for the ecological assessment. This GIS-based
mapping system helps to evaluate the impact
of development works on the estuary’s ecological functions by monitoring various representative species. It was used to assess the ecological
effects of the experimental intervention work by
comparing gains and losses in the estuary’s ecological functions.
4.4. Updating and Optimisation of
Comprehensive Scenarios
To provide assistance in decision making, the
study programme included an evaluation of the
trend scenario, representing the absence of any
major restoration work and the likely morphological and hydro-climatic changes that will occur by
2040, and of the comprehensive morphological
scenario defined in 2006. This was updated and reevaluated during the study phase in light of progress in the feasibility studies for the experimental
operation and optimised by defining the various
solutions more clearly.
4.5. Design of the Experimental Mud Flat
and Consultation
A specific aim was to make progress with the feasibility study for the experimental mud flat. This
involved adopting a similar approach to that
proposed by PIANC in its ‘Working with Nature’ research programme [PIANC, 2008]. It included the
following four stages:
i) Defining project requirements and objectives.
This stage was carried out in the context of the
‘downstream predictive studies’.
ii) Understanding the environment. This stage involved numerous series of measurements in the
field, hydro-sedimentary modelling and use of
a model of the estuary’s ecological functions.
For the experimental operation, this meant initially determining a preferred site on the right
bank between Donges and Cordemais and
performing an exhaustive analysis.
iii) Constructively involving all stakeholders in order to identify ‘win-win’ situations. A working
group of players and users was set up by the
GIP LE for this purpose, comprising representatives of government agencies, the Nantes
– Saint-Nazaire port authority, the Coastline
Conservation Authority (‘Conservatoire du
Littoral’), environmental protection associations, farmers, hunters and marshland users’
federations. This group met five times to define
specifications for the operation, allowing for
the various usages found in the area, and then
to evaluate the proposals put forward by the
consultants in charge of designing the experimental mud flat. Contributions to this process
included the design studies for the mud flat
and specific work to assess its implications for
the farming profession.
iv) Preparing proposals/initial designs for the project to meet navigational and environmental
requirements. The comprehensive solutions defined in 2006 in fact took navigational requirements into account as a project constraint.
Two alternative schemes covering a hundred
hectares were defined for the experimental
operation, taking into account the specifics of
the site, constraints connected with usage and
the objectives defined.
The permanence of the works was studied in
depth. In particular, it appeared necessary to ensure dynamic exchanges of water between the
mud flats and the meadows situated behind them
in order to encourage flow on to the mud flats, a
necessary condition for maintaining them. Studies
performed on the two sites also showed that it was
possible to design a scheme in which both the mud
flat and the channels created to connect it with
the meadows behind had every chance of lasting
provided such exchanges were guaranteed.
The experimental works indeed indicated that the
mud flats would contribute to the restoration of
the estuary, but they did not cover a large enough
area to produce a sufficient effect on hydro-sedimentary processes in the estuary. The overall effect of the project on the ecological functions of
the estuary was positive, but it also had significant
impacts on existing ecosystems that would prob-
ably require mitigating measures (see details in
Bona et al., 2012). The process also helped to define the technical and legal feasibility of such a
scheme.
5. UPDATING AND FINETUNING OF THE
COMPREHENSIVE SCENARIOS
5.1. The Trend Scenario without any
Intervention
This scenario includes an estimation of the morphological changes occurring in the estuary by
the year 2040 in the absence of any new development, coupled with a climate change scenario
in which the average sea level would rise by 0.2 m
and the low flow and mean discharge of the Loire
would fall.
The trend scenario for the estuary gives an important insight into the stakes involved in this programme. Roughly, it leads to a rise in sea level,
upstream incursion of salinity and of the maximum
turbidity zone, as well as the prospect of a reduction in the surface area of the mud flats.
All of this would:
• harm water quality and affect offtake and dependent biological functions;
• modify flood risks: these would be aggravated in
the downstream part of the estuary, with floods
rising to near historic levels or reference levels
considered up to now for town planning in the
Nantes urban area;
Fig. 7: The two sites studied
143
• weaken the trophic functions of the estuary, by
reducing the surface areas of the mud flats;
• increase submersion risks for meadows on islands
in the Loire; such changes pose the question of
how far the current farming system is able to
adapt.
scenario represents long-term investment of € 128
million. The benefits to be obtained from a larger
area of mud flats would be limited, whereas actions
to raise the bed elevation (morphological scenario)
would reinforce the effects of the mud flats.
5.2. The Comprehensive Morphological
Scenario
The principles identified in 2006 were translated into
a comprehensive scenario including the creation
of 515 ha of mud flats and raising of the bottom of
the Nantes channel to an average elevation of
-5 m CM. The comprehensive scenario, identified
in 2006 and re-evaluated in 2010, provides an effective answer to the various objectives defined. It
counteracts the effects of the trend scenario and
improves the present situation. The development
works considered have a significant positive effect on the status of the water body (namely by
causing the maximum turbidity zone and salinity
to retreat further downstream and raising the lowwater level) while restoring the areas of major importance for the estuary’s ecology.
The questions raised by the downstream programme
and in particular the amount of funding needed in
the medium term (€ 190 million) led the GIP Loire
Estuaire to examine the effectiveness of the comprehensive development scenario in greater detail
and especially to define the minimum investment
needed to fulfil the objectives initially considered,
or at least some of them. A detailed analysis of the
various solutions revealed that:
• actions consisting of raising the bed upstream
of Nantes have little influence on the estuary
downstream of Nantes;
• actions limited to raising the bed of the Nantes
channel would require a certain ‘artificialisation’ of the estuary in order to be morphologically stable (building of structures, addition of
very coarse materials). To be effective they
would be expensive (costing € 60 million-€ 300
million) and therefore appear to be unsuitable
(in terms of cost, technical feasibility and statutory compliance);
• the creation of mud flats is the main lever for
acting on the estuary’s hydro-sedimentary system. Different extents of mud flats were evaluated with respect to indicators connected with
the objectives sought (availability of water resources with less than 1g/l of salt; incursion of
the maximum turbidity zone into the Nantes
channel).
An area of 250 ha of mud flats would have little effect in relation to the trend situation whereas an
area of 340 ha would produce convincing results:
smaller maximum turbidity zone in the Nantes channel, salinity slightly reduced in comparison with the
trend situation, gain in mud flats. This ‘optimised’
144
Fig. 8: Change in main indicators in relation
to the present situation
The different tests performed give a clearer idea
of the minimum intervention threshold (340 ha)
needed to obtain a tangible effect in response to
all the objectives of the programme and in particular those connected with the status of the estuary
water body.
6. THE RESULTS OF TWENTY
YEARS OF STUDIES
The Loire estuary is certainly one of the most studied in Europe thanks to a succession of scientific
programmes and studies that have been carried
out. Initially (1993 and 1994) these produced a
precise assessment of the degradation suffered
by the estuary over the past century as a result of
work to improve its navigability.
‘Predictive modelling’ was carried out from 1995
to 2000 and ‘downstream predictive studies’ were
implemented from 2000 to 2006 with a view to defining a restoration programme. Two approaches
were considered: a conventional approach involving the building of a structure and a ‘morphological’ approach working on the geometry
of the estuary. The latter, which produces results
much more slowly but was considered to be curative and resulting in a satisfactory state of equilibrium, was finally preferred to the former, which was
viewed as palliative and resulting in ‘artificialisation’ of the estuary.
A detailed and precise understanding of the
physical, biological and social environment of
the estuary proved to be essential for this second
approach. This led the stakeholders involved in
the estuary to create the GIP Loire Estuaire, the
main role of which was to define and manage a
set of indicators representative of characteristic
phenomena in the fields of hydraulics, sedimento-
logy, water quality, natural heritage and land use,
and to use the original results obtained from the indicators or specific studies in communicating with
an informed, aware public concerning the state
of the river and its estuary. Major measurement
campaigns have been implemented since in the
field since 2000 and a permanent network of six
multi-parameter sensors (SYVEL) was set up in 2007
to provide continuous monitoring of water quality
in the estuary. These data represent a capital of
knowledge that is essential for understanding the
functioning of the estuary.
The GIP LE was then assigned new tasks, one of
which was to perform predictive studies downstream of Nantes in order to find and then implement a sustainable scenario for restoring the estuary. This stage of investigating, finalising, optimising
and then evaluating different scenarios was based
to a great extent on a comprehensive 3-D hydrosedimentary numerical model of the estuary capable of accurately reproducing the physical processes that govern the dynamics of water movement,
salinity and turbidity, but also of evaluating different development solutions. The challenges posed
by the estuary meant that various innovations were
needed in order to finalise the model and the results
finally obtained were validated by a committee of
European experts, thus underscoring the quality of
the work carried out. The model provided a clearer
understanding of the current functioning of the estuary and helped in evaluating the impact of different types of intervention.
The pre-operational programme initiated in 2007
has taken the issue a stage further. The approach
now being considered is a similar one to that recommended by PIANC in its document on ‘Working
with Nature’, where it takes a clear stand on this
matter. This considers project objectives primarily
from the point of view of the natural system rather
than from that of technical design and lays emphasis on prior consultation with all the stakeholders involved.
At the present time, the comprehensive restoration
scenario adopted is an ambitious one, as it aims
to re-establish more balanced hydro-sedimentary
dynamics throughout the estuary. Extensive – and
very expensive – work is to be carried out, involving the re-creation of around 340 ha of intertidal
mud flats. It is for this reason that a first experimental
stage has been studied and is still being discussed
at the present time. The feasibility study has already
shown the ecological advantages of such an operation while at the same time underlining its technical, ecological, legal and social complexity.
7. REFERENCES
Bona, P., Prud’homme Lacroix, B., Walther, R., Rivier,
A., Rieu, J., David, E. and Hamm, L. (2010): “Amé-
lioration du fonctionnement hydrosédimentaire de
l’estuaire de la Loire: leviers d’intervention et modélisation hydrosédimentaire tridimensionnelle”, La
Houille Blanche, n°6, 25-32.
Bona, P., Prud’homme Lacroix, B., Ledoux, S., Thiébot, L., Walther, R. and Hamm, L. (2012): “Développement de leviers d’intervention pour la restauration
de l’estuaire de la Loire: Avancées et perspectives”,
Comptes-rendus du colloque Grands Aménagements Hydrauliques, Paris, 14-16 November 2012,
CD-ROM published by the Société Hydrotechnique
de France.
GIP Loire Estuaire (2006): “Etudes Prospectives
aval, Tome 1: les objectifs, un nouvel équilibre pour
l’estuaire de la Loire”, Loire Grandeur Nature Pays
de Loire inter-regional programme, 2000-2006.
GIP Loire Estuaire (2007): “Etudes Prospectives aval,
Tome 2: les scénarios, Une démarche progressive
pour l’estuaire de la Loire”, Loire Grandeur Nature
Pays de Loire inter-regional programme, 2000-2006.
GIP Loire Estuaire (2008): “Etudes Prospectives aval,
Tome 3: les orientations, Un programme opérationnel
pour l’estuaire de la Loire”, Loire Grandeur Nature
inter-regional programme.
Hamm, L. and Walther, R. (2008): “Morphodynamic
coupling of bottom roughness and fluid mud for
modelling tidal propagation in the Loire estuary
(France)”, Proc. 31st International Conference on
Coastal Engineering (ICCE 2008), Hamburg, World
Scientific, Vol. 3, 2832-2841.
PIANC (2008): “Œuvrer avec la nature/Working with
Nature”, Position paper de la commission EnviCom,
October 2008, revised January 2011, Available from
http://www.pianc.org/edits/wwnpositionpaper.htm
Accessed 31 January 2013.
Walther, R., Bertrand, O., Rieu, J. and Hamm, L. (2007):
“Modélisation tridimensionnelle de la salinité et de la
turbidité dans l’estuaire de la Loire: couplage des
processus”, La Houille Blanche, n°4, 47-55.
Walther, R., Rivier, A., Rieu, J., David, E. and Hamm,
L. (2009): “Modélisation tridimensionnelle hydro-sédimentaire de l’estuaire de la Loire – Evaluation de
modèles de turbulence verticale”, Comptes-rendus
des journées de l’Hydraulique – congrès annuel de
la Société Hydrotechnique de France “Morphodynamique et gestion des sédiments dans les estuaires,
les baies et les deltas”, Paris, September 2009 (available on CD-ROM from the SHF).
Walther, R., Schaguene, J., Hamm, L. and David,
E. (2012): “Coupled 3D modelling of turbidity maximum dynamics in the Loire Estuary, France”, Proc.
33rd International Conference on Coastal Engineering (ICCE 2012), Santander, 1-6 July 2012, Coastal Engineering Proceedings, 1(33), sediment.22.
doi:10.9753/icce.v33.sediment.22.
145
SUMMARY
Like most of the major European estuaries, that of
the Loire underwent extensive development in the
20th century with a view to improving its navigability. The work carried out in the context of such development seriously disturbed the hydro-sedimentary processes of the estuary, leading in particular
to a deterioration in water quality in terms of salinity and suspended sediment and considerably reducing the areas occupied by intertidal mud flats,
which are an important habitat in the ecosystem.
This realisation led stakeholders to undertake an
ambitious programme of studies and river monitoring work in the 1990s, the principal stages of which
are recalled here. The main results have been the
introduction of an estuary indicator observation
network, the development of a comprehensive
‘morphological’ restoration scenario for the estuary whereby the mechanisms that trap sediment
in the inner estuary are reduced while at the same
time restoring the estuary’s major ecological functions, and the development of a pre-operational
approach whereby work can be implemented in
a progressive, concerted manner on the basis of
an experimental programme currently being discussed.
RESUME
Comme la plupart des grands estuaires européens, celui de la Loire a connu sur le dernier siècle des aménagements majeurs visant à améliorer
sa navigabilité. Les travaux réalisés ont fortement
perturbé le fonctionnement hydrosédimentaire
de l’estuaire et conduit à dégrader notamment
la qualité des eaux en termes de salinité et de
matières en suspension et à réduire fortement la
surface occupée par les vasières intertidales qui
constituent un maillon important de l’écosystème.
Ce constat a conduit les acteurs estuariens à
engager dans les années 1990 un programme
d’études et de suivi ambitieux du fleuve dont nous
retraçons ici les principales étapes. Les principaux
résultats acquis sont la mise en place d’un réseau
d’observation d’indicateurs estuariens, la mise au
point d’un scénario global de restauration ’morphologique‘ de l’estuaire permettant de diminuer
les mécanismes de piégeage de sédiments dans
l’estuaire interne tout en restaurant des fonctions
écologiques majeures de l’estuaire ainsi que le
développement d’une approche pré-opérationnelle permettant une réalisation progressive et
concertée à partir d’un programme expérimental
en cours de discussion.
ZUSAMMENFASSUNG
Wie die meisten großen europäischen Ästuare hat
auch das der Loire im 20. Jahrhundert im Hinblick
auf die Verbesserung der Schiffbarkeit eine weitreichende Entwicklung durchgemacht. Die Arbeiten,
die im Zusammenhang mit einer solchen Entwicklung durchgeführt wurden, haben die Hydro-Sedimentationsprozesse im Ästuar erheblich gestört,
was insbesondere hinsichtlich des Salzgehalts und
der gelösten Sedimente zu einer Verschlechterung
der Wasserqualität geführt hat und zu einer erheblichen Reduzierung der Wattbereiche, die einen
bedeutenden Lebensraum innerhalb des Ökosystems darstellen. Die Durchführung dieser Arbeiten veranlasste Interessengruppen in den 1990er
Jahren dazu, ehrgeizige Studienprogramme und
146
Monitoring am Fluss durchzuführen, deren Hauptetappen hier wiedergegeben werden. Die wesentliche Ergebnisse führten zu der Einführung
eines Ästuar-Indikator-Beobachtungs-Netzwerks,
der Entwicklung eines umfassenden ‘morphologischen‘ Wiederherstellungszenarios für das Ästuar, in
dem jene Mechanismen reduziert wurden, welche
das Sediment im Inneren des Ästuars binden,
während zur gleichen Zeit die wesentlichen ökologischen Funktionen des Ästuars wiederhergestellt
und ein funktionsfähiger Ansatz entwickelt wurde,
wodurch die Arbeiten in einer fortschreitenden,
aufeinander abgestimmten Weise auf der Basis
experimenteller Programme, die kürzlich diskutiert
wurden, durchgeführt werden können.
ThE SEINE-NORD EUROPE CANAL –
ACCOUNTING fOR MULTI-PURPOSE APPLICATIONS
Of ThE wATERwAY IN ThE PARTNERShIP CONTRACT
CANAL SEINE-NORD EUROPE –
PRISE EN COMPTE DE LA MULTI-fONCTIONNALITé DE
LA VOIE D’EAU DANS LE CONTRAT DE PARTENARIAT
BENOÎT DELEU
Deputy Director Direction of European waterways
and Innovation, VNF
175, rue Ludovic Boutleux 6
2400 Béthune
France
Tel.: +33 3 21 68 83 62
KEY WORDS: wide-gauge canal, regional devel-
have not traditionally had relations with waterways. As the find economically viable solutions in
waterway transport, they will opt for modal shift.
MOTS-CLES: canal à grand gabarit, développement régional, environnement, partenariat publicprivé, critères de performance
2. THE STAKES FOR
ECONOMIC AND INDUSTRIAL
DEVELOPMENT OF THE CANAL
opment, environment, public-private partnership,
performance criteria
1. INTRODUCTION
Major transport infrastructure projects such as the
Seine-Nord Europe Canal primarily fulfil an economic role. Such projects must enable the overall transport system to improve its competitiveness
and enhance efficiency of logistics chains in the
European economy. In the case of the SeineNord Europe Canal, this means linking the North of
France to the 20,000 km of waterways in the European wide-gauge network.
The improvement to the transport network will
have a positive impact on the competitiveness
of the areas the canal passes through. Its proximity to one of the major commercial axes should
strengthen the competitiveness of import and export activities by regional businesses and attract
new industrial activities as it is these that stand to
gain the most from waterway transport. This will
thus contribute to the re-industrialisation of the regions that have in some cases been abandoned
by this type of activity. In addition, the installation
of four new multi-modal platforms connected to
the road and rail networks will draw activities that
The European Seine-Scheldt river link project represents a new system for the transport of goods
between France, Belgium, The Netherlands and
Germany, situated at the heart of a wide-gauge
waterway network that serves the major economic centres of northern Europe. This area is characterised by intense cross-border flows of goods
and by one of the highest levels of saturation of
road transport on the north-south axis. The SeineScheldt link includes several sections in France and
Belgium, which, once the wide-gauge Seine-Nord
Europe Canal is in operation, will join together to
create a single major wide-gauge river link.
Although development work has been underway
since 2000 on the North and South parts of the
link, in both France and Belgium, the Seine-Nord
Europe wide-gauge canal to be built between
Compiègne and Aubencheul-au-Bac is the central link of the Seine-Scheldt connection, which
was selected as one of the thirty priority projects
for the Trans-European Transport Network (RTE-T) in
2004.
147
Fig. 1: The Seine-Nord Europe Canal – central link of the Seine-Scheldt connection
Seine-Nord Europe means the creation of a new
106 km canal through two French regions: Picardie
and Nord-Pas-de-Calais, whose technical characteristics match the European waterway classification for navigable waterways of international
concern known as ‘class Vb’.
It is made up of the following features:
- eight reaches connected by seven locks with
a drop height of between 6.4 and 30 metres,
equipped with water-saving basins;
- two reservoir basins for water supply during lowflow periods;
- three aqueducts including one 1,330 metres
long enabling crossing of the Somme;
- four multi-modal platforms and seven quays to
serve as cross-over points with other modes of
transport (road and rail);
- five reception facilities for community and individual pleasure boating.
The Seine-Nord Europe project is part of a broader
148
approach towards both development and competitiveness for the region, reducing the environmental impact of transport and enhancing the
multi-purpose functions of waterways. The project
meets several public policy objectives:
- eliminating the major bottleneck on the European wide-gauge waterway network;
- improving the competitiveness of businesses
by making the advantages of water transport
available to them;
- strengthening the integration of the Great Parisian Basin and Nord-Pas-de-Calais into the core
of the European economy and contributing to
regional development;
- supporting the development of French maritime
ports by developing their hinterland;
- developing the accessibility of goods at the
heart of major agglomerations;
- rooting sustainable development stakes in transport policies;
- enhancing the hydrological and tourism advantages offered by waterways.
3. REGIONAL PLANNING
AND DEVELOPMENT
PERSPECTIVES FOR THE
PROJECT
One of the main features of the economic influence of the project for the regions it crosses lies in
the creation of activity zones to be supported by
the future canal: multi-modal port zones, loading
docks and agricultural storage and shipping platforms. These are to be spread across four largescale port activity zones intended for industrial
and logistics usage. Cambrai-Marquion, Péronne
Haute Picardie, Nesle and Noyonnais.
• Waterway tourism: All of the tourist activities
brought about by the opening of the canal
could generate a total turnover of € 46.5 million
in 2020. The associated added value is estimated at 15 % of the turnover according to predictions, being € 7 million.
• Supply of raw water: The agglomeration of Lille
is currently supplied by the Chalk aquifer (50 million m3), the Carboniferous aquifer (20 million m3)
and rivers water (15 million m3). These resources
may prove insufficient in about ten years’ time,
especially during dry years. Studies carried out
during the preliminary project phase confirmed
the possibility of transferring 1 to 2 m3/s from the
Oise basin to the North of France with a view to
strengthen the prospects for the supply of drinking water to the North of France.
• Production of renewable energy: Recovery
of the land running alongside the canal offers
potential for the production of wind and photovoltaic energy or from biomass.
4. ENVIRONMENTAL
INTEGRATION FOR THE
PROJECT
4.1. A Project that Respects Water
Resources
Preserving Resources
Fig. 2: The four platforms of Seine-Nord Europe
These four platforms benefit:
o Enlargement of the hinterland of French maritime ports
o New provisions for massified logistics, that will be
able to take advantage of the inter-modality
to be set up between maritime, waterway, rail
and road transport
o The competitiveness of businesses in the French
regions of Picardie, Nord-Pas-de-Calais and the
greater Parisian basin
The construction of the Seine-Nord Europe Canal
also enables the development of other activities,
of which the most significant relate to water tourism (river cruises and private boating), the supply
of raw water to agglomerations in the North of
France and the production of renewable energy.
The hydraulic design of the canal has been set as
a high performance objective, with the aim of saving water as a key priority. To this end, the canal
will be fitted with a sealing system, whose average
permeability should not exceed the equivalent of
a 30 cm layer with a permeability coefficient of 10
-8 m/s. The locks themselves will be equipped with
water-saving basins and water recycling systems.
All of these measures will allow the 106 km-long canal to consume a maximum of just 1.2 m3 water/s,
including evaporation and safety margins.
The second essential point regarding hydraulic
design aims to develop a supply scheme that
is respectful of natural surroundings and other
uses. The Oise has been selected as the only supply source because of the good quality and hydraulics of the water. The canal will be supplied
through continuous drawing from the Oise, resource permitting, which is to say once the flow of
the Oise stays above a threshold flow that takes
into account the needs of the surrounding area
and uses. In the event of low-flow on the Oise, water storage in two reservoir basins guarantees the
supply to the canal. The water intake has been
positioned as far downstream as possible on the
water course, nearest to the confluence with the
Aisne, in order to keep the impact on the natural
stretch of the Oise and the Natura 2000 area to a
minimum, protecting the valley.
149
Fig. 3: Diagram showing the water supply for the Seine-Nord Europe Canal
As a new water body, the Seine-Nord Europe Canal has a duty to achieve its ecological potential.
The Oise was also chosen as the source of the
water supply for this reason, thus guaranteeing a
good quality supply. In order to preserve the quality of the resource for the length of the canal, water
renewal is considered from the reservoir basins.
4.2. A Project for a Living Canal,
Integrated into the Green and Blue Belts
A Project Designed to Limit the Impact on Biodiversity
The Seine-Nord Europe Canal project has been
designed in accordance with the ‘Avoid, Reduce,
Compensate’-approach which must currently
guide all development projects. This approach
is based on the principle of integrating environ-
mental issues into the design data for the project,
on the same level as other technical or financial
items. Primarily, this means designing the project
is such a way as to avoid environmental impact
as far as possible, including for the choice of the
most fundamental decisions regarding the project
(nature of the project, location, etc.). With this in
mind, the design plans for the Seine-Nord Europe
Canal have made it possible, to draw up a route
with minimal impact, avoiding sites of interest and
sensitive natural habitats as far as possible (for example, in the river Sensée sector).
Where passing through sensitive areas has been
unavoidable, integration measures have been put
in place to limit the impact of the project. In this
way, a 1,330 m long aqueduct will cross the valley
of the river Somme, respecting the continuity of
the ecological corridor made up by the river.
Fig. 4: Photomontage of the river Somme aqueduct (©VNF-Archivideo)
150
Finally, the compensatory measures are defined
according to the residual impact. The equivalence between the loss and compensation will be
not only quantitative (surface), but also calculated in terms of quality (biodiversity) and ecological
functions.
A range of compensatory measures has thus been
planned to off-set the impact of the various types
of environment and habitats affected. In addition
to ‘heavy’ ecological development in some sectors for the re-construction, rehabilitation or restoration of functional environments, preservation
action for existing areas as well as lighter developments, such as planting hedges, creating ponds,
building roost boxes, nest boxes or shelters for chiroptera or birds.
By way of example, the area of forest that would
have to be cleared to make way for the construction of the project is estimated at around 70 ha.
Reforestation will be carried out at a ratio of 4:1,
making around 280 ha, including 1/1 for ecological objectives and 3/1 for forestry objectives. Regarding wetlands, the off-set area should be at
least 1.5 times the affected area, making more
than 135 ha for the 90 ha affected.
4.3. A Project for a ‘Living Canal’ in order
to Achieve the WFD Objectives
In order to meet the requirements for good ecological potential set by the Water Framework Directive (WFD), specific ecological installations
such as 25 km of lagooned embankments and
hydrological extensions are planned. They will enable the development of different species of flora
and fauna, fulfilling the role of the ‘green lung’ of
the canal.
This innovative design of the embankments and
extensions will allow the canal to develop live
characteristics. Given the good design and good
management, these areas could offer a very diverse environment for flora and become a sanctuary or a zone for breeding and nurturing young
for a large number of animal species, particularly
aquatic species. The methods for maintaining and
managing these new spaces will then become the
key to their ecological efficiency and durability.
4.4. A Human Project Integrated into its
Surroundings
Use, Landscape and Heritage
The Seine-Nord Europe Canal will represent a new
axis that cuts across and joins together the territories it passes through. The change in usage and
trade in the region has therefore been integrated
as a key challenge in the construction of the canal.
As regards integration into the landscape, respect
for the identity of territories has been set as a priority. This work, together with the architectural handling of the structures, to which it is closely linked,
has been entrusted to designers recognised by
their peers. Designing the identity of the project
and the shape of the landscape development
policy will be coherent with the ecological stakes
mentioned above.
Finally, preservation of the cultural heritage has
been integrated into the consideration of the environmental challenges. In this way, the diagnostic studies and archaeological digs have already
been carried out along the proposed path in order to identify remains.
In the impact study presented in 2007, VNF made
a commitment to setting up an environmental
observatory in order to monitor the effect of the
project on the main environmental features. In the
report, the public inquiry supported this commitment and insisted on the idea that the observatory should be “set up as early as possible in order to
carry out an inventory before beginning work and
to be able to then monitor the progress of the work
and their impact on the natural surroundings”.
This observatory was established in 2009. It is made
up of independent experts, whose expertise covers the main effects of the project on the environment, representatives of State services in charge
of water, ecology and town and country planning
policies.
Its goal is to guarantee the integration of the project within the surrounding area in the long-term
and verify the implementation and efficiency of
the compensatory measures proposed, to ensure
transparency between all of the stakeholders. The
works are structured around three committees
who are responsible for issues relating to water resources, biodiversity and landscape respectively.
5. THE PARTNERSHIP
CONTRACT AND THE
PERFORMANCE CONTROL
Opting for a partnership contract enables optimisation of the cost of the project and a reduction
to the construction time. These contracts meet the
demands of a commitment in terms of duration
and quality of the service provided to users and
the upkeep of infrastructure. In addition, putting
together groups of private partners makes it possible to pool highly specialised expertise in a range
of areas that are specifically adapted to the various functions of the project, on a European level,
both in terms of construction and in terms of the
whole range of services made available to the
market and the region by the time the canal is
151
opened, thanks to the multi-purpose functions of
the waterway.
This tool also enables overall management of complex projects, by integrating infrastructure as well as
the additional activities related to it into the same
contract. The project benefits from the development of associated economic activities put forward by the private partner through the ‘competitive dialogue’ procedure.
The competitive dialogue gives private partners
and the public entity the opportunity to gradually
optimise the project, in order to come to the best
suitable solution for the project in controlled risk
conditions. This discussions and exchanges pave
the way for the implementation of new and innovative solutions.
The Seine-Nord Europe partnership contract is built
on performance objectives that measure the quality of service offered to users, the quality of the upkeep of the infrastructure and, last but not least, the
control of the environmental impact.
The performance objectives linked to transport aim
to guarantee transport time for vessels traveling
along the link. These objectives are based on an
average transit time and on requirements regarding availability of the structures.
Traffic simulations carried out on a flow model developed by the Centre d’Etudes Techniques Maritimes
et Fluviales (French Institute for Inland and Maritime
Waterways) have shown that he average journey
for a wide-gauge fleet was 17 hours and that 90
% of the fleet covered the length of the canal in
less than 21 hours. This data is solid, fitting with the
volume of traffic except where the locks approach
saturation point. These values have therefore been
maintained in order to characterise the canal operating performance. The partner must abide by the
performance up to the saturation threshold they
present in their bid. When the saturation threshold is
reached, VNF and the partner agree to define new
performance objectives in light of the situation or
to double the number of locks.
The reliability and availability objectives aim to
guarantee that the infrastructure remains open to
navigation. A distinction is made between closure
of the canal for offline periods on the one hand
and unforeseen interruptions due to problems with
operating the structures on the other. The reliability and availability objectives have been set based
on the past experience of wide-gauge waterway
managers on a European level.
For offline periods, the objectives distinguish between annual offline periods for carrying out preventive maintenance operations and night-time
interruptions enabling more frequent and shorter
operations. The periods reserved for annual offline
periods are shorter in the initial years of the structure
following the installation adjustment period. This has
Table 1: Performance criteria for availability of the link
152
been set at eight days per year, based on experience from the Rhone, while retaining the possibility
of carrying over a certain proportion of the allocated time from one year to the next.
A summary of these availability objectives is shown
in the table on the previous page.
Reliability objectives emerge from the statistics on
wide-gauge structures in Belgium and Germany.
The main objective involves limiting interruption to
the flow of traffic along the canal to less than 100
hours per year, which would mean 99 % reliability
across the whole link. The number of stoppages
is also limited in order to limit disruption for users
and to encourage the partner to return to using
of the waterway, even in downgraded mode. A
distinction is drawn according to the duration of
stoppages. The number of stoppages of between
3 and 8 hours is limited to 7. At the most, a stoppage of 8 hours is permitted provided that it does
not go beyond 3 days.
The performance objectives cover the condition
of the structures for the duration of the contract.
The partner and VNF have the indicators of the
operating condition of the structures stipulated
in the contract. This operating condition indicator characterises the suitability of the structures for
correct operation.
In terms of the environment, waterproof seal performance is taken into account, as part of the water-saving approach explained above, as are water quality, quality of implementation of ISO system
14 001, renewable energy production and energy
consumption.
The waterproof seal indicator measures loss
through infiltration. Checks can be carried out
each year during the offline period with direct
measurement of the lowering of the water course.
The cost of penalty fines is fixed in such a way as to
encourage the partner to identify the location of
leakages and carry out repairs.
The water quality indicators aim to ensure that the
ecological potential of the canal is maintained
alongside the quality of raw water for the production of drinking water.
The energy indicators aim to ensure operational
efficiency of the canal, according to traffic, on
the one hand, i.e. the total electricity consumption with regard to a contractually agreed reference and minimum production of renewable energy on the other.
Finally, the contract provides for indicators that
measure user satisfaction. This more qualitative
measurement is based on satisfaction surveys and
on the duration of intervention by the partner for
incidents beyond their control (accidents, load
losses, etc.)
These performance objectives are quite close to
those established on the PIANC report 111 on the
definition of performance indicators for waterway networks. Indeed, the parts relating to transit
time or crossing time though locks, the reliability of
Table 2: Type of performance indicators for the Seine-Nord Europe partnership contract
153
locks, etc. are also found here. The PIANC WG 111
report indicators are broader as they cover the
entire transport chain, including port services and
are intended for use by institutional stakeholders
in order to determine the overall efficiency of the
transport system.
In conclusion, the Seine-Nord Europe Canal combines several economic, social and environmental functions. The partnership contract is a suitable
format for the completion of this complex project
as it enables control over a number of different
objectives, arising from an initial dialogue with
the stakeholders, within a contractual framework.
Performance measurement is ensured through
the monitoring of indicators and gives rise to an
assessment each year. These mechanisms aim to
provide users or other beneficiaries with the ‘best’
possible quality of service, while taking into account progress in the field of waterway management.
SUMMARY
As a frontline project for trans-European transport networks, the Seine-Scheldt link will ensure a
wide-gauge waterway connection from the Seine
basin through to the Scheldt and Rhine basins.
Seine-Nord Europe is a sustainable development
project. Environmental integration means special
consideration for economic management of water resources and is underpinned by the principle
of working with nature to develop solutions that
respect the natural surroundings. The realisation of
Seine-Nord Europe through a partnership contract
enables a commitment to be made regarding the
performance of the structure and offers guarantees as to maintaining the infrastructure in good
condition over time.
This article presents the Seine-Nord Europe Canal,
which is at the heart of the Seine-Scheldt link, and
provides information about the functions the canal fulfils as well as the principles of environmental integration. The article explains how the various functions of the canal are taken into account
in the performance objectives of the partnership
contract.
RESUME
Projet prioritaire des réseaux transeuropéens de
transport, la liaison Seine-Escaut assurera la connexion fluviale à grand gabarit depuis le bassin de
la Seine jusqu’aux bassins de l’Escaut et du Rhin.
Seine-Nord Europe est un projet de développement durable. L’insertion dans l’environnement
apporte un soin particulier à la gestion économe
de la ressource en eau et retient le principe de
travailler avec la nature en développant des solutions respectueuses des milieux naturels. La réalisation de Seine-Nord Europe en contrat de
partenariat permet d’avoir un engagement sur les
performances de l’ouvrage et donne des garanties sur le maintien en bon état de l’infrastructure
dans la durée.
Dans cet article, on fera une présentation du
canal Seine-Nord Europe au sein de la liaison
Seine-Escaut, on donnera des indications sur les
fonctions assurées par ce canal ainsi que sur les
principes de son insertion environnementale, enfin, on décrira comment les différentes fonctions
du canal sont prises en compte dans les objectifs
de performance du contrat de partenariat.
ZUSAMMENFASSUNG
Als ein Projekt in vorderster Front des transeuropäischen Transportnetzwerks wird die Seine-Schelde-Verbindung eine weiträumige Wasserstraßenverbindung vom Seinebecken bis zur Schelde und
dem Rheinbecken sicherstellen. Seine-Nordeuropa ist ein nachhaltiges Entwicklungsprojekt. Die Integration von Umweltbelangen stellt eine besondere Herausforderung für das wirtschaftliche
Management der Wasserressourcen dar und wird
unterstützt von dem Prinzip „Working with Nature“,
um Lösungen zu entwickeln, die das natürliche
Umfeld berücksichtigen. Die Umsetzung des SeineNordeuropa-Projekts mittels eines Partnerschafts154
vertrags erlaubt eine Verpflichtung bzgl. der Leistungsfähigkeit der Anlagen und bietet Garantien,
dass die Infrastruktur während der Lebensdauer in
einem guten Zustand gehalten wird.
Dieser Artikel stellt den Seine-Nordeuropa-Kanal
vor, der sich im Zentrum der Seine-Schelde-Verbindung befindet, und liefert Informationen über die
Funktionen, die der Kanal erfüllt, ebenso wie über
die Grundsätze zur Einbindung der Umweltbelange. Der Beitrag erklärt, wie die verschiedenen
Funktionen des Kanals bei den Leistungszielen des
Partnerschaftsvertrags berücksichtigt wurden.
AVANCEMENT DU PROJET DE RéTABLISSEMENT
DU CARACTèRE MARITIME DU MONT-SAINT-MIChEL
PROGRESS Of ThE RESTORING OPERATION Of
ThE MONT-SAINT-MIChEL’S MARITIME ChARACTER
ROMAIN DESgUéE
BRUNO LEgENDRE
Syndicat Mixte Baie du Mont-Saint-Michel
2, rue du Prieuré
BP 29
50170 ARDEVON
France
E-mail: M. Desguée: [email protected]
E-mail: M. Legendre: [email protected]
JOËL L’HER
CETMEF,
Centre d’études techniques maritimes et fluviales
Technopôle Brest-Iroise
BP 05
29280 PLOUZANÉ
France
KEY WORDS: Mont-Saint-Michel, hydraulic works,
hydro-sedimentary studies, dam, hydraulic flushing
MOTS-CLES: Mont-Saint-Michel, aménagements
hydrauliques, études hydrosédimentaires, barrage,
chasses hydrauliques
1. LE PROJET DE
RETABLISSEMENT DU
CARACTERE MARITIME DU
MONT-SAINT-MICHEL
L’opération de rétablissement du caractère maritime du Mont-Saint-Michel entre dans sa dernière
phase de travaux qui porte sur la réalisation des
aménagements hydrauliques à l’aval et à l’amont
du nouveau barrage sur le Couesnon jusqu’à l’anse
de Moidrey. Ces travaux devraient s’achever en
2015 après la mise en service du pont-passerelle
et la destruction de la digue-route.
Celle-ci fut contestée dès sa construction en 1879:
« Nous avons une chose unique au monde, si belle
qu’on ne la peut imaginer quand on ne l’a pas
vue. Un bijou de granit, un colosse de dentelle,
une merveille incomparable encadrée dans un
paysage d’une invraisemblable beauté, dans un
golfe de sable jaune, s’étendant à perte de vue.
Les ingénieurs sont arrivés qui ont fait une digue. La
digue menace le monument et doit faire pousser
des choux dans la mer de sable qui semble, au
soleil couchant, un océan d’or », écrivait Guy de
Maupassant en 1884.
Cet ouvrage s’inscrivait dans la logique de la poldérisation de la baie lancée en 1769 par Quinette
de la Hogue qui obtint une concession de 2000
hectares et poursuivie par la Compagnie des Polders de l’Ouest à la fin du 19ème et au début du
20ème siècle. Jusqu’en 1969, date de construction de l’ancien barrage sur le Couesnon, les
aménagements dans la baie ont eu pour effet
d’accélérer son colmatage par des sédiments et
de rapprocher les bancs d’herbus du rocher sur
lequel se dresse l’abbaye du Mont-Saint-Michel.
155
Le projet actuel est lancé en 1995, après de nombreuses tentatives portées par diverses commissions. Trois objectifs lui sont fixés:
chasse dans la baie, l’aménagement de l’anse
de Moidrey, l’optimisation des points de rejets de
la tangue issue des terrassements à l’aval du barrage, etc.
• rendre à la marée et aux sables l’espace occupé par la digue et les parcs de stationnement,
• libérer les abords du Mont-Saint-Michel de la
présence des voitures,
• assurer un accès permanent au Mont tant pour
les besoins des visiteurs que pour les Montois.
Les études de définition se déroulent jusqu’en
2001. D’importantes études hydrosédimentaires
sont menées pour répondre à l’objectif de rétablissement du caractère maritime en exploitant au
mieux les forces de la marée et la puissance de
chasse du Couesnon. Un modèle physique hydrosédimentaire de 24 m sur 48 m est notamment
construit par la SOGREAH pour tester différents
aménagements. Les études s’appuient aussi sur
l’important effort de recherches hydrosédimentaires mené depuis les années 1970 qui a fait progresser considérablement la connaissance scientifique de la baie du Mont-Saint-Michel.
Un projet est établi et validé en 2000 par une commission scientifique présidée par Fernand Verger.
La déclaration d’utilité publique (DUP) est prononcée le 21 juillet 2003. Les aménagements hydrauliques prévoient la construction d’un nouveau
barrage permettant la pénétration de la marée
dans le Couesnon pour assurer des chasses avec
des volumes renforcés par l’aménagement du
Couesnon et la création d’un réservoir dans l’Anse
de Moidrey. Par ailleurs, un seuil hydraulique permet de partager le Couesnon en un bras à l’Ouest
et un bras à l’Est du Mont.
Les travaux commencent en 2005 et, en 2006,
le projet est confirmé avec quelques aménagements optimisant les épis, le positionnement du
chenal Ouest, la longueur du pont-passerelle et la
position du seuil de bipartition du Couesnon.
Pour conseiller le Maître d’Ouvrage aux différentes étapes de la réalisation du projet un comité de suivi hydrosédimentaire est constitué en
juillet 2007. Ce comité présidé par Pierre-Louis
Viollet, a dans un premier temps, recommandé
le développement d’un modèle numérique de
transport sédimentaire. L’outil construit à partir
d’un maillage géométrique de la baie, calcule en
différents points des paramètres (hauteur d’eau,
vitesse, concentration) en simulant la dynamique
sédimentaire par des lois physiques. Le comité a
suivi le développement de cet outil qui malgré sa
sophistication à la pointe de l’état de l’art actuel,
reste loin de pouvoir fournir des certitudes compte
tenu de la complexité des phénomènes modélisés. Le comité l’a néanmoins exploité pour étayer
les avis que lui a demandé le Maître d’Ouvrage
sur différents questionnements, tels que la longueur du pont-passerelle, le cône hydraulique de
156
Fig. 1: Schéma global des aménagements
programmés
2. LE BARRAGE SUR LE
COUESNON
Ouvrage d’art à part entière, construit entre 2006
et 2009, l’architecture du barrage intègre toutes
les dimensions d’un site où nature, technique et
culture se rencontrent de façon exceptionnelle.
Elle concilie une juste inscription dans le grand
paysage de la baie, mêlant les fonctionnalités
techniques de gestion des eaux et des espaces
publics de découverte et de contemplation.
Partie intégrante de la baie, en relation sensible
avec le Mont Saint-Michel, le barrage s’inscrit
dans une dimension culturelle profonde qui entre
en résonance avec le génie du lieu et l’imaginaire
collectif qui s’y rattache.
2.1. Principes de conception: entre
équipements hydrauliques et espaces
de contemplation
Au-delà de sa fonction première de régulation
des eaux, le barrage est conçu, dans toutes ses
dimensions, pour prendre en compte et révéler le
caractère exceptionnel du site. Dans sa fonctionnalité hydraulique, le projet est dessiné à partir du
principe dit de ‘la vanne-secteur’, dont la géométrie se déduit des contraintes de gestion des eaux.
Pour des raisons à la fois techniques et architecturales, les huit ensembles de vannes implantés à
l’amont du barrage, côté Couesnon, permettent
de libérer face à la mer et au Mont une perspective dégagée sur le paysage.
me les sextants, en référence au déplacement cyclique des astres qui anime les marées. La poussée
horizontale des vérins qui actionnent les vannes
joue dans la direction contradictoire du mouvement des eaux de mer et des eaux du Couesnon.
L’ensemble cylindrique que forment les seize roues
dans la perspective du barrage est directement
appréhendable depuis le pont-promenade par le
public.
Dans sa dissymétrie, l’ouvrage propose, en complément des équipements hydrauliques, la création d’espaces publics majeurs au-dessus des
eaux: face au Mont, le pont-promenade et le
balcon maritime offrent au public un espace de
contemplation unique. La perspective s’ouvre sur
le Mont. Au sud, côté terre, ils permettent de contempler le fleuve canalisé et l’efficacité mécanique des équipements en mouvement régulier.
2.2. Les équipements hydrauliques
Le projet est dessiné à partir du principe classique
de la vanne-secteur. Chacune des huit vannes est
actionnée par deux vérins hydrauliques. L’entité
homogène que forment la vanne-secteur, ses
deux bras et les deux vérins qui les actionnent,
constitue de par sa spécificité et sa mobilité cyclique l’élément original du projet ; sa répétitivité
dans les huit passes du barrage lui confère une importance singulière.
Fig. 2: Dessin des vannes secteurs et réalisation
finale
Le dessin de l’armature des vannes renvoie aux
formes circulaires des instruments de marine com-
Fig. 3: Schémas du barrage et détails de la
maquette des vannes secteurs
157
La rotation des vannes permet d’assurer le remplissage par ‘sur-verse’ (par-dessus la vanne) pour
limiter les apports de sédiments et de vidange par
une ouverture progressive en ‘sous-verse’ (sous la
vanne), ainsi que l’ouverture hydraulique totale,
en fonction du jeu des marées et du mouvement
des eaux du Couesnon.
2.3. Les espaces ouverts au public
Le pont-promenade est traité comme un espace
de déambulation, de liaison entre les deux berges
du Couesnon, en continuité de plain-pied avec
les chemins aménagés sur les digues est et ouest.
Une grande qualité de prestations est conférée
à son traitement architectural: transparence du
garde-corps côté terre, ossature en acier peint,
‘bastingage’ en bronze, allège coupe-vent en
verre sérigraphié, finition du sol en béton désactivé et insertion d’éléments de granit, suivant la
trame du barrage.
terres, entre puissance des éléments naturels
et mécanique de régulation ; le seul endroit de
la baie au-dessus des eaux, avec le futur pontpasserelle, où il soit possible de demeurer lors des
marées hautes. Le garde-corps du balcon maritime forme une sorte de longue table cintrée telle
un bastingage, en figure de proue au-dessus des
eaux, face au Mont Saint-Michel. Devant le grand
paysage de la baie, il est couronné par un pupitre de bronze linéaire : le pupitre des lettres. Sur sa
surface sont gravés les quatre alphabets qui ont
fondé l’histoire écrite de l’Europe, dont le Mont
Saint-Michel demeure un des repères vivants: les
alphabets hébreu et arabe, s’écrivant d’Est en
Ouest ; les alphabets grec et latin, d’Ouest en Est.
2.4. La technicité du barrage
D’une longueur totale de 138,46 m culées comprises et d’une largeur maximale de 32,4 m (portée maximale du balcon maritime), le barrage est
équipé de 8 passes de 9 m de largeur hydraulique
chacune et de 2 écluses à poissons de 3,10 m de
large, situées de part et d’autre de l’ouvrage.
Constitué de 9 piles de dimensions variables (23 à
27m pour 1, 8 m de large), il est étanche jusqu’à la
cote: 9,40 m IGN 69.
Fig. 4: Schémas du barrage et détails de la
maquette des vannes secteurs
Le balcon maritime est dessiné comme un espace
suspendu, projeté vers le Mont, sur cette ligne de
partage symbolique entre baie et intérieur des
158
Fig. 5: Vues amont du barrage, vannes ouvertes
Fig. 6: Principe simplifié de fonctionnement du barrage
La fonctionnalité première de cet ouvrage est
de redonner au Couesnon une force suffisante
pour éroder les fonds sédimentaires aux abords
du rocher en effectuant régulièrement des lâchers d’eau. L’efficacité hydraulique des remplissages et vidanges, dépend du débit d’apport du
Couesnon fluvial et du niveau de la mer. Son cycle
de fonctionnement, décrit ci-dessous, est dicté
par le rythme des marées: les remplissages fluviomaritimes débutant 10 minutes avant l’heure de
pleine mer, les lâchers d’eau, 6 heures plus tard.
Les 8 vannes du barrage fonctionnant dans les
deux sens, elles permettent, en phase de remplissage, de limiter les apports de sédiments dans
les parties amont de l’ouvrage: les entrées d’eau
se font alors par sur-verse. A l’opposé, au moment des lâchers d’eau, les écoulements se font
par sous-verse, permettant ainsi au courant pouvant atteindre 100 m3/s, de nettoyer le radier de
l’ouvrage et d’ainsi reprendre les sédiments déposés en amont de ce dernier.
3. LES AMENAGEMENTS
HYDRAULIQUES
Le nouveau barrage ne saurait, à lui seul, restituer
toute sa puissance au Couesnon, mais conjugué
à des aménagements hydrauliques, il donnera
à nouveau au fleuve la force perdue au fil des
ans depuis plus de quarante ans. Les aménagements hydrauliques prévus à l’amont et à l’aval
du barrage vont en effet aider ce dernier à agir
plus efficacement pour redonner au Couesnon la
force d’emporter au loin du Mont les sédiments et
d’entretenir un environnement maritime autour
des remparts.
3.1. Les aménagements à l’amont
du barrage
L’ensemble des aménagements hydrauliques
amont est réalisé sur une période de 4 ans, de
septembre 2011 à début 2015. Après le nettoyage
et l’élagage préalables des berges, réalisés début
2010, le fond du lit du Couesnon est curé. Cette
opération porte sur les 4,7 km de fleuve situés à
l’amont du nouveau barrage, jusqu’à l’anse de
Moidrey. Ces travaux, qui consistent à extraire
455.000 m3 de sédiments permettront, à terme,
d’obtenir un volume de stockage de 800.000 m3
dans le lit du fleuve.
En complément du dragage du lit du fleuve, l’anse
de Moidrey, progressivement comblée au fil du
temps, se voit modifiée pour devenir une véritable
réserve en eau. Pour lui rendre cette capacité, un
réservoir hydraulique d’une capacité de 300.000
m3 est reconstitué à travers 36 ha de canaux (9 km
au total, pour 700.000 m3 de matériaux extraits) sur
les 86 ha qu’elle compte.
Avec l’ensemble de ces travaux, le Couesnon
retrouvera une capacité de stockage de près
d’1,1 million de m3 d’eau en moyenne, pour des
marées de coefficient 95 ; pouvant aller jusqu’à
un volume de 1,4 millions de m3 d’eau stockés lors
des périodes de très grandes marées.
Ces différents travaux vont conduire à extraire du
lit du Couesnon et de l’anse de Moidrey quelque
1,2 million de m3 de tangue. Grâce à sa teneur
en calcaire, ce sédiment gris argenté, mélange
de sablons et de débris coquillés, propre à la baie
du Mont-Saint-Michel, s’avère être un excellent
complément minéral pour les terres agricoles des
polders. Il permet également de satisfaire plusieurs centres équestres intéressés pour utiliser ce
matériau adapté aux articulations des chevaux.
Différentes pistes de valorisation locale de ce
sédiment ont donc été étudiées. L’ensemble de
ces matériaux excédentaires sera alors, tout au
long de ces 4 années de chantier, utilisé pour le
rechargement de parcelles agricoles environnantes, l’amendement de certaines parcelles et
le rechargement de centres équestres. Au final,
l’intégralité du matériau sera valorisée localement, cette valorisation faisant partie intégrante
de ces travaux hydrauliques amont.
159
bonne répartition des chasses du barrage de part
et d’autre du Rocher.
Pour compléter ces aménagements, des épis déflecteurs et écarteurs accompagneront et faciliteront la divagation du Couesnon sur les grèves. Les
courants circuleront ainsi plus facilement et plus
fortement autour du Mont, empêchant les sédiments de se déposer toujours au même endroit.
Les aménagements hydrauliques à l’aval du nouveau barrage sur le Couesnon nécessitent différentes techniques de dragages très particulières,
qui sont de plus réalisées dans un environnement
très contraignant (interventions en fonction des
marées, des débits du Couesnon et de la gestion du nouveau barrage). Les interventions ont
en effet lieu à la fois dans le lit du fleuve et sur les
herbus, pour permettre de remanier au total plus
de 850.000 m3 de sédiments. Ces derniers sont soit
réutilisés sur le site (remblaiements de fouille, réalisation de nouveaux ouvrages, etc.), soit évacués, pour 400.000 m3 environ, par la technique du
‘dragage à l’américaine’, qui est régulièrement à
l’œuvre dans les ports industriels.
Fig. 7: Dragage dans le Couesnon, décapage
des exhaussements et terrassements
dans l’Anse de Moidrey
3.2. Les aménagements à l’aval du
barrage
160
Fig. 8: Image de synthèse des résultats escomptés
dans l’estuaire du fleuve Couesnon
Fig. 9: Pelle amphibie et travaux hydrauliques
en aval du barrage
Les travaux d’aménagement hydrauliques aval,
débutés en septembre 2011 s’étalent sur 4 années. Dans le cadre de ces travaux, une partie
des cordons d’enrochement qui enserraient le
Couesnon est démantelée. Ils servent à la réalisation d’un seuil de partage qui serpente sur 2 km,
depuis le barrage jusqu’au pied du Mont, afin de
mieux guider l’action des lâchers d’eau. Les deux
chenaux Ouest et Est ainsi formés garantiront une
Cette technique consiste, après extraction, à
relâcher les sédiments directement dans le lit du
fleuve Couesnon, pendant les périodes de lâchers
d’eau du barrage et pendant la marée descendante afin de bénéficier d’une évacuation vers le
large grâce à l’action du courant. Cette méthode
est utilisée aussi bien pour des sédiments extraits du
lit du Couesnon, après traitement préalable (aspiration dans l’eau et triage par un godet cribleur
aspirateur de type REMU), que pour les sédiments
extraits des herbus. Tous les volumes sont donc soit
transportés vers un atelier de dragage où les sédiments seront mélangés avec de l’eau sous pression avant d’être rejetés dans le fleuve via une
canalisation flottante, soit évacués directement
au moyen d’une pelleteuse amphibie équipée
du godet REMU. Au final, contrairement aux aménagements hydrauliques à l’amont du barrage,
l’intégralité des matériaux excédentaires sera soit
réutilisée directement sur site, soit évacuée au fil
des lâchers d’eau du barrage et des marées descendantes, l’obligation étant de n’exporter aucun matériau vers l’extérieur du site.
actère maritime du Mont-Saint-Michel: les solutions
proposées – programme technique détaillé ».
Morelon, J.-P. (1999): « Un projet d’équilibre pour la
reconquête d’un site exceptionnel: le Mont-SaintMichel », Échos du conseil général des ponts et
chaussées.
Verger, F. (2000): « Entre terre et mer: le Mont-SaintMichel », Pour la Science (édition française de scientific american) n°274.
Caude, G. et L’Her, J. (2005): « Rétablissement du
caractère maritime du Mont-Saint-Michel : modélisation et suivi environnemental », la Houille
Blanche, n°3.
De Beaulaincourt, F.-X. et L’Her, J. (2007): « Le rétablissement du caractère maritime du Mont
Saint-Michel – le comité de suivi scientifique des
travaux hydrosédimentaires », Colloque SHF-AIPCN-CETMEF ‘Grands Aménagements’, Paris.
Fig. 10: Vue sur la structure métallique du futur
pont-passerelle entre le continent et le Mont,
dont la mise en service est prévue pour le
printemps 2014
4. EN CONCLUSION
Le caractère singulier exceptionnel du MontSaint-Michel et de sa baie, « double œuvre de la
nature et de l’art », comme l’écrivait Victor Hugo,
impose des conditions particulières à la réalisation
des travaux pour la requalification durable de ses
abords. Aujourd’hui, alors que le chantier est encore en pleine activité, le visiteur peut déjà percevoir le début de la concrétisation des objectifs visés
par les promoteurs du projet, avec la libération de
l’abord du Mont de la présence des voitures et les
premiers signes de la réappropriation de l’espace
proche du Mont par les marées grâce à l’action
des chasses du barrage sur le Couesnon.
5. BIBLIOGRAPHIE
Ministère chargé de la Culture, ministère chargé de l’Environnement, ministère chargé de
l’Équipement (1995): « Projet de rétablissement du
caractère maritime du Mont-Saint-Michel ».
Séguin, J.-F. (1998): « Mont-Saint-Michel – La reconquête d’un site », Le cherche midi éditeur.
Migniot, C. (1998): « Rétablissement du caractère
maritime du Mont-Saint-Michel – Synthèse des
connaissances hydro-sédimentaires de la baie ».
Mission Mont-Saint-Michel (1999): « Rétablir le car-
Caude, G. (2008): « Le Mont-Saint-Michel retrouve
son caractère maritime – Brève synthèse du projet
de rétablissement », revue technique maritime et
fluviale n°1 – CETMEF.
Desguée, R. (2012): « Le rétablissement du caractère maritime du Mont-Saint-Michel », Colloque
SHF-AIPCN-CETMEF ‘Grands Aménagements durables’, Paris.
Syndicat mixte Baie du Mont-Saint-Michel (1997):
« Rétablissement du caractère maritime du MontSaint-Michel – retrouver le Mont-Saint-Michel dans
sa vérité – Projet ».
Syndicat mixte Baie du Mont-Saint-Michel – Revue
la baie n°1 (août 1997) à 31 (novembre 2012) et
suppléments :
Dossier hydrosédimentaire:
- n°1 les études hydrosédimentaires: démarches
et solutions (mars 2001),
- n°2 les suivis hydrosédimentaires: comprendre
et adapter (juin 2010).
Dossier environnement:
- n°1 environnement et paysage: retrouver la nature profonde de la baie (octobre 2001),
- n°2 environnement et paysage: le programme
de suivi (juin 2009).
Site Internet: http://www.projetmontsaintmichel.fr
Crédits photos/illustrations/schémas:
Thomas Jouanneau, Altibreizh, Daniel Fondimare
et Nicolas Borel, photographies/Luc Weizmann
Architecte, croquis et dessins/Catherine Claden,
maquette/Aprim - Syndicat Mixte Baie du MontSaint-Michel, schémas.
161
SUMMARY
The restoring operation of the Mont-Saint-Michel’s
maritime character, launched in 1995, aims to return the surrounding of the Mont-Saint-Michel to
the sea and the sand. Important hydro-sedimentary studies have established a project that involves
the construction of a new dam allowing penetration of the tide in the Couesnon to ensure flushes
with strengthened volumes. The work began in
2005 and is monitored by a scientific committee.
The dam on the Couesnon was completed in
2009. Its architecture integrates all dimensions of a
site where nature, art and culture meet in exceptional circumstances. Design principles aimed at
integrating required hydraulic functionalities and
the creating of a space for contemplation.
From the hydraulic point of view, the dam has
eight valves operated by two hydraulic cylinders
each. The rotations of the valves ensure the filling
by overflow to reduce the insertion of sediments
and the discharge by underflow to optimise the
effect of flushing. The dam is also a space open to
the public: the promenade deck and maritime observation terrace are treated as a space for walking and a liaison between the two banks of the
Couesnon. The dam is about 140 m with 8 passes
of 9 m of hydraulic width each and 2 fish ways. His
first feature is to restore Couesnon sufficient power
to erode bottom sediments near the Mount. The
hydraulic efficiency of the filling and emptying depends on the flow contribution of the Couesnon
river and on the sea level. The dam works in two
directions, allowing, in the filling phase, to limit the
sediment intrusion in the upstream of the dam: the
water inputs are then realised by overflow. In contrast, at the time of release of water, flows are by
underflow, thereby creating a flushing current.
Upstream of the dam, facilities include cleaning
and pruning of banks, as well as the cleaning of
the bed of the Couesnon to create a storage volume of 800,000 m3. In addition a water reserve
capacity of 300,000 m3 is reconstituted in Moidrey
cove across 36 acres of canals. Through this work,
the Couesnon find a storage capacity of nearly
1.1 million m3.
Downstream of the dam the works focus on the
realisation of a dividing rockfill from the dam to
the foot of the Mount, to create two channels
of Couesnon which ensure a good distribution of
flushing. This development is complemented by
hydraulic structures: the creation of two priming
channels and deflector and protector rockfills. The
work is carried out in a very constraint environment
given the tidal flows of the Couesnon river and
the management of the dam. One implemented
technique consists in the disposal of sediments
162
directly into the Couesnon river during periods of
water releases from the dam and during the ebb
tide to receive a discharge to sea due to the action of the current.
RESUME
L’opération de rétablissement du caractère maritime du Mont-Saint-Michel lancée en 1995 vise
à rendre à la marée et aux sables les abords du
Mont-Saint-Michel. D’importantes études hydrosédimentaires ont permis d’établir un projet qui
prévoit la construction d’un nouveau barrage
permettant la pénétration de la marée dans le
Couesnon pour assurer des chasses avec des volumes renforcés. Les travaux ont débuté en 2005 et
sont suivis par un comité scientifique.
Le barrage sur le Couesnon a été achevé en 2009,
son architecture intègre toutes les dimensions d’un
site où nature, technique et culture se rencontrent
de façon exceptionnelle. Les principes de sa conception visent à intégrer les fonctionnalités hydrauliques souhaitées et la création d’un espace
de contemplation.
une bonne répartition des chasses. Cet aménagement est complété par des ouvrages hydrauliques
: la création de deux amorces de chenaux et
d’épis écarteurs et protecteurs. Les travaux sont
réalisés dans un environnement très contraignant
compte tenu des marées, des débits du Couesnon
et de la gestion du barrage. Une technique mise
en œuvre consiste à relâcher les sédiments directement dans le lit du fleuve Couesnon, pendant les
périodes de lâchers d’eau du barrage et pendant
la marée descendante afin de bénéficier d’une
évacuation vers le large grâce à l’action du courant.
Du point de vue hydraulique, le barrage comporte huit vannes actionnées par deux vérins hydrauliques chacune. La rotation des vannes permet d’assurer le remplissage par sur-verse pour
limiter les apports de sédiments et la vidange par
sous-verse pour optimiser l’effet des chasses. Le
barrage est aussi un espace ouvert au public: le
pont-promenade et le balcon maritime sont traités
comme un espace de déambulation et de liaison
entre les deux berges du Couesnon. Le barrage
d’environ 140 m est équipé de 8 passes de 9 m
de largeur hydraulique chacune et de 2 écluses à
poissons. Sa fonctionnalité première est de redonner au Couesnon une force suffisante pour éroder les fonds sédimentaires aux abords du rocher.
L’efficacité hydraulique des remplissages et vidanges, dépend du débit d’apport du Couesnon
fluvial et du niveau de la mer. Le barrage fonctionne dans les 2 sens, permettant, en phase de
remplissage, de limiter les apports de sédiments
dans les parties amont de l’ouvrage : les entrées
d’eau se font alors par sur-verse. A l’opposé, au
moment des lâchers d’eau, les écoulements se
font par sous-verse, permettant ainsi de créer un
courant de chasse.
En amont du barrage, les aménagements comprennent le nettoyage et l’élagage des berges,
ainsi que le curage du fond du lit du Couesnon
pour obtenir un volume de stockage de 800.000
m3. En complément une réserve en eau d’une capacité de 300.000 m3 est reconstituée dans l’anse
de Moidrey à travers 36 ha de canaux. Grâce à
ces travaux, le Couesnon retrouvera une capacité de stockage de près d’1,1 million de m3.
A l’aval du barrage les travaux d’aménagement
portent sur la réalisation d’un seuil de partage
depuis le barrage jusqu’au pied du Mont, afin de
créer deux chenaux du Couesnon qui garantiront
163
ZUSAMMENFASSUNG
Der Wiederherstellungsprozess des maritimen
Charakters des Mont-Saint-Michel, der im Jahr
1995 begonnen wurde, hat eine Meerwasser- und
Sandumgebung des Mont-Saint-Michel zum Ziel.
Bedeutende hydro-sedimentäre Studien dienten
als Grundstein eines Projekts, das den Bau eines
neuen Damms beinhaltet, der das Eindringen der
Tide in den Couesnon erlaubt und so das Ausschwemmen in größerem Umfang sicherstellt. Die
Arbeiten begannen im Jahr 2005 und werden von
einem wissenschaftlichen Komitee begleitet.
Der Damm am Couesnon wurde im Jahr 2009 fertig gestellt, seine Architektur verflechtet sämtliche
Dimensionen an einem Schauplatz, an dem Natur,
Kunst und Kultur in außergewöhnlicher Weise aufeinandertreffen. Die Gestaltungsgrundsätze hatten zum Ziel, die erforderlichen hydraulischen
Funktionalitäten mit dem Schaffen eines Ortes der
Kontemplation zu verbinden.
Aus hydraulischer Sicht hat der Damm acht Durch-lassventile, die jeweils von zwei hydraulischen
Zylindern betrieben werden. Die Rotation der Ventile sorgt beim oberstromigen Überlaufen für einen
reduzierten Sedimenteintrag und regelt zugleich
das Rücklaufgeschehen, um den Spüleffekt zu
optimieren. Der Damm ist auch ein für die Öffentlichkeit geöffneter Raum: Das Promenadendeck
und die Seeterrasse sind begehbar und bilden so
eine Verbindung zwischen den beiden Ufern des
Couesnon. Der Damm ist ca. 140 m lang, besitzt
acht Durchlässe mit jeweils 9 m hydraulischer Breite und verfügt über zwei Fischpässe. Seine Hauptaufgabe ist es, dem Couesnon genügend Kraft zu
liefern, um die Bodensedimente in der Nähe des
Berges Saint-Michel zu erodieren. Die hydraulische
Effizienz des Füll- und Entleersystems hängt von dem
Zufluss des Couesnon und zugleich von der Höhe
des Meeresspiegels ab. Der Damm funktioniert in
zwei Richtungen, wodurch es möglich ist, während
der Füllphase den Sedimenteintrag oberstrom des
Damms zu begrenzen: Die Wassereinträge werden
hierbei durch Überströmung erzielt. Im Gegensatz
dazu wird bei ablaufendem Wasser durch Unterströmung eine Spülströmung erzeugt.
Oberstrom des Damms gibt es Vorrichtungen
zum Reinigen und Freischneiden der Böschungen, ebenso wie zur Reinigung des Bettes des
Couesnon, was zu einem Speichervolumen von
800.000 m³ führt. Zusätzlich wird in der MoidreyBucht eine Wasser-Reservekapazität von 300.000
m³ auf einer Fläche von über 36 Acre (1 Acre ~
4047 m²) des Kanals wiederhergestellt. Dadurch
beträgt die Speicherkapazität des Couesnon fast
1,1 Mio. m³.
Unterstrom des Damms konzentrieren sich die Ar-
164
beiten auf die Errichtung einer trennenden Steinschüttung vom Damm zum Fuße des Berges, um
zwei Kanäle für den Couesnon zu bauen, die eine
günstige Verteilung der Spülströmung gewährleisten sollen. Dieser Ausbau wird durch weitere
hydraulisch wirksame Elemente vervollständigt:
Bau von zwei Grundkanälen sowie abweisende
und schützende Steinschüttungen. Die Arbeiten werden in einer eng begrenzten Umgebung
durchgeführt, bedingt durch die Tideströmungen
im Couesnon und den Betrieb des Dammes. Eine
implementierte Verfahrenstechnik besteht in der
Ablagerung von Sedimenten direkt im Couesnon
in Zeiten, in denen das Wasser aus dem Damm
strömt sowie während Ebbe, um bedingt durch die
Strömung einen Abfluss zum Meer zu erreichen.
MONITORING Of PORT 2000
ENVIRONMENTAL MEASURES
LE SUIVI DES MESURES
ENVIRONNEMENTALES DE PORT 2000
PASCAL gALICHON
Grand Port Maritime du Havre
Terre-Plein de La Barre
BP 1413
76067 Le Havre Cedex
France
Tel: +33 (0)2 32 74 70 30
KEY WORDS: Seine estuary, compensatory mea-
sures, scientific follow-up, morphology, biological
resources
MOTS-CLES: estuaire de la Seine, mesures compensatoires, suivis scientifiques, morphologie, ressources biologiques
1. INTRODUCTION
promote biodiversity in the Seine estuary and to
support the management of nature areas (Nature
Reserve and specific ‘Espace Préservé’ (Preserved
area immediately southeast of Port 2000). To assess the impact of these environmental measures,
a large-scale scientific monitoring programme has
been implemented since 2000 in conjunction with
the Scientific Council of the Seine Estuary.
After describing the main infrastructure of Port 2000
and the associated environmental measures, this
paper presents the various scientific programmes
and discusses the main methodological lessons
learnt in the conclusion.
2. PORT 2000 AND THE MAIN
ENVIRONMENTAL MEASURES
2.1. Port Infrastructure
With more than € 50 million dedicated to environmental measures, Port 2000, an extension to the
port of Le Havre constructed between 2001 and
2005, is part of a genuine sustainable development
policy for the Seine estuary carried out in close cooperation with the stakeholders concerned. Half
of that budget has been allocated to an extensive programme of rehabilitation of the mud flats,
an environment conducive to development of
organisms that form a vital link in the food chain
for many species. Other measures include the creation of new rest areas for birds, the aim being to
The work exclusively relating to the port (Fig. 1 on
the next page) mainly comprises a breakwater
some 5.5 km long extending into the estuary of
the Seine to shelter 4.2 linear km of quays. Access
to the quays is via a navigation channel approximately 7 km long dredged in the riverbed which
was previously located at – 3m LHSL (Le Havre
Sea Level), down to a depth of – 16 m LHSL over
a width varying from 300 to 600 m. It joins the shipping channel about 1km from the entrance channel to the port of Le Havre. Some 60 million m3 of
material have been dredged half of which being
reused in the civil engineering works (reclamation
and breakwaters), the remainder being deposited
in the sea off Octeville outside the estuary.
165
Since the Port 2000 facilities reduce the width of
the estuary in its downstream section, an increase
in currents was expected, resulting in the erosion
of the Northern trench of the Seine estuary located directly south of Port 2000. To support this
change in the bottom and minimise its impact,
support dredging to help recalibrate the Northern
trench was carried out. Sedimentological studies
conducted by SOGREAH showed the dredging
work was of interest both in controlling the sedimentological changes in the Northern trench and
the access channel to the Port of Rouen, but also
of ecological interest as a means of preserving the
mudflats and the species that live within them, located at the foot of the Pont de Normandie (Normandy Bridge).
Modelling was used for the preliminary sizing of
the volumes, locations and phasing of the support
dredging work. Regular monitoring of the bottom
during construction work allowed the dredging
to be adapted according to the morphological changes observed (3.5 million m3 have been
dredged).
tion work began on Port 2000. This first environmental measure to be implemented, the construction
of a bird resting area near to the dune zone, was
completed in February 2002 before any work took
place on the site requiring compensation. Covering a surface area of some 30 ha, the land was
remodelled to encourage usage of the site by water birds of the estuary (ducks and other species
feeding on the mud flats at low tide) needing rest
areas at high tide.
Ornithological monitoring by the Avifauna Observatory of the Seine Estuary resulted in additional
developments to increase the site’s attractiveness.
For example, an area was regraded to promote
the nesting of avocets, and a gate to manage
the water levels inside the resting area were put in
operation in 2005. The most recent monitoring has
indicated a gradual increase in site occupancy,
which is now promising, in particular through the
effective management of water levels by the Maison de l’Estuaire. In 2010, nesting by 10 different
species was observed, including 50 pairs of avocets.
2.2.2. The Bird Resting Island in the Seine
Fig. 1: Location of the various facilities
2.2. Environmental Work
The environmental interest of the Seine estuary
and the findings concerning its past changes
led the Grand Port Maritime du Havre to implement, as part of the Port 2000 project, a major programme of environmental measures designed to
preserve and develop the environmental features
which were declining, mainly due to the reduction in the surface area of the interdidal mudflats.
These measures included development work.
2.2.1. ‘The Dune Bird Resting Area’: An Area of
Peace and Quiet for Water Birds
Defined in relation with the regional environment
directorate (DREAL) and the organisation in charge
of the nature reserve (Maison de l’Estuaire), the development work was carried out during the winter
of 2001-2002, the aim being to provide a functional replacement for the site (which now no longer
exists) where birds concentrated before construc166
Designed to accommodate seabirds and diversify the sites for the different species of seabirds to
nest and rest, an island covering five contiguous
hectares at low tide is located in the southern part
of the estuary (opposite Villerville). Its construction
was completed in April 2005. The site, which is one
of its kind, is 320 metres long and 200 metres wide.
Its main characteristics (shape and land level)
were defined in very close cooperation between
the regional environment directorates (DREAL)
for Upper and Lower Normandy, the Normandy
Ornithological Group (GONm) and the port engineers.
In accordance with the decree creating the Nature Reserve inside which it was built, except for
the officers of the Maison de l’Estuaire who carry
out the scientific monitoring of its use by birds and
the eventual introduction of other species of flora
and fauna, all forms of human presence are prohibited in order to preserve the tranquillity of the
site. A video camera has been installed to improve
the quality of follow-up without disturbing the birds
on the island.
The first bird counts that were made immediately
showed the merits of the design of the island with
more than a thousand birds of more than twenty
different species regularly nesting and resting on it.
Since then, nearly sixty species of birds have been
observed, at least three of which breed on the
island in 2010 (Common Shelducks, Great BlackBacked Gulls and Mallards). Botanical monitoring
has shown the presence of about 70 plant species
including a growing number of heritage species.
2.2.3. Restoration of the Interdidal Mud flats, a
Major Environmental Component of Port 2000
During the consultations held throughout the development phase of the Port 2000 project, it quickly became apparent that the major environmental challenge of the Seine estuary concerned the
mudflats, whose surface area was very significantly
decreasing (by some 25 ha/year). It was therefore
agreed that the main environmental measure of
Port 2000 should focus on a programme to rehabilitate the intertidal estuary mud flats, the aim being to impede the progression of grassy marshes
and to create new mud flats.
The rehabilitation work on the mud flats was specified further to the various studies that were carried
out.
Fig. 2 locates the various works, namely:
• a curved seawall oriented in the southwest/
northeast direction connected to the north lowcrested Seine breakwater opposite Honfleur
• a breach in the breakwater 550 m long, 2 km
upstream of the Pont de Normandie
• raising the current breach
• the digging of a channel between the current
breach and the future breach
• raising the North low-crested breakwater by
1 metre between the current breach and the
head of the seawall described above
• the installation of a layer of pebbles and rocks
to protect the bridge piers of the viaduct of the
Pont de Normandie
Initiated during the summer of 2003, the rehabilita-
tion work on the mud flats was completed in the
summer of 2005. Several phases of implementation were deemed necessary in order to let nature
take its course and to check step-by-step the accuracy of the modelling carried out during the design phase.
Scientific monitoring of the rehabilitation programme of the mud flats of the Seine estuary
made between 2005 and 2010 highlighted several
findings on the bio-hydro-sedimentary situation of
the mudflats, namely:
• The progression of the grassy marshes had effectively been halted
• Mud flats were effectively developing over
more than 100 ha downstream of the facilities
(along the low northern breakwater and south
of the dune bird sanctuary)
• The ‘Banc de la passe’ east of the curved scanwall has risen in height. It mainly consists of sand,
recently covered by a mud layer progressing
from west to east, which is encouraging,
• On the other hand, a significant input of sediment is occurring in the environmental channel
dredged upstream of the Pont de Normandie.
This development, which had not been envisaged when designing the facilities, is continuing
to be monitored in close conjunction with the
Scientific Council of the Seine Estuary.
In addition, scientific monitoring of the biological
elements can be used to highlight the relationships between the physical environments and
living habitats observed. Overall, in terms of the
species found, the northern part of the estuary is
becoming increasingly marine in nature, although
Fig. 2-3: Location and layout of the development
167
it is not possible to determine whether this is due
to the impact of the development work or to the
low flow rates of the river Seine since the end of
the work.
vironment. A new management plan developed
on the basis of scientific surveys carried out during the first management plan has been adopted
with the same partners for the 2012-2016 period.
2.2.4. Environmentally Oriented Beach
3. THE GENERAL
ORGANISATION OF
SCIENTIFIC MONITORING
Since the construction of Port 2000 removed
a beach on which a protected species grew
(‘Crambe maritima’), it was necessary to recreate a similar environment in order to re-introduce
the species. The environmentally oriented beach
marks the eastern tip of the backfilled area south
of the Charles Laroche dyke. Constructed in 2003
under the protection of the breakwaters of Port
2000, it is a little over 500 m long and its initial cross
section has beach slopes similar to those observed
in the natural environment. Experimental settlement took place. Monitoring carried out after the
first attempts to implant ‘Crambe maritima’ by the
Bailleul National Botanical Conservatory showed
that the instability of the beach was such that the
deliberate settlement of ‘Crambe maritima’ was
not sustainable. The operation will be renewed
once the beach has become more stabilised. In
addition, it is worth noting that instances of natural colonisation by ‘Crambe maritima’ have been
found on the outer beach of Port 2000, which was
built at the head of the Northern breakwater for
hydraulic purposes (to decrease the number of
overflows).
2.2.5. The Creation and Ecological Management of a Preserved Area of 70 Hectares
During the preliminary studies for Port 2000, various rare or protected species were identified in a
natural area of some about 70 hectares that the
Grand Port Maritime du Havre decided to preserve. It included plants (several orchids, marsh
peas and dune grass), amphibians (frogs, newts,
toads) and birds (nesting, migrating and wintering species). This area – now called the ‘Preserved
Area’ – was originally intended for logistics facilities to the Southeast of Port 2000.
The main measures for the management and scientific monitoring of this Preserved Area were entrusted by a convention to the Maison de l’Estuaire
and the Bailleul National Botanical Conservatory
as part of the management plan for the Preserved
Area. The plan includes various restoration and
management operations of the more interesting
habitats and scientific monitoring of the protected
species. In particular, since 2001, the botanists at
the Conservatory have been entrusted with managing sectors in which the Liparis Loesel orchid
grows (a plant protected at the European level).
An environmental management plan was drafted
for the 2004/2011 period with the help of the Nature Reserve, the Bailleul National Botanical Conservatory and the Regional Directorate for the En168
3.1. General Monitoring Specifications
With the help of the scientists working on the
Seine estuary, an extensive programme of scientific monitoring operations in areas likely to be
affected by Port 2000 was developed. In order
to be consistent with the various already existing
scientific programmes on the Seine Estuary, mainly the Seine-Aval programme, the specifications
for the monitoring operations were presented by
the Grand Port Maritime du Havre and approved
by the Scientific Council of the Seine Estuary. This
council consists of a dozen scientists covering
various areas of major interest to the Seine estuary (sedimentology, water quality, biological resources, etc.). It also helps interpret the results.
3.2. Implementation of Monitoring
Apart from monitoring the change in the bottom
carried out by the ports of Le Havre and Rouen,
both of which have the means and skills to acquire this type of data (the interpretation being
entrusted to outside consultants), scientific monitoring is entrusted after open and competitive
calls for proposals (except in cases of unique
expertise), to the appropriate laboratories or
authorities. Funding is overwhelmingly provided
by the Grand Port Maritime du Havre except in
certain cases where pooling with other partners
proved relevant.
3.3. Dissemination of Results
The scientific monitoring results in reports and
regular presentations to the Scientific Council of
the Seine Estuary, which helps interpret the results and ensures consistency with other scientific
programmes existing on the estuary. In addition,
depending on the topics, the results may be exchanged with other more specialised bodies (research teams, etc.).
To help the dissemination of knowledge and improve the sharing of information on changes in
the estuary, the acquired data are also made
available to the all the scientific community and
more particularly that associated with the SeineAval scientific programme through the Seine-Aval
Public Interest Group which unites scientific research across the Seine estuary and the eastern
Bay of the Seine.
4. THE SCIENTIFIC
MONITORING PROGRAMME
4.1. The Different Themes and General
Methodologies
The scientific monitoring of Port 2000 focuses on:
- the changes in the beds of the estuary from both
the morphological and granulometric points of
view, because the types of sediment influence
the types of living organisms that live in them,
- the biological resources of the estuary with
specific respect to the benthic and suprabenthic species, the fish and shellfish and finally the
birds,
- the protected species on land (flora and fauna)
that have been subject to special conservation
measures.
4.1.1. Monitoring Changes in the Beds
of the Estuary
Monitoring the changes in the beds comprise first
of all the morphological changes, but also the
changes in the nature of the sediments. Monitoring is mainly carried out by the Grands Ports Maritime of Rouen and Le Havre, both of which have
the technical and human resources needed to
conduct the monitoring operations and analyse
their results in conjunction with specialised consulting firms. Throughout the construction period
(January 2002 - March 2005), surveys of the Northern trench were carried out every two months and
an overview of the readings for the entire estuary
is produced once a year by the Grand Port Maritime of Rouen.
In conjunction with the bathymetric readings for
the Northern trench of the Seine estuary, sediment
samples are taken twice a year to clarify the sedimentary dynamics observed.
Because of the difficulty of access to certain areas (the high intertidal mudflats) and the development of airborne laser techniques (LIDAR), bathymetric surveys are completed by surveys using this
technology. Surveys of this type were carried out in
2001, 2004, 2006, 2008, 2010 and annually since. It
should be noted that these quantitative data are
supplemented annually by high-resolution photographs of sedimentary structures that enable a
spatial approach. This work is done by Mr A. Cuvilliez of the University of Le Havre in continuity to the
work for his PhD thesis.
During the construction work on Port 2000, observations were regularly detailed in a technical
committee chaired by the Director of the Centre
for Maritime and Fluvial Studies (CETMEF). It was
this committee which checked that the chang-
es observed were consistent or inconsistent with
those forecasted by the various models and decided whether adaptations in the phasing of the
works and support dredging were needed in order to minimise the impact of construction work
on the dynamics of the estuary and particularly on
the mudflats and the navigational channel of the
Port of Rouen. The Scientific Council of the Seine
Estuary was also informed of the observations and
measures taken.
Since the end of the construction work and after a
call for proposals, the bed development data acquired are provided to ARTELIA which carries out
an annual analysis that is presented to the Scientific and Technical Council of the Seine estuary. All
the data acquired and their interpretation are of
particular use in the production of a digital 3-D hydrosedimentary model of the Seine estuary which
was entrusted to ARTELIA after a European call
for proposals, its purpose being on the one hand
to understand the changes better and secondly
to study what additional developments might be
considered in order to improve the effectiveness
of the developments made to date.
4.1.2. Monitoring the Biological Resources of the
Estuary
Preceded by overviews of existing knowledge in
1994-1995, scientific monitoring of the biological
resources in the estuary began before the construction work in order to have an initial situation
report with which to establish a reliable baseline
on the one hand and on the otherhand a diagnosis as relevant as possible on the impacts of the
project.
Benthic species
The monitoring of benthic species involves three
components: the intertidal benthos, the subtidal
benthos and the suprabenthos.
Monitoring of the intertidal benthos is performed
in conjunction with the Maison de l’Estuaire, which
is in charge of managing the Nature Reserve. As
part of Port 2000, since 2002, a campaign has
been carried out in September each year on eight
radial sectors located on either side of the Pont de
Normandie.
Monitoring of the subtidal benthos was entrusted
to the Normandy Coastline Monitoring Unit, two
campaigns per year (in September and March)
having been conducted since 2002, after an initial
situation report done in 2001.
Monitoring of the suprabenthos was initially carried out by the laboratory of the Wimereux Marine Station and Caen University. Initiated in 2001,
two campaigns per year took place until 2006,
but given the absence of any significant changes
169
in the suprabenthic species, the following campaigns took place in 2011-2012.
an inventory, carried out with the help of the Normandy Ornithological Group.
The analysis of the changes in benthic species
confirms the increasingly maritime nature of the
northern trench of the Seine estuary.
Since 1999, data are routinely acquired by the
bird observatory set up by the Maison de l’Estuaire
in conjunction with the Boucles de la Seine Normandy Nature Park. The operations are partially
financed by Port 2000 funding reserved for scientific monitoring. They include systematic monitoring
of the most interesting species, mainly based on
monthly readings for the entire Seine estuary with
more detailed observations on the facilities provided for birdlife (dune bird resting area and the
resting island). The data thus acquired also serve
as input for national statistics on the observation
of birdlife.
Fishery Resources
Given the major impact that Port 2000 might have
had on commercial fishing activities, the first annual monitoring of fish nurseries was entrusted to
IFREMER in 1995 long before any work in the Estuary. After consultations with professional fishermen, monitoring of the fishery resources was
increased from 2000 onwards. The Normandy
Coastline Monitoring Unit has carried out between
6 and 8 campaigns every year since June 2000.
Each campaign involves 32 research trawls covering the whole of the estuary. It is supplemented by
specific fisheries in the run-off channels that constitute related intertidal habitats of interest to certain species of the juvenile fish (sea bass, flounder,
smelt, etc.).
The variations in fish populations observed differ
according to the species concerned and range
within the classic inter-annual oscillations observed
on other sites that have not been subject to construction work.
Over and above the evaluation of the impact of
construction work on Port 2000, these monitoring
operations have also improved knowledge on the
one hand of shrimp cycles in the Seine estuary,
and on the other that of the role of all the small
rivers in the estuary for certain species of juvenile
fish such as bass. In addition, by starting to have a
long chronological series of observations (of more
than ten years) it is possible to highlight correlations with multi-annual kinetic phenomena.
Faced with the need for as accurate an estimation
as possible of the impact of Port 2000 on professional fishing, in addition to the scientific monitoring of the resources mentioned above, monitoring
systems on economic fishing issues have also been
implemented. For example, in close conjunction
with local fishing committees in Le Havre and Honfleur-Courseulles and under the aegis of the Directorate-General for Maritime Affairs and Fisheries, a
system for collecting catch data was introduced
in 2000. In view of its relevance especially for professional fishermen, the system originally intended
to last the same period as the construction work,
i.e. until 2005, was initially extended until 2011 and
then again until 2015.
Birdlife in the Estuary
Sparse data on birdlife in the estuary existed prior
to 1995, and so the Port of Le Havre Authority entrusted the Andrews firm of consultants in 1995 with
170
4.1.3. Monitoring of Protected Species
on Land
An inventory of the species of flora and fauna in
the area concerned by the future Port 2000 terminals was completed in 2001. Noteworthy results included the presence of protected species of amphibians (Natterjack toad and Common parsley
frog) and plants (Liparis loeselii, Oxtongue Broomrape, seakale – ‘Crambe maritima’).
For the amphibians, before any work began, it was
decided and authorised to capture and then release the amphibians on sites safe from any development. Scientific monitoring of the success of the
operations was carried out for three years by the
LBPA of the University of Savoie, making it possible
to assess the development of the species transferred and to acquire further knowledge about
the behaviour of these animals. The monitoring
showed that on two of the three sites selected, the
transferred individuals were still present. Since this
initial monitoring, other operations were undertaken over the period 2009-2011 by Fauna Consult to
have a vision of the development of the species
still present in large numbers in the port area and
that their state of health is good.
For plant species, the main management and
scientific monitoring measures involved the Preserved Area except for the ‘Crambe maritima’,
which was replanted on the ecological beach.
Implementation of the management action plans
for the Preserved Area was entrusted to the Maison
de l’Estuaire and to the Bailleul National Botanical
Conservatory. Within that framework, since 2001,
the botanists at the Conservatory have been entrusted with managing sectors in which the Liparis
Loesel orchid grows (a plant protected at the European level). For example, in the autumn of 2004,
they began experimental digging in these sectors
in order to promote soil moisture, a crucial factor
for the survival of this wetland plant. At the end
of 2003, the same botanists planted a protected
species, Oxtongue Broomrape, in the Preserved
area, to ensure its preservation outside the areas
affected by Port 2000. Annual monitoring is undertaken to examine the dynamics of the species
and guide management actions.
5. CONCLUSION
5.1. Scientific Monitoring as a Means for
Dialogue and Consultation
The quality of the scientific monitoring carried out
before the start of the construction work on Port
2000 was necessary to have a satisfactory situation report integrating the multi-annual variations
of the various parameters monitored. Recognition
of the quality of the initial data is important, first in
order to correctly understand the impact of Port
2000 and secondly, to facilitate the dialogue between the contracting authority and the various
stakeholders involved, because only quality data
enables consultation based on mutually recognised objective facts rather than on more or less
properly-substantiated assumptions. For that quality to be recognised, the methodologies used require validation by parties other than the project’s
proponents.
addition, it was considered absolutely vital both
from a purely scientific point of view and from the
financial point of view, on the one hand that the
scheduling of scientific monitoring operations be
conducted in line with other scientific monitoring
programmes existing in the same region, and on
the other hand, that they have the benefit of a
multidisciplinary scientific structure capable of assessing and adapting them in accordance with
the results observed.
For these various reasons, this type of scientific
monitoring of the impacts of facilities must be set
up from the start as a partnership approach in order to share the costs and exchange the knowledge acquired on a sustainable long-term basis.
With this in mind, the provision of data acquired
must be based on partnerships with organisations
such as Scientific Public Interest Groups (the Seine
Aval public interest group in our case) or a Regional Biodiversity Observatory.
5.2. Scientific Monitoring as a Basis for
Adaptive Management
Carrying out port construction work and environmental projects at the same time was one of the
major technical difficulties in Port 2000, since all of
them had to be studied, selected and implemented in order to minimise the impact of port activities
on the estuarine environment. The scientific monitoring operations carried out during construction
work and more particularly those concerning the
changes in the riverbeds have made a significant
contribution to the optimisation of project management. Similarly, the scientific monitoring operations carried out to assess the effectiveness of
the environmental work are essential in order to
develop adaptive management strategies, because ecological engineering is not as exact a
science as port engineering and it should always
be possible to adapt the facilities on the basis of
the observations performed.
5.3. Scientific Monitoring as a Sustainable
Partnership Approach
The scientific monitoring associated with Port 2000
was originally scheduled to last a maximum of 10
years. Because of the estuarine dynamics, the
multi-annual variations observed and the difficulty
in interpreting certain evolutions, it was considered necessary to maintain the monitoring longer
than the initial ten-year period. In addition, the
data acquired during the monitoring of the facilities associated with Port 2000 proved to be useful
to other stakeholders, whether scientific or not. In
171
SUMMARY
Port 2000, which is a large-scale extension of the
port of Le Havre with 4.2 km of quay dedicated
to container traffic, included significant environmental measures (€ 50 million). With input from the
scientists working on the river Seine estuary, a vast
programme was drawn up of scientific surveys in
the areas affected by Port 2000 and its environmental measures. Focusing on consistency and
knowledge sharing, the programmes were defined in conjunction with the Scientific Council of
the Seine Estuary, which also helps interpret the
results. The main topics followed up include the
hydro-sedimentary dynamics of the Seine estuary,
its biological resources and protected species.
The scientific surveys were seen to be essential as
a means of constituting a solid basis for cooperation with the various stakeholders in the Estuary,
and needed in order to adjust the facilities with respect to the results obtained and the requisite objectives. Initially scheduled for a ten-year period, it
has been decided to extend the programme and
develop partnerships with scientific groups in order
to share and further the knowledge acquired.
RESUME
Port 2000, importante extension du port du Havre
(4,2 km de quai dédiés au trafic conteneur) a intégré des mesures environnementales conséquentes
(€ 50 millions). Avec l’aide de scientifiques travaillant sur l’estuaire de la Seine, un important programme de suivis scientifiques dans les domaines
sur lesquels Port 2000 et ses mesures environnementales ont des impacts a été élaboré. Dans un souci
de cohérence et de partage des connaissances,
la définition de ces programmes a été faite en
lien avec le Conseil Scientifique de l’Estuaire de
la Seine qui concourt aussi à l’interprétation des
résultats. Les principales thématiques suivies sont:
la dynamique hydro-sédimentaire de l’estuaire de
la Seine, les ressources biologiques estuariennes et
des espèces protégées terrestres.
Les suivis scientifiques sont apparus essentiels pour
constituer des bases solides de concertation avec
les différents acteurs de l’Estuaire et nécessaires
pour pouvoir adapter les aménagements faits au
regard des résultats observés et des objectifs recherchés. Initialement programmé sur 10 ans, il
est apparu utile d’aller au-delà de cette durée et
de développer les partenariats avec les groupements scientifiques pour mutualiser et consolider
les différentes connaissances acquises.
ZUSAMMENFASSUNG
Bei dem Projekt „Hafen 2000“ handelt es sich um
eine großräumige Erweiterung des Hafens von
Le Havre mit einem 4,2 km langen Kai für Containerschiffe, das zudem bedeutende Umweltschutzmaßnahmen (50 Mio. €) beinhaltet. Mit Hilfe von
Wissenschaftlern, die im Mündungsgebiet der
Seine arbeiten, wurden umfangreiche wissenschaftliche Studien sowie Umweltschutzmaßnahmen für die betroffenen Gebiete erarbeitet. Mit
Schwerpunkt auf Konsistenz und Wissensaustausch
wurden die Programme zusammen mit dem Wissenschaftsrat für die Seine-Mündung (Scientific
Council of the Seine Estuary) definiert, der auch
dabei helfen wird, die Ergebnisse zu interpretieren.
Die Hauptthemen, die verfolgt werden, sind die
172
Hydro-Morpho-Dynamik im Seine-Ästuar, dessen
biologischen Ressourcen und die dort geschützten Arten.
Die wissenschaftliche Begutachtung wurde für
notwendig erachtet, um eine solide Basis für die
Kooperation mit den verschiedenen Akteuren im
Seine-Ästuar aufzubauen und um die Raumplanung an die gewonnenen Ergebnisse und die
gesetzten Ziele anzupassen. Es wurde beschlossen, das ursprünglich für 10 Jahre vorgesehene
Programm auszudehnen und Partnerschaften mit
wissenschaftlichen Gruppen aufzubauen, um das
erlangte Wissen zu teilen und zu erweitern.
L’AMBITION D’UNE STRATéGIE NATIONALE POUR LES
TRANSPORTS MARITIMES ET fLUVIAUx EN fRANCE
RéPONDANT AUx ENJEUx DE LA TRANSITION éCOLOGIqUE
ThE AMBITION fOR A MARITIME AND INLAND wATERwAY
TRANSPORT STRATEGY IN fRANCE AS AN ANSwER
TO ThE ChALLENGE Of ECOLOGICAL TRANSITION
JéRÔME MEYER
Chef du bureau de
l’analyse économique des
transports fluviaux et
maritimes et des ports
Tél.: +33 1 40 81 73 43
Fax: +33 1 40 81 72 90
E-mail: jerome-a.meyer@
developpement-durable.gouv.fr
THIERRY LAgADEC
Chargé d’études économiques,
bureau de l’analyse économique
des transports fluviaux et
maritimes et des ports
Tél.: +33 1 40 81 84 72,
+33 1 40 81 72 90,
E-mail: thierry.lagadec@
DIDIER BEAURAIN
Chef du bureau du transport
fluvial
Tél.: +33 1 40 81 13 22,
+33 1 40 81 72 90,
E-mail: didier.beaurain@
KEY WORDS: ports, waterways, strategy, infrastructures, services
MOTS-CLES: ports, voies navigables, stratégie, in-
frastructures, services
1. LA SITUATION DU TRANSPORT MARITIME ET FLUVIAL
HéLÈNE FREYTOS
Chargée d’études « Développement durable du
transport fluvial », bureau du transport fluvial,
Tél.: +33 1 40 81 22 36, Fax: +33 1 40 81 72 90,
BENJAMIN BOYER
Chargé d’études « Réglementation technique du
transport fluvial », bureau du transport fluvial
Tél.: +33 1 40 81 72 65, +33 1 40, Fax: 81 72 90,
gAUTIER HOUEL
Chargé de mission « Réforme des voies navigables »,
bureau des voies navigables,
Tél.: +33 1 40 81 87 73, Fax: +33 1 40 81 16 61,
YOANN LA CORTE
Adjoint au chef du bureau
des voies navigables
Tél.: +33 1 40 81 13 42
Fax: +33 1 40 81 16 61,
E-mail: yoann.la-corte@
developpementdurable.gouv.fr
EN FRANCE ET EN EUROPE
Depuis un demi-siècle environ, le volume du trafic
maritime mondial n’a cessé de croître. On observe
sur les dix dernières années un taux de progression
annuel en volume d’environ 4 %. Le développement des gains de capacité unitaire par navire a
favorisé la progression constante du tonnage des
marchandises transportées dans un contexte de
globalisation des échanges.
173
Le ‘rail du Nord’ européen est la deuxième façade maritime mondiale. De la mer du Nord à
l’océan Atlantique en passant par la Manche,
il s’agit de la principale interface maritime de
l’Europe. Il génère plus de 600 millions de tonnes
de trafic. Dominé par Rotterdam, le principal port
européen, Anvers et Hambourg, c’est la véritable
porte d’entrée de l’Europe.
La France était en 2010 la 6ème puissance mondiale exportatrice de marchandises et la 2ème
exportatrice mondiale de produits agricoles1. La
France compte aujourd’hui une quarantaine de
ports de commerce sur son territoire. Ces espaces
voués au transit de marchandises et de passagers concentrent des activités (industrie, logistique,
services) en constante relation avec le monde
extérieur.
Avec près de 360 millions de tonnes de fret dont
environ 50 % de vracs liquides et 13 % de marchandises conteneurisées traitées chaque année
dans les ports de commerce maritimes français, le
secteur portuaire français représente 5 % du trafic
mondial et 10 % du trafic européen. La France
compte deux ports parmi les 50 plus grands ports
mondiaux. Marseille et Le Havre sont placés aux
5ème et 6ème rangs européens en volume total de
marchandises traitées. Marseille est le 3ème port
pétrolier au monde, Le Havre est le 10ème port de
conteneurs en Europe et le port de Rouen le 1er
port céréalier d’Europe.
représente alors près de 90 % de l’ensemble du
transport fluvial européen. En France, le trafic fluvial est aujourd’hui concentré sur les voies navigables à grand gabarit. Le trafic fluvial sur le réseau
Freycinet est relativement faible et très concentré
en certains points du réseau. En tonnes transportées, le bassin de la Seine génère plus de la moitié
du trafic fluvial français. Le bassin du Rhône et de
la Saône se place en deuxième position, suivi de
la partie française du bassin rhénan (Source: Voies
navigables de France, 2011).
2. LE DEVELOPPEMENT DES
INFRASTRUCTURES FACE AUX
ENJEUX DU XXIème SIECLE
Les premiers ports français disposent d’infrastructures de qualité et capables (tirant d’eau, longueur
des quais, nombre de poste à quai) d’accueillir et
traiter tous les types de navires, même les porteconteneurs de toute dernière génération. Ils sont
équipés d’outillages modernes régulièrement renouvelés permettant de garantir un taux de productivité au-dessus de la norme internationale.
La France dispose également d’infrastructures de
transports terrestres de qualité. Les réseaux routiers
et ferrés français couvrent l’ensemble du territoire
et connectent la France à tous ses voisins européens. Néanmoins, les ports français ne bénéficient pas encore tous de connections optimisées
aux réseaux fluviaux desservant leurs hinterlands
(gabarit inadapté, hauteur des ponts, fonctionnement des écluses…).
Les efforts en matière d’infrastructures portent par
conséquent en priorité sur la desserte des ports
ainsi que sur la régénération et la modernisation
du réseau fluvial.
2.1. Privilégier les dessertes terrestres des
arrière-pays portuaires
Fig. 1: Transport de granulats par voie fluviale sur
la Seine (© Laurent Mignaux/METL-MEDDE)
De son côté, le transport fluvial ne représente
que 6 % en tonnes kilomètres des transports terrestres en Europe. L’activité du transport fluvial
est concentrée sur le bassin du Rhin qui constitue une infrastructure naturelle performante à
l’embouchure duquel se trouve Rotterdam, premier port maritime européen qui dessert de vastes
territoires industriels (la Ruhr, …). L’Allemagne et
les Pays-Bas réunis représentent près de 75 % de
l’ensemble du transport fluvial européen. Si l’on
ajoute le transport fluvial belge et français, le total
1
174
Le réseau routier français regroupe autour d’un
million de kilomètres de voies diverses. La route
représente près de 90 % des marchandises transportées sur le territoire français en tonnes kilomètres. Elle est appréciée pour sa flexibilité et sa
fiabilité et a bénéficié d’un fort développement
de ses infrastructures. Elle est par ailleurs très compétitive. Depuis 1985, les prix du transport routier
ont diminué de 30 %.
Le réseau ferré est lui-aussi très dense. RFF (Réseau
Ferré de France), gestionnaire de l’infrastructure
ferroviaire française, gère près de 30.000 kilomètres de lignes sur lesquelles circulent chaque
jour 15.000 trains de fret et de voyageurs. Ses lignes
OMC: Statistiques du commerce international 2011/Analyse spatiale du trafic des échanges de marchandises des GPM français
desservent l’ensemble des pays européens limitrophes.
Le réseau national de pipelines transporte le pétrole brut ou ses multi-produits (essence, kérosène,
gazole, fioul domestique) et approvisionne les territoires français et européens.
Le développement des modes massifiés et de
l’offre logistique associée nécessite d’améliorer les
connexions entre les ports et les réseaux fluviaux et
ferroviaires, pour une meilleure compétitivité des
modes massifiés.
Le gouvernement français a demandé d’intégrer
la modernisation et la fiabilisation des dessertes
des ports dans la stratégie des gestionnaires
d’infrastructures ferroviaires et fluviales. Définissant
les grandes orientations nationales d’infrastructures
de transport pour moderniser et fiabiliser les dessertes des ports, le gouvernement s’assure que
les dessertes des ports deviennent bien prioritaires
pour développer les modes massifiés.
renouveau de la voie d’eau, quelque peu oubliée
dans la première moitié du XXème siècle, s’impose
comme une nécessité. L’État créé l’établissement
public Voies navigables de France en 1991, sous
l’impulsion du Premier ministre Michel Rocard, et
lui confie en gestion la majeure partie du domaine
public fluvial. Un peu plus de 20 ans après la création de l’établissement, la voie d’eau française
continue, malgré le contexte de crise économique
actuel, à gagner des parts de marchés. Entre 2000
et 2010, la part modale du fluvial évolue favorablement, de 3,4 à 4,3 % (Source: Eurostat).
Cet effet, qui s’explique en partie par le rattrapage des investissements, se poursuit et contribue
notamment aux objectifs de l’État en matière de
transition écologique et énergétique. Ainsi, la voie
d’eau française a vocation à se développer et à
s’imposer comme un mode de transport massifié,
économiquement pertinent, bénéficiant d’un réseau modernisé et géré comme un véritable système industriel.
Afin de répondre à ces enjeux stratégiques, l’essor
du transport fluvial repose aujourd’hui sur la régénération et la modernisation du réseau des voies
navigables, ainsi que sur le développement commercial de la voie d’eau. C’est pourquoi, répondant aux objectifs de report modal en accompagnant le développement du trafic fluvial et assurant
la sécurité des usagers et des agents, l’Etat et Voies navigables de France (VNF) ont construit, dans
le cadre du projet ‘Voies navigables 2013’, un
programme d’investissement sur cinq ans, visant
à régénérer, mettre en sécurité et moderniser le
réseau.
Fig. 2 : Transport multimodal, trains chargés de
conteneurs au port du Havre
(© Laurent Mignaux/METL-MEDDE)
2.2. Régénérer et moderniser le réseau
fluvial
Le réseau navigable français s’étend sur environ
8.300 km. L’État est propriétaire de la plus grande
partie de ce réseau, mais celui-ci est placé sous la
responsabilité de plusieurs gestionnaires.
Depuis le 1er janvier 2013, Voies navigables de
France gère la majeure partie de ce réseau (6.740
km), la Compagnie nationale du Rhône et l’État
en gérant respectivement 500 km et 400 km.
Une partie du domaine public fluvial a été transféré par l’État aux collectivités territoriales lors
d’une première vague de décentralisation dans
les années 1990.
Avec l’émergence des préoccupations écologiques en France au milieu des années 1980, le
Le contrat d’objectifs et de performance entre l’État et VNF, pour la période 2011-2013, constitue la première phase de réalisation de ce
programme. Il se décline en actions de mise en
sécurité et de remise en état du réseau pour garantir des niveaux de fiabilité et de disponibilité du
service et des itinéraires. Il prévoit également de
passer d’une maintenance curative des ouvrages
et des infrastructures à une maintenance préventive, pour fiabiliser le niveau de service.
Sur le réseau à grand gabarit, l’État a fixé à VNF
des objectifs d’ouverture 24h/24, comme le font
déjà nos voisins du Nord, avec une navigation libre
toute l’année sur le réseau connexe à ce grand
gabarit, sur la base de douze heures par jour, sept
jours sur sept. Sur le réseau touristique, une offre
de service sera mise en place qui tiendra compte
de la saisonnalité de ce secteur et des besoins
des différents usagers. Le contrat d’objectifs et
de performance comprend enfin des opérations
de développement sur le réseau à grand gabarit,
dans une vision positive de l’évolution du réseau
et en vue des objectifs de report modal vers la
voie d’eau.
175
Ce programme d’investissement présente également un volet consacré à la modernisation des
méthodes d’exploitation et contribuera à mieux
adapter l’offre de service aux besoins des usagers
et à l’évolution des trafics français et européens et
à supprimer les situations de travail pénibles ou exposées, notamment sur les ouvrages manuels, et
optimiser les moyens nécessaires à l’exploitation
par l’automatisation, la télécommande et la
centralisation de l’exploitation des ouvrages ainsi
que par le déploiement progressif des services
d’information fluviale.
L’État a fixé des objectifs de mise en conformité environnementale, par la réalisation
d’aménagements liés aux enjeux de biodiversité,
de qualité de l’eau et de restauration des continuités.
Fig. 3 : Chantier d’aménagement d’une écluse
sur la Meuse
Cet effort s’ajoute au plan de relance portuaire,
qui comprend un volet consacré à l’amélioration
de la desserte fluviale de nos ports.
3. LES NOUVELLES
TECHNOLOGIES AU
SERVICE DU DEVELOPPEMENT
DURABLE DE LA TRANSITION
ECOLOGIQUE
Le développement de l’activité fluviale et maritime doit non seulement être porté par des infrastructures de qualité, mais aussi contribuer à des
transports plus performants et plus respectueux
de l’environnement. Pour réduire les émissions et
la consommation d’énergie, la modernisation de
la flotte et le développement de carburants alternatifs, comme le GNL, pour les bateaux et les navires passent par des innovations technologiques.
3.1. Moderniser la flotte fluviale
En France, le plan de déchirage, intervenu dans
176
les années 1990, a permis de restructurer le marché et de le préparer à la libéralisation intervenue
en 2000. Depuis, la flotte française augmente en
productivité en conservant la même capacité
d’emport (un million de tonnes avec un nombre
plus réduit de bateaux). Les plus petits bateaux
(Freycinet) sont remplacés par des bateaux de
1.000 à 1.500 tonnes qui desservent les bassins
fermés du réseau à grand gabarit français. Ces
bateaux sont souvent achetés d’occasion aux
Pays-Bas ou en Belgique. Dans ces deux pays en
effet des investissements massifs ont eu lieu depuis
2005 dans des unités neuves et de grande taille
(jusqu’à 3.000 tonnes).
La France considère que pour que le mode fluvial demeure une alternative au transport routier,
il est nécessaire de poursuivre, voire d’accélérer,
l’adaptation et le renouvellement de la flotte en
vue:
• de répondre aux besoins des chargeurs. Ainsi de
nouveaux bateaux Freycinet (la flotte Freycinet
actuelle a environ 60 ans de moyenne d’âge)
doivent être construits afin de maintenir la desserte du réseau à petit gabarit ; des grands bateaux modernes doivent arriver sur le marché
(entre 1.000 et 1.500 tonnes) afin que le transport fluvial poursuive les économies d’échelle.
• De répondre aux enjeux environnementaux. Il
s’agit de limiter les émissions des moteurs dont
la longévité ne permet pas rapidement de
passer aux nouveaux standards. Il convient de
travailler sur la conception des coques et des
moteurs afin de limiter la consommation en
énergie.
Dans le cadre d’une gestion modernisée du réseau et d’une meilleure gestion du trafic, la France
poursuit le déploiement des services d’information
fluviale et notamment incite les entreprises ayant
équipé leur bateau avec un transpondeur AIS à
installer des équipements d’aide à la navigation
afin que le système soit pleinement opérationnel
(lecteur de carte ECDIS, GPS).
Un plan d’aide à la modernisation de la flotte fluviale a donc été mis en œuvre par le gouvernement français et VNF pour la période 2008-2012
doté d’un montant de € 16,5 million. Un projet
de plan couvrant la période 2013-2017 vise plus
particulièrement à favoriser l’achat de bateaux
ou moteurs neufs ou modernes répondant à des
standards environnementaux stricts, allant au-delà des normes en vigueur.
Plusieurs solutions technologiques sont aujourd’hui
envisagées pour développer de nouveaux bateaux fluviaux et adapter les motorisations de la
flotte existante pour en particulier réduire les émissions de polluants tels que les oxydes d’azote et
les particules fines.
Tout comme dans le secteur maritime, la propulsion
au gaz naturel liquéfié s’expérimente. Toutefois, si
cette solution est pertinente pour la construction
d’unités neuves, d’autres solutions technologiques
doivent être adaptées pour la flotte existante, en
particulier pour la ‘flotte petit gabarit française’.
Pour ces bateaux, l’installation de moteurs dieselélectrique fait aujourd’hui l’objet d’une attention
particulière, au regard des gains sur la consommation, de la réduction des émissions polluants locaux avec des moteurs à régime constant, et une
meilleure gestion de la puissance motrice suivant
les secteurs de navigation.
L’évolution du cadre réglementaire devrait en
outre contribuer à ce processus de modernisation
de la flotte. La Commission européenne envisage
en effet de réviser la directive 97/68/CE relative
aux mesures à prendre contre les émissions de gaz
et de particules polluants provenant des moteurs
à combustion interne destinés aux engins mobiles
non routiers.
Fig. 4 : Transport fluvial sur la Seine
100 % des particules, de 80 % des oxydes d’azote
et de 25 % de dioxyde de carbone.
Selon certaines études (Autorité maritime danoise,
TRI ZEN), le prix de ce carburant serait néanmoins
supérieur au fioul lourd mais inférieur au gasoil
marin, ce dernier étant, à l’heure actuelle, 40 à
50 % plus cher que le fioul lourd. Le prix du GNL
serait également moins sensible aux variations des
cours du pétrole comparé à celle des carburants
traditionnels. La flotte mondiale de navires propulsés au GNL est donc en constante progression, et
pourrait atteindre au moins 1.000 navires alimentés en GNL vers 2020. Un saut majeur est intervenu avec la mise à flot du ‘Viking Grace’, ferry de
croisière, alimenté au GNL, opérant en mer Baltique entre la Finlande et la Suède. Le volume de
consommation du GNL comme carburant marin
est en augmentation et devrait atteindre 4 à 5 millions de tonnes en 2020 (Source: DNV).
Le passage au GNL va au-delà d’un simple
changement de carburant marin. Il implique la
création d’une nouvelle filière industrielle pour
concevoir et fabriquer les installations spécifiques de soutage et le développement des activités de construction navale, qui se traduit par
l’adaptation des motorisations ou la construction
des unités neuves. Ce qui représente des perspectives non négligeables pour les chantiers navals.
Cette nouvelle filière industrielle doit s’appuyer sur
des domaines d’excellence en ingénierie comme
la conception de citerne et de réservoirs mais aussi de systèmes de soutage. Ce nouveau carburant
peut favoriser la construction de navires neufs et
relancer ainsi la construction navale.
3.2. Développer l’avitaillement des
navires au GNL
Avec l’entrée en vigueur de l’annexe VI de la convention MARPOL à l’OMI au 1er janvier 2015, les
navires devront réduire leurs émissions de soufre
en Manche, en mer du Nord, en mer Baltique et
le long des côtes des États-Unis d’Amérique et du
Canada. L’emploi des carburants marins traditionnels, comme le fioul lourd (HFO), ne répond pas à
cette nouvelle réglementation. Des solutions techniques sont nécessaires à mettre en œuvre pour
développer le transport maritime en respectant
l’environnement. Des solutions alternatives existent en effet tel que l’utilisation de filtres, appelés
scrubber, l’emploi du gasoil marin ou du gaz naturel liquéfié (GNL).
Selon l’OMI et l’Union européenne, l’emploi du GNL
constitue une réponse particulièrement adaptée
et innovante aux futures normes environnementales, parce que ce carburant répond excellemment à l’ensemble des conditions posées par les
textes de l’OMI et communautaires. Ainsi, par rapport au fioul lourd, le GNL entraîne une réduction
de 100 % des émissions de dioxyde de soufre, de
Fig. 5 : Ferry manœuvrant dans le port de Marseille
4. L’AMBITION D’UNE
STRATEGIE NATIONALE
POUR LES TRANSPORTS
FLUVIAUX ET MARITIMES
Le développement des transports fluviaux et maritimes s’inscrit dans une vision stratégique qui porte
sur la qualité des services rendus.
177
4.1. La réforme de Voies Navigables
de France
Depuis sa création en 1991, le principal gestionnaire de la voie d’eau, Voies Navigables de
France, bénéficiait, pour la réalisation de ses missions, de l’appui des services de navigation de
l’État et de certaines directions territoriales de
l’État, qui étaient mis à sa disposition.
Toutefois, cette organisation ne permettait pas
d’assurer une continuité du service optimale
sur l’ensemble du réseau ou encore d’optimiser
l’allocation des moyens.
Face à ce constat, le législateur a voulu regrouper la collectivité de travail dans un seul et unique
établissement, placé sous l’autorité d’un directeur général disposant de tous les leviers d’action
nécessaires à la réalisation de ses missions.
Ainsi, la loi du 24 janvier 2012, votée à l’unanimité
en deuxième lecture au Sénat, regroupe depuis le
1er janvier 2013, au sein d’un même établissement
public administratif, les 4.400 agents des services
déconcentrés de l’État et les 400 salariés de droit
privé de VNF.
Ce rapprochement permet au nouvel établissement d’instaurer une véritable communauté de
travail et de maîtriser la totalité des moyens indispensables à son action.
Ce rapprochement permet également au nouvel
établissement public d’améliorer son organisation
territoriale. Par exemple, VNF prépare actuellement avec le soutien de l’État, la création d’une
7ème direction territoriale en Bourgogne, en lieu
et place de trois anciens services. Cette nouvelle
organisation qui est entrée en vigueur le 1er janvier 2013, permet à l’établissement, sur le territoire
concerné, de gagner en efficacité et d’avoir une
capacité d’action plus réactive et plus homogène
sur le réseau.
En outre, de nouveaux leviers d’action sont également donnés à VNF pour lui permettre de mieux
valoriser son domaine et de trouver de nouvelles
ressources à consacrer à la restauration du réseau.
4.2. La relance portuaire nationale
Avec la mise en œuvre de la réforme portuaire
de 2008, le transfert de l’outillage et du personnel
aux opérateurs privés s’est achevé en juillet 2011
et la fiabilité des places portuaires françaises s’est
améliorée. Les grands ports maritimes ont retrouvé
les moyens d’une saine compétition avec les autres ports leaders européens.
Le gouvernement affirme son ambition pour
178
l’ensemble de son système portuaire, afin de donner à la France une place de premier rang dans
le commerce international comme point d’entrée
ou hub européen, et pour contribuer au développement industriel, économique et social du
pays.
Situés à l’interface de routes maritimes et de
réseaux de transports multimodaux, les ports
français sont au cœur de la chaîne logistique
d’approvisionnement des territoires. Ils ont vocation à accueillir les multiples activités dans les secteurs logistique et industriel, notamment dans le
secteur énergétique ou sur les filières industrielles
d’avenir.
A ce titre ils concilient ambition logistique, industrielle et aménagement, dans un souci d’excellence
environnementale.
Les ports français sont des ‘architectes’ de solutions logistiques maritimes et terrestres sur un hinterland de portée européenne. Pour cela, les
ports se positionnent comme des coordonnateurs, démontrant une forte valeur ajoutée dans
la mise en place de chaînes logistiques intégrées,
économiquement compétitives et pérennes, favorisant les moyens massifiés, afin d’attirer et fidéliser les opérateurs et les clients.
Les zones portuaires sont, de par leur position
géographique, de véritables pierres angulaires du
développement industriel du pays. Les ports français ont vocation à devenir les lieux d’implantation
privilégiés d’activités industrielles et économiques
génératrices de trafics maritimes. Pour cela, ils ont
un besoin impérieux de maîtriser la gestion de leurs
espaces et de leurs capacités d’accueil.
Les ports français développent ainsi une approche
intégrée d’aménageur et de gestionnaire de leurs
espaces dans toutes leurs composantes: industrialo-portuaires, logistiques, naturels, sans négliger
l’interface ville-port, et ce en liaison avec les territoires. Les ports ont des responsabilités spécifiques
vis-à-vis de leur domaine naturel, responsabilités
qu’ils exercent, le plus souvent, en partenariat.
Ils s’attachent à une meilleure prise en compte
des enjeux environnementaux dans le respect de
leur juste équilibre avec les enjeux économiques,
équilibre dont l’État est le garant.
Pour mettre en œuvre cette ambition, les ports
peuvent s’appuyer sur plusieurs leviers : la politique
d’investissements priorisant les projets générateurs
de croissance, d’emploi et d’innovation, la promotion du dialogue social sur la place portuaire,
la valorisation des actions en matière de sécurité
des personnes et de sûreté, le développement des
compétences, l’influence du système portuaire
français au niveau européen, le développement
d’une marque forte et commune.
En présentant une stratégie globale pour les modes
massifiés, le gouvernement fixe ainsi un cap ambitieux pour développer les transports maritimes et
fluviaux et répondre aux enjeux d’une nécessaire
transition écologique.
Fig. 6: Porte-conteneurs à quai dans le port
industriel du Havre
SUMMARY
Although they have been boosted by a strong
growth of maritime and inland navigation transport, ports and inland waterway development will
only be achieved with high-level engineering and
cutting-edge technology as answers to the social,
environmental and economic challenges of the
XXIst century. This development should be supported by quality infrastructures and must foster more
efficient transports contributing to the inevitable
ecological transition. The fleet must be upgraded
and boats and ships should use alternative fuels in
order to reduce emissions and energy consumption, but for that, technological innovations are
still required. These developments are part of the
strategic vision of the services to the community
by high-volume transports.
RESUME
Dynamisés par des croissances fortes des transports
fluviaux et maritimes, les ports et les voies navigables ne peuvent se développer qu’avec l’appui
d’une ingénierie de haut niveau et de technologies de pointe pour répondre aux multiples défis
sociaux, environnementaux et économiques du
XXIème siècle. Ce développement doit être porté
par des infrastructures de qualité et contribuer à
des transports plus performants, prenant toute leur
part à la nécessaire transition écologique. Pour
réduire les émissions et la consommation d’énergie,
la modernisation de la flotte et le développement
de carburants alternatifs pour les bateaux et les
navires requièrent encore de nombreuses innovations technologiques. Ces développements
s’inscrivent dans une vision stratégique des services rendus par les transports massifiés à la société.
ZUSAMMENFASSUNG
Obwohl es starkes Wachstum im See- und Binnentransport, bei den Häfen und den Binnenwasserstraßen gegeben hat, kann eine weitere Entwicklung nur mittels hoher technischer Standards und
Spitzentechnologien erreicht werden, als Antwort
auf die sozialen, ökologischen und ökonomischen
Herausforderungen des 21. Jahrhunderts. Diese
Entwicklung sollte durch qualitativ hochwertige Infrastruktur unterstützt werden und muss zu einem
leistungsfähigen Transport beitragen unter Berück-
sichtigung, dass ein ökologischer Übergang notwendig ist. Die Flotte muss verbessert werden und
die Boote und Schiffe sollten alternative Brennstoffe verwenden, um die Emissionen und den Energie-verbrauch zu reduzieren; aber um das zu
erreichen, sind noch zahlreiche technische Innovationen erforderlich. Diese Entwicklungen sind
Teil einer strategischen Vision von Dienstleistungen, durch den Gütertransport für die Gesellschaft
übernommen.
179
180
The Rhone Traffic Management Centre
Centre de gestion du trafic du Rhône
PIERRE EMMANUEL PAREAU
ROMAIN BARTHELET
Head of Maintenance and New Projects Department
Compagnie Nationale du Rhône
2 rue André Bonin - 69316 Lyon Cedex 04
France
Tél: +33 (0)4 72 00 69 65
Responsible of Automatic Systems Division
Compagnie Nationale du Rhône
2 rue André Bonin - 69316 Lyon Cedex 04
France
Tél: +33 (0)4 72 00 68 88
KEY WORDS: locks, remote control, traffic man-
agement
MOTS-CLES: écluses, téléconduite, gestion du
trafic
Fig. 1: CNR’s
developments
on the Rhone
181
1. THE RHONE-SAONE
CORRIDOR,
A MEDITERRANEAN ARTERY
The Rhone has been developed by the Compagnie Nationale du Rhône in the framework of a
concession with the threefold objective of providing hydroelectricity production, navigation and irrigation.
The wide-gauge section of the Rhone is 330 km
long and permits the passage of multiple barge
convoys of 4,400 tonnes. It has a guaranteed
draught of 3 m and a head clearance of 6.30 m.
In this context, the Port of Lyon EdouardHerriot provides a good illustration: the volume of river traffic
handled by the port has risen by more than 7 %
over the year (compared to a fall for the basin)
and it is heavily involved in container transport
(+19 %). Thus, it forms the bridgehead and hub for
river traffic, with an interesting and promising outlook for modal changes.
However, traffic can only develop sustainably
through attracting new clients and new transport.
In 2011 river traffic amounted to 5.8 million tonnes
for a flow of 1,300 million tonnes x km. North of
Lyon, the Rhone is prolonged by the Saone river
which also allows the passage of wide gauge vessels. Together they provide a navigable waterway
more than 500 km long that serves the major industrial and agricultural regions of southern and
eastern France.
Changing logistic organisation and bringing new
entities into the basin require considerable investments.
Since the Saone and Rhone flow into the Mediterranean, their natural outlets are the ports of Marseille and Sète, the latter being linked to the river
by the Rhone canal. Nearly half (about 45 %) of
the traffic using the basin passes via one of these
two seaports, though Marseille-Fos outweighs Sète
in terms of volume.
The arrival of new modern and high capacity units
in recent years is proof of this confidence.
This highlights the importance of having a competitive maritime interface for the stakes of river development. However, taking this example alone, one
out every two containers passes via the ports of
northern Europe, thus avoiding the Rhone, whereas our ports on the Mediterranean are obviously
the natural points of entry for these containers.
To this end, CNR started to implement a plan in
2004 that focuses on the following actions:
The port reform set up in 2011 is therefore crucial
for accelerating modal transfer from road to waterway. Its deployment over the past year has
been encouraging for container traffic, which has
increased at an annual rate of nearly 10 % since
April 2011.
If other types of traffic are not as dynamic, we think
that it probably due to the gloomy economic climate and the resulting contraction in key sectors,
such as the construction and automobile industries. What is more, salt consumption was low during the winter of 2012 while cereal exports suffered
a downturn, explaining the reduction of traffic in
2012 and putting an end to a decade of growth.
Nonetheless, there is a bright side. Although it is
too early to predict a general resumption of activity, container traffic could set the example with
modal transfer; port reform also promises positive repercussions, even though confidence can
182
only be built through time. Lastly, the creation of
a Rhone-Saone ports committee, in addition to
the impetus provided by the government, should
boost modal transfer.
The confidence that skippers and transporters are
able to place in the waterway operator and in its
capacity to stand by its commitments in the longterm is a decisive factor for success.
As the operator of the navigable waterway of the
Rhone, CNR is bound to strengthen its commitment
to modernise navigation, a process that began in
2003 following the signature of its new contract.
➢Improving lock reliability
➢Commissioning a user information system (Inforhone.fr), producing ECDIS charts
➢Constructing new infrastructures (mooring
points, a container terminal at Port de Lyon)
The recent growth in traffic and the outlook for development highlight the need to adapt to meet
the new challenges:
➢Increasingly strict security and regulations for
transport (monitoring hazardous substances, increasing numbers of passengers)
➢Providing information to users and monitoring
the passage of goods through the supply chain
➢An increased workload for locks (traffic doubled
from 1998 to 2009)
As part of its second five-year plan of Missions in
the General Interest, CNR must pursue its activities
in the following three areas:
➢Continue and speed up the lock upgrading and
reliability programmes
➢Traffic management, provide new services to
skippers and crews, by facilitating the growth in
traffic and by integrating new information technologies
➢Prolong opening hours for commercial vessels
(24h/24h)
Therefore, the Company has embarked on a project to ‘Upgrade the navigable waterway’ with the
aim of passing through different stages from ‘lock
operation’ to ‘traffic management’, by setting up
a traffic management and monitoring centre and
by speeding up the programme to upgrade and
increase the reliability of the locks.
The first component of this project was to set up
a Traffic Management Centre (CGN) whose long
term mission is to manage traffic in real time and
ensure remote control of the locks on the lower
Rhone 24 hours a day.
2. THE MAIN PRINCIPLES
Setting up the Rhone Traffic Management Centre
meets the need to improve the level of service
provided to the traffic and the need to optimise
the management of the navigable waterway and
the operation of the locks.
Managing the traffic on the river requires the
permanent acquisition of information on traffic
conditions, hydrometeorological conditions, the
availability of the structures, specific conditions
(warnings to the river traffic, incidents, damage,
etc.), the position of boats and the goods transported, in order to plan lock passages, supply in-
formation and guide skippers and crews.
Furthermore, the locks must be operated as efficiently as possible, in order to reduce waiting time
and filling lock chambers without boats.
Traffic management must gather, centralise and
analyse all the information required to control a
constantly evolving situation.
Operating the locks requires a dialogue with the
sailors, traffic forecasts, ordering boat passages,
starting and monitoring lock passages and filling
a database.
Therefore, traffic management and operating the
locks complement each other, while the tasks involves are common to both, especially the acquisition and diffusion of information and the organisation of passages.
The management involved permits evolving from
a fragmented view made up of each lock to a
global view of the section of river in question.
At the same time, the workload involved in managing, operating and monitoring changes as a
function of the overall situation, the density of traffic and external events.
Designing the organisation of these activities leads
to seeking a solution that:
➢achieves the reactivity required to adapt in
real-time
Fig. 2: Block diagram of traffic management
183
➢ensures the continuity of operations
➢guarantees the level of security, traffic safety,
personal safety and the security of property
is controlled alone due to the presence of a lift
bridge.
The telecontrol operator operates the lock according to the same procedures as they would if
controlling locally (control of cycles). They have
similar interfaces (the same control buttons) and
video and PA equipment to those used when operating from a control tower. The locks can also be
operated from the control towers.
The telecontrol project has been subjected to
safety studies and an experimental phase on two
locks. The telecontrol centre has ergonomically
designed controls and information that are the
same for all the locks.
Fig. 3: View of the new traffic management
software due for commissioning in 2013
3. THE PROJECT
ORGANISATION
The project is managed completely by CNR. The
CNR Operations Division is the client for the project: it sets out the objectives, the functions, follows
up the schedules for implementation and manages the global budget for the operation.
The CNR Engineering Division acts as design and
engineering manager for the project: it sets out
the general technical design and supervises development and implementation. It also builds the
SCADA and the automated systems.
The tasks of adapting the electric and control
and instrumentation systems, the development of
video and local communications management
software applications are outsourced to specialised companies and overseen by the CNR Design
Engineer.
4. PERIMETER AND
GENERAL PRINCIPLES OF
THE PROJECT
The perimeter of the project involves the fourteen
locks on the lower Rhone, including Port Saint Louis
and Barcarin which provide access to the port of
Marseille.
Every operator at the remote-control centre has
the technical capacity to operate any lock connected to the centre.
They can supervise two lock passages simultaneously, except for the lock at Port Saint Louis, which
184
Fig. 4: A lock supervision screen
The architecture of the equipment used at the
telecontrol centre is similar to that used for the
telecontrol of CNR’s hydropower plants and it is
based on an ABB micro-SCADA.
Communication is ensured via CNR’s existing computer network for both control and instrumentation
flows and video, sound, etc.
The telecontrol is adapted to existing systems. The
oldest have been modernised and new equipment has been deployed or adapted to the locks
to ensure telecontrol (video and interphone equipment, etc.) and satisfy the specifications of safety
and ergonomics studies.
The local adaptations of automation systems are
implemented:
➢without impeding or representing a risk for navigation: tests are performed on the platform and
during programmed stoppages of navigation
(in March);
➢with the minimum impedance for all the other actions that have to be performed on the
locks (civil engineering maintenance, mechanics, electrical renovation, etc.). This constraint
was taken into account when phasing deployment.
5. ORGANISATION AND
OPERATION OF THE RTMC
ate another lock or monitor a selection of locks.
5.1. Organisation
Defining the organisation of the river traffic management centre requires knowledge and taking
account of:
➢elements that characterise river traffic
➢tasks to be performed that stem from the mode
of operation adopted
Analysis of river traffic has highlighted substantial
seasonal variation, with the number of lock passages varying from 4,000 in January to 11,000 in
July.
Whatever the season, most of the traffic occurs
during the day as night-time traffic only makes up
13 % of the total.
The number of river traffic technicians is determined so that navigation is managed under the
same conditions as presently (in terms of lock passage time and monitoring). Therefore, number of
river traffic technicians remains the same throughout the year, even if there is less traffic from October to March, which could justify a lower workforce.
The number of technicians is set at 36 organised
in teams working in 3 eight-hour shifts or in 2 eighthour shifts.
Fig. 5: Telecontrol console
In case of system failure, all the locks can be controlled from their control towers, the switch to local
control is performed in less than 30 minutes.
6. OPERATING SECURITY
Operating security guarantees the safety of passengers and personnel and the reliability of the
structures is one of the keys of the success of the
lock telecontrol project.
This element was taken into account from the outset of design and will be until the new system is
commissioned.
A global approach has been adopted that is
based on:
➢monitor two selected locks (one selection per ½
workstation)
➢operate two locks (1 lock per ½ workstation)
➢they can operate a lock (on a ½ workstation)
and monitor a selection of locks (on the other ½
workstation)
➢Continuous action during different steps of the
project to define the security studies to be carried out and the sensitive points to be given
specific attention. It is manifested by assistance
given to the owner by an independent external
consultant.
➢A working group dedicated to risk studies, composed of representatives of the designers (owner and engineer), and CNR traffic management
personnel (lock keepers, technicians, local managers). During its different meetings, this workgroup fuels overall reflection on risk studies.
➢Performing risk studies of SIST law type for each
lock managed by telecontrol.
➢The aim of the studies performed is to present a
Preliminary Safety Study in conformity with the
SIST law 2002-3 of January 3, 2002 relating to the
safety of transport infrastructures and systems.
A Preliminary Safety File (DPS) before carrying
out the works (the subject of this document is
attached in the appendices),
➢A safety report drawn up by an expert or a qualified organisation
➢A Safety File (DS) before the operation started.
NB: except for Port St Louis du Rhône which has
a lifting bridge: when a river traffic technician selects this lock in operating mode, he cannot oper-
The risk analysis performed on the locks of PierreBénite, Bourg les Valence and Avignon taking
into account the current installations, operated
There are seven technicians on duty from 6 a.m.
and 10 p.m. and four technicians at night depending on the progression of night-time traffic.
The teams are supervised by three managers.
5.2. Operating Principles
A river traffic technician can select any lock from
their workstation (validated in remote control
mode) that they manage in OPERATING mode or
in MONITORING configuration.
They can perform a maximum of two tasks simultaneously:
185
locally, showed that the level of safety was globally satisfactory. The current system therefore served
as reference to evaluate the GALE (Globally At
Least Equivalent) level of the telecontrol project’s
safety.
The main impact on safety of implementing the
telecontrol project is to eliminate both the presence of a lock keeper capable of intervening
in the lock chamber and the visual control performed by the lock keeper of a large number of
more or less dangerous situations.
Consequently, the three measures considered
that compensate for the lock keeper’s distance
from the site are the following:
➢Reinforcing the video system composed of
cameras, especially at the heads of the locks,
which requires:
• Carrying out an ergonomics study on the development of the TCMC and supervision
• Carrying out a study of the camera positions
➢A standby duty call with fast intervention in the
case of a technical problem or incident
➢The presence of seasonal workers at certain
locks to inform pleasure boat crews of the right
procedure to follow
In conclusion, the risk analysis showed that for
each risk identified, the measures considered to
reduce it were considered adequate enough for
level of safety of the installation to be globally satisfactory and equivalent to the safety level of the
reference installation.
7. ARCHITECTURE
Fig. 6: Flow diagram of the four systems
7.1. The Control and Instrumentation
System
This consists in interfacing the local automation
devices (operating PLCs known as ‘APN’, PLCs
ensuring ultimate safety known as ‘CSU’, general
service PLCs, APX, with computerised systems with
man-machine interfaces called ‘SCADA’ developed on the basis of the micro-SCADA software
from ABB.
The architecture of the telecontrol comprises four
main systems which are the following:
➢The control and instrumentation for remote lock
operations
➢The emergency stop system to ensure the safety
of the lock by tripping the power supply to the
control and instrumentation and operating devices
➢Video-monitoring to ensure visual control around
the chamber and around the lock
➢The vocal communication management system (VHF radio with the boats, PA system in the
chamber and lock lay-bys to diffuse spoken and
recorded messages, and telephones)
All the systems make use of CNR’s fibre-optic network, a computer network with a data flow rate of
1Gbits/s allowing real-time video image transmission. This network is backed up by an emergency
network which, in case of failure of the main network, guarantees a bandwidth of 1Gbits/s dedicated to the telecontrol.
186
Fig. 7: Control and instrumentation system
Fig. 8: Switching system
The local SCADAs dialog with the SCADA central
servers at the RTMC that manage all the displays
and controls on the 8 operator consoles at the
RTMC.
them to stop with certainty (by tripping the electric power supply) all the devices of the lock they
are operating. This action, called ‘stop process’, is
ensured by the normal channel of the control and
instrumentation channel system.
The central RTMC SCADA plays the role of main
switchboard: it connects an operator console with
one or more locks.
The RTMC operator has the process information of
the locks they manage on five screens. These five
screens allow him to manage two locks:
➢On the 1st screen: positions and statuses of the
devices of the 1st lock
➢On the 2nd screen: faults affecting the devices or
the system of the 1st lock
➢On the 3ème screen: positions and statuses of the
devices of the 2nd lock
➢On the 4ème screen: faults affecting the devices
or the system of the 2nd lock
➢On the 5ème screen: selection of locks being
managed
Screens 1 and 2 compose the left ½ console.
Screens 3 and 4 compose the right ½ console.
By using their five screens, the operator can also
send macro-commands interpreted and controlled by the site APN PLC:
➢cycle commands: ‘upstream cycle’, ‘downstream cycle’, ‘stop’, ‘confirmation’
➢selection commands (selection of devices,
functions, etc.)
The RTMC operator has a push button situated
on each ½ console of their workstation. It allows
Fig. 9: RTMC operator workstation – instrumentation and control part
The local and central servers are replicated in
number and in separate geographical sites in order to ensure optimal system availability.
These systems considered as belonging to CNR’s
core activity have been developed by teams
internally in view to ensuring full control over the
maintenance of these tools. The latter (PLCs, SCADA servers) are also used for other CNR operating
systems, in particular the entire management of
hydropower production.
7.2. Remote Emergency Stops
The stop process described previously uses the
normal computerised channel of the instrumentation and control system. It is replicated by an
independent system developed on the basis of
specific PLCs known as ‘APS’.
187
Each lock is equipped with an APS PLC linked to its
correspondent at the RTMC by CNR’s Ethernet IP
communication network. The safety channel thus
built permits the transmission of the emergency
stop request that the RTMC operator can activate
by pressing a button on a wall-mounted mimic
diagram panel.
The mimic diagram panel is equipped with fourteen push buttons (one per lock).
The implementation, installation, programming
and maintenance of the APS were specified in
conformity with standard IEC 61-508. The Safety
Integrity Level (SIL) defined by this standard has
been assessed for locks and level 3 was chosen.
The entire emergency stop system, from the trip
push-button to the actuators on the site has been
specifically designed and developed to obtain
SIL3 certification.
type of manoeuvre – and visually check that the
lock passage proceeds smoothly.
Electronic encoders have been installed in the
chambers. They transform the analogue video signals received by the cameras into digital signals
that are then compressed in MPEG4 standard.
Each encoder then multicasts the images on the
IP network.
The encoder is programmed in order to diffuse images with:
➢CIF quality (352 x 288 pixels), 2 CIF (704 x 288 pixels) or 4 CIF (704 x 576 pixels)
➢refreshment every 25, 12 or 6 images per second
➢an IP rate that can be limited (300 kbits/s to 3000
kbits/s)
In order to ensure high quality, most of the images
are diffused in 4CIF, 25 images per second without
limiting the bit rate.
Fig. 10: The remote emergency stop system
7.3. The Video-Monitoring System
Based on a reference framework of about sixteen
cameras located at strategic positions around the
chamber and the approach areas, the RTMC video-monitoring system permits controlling the cameras and viewing the images on three dedicated
screens on each ½ control console.
The cameras must allow verifying the position of
the boats in the chamber, which should be correctly lashed, especially in the case of pleasure
crafts – whose crews are less experienced with this
188
Fig. 11: The video system
All the images are managed at the RTMC by a
main server that diffuses them from the encoders
located on the sites. This video server is linked to
the RTMC SCADA server, as to identify the locks
managed by the operator of each console. It is
replicated to guarantee good video system availability.
The images are recorded digitally on a server and
can be accessed from a specific workstation reserved exclusively for maintenance. The operators
only have access to real-time images. The record
server is used as a backup in case the link with the
RTMC server fails.
7.4. The Vocal Communication System
This system provides the RTMC with the same communications resources as those that were used by
the lock-keeper in his control tower. To achieve
this, local communications, whether telephone,
VHF radio or via the PA system, are transmitted to
the RTMC via the CNR computer network.
• For telephone communications, acquisition is
ensured by Media Gateway telephone systems
that convert analogue telephone messages for
transmission via IP networks. They permit handling conventional telephone calls made to the
locks.
• For VHF radio and the PA system, acquisition
is ensured by ATA equipment (analogue telephone adapter) that converts VHF and PA signals (command and voice signals) for the IP
network.
➢a central management and switching system:
this system is called CTI (telephone-computer
coupling). It entails a central server at the RTMC
that links the operator’s audio interfaces with
the lock systems for which he is responsible.
The operator has a single and ergonomic ‘Audio’
interface on their console that allows them to use
any of the communication channels connected:
VHF, telephone, PA, interphone.
Fig. 13: View of the vocal command station
(VHF, telephone, PA system)
8. THE WORKS
The works essentially comprise the following:
Fig. 12: Vocal Communication System
The architecture of this system is quite similar to
that of the instrumentation and control and the
video, with:
➢a local acquisition system: for the audio, the system is non-overlapping:
➢the equipment of a development and maintenance platform at Pierre Bénite. This platform
accommodates the entire project team, the
design and engineering management and the
development teams. It also allows testing all the
systems before their deployment in production.
Tests are performed with software to simulate
the hydraulic, electric and automation behaviour of two locks. Two operator workstations at
the RTMC have been installed on this platform.
➢the works to equip the centre at Châteauneuf
and the installation of remote control equipment. These works were carried out from September 2008 to February 2009.
189
➢the development of specific software and the
procurement of computer hardware (video,
vocal communication, operation). The development of software applications linked to the
instrumentation and control system was performed by CNR’s teams, whereas the development of the video and vocal communication
systems was entrusted to external companies
under the supervision of CNR.
➢the local adaptation of the locks, comprising
in particular works on automation devices, and
improving the video equipment. This adaptation was done according to scheduling dictated by the annual stoppage of navigation on
the Rhone which takes place every year during
March for a period lasting from 7 to 10 days.
Modifications made to the electrical system
and automation devices were prepared the
previous year (from April to September), then
deployed from October to February, in parallel
with the existing systems and finally connected
when navigation was stopped in March. Therefore, in March 2008, two locks, Avignon and
Bourg-les-Valence, were prepared locally. In
March 2009, three other locks were ‘adapted’.
Five more were adapted in March 2010 and the
four remaining locks were adapted in March
2011. Once adapted, the locks can be connected to the centre outside the periods when
navigation is stopped. The first two, Avignon and
Bourg-les-Valence, were connected in April
2009, the three following locks were connected
in November 2009, four in 2010 and the last four
in autumn 2011.
➢the connection of the locks of Port Saint Louis
and Barcarin to CNR’s fibre optic network: these
two locks on the southern end of the Rhone are
not directly connected to CNR’s Ethernet network. A fibre optic link was laid along Barcarin
canal in 2011 to link these two locks.
9. THE REMOTE
MAINTENANCE SYSTEM
CNR’s teams have developed system maintenance software in parallel with the telecontrol system.
This application is used for the remote monitoring
of the equipment of the River Traffic Management
Centre and the locks under telecontrol.
Several screens permit monitoring lockage operations in real-time and checking the operation of
the global system, perform initial diagnostics and
visualise the faults and alarms.
In addition to well-designed ergonomics, the
screens are accessible to all the personnel concerned (operation, maintenance) via the CNR
intranet. The advantage of this is that the departments involved are informed in real-time by the
telecontrol system and it facilitates remote maintenance and troubleshooting operations.
Fig. 14: View of the RTMC control screen
Fig. 15: View of alarms
190
SUMMARY
The wide-gauge section of the Rhone river is 330 km
long, which, prolonged by the Saone river, forms a
corridor linking southern and eastern France with
the Mediterranean basin. The Compagnie Nationale du Rhône (CNR) holds the concession to operate the Rhone river (navigation hydropower) and
is currently carrying out a ‘Navigable Waterway
Modernisation’ project aimed at progressively upgrading aspects ranging from ‘lock operation’ to
‘traffic management’, by developing a centre for
traffic management and the remote control of
the fourteen locks built on the Rhone.
the other nine locks being commissioned in 2010
and 2011.
The originality of this centre, besides the fact that
it manages a large number of locks from a single
location, is its flexibility as it permits operating any
lock from any console, meaning that the centre
can be adapted to deal with the traffic at a given
moment and the number of persons available in
the centre.
The project has been designed and developed
from the outset by CNR’s engineering teams.
The first five locks were commissioned in 2009, with
RESUME
Long de 330 km, le Rhône à grand gabarit constitue, prolongé par la Saône, une artère fluviale
reliant les régions du Sud et de l’Est de la France
au bassin méditerranéen. La Compagnie Nationale du Rhône concessionnaire du Rhône s’est
engagée dans un projet de ‘Modernisation de
la voie navigable’ dont l’objet est de passer, par
étapes, de la ‘manœuvre des écluses’ à la ‘gestion du trafic’, en créant un centre unique pour la
gestion du trafic et la téléconduite des 14 écluses
du Rhône.
en 2009, les neuf autres écluses en 2010 et 2011.
L’originalité de ce centre, outre le nombre
d’écluses conduites depuis un seul point est la souplesse de fonctionnement qui permet de conduire n’importe quelle écluse depuis n’importe quel
demi-pupitre, offrant ainsi une grande capacité
d’adaptation en fonction du trafic et du nombre
de personnes présentes.
Le projet a été conçu et développé par les équipes
d’ingénierie de la CNR.
Les cinq premières écluses ont été mises en service
ZUSAMMENFASSUNG
Die Rhone ist 330 km lang und um die Saone verlängert, bildet sie eine Flussader, die das südliche
und östliche Frankreich mit dem Mittelmeer verbindet. Die Compagnie Nationale du Rhône (CNR),
Konzessionär für Transport und Wasserkraftanlagen
auf der Rhone, ist zurzeit dabei, ein WasserstraßenModernisierungs-Projekt durchzuführen, mit dem
Ziel, schrittweise vom manuellen Schleusenbetrieb
auf ein Verkehrsmanagement umzustellen, indem
eine Zentrale für Verkehrsmanagement und eine
Fernleitzentrale für die 14 Schleusen, die an der
Rhone stehen, entwickelt wird.
Die ersten fünf Schleusen wurden im Jahr 2009
beauftragt, die anderen neun Schleusen folgen in
den Jahren 2010 und 2011.
Das Alleinstellungsmerkmal dieser Zentrale ist neben der Tatsache, dass sie eine große Anzahl von
Schleusen von einer einzigen Stelle aus managt,
ihre Flexibilität, da sie es gestattet, jede Schleuse von jeder Konsole aus zu betreiben, was bedeutet, dass die Zentrale sich an die jeweilige
Verkehrssituation anpassen kann, auch bezüglich
des benötigten Personals.
Das Projekt wurde von dem CNR-Ingenieurteam
entworfen und entwickelt.
191
192
Numerical simulations and experimental
models: the experience of the New Locks of
the Panama Canal
Mise en œuvre couplée de modèles
numériques et de modèleS physiqueS dans
le cadre de l’étude de conception des
nouvelles écluses de Panama
SEBASTIEN ROUX
NICOLAS BADANO
Laboratoire de Mesures et d’Essais
Compagnie National du Rhône
4, rue de Chalon sur Sâone - 69007 Lyon
France
MWH Argentina
Marcelo T. de Alvear 612
C1058AAH Buenos Aires
Argentina
KEY WORDS: Panama Canal, numerical model,
physical model, lock design
MOTS-CLES: Canal de Panama, modèle numérique, modèle physique, conception d’écluse
1. INTRODUCTION
In the framework of the construction works of the
new locks of the Panama Canal, the final design
of the locks F-E system has been carried out using both a physical scale model and a set of 1-D,
2-D and 3-D numerical models. The validation of
F-E system final design had to be carried out in 16
months since this step was on the critical path with
respect to the locks construction schedule.
The physical model has been run in the Laboratory of the Compagnie Nationale du Rhône in Lyon
while the numerical model studies were performed
by MWH in Buenos Aires. Initially, numerical models
had been run to fix the design to be tested in the
physical model. Then, each model was run at the
same time, allowing to crosscheck the results and
to minimise the time to achieve the validation of
the hydraulic performance of the F-E system.
2. THE THIRD SET OF LOCK
PROJECT
Fig. 1: Third Set of Locks structure – Overall view
193
The Panama Canal Authority (ACP) decided to
build a new lane along the Panama Canal that
will double capacity and allow more traffic. Along
with this new lane, two sets of larger locks, referred
to as the Third Set, is under construction as from
2009, one set of locks in the Pacific end and another one in the Atlantic side. Each set of locks will
have three consecutive chambers with lengths
varying between 427 m and 488 m, depending
on the position of the inner gates, and a width
of 55 m. The design ship is a so-called New Panamax 13,000 TEU container carrier (366 m x 48.8 m
x 15.2 m; CB = 65 %). Because water consumption
is a major issue, each of the six new locks will be
equipped with three Water Saving Basins (WSB).
This ‘3 locks & 9 WSB’ configuration will help to
save 87 % of the water required for the transit of
one ship between from Pacific ocean to the Gatun lake and the Atlantic ocean (as compared
to a single lift lock with no WSB). Even though the
new locks will be wider and longer than the existing locks, they will consume 7 % less water than the
latter when the WSB are used.
The New Locks F-E system is described on the Fig.
2:
This side wall F-E system is specific because of its
double culverts configuration which allows for a
balanced flow distribution along the lock chamber. The lock chamber can be filled (or emptied)
both by the upper lock or Gatun Lake and by the
lateral WSB.
The culverts dimensions are outstanding since the
8.30 m wide by 6.50 m high main culvert is wide
enough to allow the transit of two railroads.
3. PRESENTATION OF THE
MODELS USED DURING THE
FINAL DESIGN STUDY
3.1. Numerical Models
State-of-the-practice software was used to study
the different problems:
- Local head losses at the different system components were computed using 3-D models
based on OpenFOAM, a formerly commercial
code that has become freely available. Its main
Fig. 2: New Locks F-E system
Fig. 3: Pictures of the central flow divider, main and secondary culverts
194
advantages over comparable commercial
software are its high-performance (Linux-based,
parallel processing), access to a worldwide forum to request support, and its flexibility to introduce new features, if needed.
- The filling/emptying times and maximum flow velocities were calculated with a 1-D model based
on the commercial software FlowMaster V7.
- The hawser forces were inferred from the water
surface slope values correlated during previous
design phases. The water surface slopes were
obtained using a 2-D model based on Hidrobid
software (a numerical code developed by Instituto Nacional del Agua) which is similar to other
software like Mike 21 – by DHI –, or Delft2D.
All the models went through calibration or validation processes. The validation of OpenFOAM was
based on comparisons with existing experimental
results. The 1-D model was first calibrated by comparison with experimental results from measurement carried out on the conceptual design physical model and with the results of the 3-Dmodels.
Then, when the physical model tests started, the
results achieved were also used. The 2-D model
was validated by comparing its results with the
results obtained with software Delft2D and with
measurements performed in the physical model.
3.2. Physical Model
A scale model, 60 m long and 10 m wide, representing two lock chambers, three Water Saving
Basins (WSB) associated to the lower chamber,
one fore bay and one tail bay has been built at
scale 1/30 in CNR laboratory.
and WSB conduits
- The pressure in the culverts and downstream the
valves
- The valve positions
- The longitudinal and transversal hawser forces
(i.e. the longitudinal and transversal components of the hydrodynamic force exerted by the
water on the ship’s hull)
In order to handle the amount of information, a
dedicated program has been developed (with
the Labview software), allowing:
- To look in real-time at every data transmitted by
all the sensors equipping the physical model
- To operate the physical model manually, i.e.
setting the position of every valves, the water
level in every lock chambers or WSB
- To define the calibration equations of every sensors
- To program the parameters for the tests (initial
water level, valves operating schedules, sensors
activated for data acquisition)
- To record the sensors measurements in several
format (Tension, intensity, physical model (i.e.
scale) value and prototype value)
A set of three ship models (one 12,000 TEU PostPanamax containership, one 8,000 TEU containership and one dry bulker) at scale 1:30 were used for
carrying out the tests in the physical model aimed
at measuring the total forces exerted on the ship’s
hull and calculate the hawser forces and vessel
displacements.
The tests have been carried out through four tasks,
starting with tests in steady flow conditions used to
assess the flow distribution along the lock chamber and assess the head losses in the F-E system.
The two following tasks aimed at verifying the F/E
system proposed in the tender design by the Contractor will permit to comply with the hydraulic
performances requested by the ACP. The last task
aimed at assessing the F/E system performance for
debased conditions (i.e. for different equipment
availability scenarios) but also for specific type of
vessel other than the design vessel.
At the end of the study, more than 1,500 tests were
performed on the physical model in one year.
Fig. 4: General view of the physical model
This model has been equipped with about 100
sensors in order to measure:
- The water levels in the lock chambers, basins,
fore and tail bays
- The longitudinal and transversal differential water levels in the lock chamber (i.e. the longitudinal and transversal water slopes)
- The velocities and flow rate in the main culverts
4. COMBINED USE OF
PHYSICAL MODEL AND
NUMERICAL MODELS
The final design study of the New Locks F-E system
has been performed by implanting simultaneously
numerical model (1-D, 2-D and 3-D) and a physical model. The model interactions are described
in the Fig. 5 on the next page.
195
Fig. 5: Combined use of numerical and physical model
The combined use of physical and numerical
model is presented through three examples in the
sections hereafter.
4.1. Calibration of the 1-D Model of the
Lock F-E System
The entire F-E system has been modeled with the
Flowmaster 1-D software, representing and setting
the parameters of every component such as reservoirs, culvert, bends and valves, the most common components of internal flow system being
already available in the software library.
Anyway, some components such as the central
flow connection present a very complicated hydraulic shape whose head losses coefficient can
not been set without additional calculations with
3-D model and measurements carried out on the
physical model.
Fig. 6: Central flow connection
196
The physical model was equipped with flowmeter and differential pressure sensors implemented
along the F-E system, the measurement of the discharge and the pressure drop allowed to calculate the head losses of the different section, especially between the complex hydraulic shapes.
Once the 1-D model has been calibrated, it becomes a very efficient tool allowing to perform
fast sensitivity analysis, in order to define the operating parameters (i.e. valve opening schedule)
before testing them on the physical model.
The construction of two 1-D numerical models, one
at scale 1/30 and the other at prototype dimensions, also gave very valuable information on the
scale effects. Indeed, even if the flow condition
is turbulent in the physical model at the selected
scale (Reynolds numbers are ranging between
105 and 106) it does not represent completely
well all the factors involved in the F/E processes.
In particular the friction losses in smooth conduits
are over-predicted (Reynolds numbers on the prototype are ranging between 107 and 108). Special considerations must be made to accurately
compare results from the physical and numerical
models and correction must be applied to the
physical model results in order to obtain the performance expected on the prototype. According
to the F-E operation (i.e. between the Gatun lake
and a lock chamber, between two locks chambers, between a lock chamber and the ocean
or between a lock chamber and a WSB), the F-E
times have to be reduced from 4 % to 16 % and
the discharge peaks values have to be increased
from 4 % to 10 %.
4.2. Assessment of the Flow Distribution
Through the Lateral Ports
The F-E system designed for the New Locks of the
Panama Canal is a ‘double-culverts lateral F-E system’.
It is composed by one main culvert (8.30 m x 6.50
m) connected to two secondary culverts (6.50 m
x 6.50 m) in the centre of the lock chamber. Each
secondary culvert feeds the lock chamber by
means of 10 ports of 2 m x 2 m as shown on Fig. 7.
Achieving a balanced flow distribution along the
lateral ports is something of first importance in order to have smooth filling conditions and limiting
as far as possible the forces exerted on the vessel
(and consequently the reaction forces applied in
the mooring lines). Before running all the F-E scenarios, a lot of measurements were carried out on
the physical model in steady flow condition to assess the symmetry of the flow entering into the lock
chamber. These measurements were carried out
with propellers positioned at the mouth of the port
in the lock chamber.
Anyway, the flow existing each of the twenty ports
along one lock wall is not symmetrical with respect
to the vertical and horizontal axis of the port because of the velocity component in the secondary culvert.
numerical model gave very valuable data, such
as distribution of the flow in every port and allowed to set an appropriate measurement protocol for every port (i.e. to define if 1, 2 or 4 measurements were necessary to asses properly the port
discharge).
All this set of data allowed to get an accurate and
comprehensive knowledge of the flow conditions
in every port and to validate the efficiency of F-E
system regarding the flow distribution.
All this set of data allowed to get an accurate and
comprehensive knowledge of the flow conditions
in every port and to validate the efficiency of F-E
system regarding the flow distribution.
4.3. Upgrade of Some Components of
the F-E system Tender Design
The combined use of physical and numerical model has demonstrated its full efficiency through the
modification of one main culvert valve layout.
Fig. 7: Plan view of the half-lock chamber and its lateral feeding system
Fig. 8: Flow direction in the ports
Fig. 9: Numerical calculation Vs observation on physical model
Fig. 10: Original layout of the far main culvert valves
197
The series of tests carried out on the physical
model allowed to detect visually that some air
was sucked in the main culvert downstream of
the valve n° 5 (as shown on Fig. 10) but not downstream to the valve n° 6 while both of them were
opened according to the same schedule.
the retained configuration has been installed on
the physical model for validation. It finally proved
to work perfectly as expected according to the
numerical model results.
This methodology has permitted in a very short
time (i.e. less than three months) to ensure the results by cross-checking the data on both model
and to optimise the F-E system modification from a
financial point of view.
5. CONCLUSIONS
Fig. 11: Air entrainment under valve n°5
A 3-D numerical model of the valve has been implemented. It was validated on the basis of data
measured on the physical model (especially pressure). It showed that the culvert asymmetry of the
proposed layout generated a recirculation in the
internal branch, increasing locally the head loss
and creating unbalance flow conditions between
the two valves even for the same opening schedule. It resulted from this diagnosis that the valves
would have to be depenned and that a more
symmetrical layout would have to be selected.
A new configuration of the valve layout has then
been studied with the numerical model in order to
set rapidly what would be the optimal elevation
for the valves (with respect to the hydraulic performance and the excavation volume) and only
The studies to define the Final Hydraulic Design of
the Panama Canal Expansion Project required the
simultaneous implementation of several numerical models performed in Buenos Aires Office and
a scale physical model performed in a laboratory
located in Lyon, France. In spite of the distance
between the two teams, the combined use of
physical and numerical models has demonstrated
its full efficiency (in term of results accuracy and
time saving) through the modification of some
components of the F-E system.
It also allowed performing efficient crosschecking
of the data, each model being used when needed to support and complete the results achieved
on the other. The assessment of the model and
prototype performance, especially the scale effects, can not be obtained without implementing
both models.
Due to recent progresses, it seems that the numerical modeling is mature enough to complement
the traditional approach based only in the use of
physical modeling. Each one provides different
advantages, allowing to overcome the characteristic limitation of the other. The combined use of
these two types of models becomes an efficient
way of predicting the behavior of the final project.
Fig. 12: Flow pattern downstream the far main culvert valves
198
SUMMARY
The final design of the Panama Canal new locks
filling and emptying system has been performed
by implementing simultaneously a physical model in the laboratory of the Compagnie Nationale
du Rhône in Lyon (France) and several numerical
model in the offices of Montgomery Watson Harza
in Buenos Aires (Argentina).
The combined used of physical and numerical
model gives birth to a very powerful ‘hybrid’ mod-
el that helps the designer to minimise the calculation time, crosscheck the results, access to a large
number of data and improve the prediction of the
hydraulic performance of the prototype. In the
case of the final design study of the Post-Panamax
locks, the combined use of a physical model, 1-D,
2-D & 3-D numerical models have proven to be a
very efficient tool through a lot of cases which are
presented in this paper for some of them.
RESUME
Les études de conception finale du système
d’alimentation des Nouvelles Ecluses du Canal de
Panama ont été menées en mettant en œuvre à
la fois un modèle physique et plusieurs modèles
numériques. Le premier a été construit au sein du
laboratoire de la Compagnie Nationale du Rhône
à Lyon alors que les seconds ont été développés
par Montgomery Watson Harza à Buenos Aires.
L’utilisation couplée des modèles physique et nu-
mériques permet de générer un modèle ‘hybride’
très efficace afin d’optimiser les durées des calculs
et la quantité de données collectées, de procéder
à des inter-validation des résultats et d’améliorer
l’évaluation des performances hydrauliques du
système d’alimentation des écluses. L’intérêt de
l’utilisation d’un modèle hybride dans le cas de la
conception du système de remplissage/vidange
des écluses de Panama est illustré dans cet article
à travers quelques exemples.
ZUSAMMENFASSUNG
Die endgültige Konstruktion des Füll- und Entleersystems der neuen Schleusen am Panama Kanal
wurde entwickelt, indem gleichzeitig ein physikalisches Modell im Labor der Compagnie Nationale
du Rhône in Lyon (Frankreich) und verschiedene
numerische Modelle bei der Firma Montgomery
Watson Harza in Buenos Aires (Argentinien) eingesetzt wurden.
Die gekoppelte Anwendung eines physikalischen
mit numerischen Modellen führt zu einem sehr lei-
stungsfähigen ‚Hybrid‘-Modell, das den Konstrukteuren dabei hilft, Rechenzeiten zu minimieren,
die Ergebnisse zu überprüfen, umfassende Datensätze zu erhalten und die Vorhersage zum hydraulischen Verhalten des Prototyps zu verbessern.
Im Fall der abschließenden Entwurfsstudie der
Post-Panamax-Schleusen hat die Kombination
eines physikalischen Modells mit 1D, 2D und 3D
numerischen Modellen gezeigt, dass dies in vielen
Fällen ein sehr effektives Werkzeug ist. Einige Modelle werden in diesem Artikel vorgestellt.
199
200
GRAND PORT MARITIME DU hAVRE
‘wORKING wITh NATURE’
ThE ‘EMERhODE’ PROJECT IN LE hAVRE
IMPROVING wATERwAY CONNECTIONS AND LAND RESERVES:
AN OPPORTUNITY fOR ThE NATURE RESERVE?
‘œUVRER AVEC LA NATURE’
LE PROJET ‘EMERhODE’ AU hAVRE
AMéLIORATION DES DESSERTES fLUVIALES ET RéSERVES fONCIèRES:
UNE OPPORTUNITé POUR LA RéSERVE NATURELLE?
PAUL SCHERRER
Grand Port Maritime du Havre (GPMH)
Projects and Engineering Director,
Member of the Executive Board
BP 1413
France
Tel: +33 (0)2 32 74 73 40
Fax: +33 (0)2 32 74 73 45
JEAN-PIERRE gUELLEC
Grand Port Maritime du Havre (GPMH)
Deputy Director and Projects Officer
EMERHODE Project manager
BP 1413
Tel: +33 (0)2 32 74 73 15
Fax: +33 (0)2 32 74 73 62
1.THE ‘WORKINg WITH
NATURE’ PHILOSOPHY
PIANC established a standing committee on the
environment at the Seville Congress in 1994. The
committee later became the Environmental Commission – EnviCom. EnviCom meets twice a year
in February at the PIANC headquarters in Brussels, Belgium and during the autumn in one of the
member countries.
It thus met in Strasbourg in September 2008 at the
invitation of the Central Commission for Navigation
on the Rhine (CCNR) and in the autumn of 2010
in Le Havre, France at the invitation of the Grand
Port Maritime du Havre (GPMH). Its last meeting in
2012 was held in Koblenz, Germany at the invita-
tion of the German Federal Institute of Hydrology
(BAFG).
Paul Scherrer is the French representative within
EnviCom.
In 2008, PIANC, on the proposal of the Environmental Commission, issued a position paper entitled ‘Working with Nature’, which in fact led to
the proposal of ‘doing things’ in a different order.
The document was updated by PIANC in January
2011. It is available on the PIANC website in a wide
range of languages (http://www.pianc.org/wwnpositionpaper.php).
The ‘Working with Nature’ philosophy can be
summed up as carrying out projects in four steps:
201
1) Establishing project needs and objectives
2) Understanding the environment in the whole
of the project area
3) Making meaningful use of stakeholders’ commitments to identify win/win opportunities
4) Preparing initial project proposals/design that
meet the needs of navigation and the environment
This is a subtle but important evolution in the way of
approaching project development. ‘Working with
Nature’ first of all considers the project objectives,
firstly from the point of view of the natural system
rather than from that of its technical design. This
approach is seen to be extremely important, on
the one hand, as a means of reducing the delays
and frustrations of all kinds arising from the implementation of projects and, on the other hand, as a
means of better meeting all the expectations and
optimising the sharing of benefits in the completion of projects.
2. THE CREATION OF AN
INTERNATIONAL DATABASE
At the end of 2012, the Executive Committee (ExCom) of PIANC, on the proposal of EnviCom, created an online international database designed
to recognise projects conducted according to
the ‘Working with Nature’ philosophy.
Two types of project can be entered:
- Those that have not yet been consented by receiving the administrative authorisations which
may be included in the database with the status of ‘Candidate for a Certificate of Recognition’ if their development demonstrates the inclusion of elements of the ‘Working with Nature’
philosophy
202
- Those that have been implemented or which
have at least obtained all their consents and
are therefore included in the database with the
‘Certificate of Recognition’
Recognition is given to projects by a unanimous
jury representing all PIANC Commissions.
In addition, every four years, in conjunction with
the PIANC World Congress, an Award will be granted to the best ‘Working with Nature’-project.
3. THE EMERHODE PROJECT
IN LE HAVRE
An operation led by the Grand Port Maritime du
Havre in the eastern part of the alluvial plain of the
Seine Estuary can be seen as an application of the
new ‘Working with Nature’ philosophy. The project
involved the creation of a canal for inland navigation vessels connecting the Grand Canal du
Havre with the Tancarville Canal together with the
extension of the eastern part of the port industrial
zone and the improvement of the environmental
capacities of the Seine estuary Nature Reserve.
After the public debate (which ran from October
8, 2009 to February 7, 2010), the project became
much more ambitious and wider-ranging, its objective now being to determine the most harmonious and sustainable development possible of
an alluvial plain covering some 3,000 hectares. It
is now called the EMERHODE project (the French
acronym for ‘multimodal efficiency, economics
and hydraulic networks: an opportunity for sustainable development of the estuary’).
In accordance with the philosophy of ‘Working
with Nature’, the studies for the project, for the
time being, have taken place in four phases:
1) Definition of the project needs and objectives. The main objectives of the project are
to improve the waterway connections either
for pushed convoys or for large-scale self-propelled shipping, while reducing the congestion
of road and rail traffic by limiting the need for
opening of the movable bridges. Another of
the project objectives is to develop the port industrial zone in the eastern part of the alluvial
plain of Le Havre while improving the environmental capacities of the Nature Reserve.
2) Understanding the environment in the whole
of the project area consisting of estuary wetlands. A large-scale mathematical model of
the hydraulic functionalities of the whole area
has been worked out. The model has more
than 130,000 meshes. Its calibration has resulted in the accurate simulation of the complex
operation of the hydraulics in the area with, in
particular, the presence of two distinct water
tables. In addition, the conventional fauna/
flora inventories for operations of this type have
been completed by the search for a comprehensive ecological assessment, area by area.
3) Making meaningful use of stakeholders’ commitment to identify win/win opportunities. In
2008 and 2009, several consultation meetings
were held to introduce the study process before the public debate. The public debate
was held from October 8, 2009 to February 7,
2010. It helped make significant progress to the
project, as noted by Supervisory Board of the
Grand Port Maritime du Havre in its decision of
June 25, 2010 to pursue the studies of different
alternatives.
It should be noted that the studies now include
two new chapters directly resulting from the consultation:
• A study of the opportunities to decompartmentalise the entire eastern part of the alluvial plain
in order to make the wetlands more estuarine.
The study clearly shows the need for shared
choices in terms of the biological functionalities
that should be given priority in the framework of
the project, with particular respect to the Nature Reserve.
• A study to improve the circulation of water between the North and South of the area. Under
the cliff to the north, there are several natural
springs, whose runoff is hampered by roads and
the Tancarville Canal. The study highlighted the
possibilities to restore freshwater runoff to the
North of the Tancarville Canal, while the relevance of transferring them south of the Canal
remains to be demonstrated.
These studies are therefore continuing as well as
the consultation with, in particular, four workshops
held in June 2011 followed by a public review
meeting on July 5, 2011. Similarly, in late 2011, four
workshops were held, attended each time by between 30 and 50 participants, followed by a public
meeting in January 2012 involving a hundred participants. The consultation continued throughout
2012 during the completion of the studies, which
should facilitate the selection of a landscape
scheme by the Supervisory Board of the GPMH.
4)Preparing complete project proposals/design
that meet the needs of navigation and the environment. Already, the use of the ‘Working with
Nature’ process has enabled certain impacts to
be avoided (such as the choice of vertical canal banks to reduce land use and improve boat
guidance), while eliminating others (such as the
production a prototype side canal to recharge
the groundwater table and suppress the drainage effect caused by digging the canal) and
reducing others (lowering the reference speed
of trains to limit railway rights-of-way).
203
For example, given the hydraulic studies and the
consultations prior to the public debate, it was decided to add, alongside the new river canal on
the Nature Reserve side, a side canal in which the
water level will be maintained at a level such that
there is no lowering of the water table due to the
presence of the canal.
Following the public debate, it was decided to
dig a life-size test side canal approximately 100
metres long. The chosen location is alongside the
Tancarville Canal in order to demonstrate the effectiveness of such a scheme in raising the aquifer. After a few difficulties involved in finding the
204
optimal level at which to dig the side canal, given
the presence of impermeable land alongside the
Tancarville Canal, the side canal demonstrated its
effectiveness.
The project was presented as part of the new international ‘Working with Nature’ database and
recognised by the jury consisting of members of
all PIANC Commissions as being a ‘Candidate for
a Certificate of Recognition’, thereby recognising the application of the ‘Working with Nature’
philosophy in the different phases of the project
already undertaken.
SUMMARY
This paper presents the PIANC ‘Working with Nature’ philosophy established in 2008 and revised in
January 2011, which basically means doing things
in a different order:
Furthermore, an operation is described carried
out by the GPMH in the eastern part of the alluvial
plain of the Seine Estuary, which is seen as a good
illustration of this new philosophy.
1)Establishing project needs and objectives
2)Understanding the environment in the whole of
the project area
3)Making meaningful use of stakeholders’ commitments to identify possible win-win opportunities
4)Preparing initial project proposals/design to benefit navigation and nature
This project, which is still in the study phase, is one
of the first projects with ‘Candidate for a Certificate of Recognition” status in the new PIANC international ‘Working with Nature’ database.
RESUME
Le présent papier présente la philosophie de
l’AIPCN ‘Œuvrer avec la Nature’, élaborée en
2008 et réactualisée en janvier 2011 qui peut se
résumer en réaliser les projets dans un ordre différent, à savoir:
1)Etablir les besoins et objectifs du projet
2)Comprendre l’environnement dans la globalité
de la zone du projet
3)Faire appel d’une manière constructive à
l’engagement des parties intéressées pour identifier les opportunités de gagnant/gagnant
4)Préparer des propositions/conceptions initiales
pour le projet répondant aux besoins de la navigation et de l’environnement.
Est ensuite présentée une opération menée par le
GPMH à l’Est de la plaine alluviale de l’Estuaire de
la Seine qui paraît un bon exemple de l’utilisation
de cette nouvelle philosophie.
Ce projet, encore en phase d’études, est l’un des
tous premiers reconnus comme ‘candidat pour
un certificat de reconnaissance’ dans la nouvelle
base de données internationale de l’AIPCN ‘Working with Nature’.
ZUSAMMENFASSUNG
Dieser Artikel präsentiert die PIANC ‚Working with
Nature‘ Philosophie, die im Jahr 2008 aufgestellt
und im Januar 2011 überarbeitet wurde; grundsätzlich bedeutet sie, Dinge in einer bestimmten
Reihenfolge zu tun:
1)Aufstellen der Projektanforderungen und -ziele
2)Verstehen der Projektumgebung im Gesamtkontext
3)Sinnvolle Nutzung des Engagements von Interessensgruppen, um mögliche Win-Win-Situationen
zu identifizieren
4)Vorbereitung der ersten Projektvorschläge/der
ersten Projektgestaltung unter Berücksichtigung
der Bedürfnisse von Schifffahrt und Natur
Außerdem wird eine Maßnahme beschrieben, die
von GPMH im östlichen Teil der Schwemmlandebene an der Seine-Mündung durchgeführt wurde,
welche als ein gutes Beispiel für die Anwendung
dieser neue Philosophie angesehen wird.
Dieses Projekt, das sich noch in der Studienphase
befindet, ist eines der ersten Projekte mit dem Status ‚Anwärter für ein Zertifikat‘ in der neuen internationalen PIANC Datenbank ‚Working with Nature‘.
205

Technical articles provided by the French Section, host

Transcription

Similar documents

lernex pro

Ms. Sani Mariama Moussa: H.E. Alpha Souley Bah Mr. Gerardo

draft programme - Suez environnement

280108 Notice

manuel installation - Boutique Aqwa Expert

TP d`électrotechnique : onduleur triphasé 24 volts

- Annales de Limnologie

M. Dominique Genty 47 years old Orsay, France dominique.genty

VOL. 71, NO. 3 Avril -- April 2012 - AAFI

Swimming CASE: GSAF 1999.04.11 DATE: Sunday April 11, 1999