Seasonal erodibility measurements at Peterstone Wentlooge, Cardiff

Transcription

Seasonal Erodibility Measurements at
Peterstone Wentlooge, Cardiff, UK,
April 1997 to January 1998
Data Report
H J Mitchener (HR)
D J O'Brien (Cardiff University)
R J S Whitehouse (HR)
ReportTR 57
April 1998
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HR Wallingford
Address and Registered Office: HR WalUngford Ud.
Te): +44 (0) 1491 835381 FiIX: +44 (0) 1491 832233
Reglstered!n England No. 2562099.
Ho\\buy Park, Wallillgford. OXON QXIO 8BA
HR Wallingforo Is a whoIy � .s!lbsi1iary of M WBlIilgford Group lid.
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HR Walllngford
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TR51
Contract
This report describes work funded by the Commission of the European Communities, Directorate General
for Science, Research and Development under contract number MAS3-CT95-0022 as part of the
INTRMUD collaborative research programme. It is published on behalf of the Commission of the
European Commnnities, but any opinions expressed in the report are not necessarily those of the
Commission. The HR Wallingford job number was rcs 16116. The work was carried out by H J Mitchener
and R J S Whitehouse of HR Wallingford Lld, and D J O'Brien of the University of Cardiff, Department of
Earth Sciences. The project was managed by Dr R J S Whitehouse.
Prepared by
Approved by
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Summary
Seasonal Erodibility Measurements at Peterstone Wentlooge, Cardiff, UK,
April 1997 to January 1998
Data Report
H J Mitchener (HR)
D J O'Brien (Cardiff University)
R J S Whitehouse (HR)
RepOlt TR 57
April 1998
Staff from HR Wallingford Lld and University of Cardiff took part in a seasonal
erodibility survey at Peterstone Wentlooge mudflat site situated on the north bank
of the Severn Estualy, UK. The site was visited systematically every month
during full moon spring tides and erodibility measurements and sediment sampling
were caITied out over the low water period. The objective of the survey was to
collect a data set of erodibility and surface sediment properties so that seasonality
of sediment characteristics could be investigated, and intercomparisons between
erodibility and sediment properties could be made.
The survey months were April to September 1997, with an additional day's survey
during JannalY 1998 to represent winter conditions. 3 different stations were
monitored during the survey, on a shore-normal transect extending seawards from
Mean High Water Neaps level. The locations were named A, C and CID, located
200m, 400m and 450m offshore respectively. These locations corresponded to
comparable stations set up for a long-term bed-elevation survey set up by O'Brien
in 1996.
During each day's deployment SedErode (HR Wallingford's instrument for
measuring the critical erosion shear stress of muddy sediments in-situ) was
deployed 3 times at each station to measure erodibility. Surface sediment scrape
samples were also taken by University of Cardiff and analysed for bulk density,
mass loss on ignition, grain size analysis, and colloidal carbohydrate content.
Sediment temperature and hand shear vane measurements were also taken together
with detailed observations and photographs of each site.
During the survey period there was substantial erosion at the site, in excess of
50mm at site C. The surface soft mud deposit had been largely eroded by the time
of the January 1998 survey, and the underlying Flandrian clay was exposed, fully
at site B/C (350m offshore), and in patches at other sites. There were a large
number of ragworms (Neries diversicolor) and small snails (Hydrohia ulvae)
observed at the site living within the surface soft mud layer during the summer
months. During January 1998, there was little or no evidence of these species
within the Flandrian clay, and they appeared to have died back and disappeared
along with the surface mud sheet. The surface mud density and loss on ignition
values were significantly different for the surface mud sheet and underlying
Flandrian clay.
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A total of 54 measurements of surface erodibility and surface sediment properties
were taken. The critical erosion shear stress values ranged from 0.1ONm'2 to
0.46Nm,2 over the 3 stations, and this covered a wide range of climatic conditions
and surface mud characteristics. The surface sediment bulk density ranged from
1174kgm,3 to 1406kgm,3 for the surface mud sheet and 1448kgm,3 to 1602kgm,3
for the Flandrian clay.
The mud was predominately comprised of clay and silt, with most surface material
containing less than 5% sand by weight. The median grain size values were also
low ranging between 1.6 and 6.1 microns. The silt fraction was the most dominant
with values between 41% and 79%, and the clay fraction ranged between 21% to
56%. There were no significant variations in the grain size distribution of the
surface mud samples during the seasonal survey.
The loss on ignition (LOI) values were high for the summer mud sheet between
7.39% and 14.40% by weight, and appeared to weakly reflect the sediment
temperature on the day and the biological activity. The colloidal carbohydrate
values followed the LOI trend and were between 0.49mgg" and 6.48mgg" . The
January 1998 values of LOI and colloidal carbohydrate were much lower in the
colder conditions and reflected the low biological activity observed.
Some preliminary correlations in the data set are presented. The processed data
can now be analysed further and compared or correlated with other relevant data to
assess the processes occurring at the Peterstone Wentlooge site, Cardiff in the
Severn Estuary, UK.
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Contents
Title page
Contract
Summary
Contents
iii
v
vii
1.
Introduction
2.
Objectives
3.
SedErode Instrument.
3 .1
Description
3.2
Deployment method
3 .3
Analysis
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4.
Site Description
4.1
General morphology
4.2
Small scale features
Survey station characteristics
4.3
1
1
1
2
2
3
3
.4
5
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1
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5.
Sampling Strategy
6.
Results
6.1
6.2
6.3
6.4
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Temporal patterns
ErodibiIity
Grain size
Temperature and biological parameters
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5
6
6
7
7
8
7.
Discussion ................................................................................................... 8
8.
Acknowledgements .
9.
References................................................................................................. 10
.
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9
Tables
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
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Overview of seasonal erodibiIity measurements
Deployment times and conditions
Results from survey 1 on 22 April 1997
Results from survey 2 on 22 May 1997
Results from survey 3 on 19 June 1997
Results from survey 4 on 22 July 1997
Results from survey 5 on 19 August 1997
Results from survey 6 on 18 September 1997
Results from survey 7 on 14 January 1998
Averaged data for the Cardiff seasonal survey
Standard deviation data for the Cardiff seasonal survey
Cardiff seasonal data intercomparisons
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Contents continued
Figures
Figure I
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Peterstone Wentlooge mudflat general location plan
Erodibility seasonal survey sampling locations
SedErode head unit
Time series of critical erosion shear stress and surface sediment
water content
Time series of surface sediment loss on ignition and bulk density
Time series of surface sediment colloidal carbohydrate and
temperature
Critical erosion shear stress against sediment water content and
bulk density
Critical erosion shear stress against sediment temperatnre and loss
on ignition
Grain size distribution plots for site A (soft mud sheet) and site
B/C (Flandrian clay) on 14 January 1998
Colloidal carbohydrate and loss on ignition against sediment
temperature
Plates
Plate I
Plate 2
Plate 3
Plate 4
Plate 5
Plate 6
Plate 7
Plate 8
Plate 9
Plate 10
Plate II
Plate 12
Peterstone Wentlooge general site
Transition zone, saltmarsh and bund
SedErode at site I CIDI April 1997, and at site B, looking onshore
January 1998
Main drainage runnels and bank collapse on 16 and 18 September
1997
Exposed Flandrian base clay and surface featnres at station CID
and runnel bank layering.
Layering featnres at site CID September 1997, showing exposed
Flandrian clay layers, and soft mud sheet remnant
Surface features at station A in January 1998, showing scour
erosion marks and bird footprint patterns in soft mud
Station A onshore and offshore view in September 1997
Station A surface features in April and September 1997
Station C surface features in June and September 1997
Station C surface features in May and September 1997
Station CID surface featnres in May and June 1997
Appendices
Appendix I
Appendix 2
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Sediment Analysis Methods
SedErode Data Plots
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1.
INTRODUCTION
SedErode (ISIS Mark II, Mitchener 1996) was deployed on 7 different days over a 10 month period at the
Peterstone Wentlooge mudtlat site in the Severn Estuary, UK to monitor sediment erodibility on a
seasonal timescale. During the survey HR Wallingford Lld took erodibility measurements at 3 stations on
the mudtlat in collaboration with the University of Cardiff, Department of Earth Sciences, who undertook
surface sediment sampling simultaneously at the same sites. The sediment samples were analysed by the
University of Cardiff to obtain physical and biological sediment properties.
This report is primarily a data report which describes the collection, methods, analysis and results of the
seasonal survey. The report also describes the key findings of the seasonality of the sediment properties
and erodibility at this site, and some sediment property intercomparisons.
2.
OBJECTIVES
The purpose of the seasonal survey was to provide a comprehensive data set of sediment erodibility and
associated physical and biological properties. The data set was collected systematically under the same
tidal conditions (full moon spring tide) in order to try and minimise the tidal intluence and highlight any
underlying seasonal trends. The data was collected to INTRMUD protocols (INTRMUD 1997) and
provides a dataset within the INTRMUD project to investigate sediment property relationships existing on
intertidal mudtlats. It is anticipated that the INTRMUD participants will use the data collected to
parameterise mudflat processes and further our understanding of in-situ erodibility.
3.
SEDERODE INSTRUMENT
3.1
Description
SedErode has been developed to measure the erosion shear stress of cohesive sediments in-situ. The need
for such an instrument was identified because of the difficulty of simulating natural conditions in the
laboratory, and the effects of collection, transport and storage on field sediment samples. SedErode is the
successor to ISIS (Instrument for shear Stress In-Situ) and is a portable, fully contained instrument for use
on intertidal mudflats and other cohesive sediments (Mitchener et aI, 1996). Williamson and Ockenden
(1996) give a full teclmical description of ISIS.
The basic principle of SedErode is that known shear stresses can be applied to a mud surface and the bed
response (turbidity) can be monitored. From these measurements the erodibility can be assessed.
The instrument consists of 2 units: a bell head unit and a pump and control unit. The instrument is fully
portable, with internal rechargeable batteries and has been designed for use on intertidal mudtlats. Figure
3 shows the major components of the SedErode system.
The shear stresses applied with SedErode are generated by water tlow through the circular, bell-shaped
head which fits inside a cylindrical perspex column with an annular clearance of 3mm. The bell head is
positioned 5.8mm above the sediment surface and water is drawn radially across the test surface, up
through the centre of the bell, and recirculated to be replaced under the bell head via a diffuser.
A mixing chamber within the recirculating system allows the eroded sediment to be thoroughly mixed
into the system volume and a nephelometer measures the turbidity of the recirculating water. The volume
of the SedErode recirculating system is approximately 1 litre. During each SedErode test a solid state
logger records both the reservoir turbidity and the recirculating tlow discharge. These are also noted at
regular intervals by the operator during a measurement run.
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During an erosion test the flow discharge is progressively increased in small steps until a turbidity jump is
observed, which corresponds to material being removed from the bed surface and mixing into the
recirculating volume. At this point the critical shear stress for the initiation of erosion is exceeded.
FUlther increases in the applied shear stress result in further sediment being eroded from the bed surface
and confirm that surface erosion has been initiated.
3.2
Deployment method
A 9cm diameter flat mud surface was selected for each measurement and a photograph of the site was
taken prior to positioning SedErode. The SedErode head unit was then planted into the mud bed so that
the locating tube was pushed into the bed and the unit rested on the supporting flange. (Plate 3 shows
SedErode deployment at station CD1 in April 1997). This isolated a 9cm diameter area of mud surface.
With the bleed valves open to expel air, the SedErode system was carefully filled with local, clear
seawater (collected at high water and left to settle and deaerate overnight before each deployment). The
bleed valves were shut and the power cable and logging connections were established. The nephelometer
turbidity sensor was zeroed, and logging of discharge and turbidity commenced. The logging interval
was 2 seconds. The lowest discharge setting (i.e. the lowest applied shear stress) was applied for at least
2 minutes to allow the water within the recirculating system to become fully mixed. This allowed a
baseline turbidity to be established prior to increasing the applied shear stresses and monitoring the
erosion response. The discharge was increased in controlled steps to apply increasing shear stress steps to
the mud surface.
The measurement run took about 10-20 minutes to complete at each site, with additional time for
sediment observations and surface sampling.
3.3
Analysis
Each SedErode run resulted in a raw time series of time, voltage output from the nephelometer (turbidity
sensor) and pump operating voltage at 2-second intervals. The raw data was downloaded onto computer
and 3.5" disks at the end of each survey day. The raw data was then processed via calibration functions to
produce time series of applied shear stress and Cardiff mud concentration within the SedErode
recirculating system.
The pump voltage was recorded on channel 7 of the data logger. This data was processed into discharge
via the SedErode pump calibration (pump A) using the following equation:
Q
=
(1)
0.2352.ln (PV) -0.1877
where:
Q = discharge (lis)
PV logged pump voltage
The fit parameter 1'2 was above 0.99 for this regression.
=
The applied shear stress was then calculated using the mud temperature and eroding water salinity which
determined the coefficient A in the relationship (Mitchener et al 1996):
(2)
�,p=A.Q
where:
A = dimensional coefficient dependent on salinity and temperature
�,p applied bed shear stress (Nm·2)
=
The nephelometer output was recorded on channel 8 during the SedErode deployments. Scale 3 was used
throughout the deployments in which the millivolt output from the nephelometer was directly equivalent
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to the measured NTU (Nephelometer Turbidity Units). The nephelometer was post-calibrated at HR
WalIingford Lld against calibration suspensions made up with surface mud collected from the Peterstone
Welltlooge mudflat. The suspensions were in the range 0 to 2000mg/1. Three NTU readings were
recorded for each concentration. The recorded millivolts were processed via a 2-stage calibration: first
from millivolts to NTU, and then from NTU to Cardiff mud concentration via the following equation:
Cardiff mud concentration (mg/I)
=
1.4904 (NTU)
(3)
The fit parameter r2 was 0.992 for this regression.
Observations and photographic records were added to the shear stress versus concentration plots (EXCEL
worksheets) for each deployment together with the calibrated time series of applied shear stress and
suspended mud concentration.
The incipient point of erosion corresponded to an increase in the concentration profile above the baseline
which indicated that material had been removed from the bed and mixed into the recircnlating system.
On the time series plots these shear stress steps are indicated as �A and �B which are the lower and upper
shear stress steps respectively. For runs where erosion started at the lowest applied shear stress �B. then �"
was calculated as the average between 0 and �B. Further higher applied shear stress steps then resulted in
higher concentrations and confirmed that surface erosion had been initiated. The increase in
concentration was sometimes reflected in an associated spike in the erosion rate, but was dependent on
the nature of erosion. For small, slow increases in concentration associated with discrete small particle
removal the erosion rate spikes were small, and almost insignificant, compared with the sharp
concentration rises and erosion rates associated with bulk surface rupture.
The erosion rate was also calculated from the concentration time series based on the area under the
SedErode head of diameter 9cm and the logging time interval of 2 seconds, and the SedErode
recirculating volume of I litre.
The SedErode data was output as time series plots of applied shear stress against concentration and
erosion rate, together with surface sediment observations and properties (Please see Appendix I).
4.
SITE DESCRIPTION
4.1
General morphology
Figure 1 shows the general Peterstone Wentlooge location map. The survey site was located mid-way
between Cardiff (to the West) and the River Usk at Newport (to the East) on the northern side of the
Severn Estuary. The estuary has a large tidal range, and is macrotidal, with a major fetch to the West,
facing the Irish Sea. Typical tidal ranges during the spring tide conditions under which the seasonal
survey was conducted were 11.3 to 14.3m. Plate 1 shows the Peterstone Wentlooge site looking onshore
from about 500m offshore. The mudflat site faces south-east, with a width of about lkm, and has a slope
of about 1:93.
Figure 2 shows a cross-shore profile of the seasonal survey transect. The site is backed by a bund for sea
protection, and a narrow saltmarsh, which was covered in Spartina grass during the summer months
which extends lOOm offshore. The saltrnarsh has a ridge-runnel structure, aligned approximately
onshore-offshore, in an irregular pattern, with consolidated ridges. The runnels in the saltmarsh are filled
with broken shell deposits which may be associated with storm events during which material is thrown
onto the upper mudflat. There is a transition zone between lOO to 200m offshore, where the topography
changes from a corrugated saltmarsh with vegetation to the soft, flatter mudflat proper. Plate 2 shows the
transition zone, saltmarsh and bund, and the runnel structures extend into the saltmarsh. Sed Erode was
deployed on the mudflat proper and Plate 3 shows SedErode in position at station CIDl on 22/4/97. The
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lower photograph shows the general site looking onshore from about 300m offshore. It shows the
meandering ridge-runnel system flattening out onshore towards the saltmarsh.
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4.2
Small scale features
Plate 4 shows a close up photograph of runnel features on 16 and 18 September 1997. The upper plate,
taken on I 6 September, shows shell fragments in the deepest part of the channel, and the black speckled
appearance of the runnel banks is due to the migration of small snails (Hydrohia ulvae) into the damp
areas of the mudflat. In the foreground the mud surface is covered by small holes, which are the burrows
of the ragworm (Nereis diversicolor), which favoured the drier, raised areas of the mudflat. In the top
right background of the upper photograph there are bird prints which have disturbed the surface of the
mud. The larger pits in the photograph may be holes made by bird beaks during feeding in search of
worms under the surface. The lower plate shows the same drainage runnel on J 8 September 1997 (2
days after the upper photograph). This photograph shows a recently deposited mud sheet, which forms a
blanket over the site of the order 2 -3cm thick and overlies the previous bed surface. This order of
deposition over a single tide has been found previously at this site (O'Brien and Whitehouse, in prep.). It
is interesting to note that the biology has quickly adapted to the new surface, and worm holes, bird
footprints and snails are reestablished. The mud is typically underconsolidated, and the edge of the runnel
has undergone partial erosion by slumping of the bank into the channel. Eroded material is typically
observed as small, spherical balls which were transported downstream in the drainage channels during the
run-off period.
The whole site has an underlying layer of consolidated blue-grey Flandrian clay, and there are also
sporadic exposed peat outcrops further offshore. The Flandrian clay was usually covered by a soft brown
surface mud layer of varying thickness between Ocm and 30cm. Station A, closest to the shore had a
persistent depth of 8cm to 10cm of surface deposit over the summer months which dropped sharply in
November 1997 to l cm in January 1998. Station C was slightly thicker with surface layer thickness
between 9cm and 14cm in the summer months and sharply dropped during the winter to 2cm. Station
CID had a thicker surface deposit than the upper mudflat, which gradually receded during the summer
months. The sheet was at its thickest at this site in May 1997, at 28cm and dropped slowly during the
whole survey period to l lcm. In general, at the Peterstone Wentlooge site, the thicker the sediment layer,
the lower the topographic position (O'Brien and Whitehouse, in prep.)
During the early part of the survey, in April and May 1997, the mudflat sites were characterised by a soft
mud sheet over the majority of the transect. Plate 5 shows the exposed blue-grey Flandrian clay base
during September 1997, after substantial erosion, with outcrops of soft mud on the ridges. The surface of
the eroded mud is pitted and irregular, and still contains many worm burrows. The lower plate shows the
edge of an exposed eroded gully, where distinct layering is visible. The layers probably represent tidal
depositional events which are quite uniform between 5 and IOmm thick (O'Brien and Whitehouse, in
prep.). There are softer mud deposits still visible in patches at the edge of the runnel bed and sporadically
in more of protected areas of the mudflat surface.
Plate 6 shows distinct consolidated layers within the Flandrian clay at site CID in September 1997. It also
shows the very rough small scale topography of the eroding bed surface, which is in clear contrast with
the smooth freshly-deposited surface shown on previous plates. The lower photograph shows the eroded
surface at this site and a thin veneer of soft mud on top of the base clay. The edge of the eroding patch is
ragged, and the eroded surface is again very irregular and pitted.
Plate 7 shows additional surface features observed at station A during January 1998. The upper
photograph shows longitudinal scour marks in the surface soft mud aligned in the onshore-offshore
direction. There was a large flock of birds at the site before the January 1998 survey, and the lower
photograph shows the highly disturbed surface soft mud which is roughened by the action of bird
footprints.
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4.3
Survey station characteristics
Station A, 200m offshore, was typically flatter and smoother than the offshore stations, with less
pronounced ridge-runnel features and drainage gullies extending offshore from the saltmarsh edge at
approximately 15m intervals in the longshore direction. Plate 8 shows the onshore (upper) and offshore
(lower) views at this site in September 1997. Plate 9 shows station A in April and September 1997
respectively, and shows flat ridge-runnel featnres in April which are smoothed out by a soft surface
deposit in September which largely blankets out the topographical features leaving only the major
drainage runnels as clear features.
An irregular shore-normal ridge runnel system developed further offshore, and station C, 400m offshore,
represented the developing topography, with station CID having a fully developed ridge runnel
topography. Plate 10 shows site C with smoother topography after a depositional tide (upper photograph
in June 1997) and more pronounced pitted ridge runnel featnres after an eroding tide ( 16 September
1997). Plate II shows site C after substantial deposition on 18 September, 2 days later, when the pitted
features have been obscured by a blanket deposit.
An established ridge runnel system was typically found 300m to 500m offshore. The typical developed
ridge widths were 40 to 70cm, with a height of 10cm. The drainage channels cut though the ridge-runnel
system at 10 to 20m intervals, and were aligned more directly onshore-offshore. Site CID was located in
this area, 450m offshore, and was characterised by a persistent irregular ridge-runnel system. Plate 12
shows site CID in May and Jnne 1997, and shows the established ridges at this site. The May photograph
(npper) shows the situation when the runnels have been partly filled in by a surface deposit.
5.
SAMPLING STRATEGY
The seasonal survey was carried out systematically so that the same deployment protocol was applied
during each survey visit. The survey stations were visited sequentially offshore, with deployments first at
station A, then C and finally station CID. This meant that similar exposure times were experienced at
each site before deployment commenced. During the April survey, there were some difficulties in
deploying SedErode at station C because of drainage though wormholes during SedErode filling, and for
this survey, site CID was sampled before going back to site C later in the day. The filling and bleeding
procedure was also improved after the April survey. SedErode measurements were always taken on
ridge featnres during the survey.
Table I shows a summary of the seasonal sampling schedule, and the number of successful deployments
at each station. There were some filling difficulties due to drainage through wormholes, especially during
the summer months at stations C and CID, when the volume of burrows within the sediment matrix was
estimated at over 30% by volume. A total of 54 measurements of critical erosion shear stress
measurements were made and analysed and 70 surface sample scrapes were analysed for physical and
biological properties.
Each SedErode measurement was supported by detailed surface sediment observations and photographs,
5 shear vane measurements, eroding water salinity determination and surface sediment temperature. A
Pilcon hand shear vane was used with a vane diameter of 33mm and 5cm length inserted to an operational
depth of 3-8cm.
Surface sediment scrapes were taken by the University of Cardiff by lightly skimming a spatnla edge over
the sediment surface. The samples were analysed for physical and biological sediment properties. Three
surface scrape samples were taken at each SedErode deployment site, at the same time as SedErode
measurements were being taken. One sample from each site was kept on ice until it could be frozen prior
to carbohydrate analysis. The second sample was analysed for physical properties (bulk density, loss on
ignition and grain size distribution), and a third sample was stored as an archive sample. Appendix I
describes the methods as used by the University of Cardiff to analyse the sediment samples. It must be
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noted that although physical sediment properties were analysed for each SedErode site, the carbohydrate
analyses were only carried out on the mid-sample from each station (typically site number '2' -for
example from deployment 5CID2).
Table 2 shows the climatic conditions on the survey dates. The weather conditions were very variable
during the survey, and did not typically represent the expected conditions for the months represented.
For example, the conditions during April and September were very hot and sunny, whereas May and
June were cloudy and changeable with some showers.
During April to September 1997, stations A, C and CID were visited and the surface soft mud sheet was
investigated. The January 1998 survey was undertaken to investigate the properties of the Flandrian clay,
and as many other full stations in triplicate as possible. There was limited daylight during this survey day
over the low water period, and thus only site A and site BIC (where the Flandrian clay was exposed) were
visited .
6.
RESULTS
Appendix 2 shows the detailed SedErode plots for each site, including photographs and erosion response
(concentration) time series for each deployment. Tables 3 to 9 show the detailed raw data collected for
each of the 7 survey dates. The data was then processed to investigate the mean values and variabilities
of the triplicate site data of physical sediment propelties and erodibility data. Tables 10 and 1 1 show the
arithmetic means and standard deviations of the data used for time series analysis and intercomparisons.
The critical shear stress average values are the arithmetric means of the available data, with sample
populations indicated in Table 1. The data was then investigated for seasonal trends and relationships
between sediment properties and erodibility.
Table 12 summarises the form of the relationships and the fit values, R2, to show the relative strength of
the derived relationships. The strongest relationships exist behveen colloidal carbohydrate and
temperature, and critical erosion shear stress and water content, with R2 values over 0.4. The
relationships are discussed for each sediment property in the following sections.
6.1
Temporal patterns
Figure 4 shows the mean time series data for the critical erosion shear stress and surface sample water
content during the months April to September 1997 (all data). Figure 5 shows the time series data for loss
on ignition and bulk density during the same period.
In general the average critical erosion shear stress of the mudflat surface decreased over the summer
months. This is reflected in a downward trend in the average values by about 0.2Nm·2 from April to
September. The highest value in �"was 0.45Nm'2 found at site CID in May and the lowest values
(0.IONm,2 to 0.13Nm,2) were found at site A, which corresponded to erosion occurring at the lowest
SedErode applied shear stress. The water content at site CID was also much lower than the other 2 sites,
and instead there is a gradual decrease in water content with time as seen at A and C, there is only a slight
increase at site CID in August and September.
Between April and September 1997 sites A and C on the upper mudflat show a decrease in erosion
resistance which appears to be connected to the overall increase in water content, or softening of the
surface deposit at these sites.
Site CID however, on the established ridge-runnel region lower down the mudflat, shows a different
erosion character to sites A and C. The average erodibility data shows more variability and there is a less
distinct seasonal trend. But interestingly, standard deviations of the erodibility triplicate measurements
:pHR Walllngford
IIII.:i
6
TR 57 07104198
decrease from site A to CID (down the mudflat). So although the erodibility changes more at site CID,
the repeatability of the measurements and spatial homogeneity increases at this site. This may be due to
the persistence of the ridge runnel features and microtopography, and the erosion variability throughout
the survey period due to the erosion occurring at the site exposing different sediment surfaces.
Figure 6 shows the time series data for colloidal carbohydrate content and surface sediment temperature.
Sites A and C show sinusoidal shaped curves for the time series of LaI, carbohydrate and temperature
between April and September, with a reduction to June, then an increase up to August and a further
reduction after September. The increase in these properties may reflect a bloom in biological activity
over the summer months due to increased primary productivity due to more sunlight and higher
temperatures. Site CID does not show this relationship for carbohydrate, and instead gradually increases
from May to September.
6.2
Erodibility
The strongest relationship between the critical erosion shear stress exists for surface physical sediment
properties (Table 12). Critical erosion shear stress decreases linearly with water content of the surface,
with an R ' value of 0.42, and increases with bulk density with an R ' value of 0.32. There appears to be a
weak relationship between critical shear stress and decreasing temperature which has a fit of 0.24. The
relationships between critical shear stress and biological parameters and grain size are less pronounced
with R2 values for these relationships below 0.20. Figures 7 and 8 show the 4 strongest relationships
between critical erosion shear stress and water content, bulk density, temperature and LOI respectively.
There is considerable scatter in the erodibility data for these relationships which reflect the spatial
inhomogeneity of the sediment and the fact that erodibility is dependent on a complex combination of
sediment properties and erosion/deposition history. Localised bioturbation and organism spatial migration
will also result in small scale spatial and temporal variations in erodibility. There is no relationship
between vane shear strength and critical erosion shear stress (Table 12) which further indicates the
layered strncture of the sediment and inhomogeneity of surface characteristics as compared to the
underlying sediment structure.
6.3
Grain size
The grain size was fairly uniform at the site, with d,o between 1.6 and 6. 1 microns over the survey period.
The highest values of d,o were found at site A, which reflects the coarse material persistent at this site.
The lowest value was at site CID2 in May. The predominant sediment at the survey site was silt, between
2 and 63 microns. There was typically less than 5% sand in the surface deposit, with a maximum value
of 5.8% at site CD in April. January 1998 showed no sand within the surface sediment, and the silt
content of the surface mud sheet and Flandrian clay was 20 -30% clay and 70 -80% silt under winter
conditions. The clay content ranged from 21% at its lowest at site A in April and January, and reached
56.2% at site A in July. The range of grain size parameters was low and reflected the persistence of a
dominant surface sediment, and there were no significant changes in the material composition. Given the
homogeneity of the sediment composition, it was not sensible to derive relationships between other
sediment variables, as the ranges covered were so small. There were also no spatial differences in
sediment composition across the mudflat between April and September 1997, when the surface mud
layer was present.
The situation in January 1998 was different, however, as the surface mud layer was not present at site B/C
and the underlying Flandrian clay was exposed. Figure 9 shows the grain size analysis for station A and
station B/C during January 1998. Site A represented the persistent brown surface layer, and samples from
B/C were taken from the base Flandrian clay layer. There is a distinct bimodal distribution for site B/C,
which indicates that the sediment was derived from 2 different sources. On observation of the grain size
curve for the soft mudsheet at Site A, it was clear that the surface mud at B/C was comprised of eroded
Flandrian clay and soft mud layer material.
:'PHR Walllngford
.::;
7
TR 57 {)6f()4198
6.4
Temperature and biological parameters
The temperature ranged from 8°C in January 1998 up to a peak at 30°C in July 1997. Typical values
were around 20°C during the summer months, and the values reflected the daily conditions and were
highest during calm conditions. The LOI values ranged from 7.39% in May to 14.40% in August 1997,
both at site A. Typical values were between 8 and 12% for the overall site, and peak values were found
during August and September reflecting a summer biological bloom. The colloidal carbohydrate values
also reached maximum values during the summer months. The minimum surface carbohydrate values
were encountered in cooler months of April and January at around 0.50mgg"l, and rose to 6.48mgg"1 at
site C in July. The strongest relationship for the Cardiff seasonal survey was between colloidal
carbohydrate and sediment temperature with an R2 valve of 0.64. There was only a weak relationship
however between LOI and colloidal carbohydrate as indicated by an R2 value of only 0.22 (Table 12).
Figure 10 shows the relationships between colloidal carbohydrate, loss on ignition and sediment
temperature. Both parameters increase with temperature, with high R 2 values (Table 12). This is
probably attributable to higher productivity on the mudflat surface by microphytobenthos, namely
diatoms, under sunny, warm conditions which produce colloidal carbohydrate and will increase the
organic carbon content of the surface sediment.
7.
DISCUSSION
In general there are no strong seasonal trends existing at the site in as much as the topographical
development of the mudflat during the summer months (O'Brien and Cramp, in prep.) is not reflected in
the erodibilty of the mudflat surface. There is a good relationship between the sediment compaction and
critical erosion shear stress, as represented by bulk density and water content. But surprisingly, given the
large numbers of macrofauna on the mudflat over the summer months, the erodibility was not controlled
by the biological indicators (carbohydrate and loss on ignition). The concentration of colloidal
carbohydrate, indicating the presence of diatoms, had a strong correlation with the sediment temperature
(a seasonal indicator) but did not correlate with erodibility indicating surface cohesion as would be
expected (Paterson et al. 1989). It is concluded that at this site during spring tide conditions bio
stabilization and bioturbation are secondary processes and that the inherent sediment matrix (the water
content) is the major controlling factor in governing the surface erodibilty.
The reduction in critical erosion shear stress from April to September 1997 may reflect the calm
conditions generally experienced over the summer period allowing the soft fluid mud sheet deposited at
slack tide to persist on the surface. The stability measurements were made under spring tide conditions
when deposition is likely to be at its greatest in the absence of wind waves and with increased sediment
load. (Whitehouse and Mitchener, in press; O'Brien and Whitehouse, in prep.). The erosion threshold at
site CID was generally higher than at Stations A and C. This is probably due to spatial differences in
deposition across the flat and the persistent ridges found at site CID. Station CID was visited last on each
survey day so any sub-aerial processes (drainage, drying) would have had longer to cause increases in the
surface erodibilty.
The sediment composition at Peterstone-Wentlooge is spatially consistent unlike other inter-tidal flats
where the sand fraction increases with off-shore distance (Amos, 1995). Changes in erosion shear stress
are often attributable to sediment composition (Mitchener et a1 1996) but not in this case. At this site the
surface erodibility of the sediment is the result of a complex dynamic exchange of sediment between the
mudflat and the estuary.
There was considerable evidence of layering at the site reflecting erosion and deposition events from the
observations and photographs. The lack of a relationship between critical erosion shear stress and vane
shear strength, also suggest vertical inhomogeneity, and surface properties did not reflect the sub-surface
features. This was particularly true when ridge-runnel features were smothered by a surface deposit,
leaving a soft watery exposed surface which masked a persistent sub-surface topography. This is
:JIHR Walllngford
lA:
8
TR S7 06104/98
consistent with other researchers (O'Brien and Whitehouse, in prep.) who found rapid changes in the
surface topography and layering (Mitchener et aI, 1996).
The results have demonstrated the value of long term measurements in assessing mudflat variability.
However, to enable seasonal trends in surface stability to be resolved at such an active site, it is
recommended that measurements are made at more frequent intervals to eliminate fluctuations due to
weather which appeared to dominate the mudflat processes. This was clearly demonstrated by two visits
in September 1997 which were separated by only two days but had very different mudflat characteristics
due to different preceding climatic conditions.
8.
ACKNOWLEDGEMENTS
The authors would like to thank Mr Stephen Shayler of the Department of Earth Sciences, University of
Cardiff for carrying out the colloidal carbohydrate analyses of the sediment samples. Thanks are also due
to Mrs Liz Stevenson, Mr Robert Adams and Miss Lisa Hall for their help in analysing the data and the
production of the report.
:piHR Wallrngford
£'
9
TR 57 07/04198
9.
REFERENCES
Amos C. (1995). Siliciclastic tidal flats. Geomorphology and sedimentology of estuaries. Developments
in Sedimentology 53. (Perillo, G.M.E. Ed), Elsevier Science RV. pp273-306.
INTRMUD PROTOCOLS (1997). Guide document compiled for INTRMUD partners by SERG (Severn
Estuary Research Group), Gatty Marine Laboratory, st. Andrews, Scotland, UK. February 1997.
Mitchener H. J. and Feates N. G. (1996) Field measurements of erosional behaviour and settling
velocities of intertidal sediments at the Dollard, Netherlands 2 1 -23 may 1996. HR Report No. TR 16,
HR Wallingford, Oxon, UK, November 1996.
Mitchener H.J., Torfs H. and Whitehouse R.lS. (1996). Erosion of Mud/Sand Mixtures. J. Coastal
Engineering, Volume 29, pp 1-25.
Mitchener H.J., Whitehouse R.J.S., Soulsby R.L., Lawford, V.A. (1996) Estuarine Morphodynamics
Instrument Development for Mud Erosion Measurements. Development and testing of SedErode Sediment Erosion Device. HR Report No. TR 16, HR Wallingford, Oxon, UK, October 1996.
O'Brien, D.l and Cramp, A. (in prep.). The seasonal development of a macro-tidal mudflat, Peterstone
Wentlooge, Severn EstualY, UK.
O'Brien, D.I. and Whitehouse, R.I.S. (in prep.) Medium-term mudflat dynamics: A case study from the
macrotidal mudflats on the north shore of the Severn Estuary, UK.
Paterson D.M. (1989). Short-term changes in the erodibility of intertidal cohesive sediments related to the
migratory behaviour of epipelagic diatoms. Limnology and Oceanography 34, pp223-234.
Williamson H.I. and Ockenden M.C. (1996). ISIS: An Instrument for Measuring Erosion Shear Stress In
Situ. Estuarine, Coastal and Shelf Science 42, pp 1-18.
Whitehouse, R.J.S. and Mitchener, H.J. (in press). Observations of the morphodynamic behaviour of an
intertidal mudflat at different timescales. In: Black, K. S., Paterson, D. M. and Cramp, A. (eds)
Sedimentary Processes in the Intertidal Zone. Geological Society, London, Special Publications, Vo!.
139, pp.255-271.
:.HR Walllngford
.:
10
TR 57 07fQ4198
Tables
:'PHR Walllngford
4:
TR 57 06104198
Table
1
Date
22/4/97
Overview of seasonal erodibility measurements
Survey
Number
I
Deployments at
Station A
3
Deployments at
Station C
I
Deployments at
Station C/D
3
22/5/97
2
3
3
3
19/6/97
3
3
3
2
22/7/97
4
3
3
I
19/8/97
5
3
3
2
18/9/97
6
3
3
3
14/1/98
7
3
soft mud
3 at B/C
base clay
:yHR Walllngford
lA:
-
Comments
Drainage at station C
StraightfOlward
deployments
Drainage at station
CID
Drainage at station
CID
Tide in fast at site
CID
Straightforward
deployments
Winter survey
TR 51 06104198
'<.
'.<e".
��
�
s
'5-
J:
'"
a.
Date
22 April 1997
22 May 1997
Avonmouth Low Deployment Time Conditions
Water (local time) (local)
14:42
11:00 -16:30
Sunny, calm. Short shower. Hot.
14:49
11:00 -16:30
Dull, cloudy. Some short
showers.
Daily
Maximum
temperature
(OC)
12.6
Daily Rainfall (mm)
No rain
No rain
10.0
>-3
6-
-
"
N
.g
o
�
a
g
....
....
19 June 1997
22 July 1997
�
�
11:30 -16:00
Rainy, overcast and windy.
Heavy shower
16:31
13:30 -18:30
Very hot and sunny
15:33
13:30 - 18:00
Sunny, hot. Some breeze later.
18 September
1997
14:21
12:00 -17:00
Hot and sunny. Short shower,
then windy and sunny
14 January 1998
15:01
19 August 1997
�
'"
13:27
10:30 -16:30
Low water times at Avonmouth signal station.
Meteorological data from Rhoose (Cardiff Airport) Station
Windy and cold.
2.9mm
=
=
c..
15.6
g
No rain
24.2
No rain
25.8
No rain
21.9
8.4
�
e·
No rain
S.
�.
....
�.
o
=
'"
Table 3
Results from Survey
1 on 22 April, 1997
ERODIBILITY
'tA
'tB
't"
Time
Site
(Nm-2)
Lower
(Nm-2)
Upper
(Nm-2)
Average
11: 12
lAl
0
0.25
0.13
Eroded at lowest shear stress
11 :28
IA2
0.35
0.48
0.42
Distinct mass erosion
11:50
IA3
0.27
0.42
0.34
15:47
ICI
0.32
0.43
0.37
Comments
No deployment, drainage through
wormholes
No deployment, drainage through
wormholes
IC2
lC3
Logger failed
I CD!
14:07
ICD2
0.27
0.38
0.33
Weak erosion
14:25
lCD3
0.23
0.26
0.24
Erratic erosion
�
SEDIMENT PHYSICAL PROPERTIES
Sand content
Water
d 50
content (%
(>63f1m)
(microns)
by mass)
(% by weight)
Silt content
(63)x>2f1m)
(% by weight)
Clay content
(<2f1m)
(% by weight)
1.9
57.5
40.6
2.7
2.5
52.9
44.6
205
3.1
3.4
54.8
41.8
1241
231
2.1
2.8
48.3
48.9
lC2
no
sample
lC3
no
sample
l CDI
1279
191
2.1
2.1
48.4
49.5
lCD2
1258
212
2.3
5.8
47.2
47.0
l CD3
1253
217
2.2
3.4
48.7
47.9
Site
Bulk
densi
(kgm- )
lAI
1235
238
3.1
lA2
1227
250
lA3
1264
lCl
:pHR Wallfngford
.:
TR 57 06/04/98
Table
3 (continued) Results from Survey Ion 22 April, 1997
SEDIMENT BIOLOGICAL PROPERTIES
Z
Site
Sediment temperature
(degrees C)
Loss on ignition (%
mass loss)
IAI
15.6
9.65
IA2
15.8
9.83
IA3
18.8
9.95
ICI
16.7
10.98
IC2
no sample
IC3
no sample
l CD l
21.6
10.24
l CD2
22.0
10.39
l CD3
22.1
10.55
HR Wallingford
Colloidal
carbohydrate content
(mg/g)
2.56
2.62
2.76
TR 57 06104/98
Table
Results from Survey 2 on 22nd May
4
1997
ERODIBILITY
'tA
'tB
't"
Time
Site
(Nm-2)
Lower
(Nm-2)
Upper
(Nm-2)
Average
11:38
2AI
0
0.26
0.13
Erosion from start
12:00
2A2
0.31
0.44
0.38
Weak erosion
12:30
2A3
0.26
0.35
0.30
Erosion
13:45
2CI
0.41
0.45
0.43
Erosion
14: 11
2C2
0.37
0.42
0.39
Erosion
14:48
2C3
0.25
0.36
0.31
Erosion
15:20
2CDI
0.38
0.53
0.46
Medium erosion
15:47
2CD2
0.37
0.43
0.40
Medium erosion
16:11
2cm
0.26
0.35
0.30
Medium erosion
Comments
content(%
d,o
(microns)
Sand content
(>63f.lm)
(% by weight)
Silt content
(63)x>2f.lm)
(% by weight)
Clay content
(<2f.lm)
(% by weight)
1303
172
3.3
0.8
59.1
40.1
2A2
1360
136
6.1
2.2
67.6
30.2
2A3
1350
141
6.0
1.8
67.5
30.7
2CI
1295
178
2.9
1.4
58.9
39.7
2C2
1287
184
2.6
0.4
56.4
45.2
2C3
1294
179
3.6
1.6
60.3
38.1
2CDI
1319
161
3.0
0.1
58.2
41.7
2CD2
1313
165
2.9
1.4
57.0
41.6
2Cm
1332
152
2.7
0.7
55.4
43.9
Site
Bulk
density
(kgm-3)
2Al
Z
HR Wallingford
Water
by mass)
TR 57 06104/98
Table
4 (Continued) Results from Survey 2 on 22nd May 1997
Site
(degrees C)
Loss on ignition (%
mass loss)
2AI
10.9
9.30
2A2
10.7
7.39
2A3
1 1. 1
7.45
2CI
[1.5
9.32
2C2
12.[
9.5[
2C3
11.6
9.53
2CDI
10.8
9.28
2CD2
10.9
9.70
2CD3
10.9
9.55
:'PHR Walllngford
l1li:
Colloidal
carbohydrate
content (mg!g)
0.49
1.17
0.71
TR 57 06104198
Table
Results from Survey 3 on
5
19th June 1997
ERODIBILITY
�A
�B
�"
Site
(Nm-2)
Lower
(Nm-2)
Upper
(Nm-2)
Average
I1 :32
3AI
0
0.25
0.13
Erosion from start
12:06
3A2
0.36
0.45
0.40
12:27
3A3
0.25
0.34
0.30
11:25
3CI
0.26
0.35
0.31
13:50
3C2
0.25
0.30
0.28
Mass erosion only
14:15
3C3
0.25
0.29
0.27
3 erosion phases
14:47
3CDI
0.32
0.41
0.36
Weak erosion
15:10
3CD2
0.42
0.49
0.45
Weak erosion
Time
Comments
Test failed due to draining through
wormholes
3CD3
Sand content
Water
d,o
content (%
(>63f.lm)
(microns)
by mass)
(% by weight)
Silt content
(63)x>2f.lm)
(% by weight)
Clay content
(<2f.lm)
(% by weight)
1.2
60.3
38.5
3.0
2.0
61.5
36.5
217
3.2
3.6
55.1
41.3
1250
220
2.3
2.5
52.9
44.6
3C2
1276
194
2.4
1.9
54.7
43.4
3C3
1263
207
1.9
1.2
48.1
50.7
3CDI
1353
140
2.3
3.0
50.3
46.7
3CD2
1355
139
2.7
3.2
59.9
36.9
3CD3
1357
138
2.0
3.9
46.6
49.5
Site
Bulk
density
(kgm-3)
3AI
1260
209
2.9
3A2
1248
223
3A3
1254
3CI
::pHR Walllngford
l1li.:
TR 57 06,11)4/98
Table
5 (Continued) Results from Survey 3 on 19th June 1997
Site
(degrees C)
Loss on ignition (%
mass loss)
3AI
14.5
8.08
3A2
14.4
8.17
3A3
15.6
8.11
3CI
16.4
8.65
3C2
17.3
8.66
3C3
22.1
8.89
3CDl
19.3
9.01
3CD2
20.5
9.01
3cm
19.4
8.94
:pHR WalHngford
.:
Colloidal
carbohydrate
content (mg/g)
1.04
1.09
1.67
TR 57 06104198
Table 6
Results from Survey
4 on 22nd July 1997
ERODIBILITY
tA
tB
tcr
Time
Site
(Nm-2)
Lower
(Nm- 2)
Upper
(Nm-2)
Average
13:41
4Al
0
0.22
0.11
Erosion from start
14:29
4A2
0.29
0.31
0.30
Poor record
15:01
4A3
0.31
0.36
0.33
Gradual weak erosion
15:51
4Cl
0.30
0.34
0.32
Benign erosion followed by massive
rupture
16:15
4C2
0.23
0.31
0.27
Mass erosiou
16:40
4C3
0.23
0.30
0.26
Weak erosion
18:05
4CDl
0.23
0.26
0.24
Weak erosion
Comments
Test failed due to drainage through
wormholes
Test failed due to drainage through
wormholes
4CD2
4CDJ
Sand content
Water
d50
content (%
(>63Ilm)
(microns)
by mass)
(% by weight)
Silt content
(63)X>2Ilm)
(% by weight)
Clay content
(<2llm)
(% by weight)
Site
Bulk
density
(kgm- 3)
4Al
1226
251
2.0
1.8
47.5
50.7
4A2
1282
189
1.6
2.1
41.7
56.2
4A3
1318
161
1.9
1.4
47.4
51.2
4Cl
1276
194
1.8
2.5
45.3
52.2
4C2
1287
184
1.8
2.2
45.9
51.9
4C3
1370
131
2.0
0.9
49.5
49.6
4CDl
1388
123
3.4
1.8
62.9
35.3
4CD2
1406
115
1.6
2.0
44.4
53.6
4CD3
1388
123
2.1
3.0
48.0
49.0
Z
HR Wallingford
TR 57 06I0419S
Table 6 (Continued) Results from Survey
4 on 22"d July 1997
Site
(degrees C)
Loss on ignition (%
mass loss)
4Al
27.5
10.24
4A2
29.0
9.81
4A3
28.5
10.11
4Cl
27.0
9.50
4C2
27.0
9.59
4C3
27.0
9.15
4CDl
8.52
4CD2
9.27
4CD3
9.54
:.HRWalUngford
.:
Colloidal
carbohydrate
content (mg/g)
5.47
6.48
1.72
TR 57 06104198
Table
7
19'h August 1997
ERODlBILITY
1A
1B
1"
Time
Site
(Nm-2)
Lower
(Nm-2)
Upper
(Nm-2)
Average
13:37
SAl
0
0.19
0.10
Weak erosion from start
14:27
SA2
0.23
0.27
0.2S
Weak erosion
14:S1
SA3
0.19
0.22
0.21
Medium erosion
I S :30
SCl
0.23
0.36
0.30
Weak erosion
IS:S8
SC2
0
0.20
0.10
Erosion from start, then massive rupture
16:19
SC3
0.21
0.31
0.26
Weak erosion
16:49
SCDl
O.3S
0.38
0.37
Weak erosion
17:12
SCD2
0.34
0.37
0.36
Weak erosion
Comments
No time for measurement as tide coming
in fast
SCD3
Sand content
Water
dso
content (%
(>63)lm)
(microns)
by mass)
(% by weight)
Silt content
(63)x>2)lm)
(% by weight)
Clay content
(<2)lm)
(% by weight)
1.1
4S.3
S3.6
3.6
1.3
70.2
28.S
289
3.7
I .S
68.9
29.6
1247
224
1.9
0.7
47.9
SI.4
SC2
12S0
221
3.S
O.S
69.9
29.6
SC3
12S3
218
2.8
1.8
SS.7
42.S
SCD!
1340
147
2.1
2.0
48.7
49.3
SCD2
1344
14S
2.2
1.0
SO.9
48.1
SCD3
1336
ISO
2.1
0.8
SO.1
49.1
Site
Bulk
density
(kgm-3)
SAl
1196
301
1.7
SA2
1228
247
SA3
1202
SCl
:.HR WaJllngford
4:
TR 57 06/04/98
Table
7 (Continued) Results from Survey 5 on 19th August 1997
Site
(degrees C)
Loss on ignition (%
mass loss)
SAl
30.0
10.93
SA2
29.0
I 1.1S
SA3
30.0
14.40
SCI
29.3
11.89
SC2
29.0
11.0S
SC3
28.0
10.S6
SCD!
26.0
10.49
SCD2
26.S
10.31
SCD3
:..HR WaHlngford
.:
Colloidal
carbohydrate
content (mg/g)
3.7S
4.07
2.21
10.17
TR 57 06104/98
Table
8
18th September 1997
ERODIBILITY
�A
�B
�cr
Time
Site
(Nm·2)
Lower
(Nm'2)
Upper
(Nm·2)
Average
12:54
6Al
0
0.25
0.13
Mass rupture at start
13: 14
6A2
0
0.25
0.13
Mass erosion at stmt
13:35
6A3
0
0.25
0.13
Mass erosion at stmt
14:24
6C l
0
0.27
0.14
Mass erosion at start
14:43
6C2
0
0.26
0.13
15:07
6C3
0
0.24
0.12
Weak erosion at start
15:39
6CDl
037
0.42
039
Weak erosion
16: 13
6CD2
0.28
033
03 1
Weak erosion
16:37
6Cm
0.25
0.28
0.27
Weak erosion
�
Comments
Sand content
Water
d 50
(>63f.lm)
content (%
(microns)
by mass)
(% by weight)
Silt content
(63)x>2f.lm)
(% by weight)
Clay content
(<2f.lm)
(% by weight)
2.0
43.4
54.6
1.5
1.3
43.5
55.2
303
1.9
1.9
473
50.8
1223
256
2.1
03
50.8
48.9
6C2
1232
243
1.9
1.9
47.0
51.1
6C3
1234
240
1.8
2.0
46.0
52.0
6CDl
1332
152
2.8
1.4
54.9
43.7
6CD2
1356
138
2.8
3.9
51.7
44.4
6Cm
1358
137
2.4
33
49.7
47.0
Site
Bulk
densi
(kgm' )
6Al
1174
348
1.5
6A2
1174
348
6A3
1194
6Cl
Z
HR Wallingford
TR 57 06/04198
Table
8 (Continued) Results from Survey 6 on 18 th September 1997
Site
(degrees C)
Loss on ignition (%
mass loss)
6A l
22.0
10.89
6A2
23.0
10.60
6A3
24.0
11.67
6Cl
23.0
1 1.43
6C2
22.5
10.78
6C3
24.0
9.75
6CDl
22.0
9.42
6CD2
23.5
8.84
6CD3
22.0
8.65
::piHR Walllngford
.::;
Colloidal
carbohydrate
content (m gig)
1.83
2.21
2.81
TR 57 0610419&
Table
9
Results from Survey
7 on 14 th January 1998
ERODIBlLITY
�A
�B
�"
Time
Site
(Nm-2)
Lower
(Nm-2)
Upper
(Nm-2)
Average
10:58
7A1
0
0.25
0.13
Mass rupture at start
11:37
7A2
0
0.25
0.13
12:02
7A3
0
0.25
0.13
12:52
7BC1
0
0.27
0.14
13:34
7BC2
0
0.26
0.13
14:19
7BC3
0
0.24
0.12
Weak erosion at start
�
Comments
Sand content
Water
d,o
content (%
(>63)lm)
(microns)
by mass)
(% by weight)
Silt content
(63)X>2)lm)
(% by weight)
Clay content
(<2)lm)
(% by weight)
Site
Bulk
densi
(kgm- )
7A1
1255
215
4.6
0.0
78.0
22.0
7A2
1251
220
4.4
0.0
76.0
24.0
7A3
1248
223
4.7
0.0
79.0
21.0
7BC1
1448
100
5.0
0.0
75.0
25.0
7BC2
1496
86
5. 1
0.0
74.0
26.0
7BC3
1602
63
4.4
0.0
72.0
28.0
Site
(degrees C)
Loss on ignition (%
mass loss)
7A1
8.0
10.02
7A2
8.5
9.08
7A3
8.0
10.05
7BC1
9.0
6.69
7BC2
8.0
6.90
7BC3
8.0
6.35
:pHRWalllngford
.:
Colloidal
carbohydrate
content (mg/g)
0.489
0.542
TR 57 01104J98
�..J
�
S
'<5I
Table
'"
a.
Site A
1 8/04/97
22105197
19/06/97
22/07/97
19/08/97
1 8/09/97
14/0 1198
Site B/C
14/0 1198
Site C
1 8/04/97
22/05/97
19/06/97
22/07197
19/08/97
1 8/09/97
Site CD
1 8/04/97
22/05/97
19/06/97
22/07/97
19/08/97
1 8/09/97
�
�
�
Averaged data for the Cardiff seasonal survey
Triplicate data for surface sediment properties except for carbohydrate where there is one detennination for each station and critical shear stress where
available data is averaged
Date
;l
10
Deployment
Sediment Vane Shear
Temp"
Strength
(kPa)
rC)
Water
Content
(%)
Bulk
Density
(kgm")
LOI
(%)
lA
2A
3A
4A
5A
6A
7A
16.7
10.9
14.8
28.3
29.7
23.0
8.2
0.5
0.8
0.9
1.0
1.3
0.9
5.6
231.2
150.0
2 1 6.3
200.5
279.2
333.4
2 1 9.5
1242
1337
1254
1275
1209
1 18 1
1251
9.81
8.05
8.12
10.06
12.16
1 1 .05
9.72
7BC
8.3
16.8
82.7
1516
6.64
1C
2C
3C
4C
5C
6C
16.7
1 1 .7
18.6
27.0
28.8
23.2
0.1
0.3
0.6
0.7
0.9
1.0
231.3
180.5
207.1
169.9
220.9
246.0
1241
1292
1263
1311
1250
1230
10.98
9.45
8.73
9.42
1 1 .17
10.65
ICD
2CD
3CD
4CD
5CD
6CD
2 1 .9
10.9
19.7
0.4
1.1
1.2
1.8
1.6
1.4
206.6
159.2
139.0
120.4
146.1
142.6
1264
1321
1355
1394
1342
1349
10.39
9.51
8.98
9.1 1
10.40
8.97
26.3
22.5
Colloidal
Carbohydrate
(mg/g)
Site A
2.56
0.49
1 .04
5.47
3 .75
1.83
Site B/C
Site C
2.62
1.17
1.09
6.48
4.07
2.21
Site CD
2.76
0.71
1.67
1.72
2.21
2.81
Median
size
(f'm)
Fraction
> 63f'm
(% sand )
Fraction
Fraction Critical
Shear Stress
63>x>2f'm <2f'm
(% silt)
(% clay) (Nm"')
2.95
5.09
3.00
1.81
2.98
1.66
4.65
2.60
1.60
2.27
1.77
1.30
1.73
0.00
55.07
64.73
58.97
45.53
6 1 .47
44.73
77.67
42.33
33.67
38.77
52.70
37.23
53.53
22.33
0.30
0.27
0.28
0.24
0.19
0.13
0.20
4.81
0.00
73.67
26.33
0.30
2.1 1
3.02
2.22
1.88
2.69
1 .92
2.80
1 . 13
1.87
1.87
1.00
1.40
48.30
57.87
5 1 .90
46.90
57.83
47.93
48.90
4 1 .00
46.23
5 1 .23
4 1 . 17
50.67
0.37
0.38
0.29
0.28
0.22
0.13
2.20
2.88
2.32
2.37
2.12
2.67
0.73
3.37
2.27
1 .27
2.87
3.77
48. 1 0
56.87
52.27
5 1 .77
49.90
52.10
48.13
0.29
0.39
0.41
0.24
0.37
0.32
42.40
44.37
45.97
48.83
45.03
....J
�
:r
'"
f
Table
11
For triplicate sediment property data only (no carbohydrate or critical shear stress values given)
Date
Site A
18/04/97
22/05/97
19/06/97
22/07/97
19/08/97
18/09/97
14/01198
Site C
18/04/97
22/05/97
19/06/97
22/07/97
19/08/97
18/09/97
14/01198
Site CD
18/04/97
22/05/97
19/06/97
22/07/97
19/08/97
18/09/97
�
�
�
�
il
Standard deviation data for the Cardiff seasonal survey
Deployment Sediment Vane Shear Water
Bulk
Temp.
Content Density
Strength
(kgm-')
(kPa)
(%)
(0C)
LOI
Median
size
(%)
Fraction
Fraction
Fraction
().lm)
> 63).lm
(% sand )
63>x>2).lm
(% silt)
<2).lm
(% clay)
lA
2A
3A
4A
5A
6A
7A
1.8
0.2
0.7
0.8
0.6
1.0
0.3
0.3
0.2
0.0
0.1
0.2
0.2
3.6
23.1
19.3
6.8
46.0
28.2
26.1
4.0
20
31
6
46
17
12
4
0.15
1.08
0.05
0.22
1.95
0.55
0.56
0.24
1.58
0.15
0.22
1.15
0.23
0.28
0.75
0.72
1.22
0.35
0.20
0.38
0.00
2.3 I
4.88
3.40
3.32
14.02
2.22
1.53
2.05
5.58
2.41
3.04
14.18
2.39
1.53
1C
2C
3C
4C
5C
6C
7BC
0.3
3.1
0.0
0.7
0.8
0.6
0.1
0.1
0.3
0.3
0.1
2.0
3.2
13.3
33.7
3.3
8.5
18.7
4
13
51
3
6
79
0.11
0.14
0.23
0.67
0.85
0.28
0.52
0.26
0.14
0.80
0.19
0.33
0.64
0.65
0.85
0.70
0.95
0.00
3.08
3.41
2.27
11.15
2.53
1.53
3.72
3.91
1.42
10.96
1.59
1.53
0.3
0.1
0.7
0.3
0.0
0.2
0.1
0.2
0.139
13.7
6.2
1.2
4.3
1.8
8.2
14
10
2
10
3
14
0.16
0.21
0.04
0.53
0.13
0.40
0.14
0.19
0.33
0.93
0.Q7
0.23
1.88
0.65
0.47
0.64
0.64
1.31
0.79
1.40
6.86
9.81
1.11
2.62
1.27
1.30
6.62
9.52
0.64
1.74
1CD
2CD
3CD
4CD
5CD
6CD
0.4
0.87
p.�
;!;
�
t
�
�
i
Table
12
Cardiff seasonal data intercomparisons
Intercomparisons based on average data.
Independent Variable (X)
Relationship Character
Equation
R2
Carbohydrate content increases with sediment
temperature
Critical shear stress decreases with water content
LOI increases with sediment temperature
Critical shear stress increases with bulk density
Critical shear stress decreases with sediment
temperature
y=0. 1965x-1.5051
0.64
y=-0.00Ix+0.4765
y=0 . 1 l 12x+7.583
y=0.0008x-0.7533
y=-0.0064x+0.4174
0.42
0.38
0.32
0.23
y=0.6093x-3.555
y=0.0262x+0.318
0.22
0.17
y=-0.0298x+0.5749
0.16
Dependant Variable(Y)
Sediment temperature (deg C)
Colloidal carbohydrate (mg/g)
Water content (%)
Bulk density (kgm" )
Critical shear stress (Nm' )
LOI (% mass loss)
Critical shear stress (Nm--)
Critical shear stress (Nm -)
LOI (% mass loss)
Colloidal carbohydrate (mg/g)
Vane shear strength (kPa)
LOI (% mass loss)
Critical shear stress (Nm- )
Colloidal carbohydrate increases with LOI
Vane shear strength increases with sediment
temperature
Critical shear stress decreases with LOI
Vane shear strength (kPa)
Critical shear stress (Nm- )
None
-
Figures
I
:pHR WaHlngford
.:
TR 57 06/04/98
Z "
I
w
w·
Z (!!
0
....
1/l
a:
0
0
.J
....
wz
w
tu
0.. :;:
Figure 1
Z
z
0:
w
>
>0:
oe:(
::l
W in
C/l
w
Peterstone Wentlooge mudflat general location plan
HR Wallingford
TR 57 06104/98
0
'"
"
�
C
0
'"
'"
1l
0>
.�
c.
E
ill
�
0
�
..,
"
..,
�
e
::;;:
w
..,
"
(J)
0
11
0
0
'"
E
"
0
c:
.0
�
E
(ij
c:
0
E
"'
C ''
c:
�
0
2
(I!
0
.c:
(fJ
��
g
(w) N O O 01 9A!IB191:1 UOnBA913
Figure 2
Erodibility seasoual survey sampling locations
:piHR WaUlngford
.:
TR 57 06104/98
5cm
Air bleed
lube
(behind)
_
_�
Tap 1
Filler
lube
Jubilee
clip
Tap 2 --�i'1
Oullel
lube
Inlel
lube
Jubilee
clip
L-�- Flowmeler
� 'Jc--- Top cap
i'ii---
I\.�=====:::;--=-
Mixing
chamber
PVC
nul
Upper '0'
ring seal
lower '0'
ring seal
Nephlomeler
gland
Pump
motor
Diffuser
Flange
Pump
pewer supply
lead
Bell
head
Cuftlng
edge
Figure 3
SedErode head uuit
:1'HR Walllngford
dII.:
TR 57 06104/98
Critical E rosion Shear Stress against Time
0.45 ,-------,
0.40
<:'; 0.35
z
-;;; 0.30
�
�
(J)
.s::
(J)
0.25
0.20
;g 0.10
()
0.05
1il
0.15
--+- Site A
__ Site C
0.00 +----,-----,.---.--r---r--!
"""- Site CD
Apr-97
May-97
Jun-97
Jul-97
Aug-97
Sep-97
Oct-97
Date
Water Content against Time
400 ,------�
1
350
--+- S ite A
300
......- Site CD
£ 250
�
!C.-
c
200
j
1 00
__ Site C
8 1 50
*
50
O +-----�----�--r_--�r_--�
Apr-97
May-97
Jun-97
Jul-97
Aug-97
Sep-97
Oct-97
Date
Figure 4
Time series of critical erosion shear stress and surface sediment water content
:'PHR Walllngford
lA:
TR 57 06104/98
Loss on Ignition against Time
14
12
m
10
,g
�
6
U)
�
E
8
>.0
9
4
-+- Site A
__ Site C
2
-'-Site CD
0
Apr-97
May-97
Jun-97
JUI-97
Aug-97
Sep-97
Oct-97
Date
Bulk Density against Time
1 450 1.======:::;--------------,
-+- Site A
1400
.;;-
'E
�
-- Site C
-'-Site CD
1 350
.� 1300
c:
Q)
'0
""
::; 1 250
to
1 200
1 1 50 �----�--r_--_r--�
Apr-97
May-97
Jun-97
Jul-97
Aug-97
Sep-97
Oct-97
Date
Figure 5
Time series of surface sediment loss on ignition and bulk density
:'PHR Walllngford
.&:
TR 57 06104/98
Colloidal Carbohydrate against Time
7
-+- Site A
6
:§
.s
0>
__ Site C
5
<D
1il
--,,-Site CD
4
"0
�
>.!:
0
-e
3
<U
0
:§
(ij
"0
2
0
()
1
0
Apr-97
May-97
Jun-97
JUI-97
Aug-97
Sep-97
Oct-97
Date
Sediment Temperature against Time
35 �------�
()
�
30
.gJ 25
0>
�
�
20
�
15
�
<D
Cl.
-
C
�
'5
c'}j
10
-+- Site A
-- Site C
5
--"- Site CD
O +-----�----�--_r--�
Apr-97
May-97
Jun-97
JUI-97
Aug-97
Sep-97
Oct-97
Date
Figure 6
Z
Time series of surface sediment colloidal carbohydrate and temperature
HR Wallingford
TR 57 06104/98
Critical shear stress against Water content
0045 .------=============-----,
E
t;
:2
,r
• Site A
0040
0.35 ·
0.30
• Site C
...
...
.
•
... Site CD
�'" 0.25
1ii
.<:
'"
0.20
y
"& 0.15
�
o
0.05
'"
'"
Q)
�
1ii
�
ro
Q)
.<:
'"
:E
(ij
0
0
•
o
0040
0.35
0.30
50
100
250
200
1 50
300
Water content (%)
350
400
1400
1450
Critical Shear Stress against Bulk Densit�
• Site A
-
_ Site C
...
...
... Site CD
0.25
0.20
0.15
-
•
0.10
y = 0.0008x - 0.7533
R =0.3163
2
0.05
0.00
1 100
Figure 7
•
-1---,---....,..----,-..,---.,--.--.-l
0045
E
t;
-0.001x + 0.4765
R2=0.4241
0.10
0.00
1"'
=
1 150
1 200
1 250
1300
3
Bulk density (kgm· )
1 350
Critical erosion shear stress against sediment water content and bulk density
:YHR Walllng/ord
.a:
TR 57 06/04198
Critical Shear Stress against Sediment Teml2erature
0.45
• Site A
• Site C
A Site CD
DAD
"'
0.35
E
6 0.30
'"
'"
�
1ii
lii
'"
.c
'"
�
'E
u
A
A•
•
0.25
0.20
y=
0.15
-0.0064x + 0.4174
R2= 0.2348 •
•
20
30
0. 1 0
0.05
0.00
0
15
10
5
25
35
Sediment Temperature (deg C)
C ritical shear stress against Loss on Ignition
0045
�
DAD
• Site A
• Site C
A Site CD
0.35
� 0.30
'"
'"
�
'"
�
'"
'"
.<=
'"
'ill
0
""
·c
0
0.25
A
--..
�
rI-
A
•
---
A
•
A
A
-
•
•
0.20
0.15
•
0.10
y=
0.05
•
-0.0298x + 0.5749
R2 = 0 . 1 639
0.00
6
Figure 8
7
8
9
LOI (%)
10
11
12
Critical erosion shear stress against sediment temperature and loss on ignition
:1'HR Wa1!Jngford
.::
TR 57 06IQ4198
100
90
80
.,
�.,
'D
<:
70
-
1---
• • • • •
/'
-Sample 7B/C mean values
50
//
20
10
o
-
.
,
-
_.
�
V. /
-
60
0
.-
--Sample 7A mean values
1:
.,
!!
40
.,
D30 1--"
a
-- -�---
AI
:/
.1
/
�/
.
-
..
J
,
I�
.
.'
.
1
10
100
Size (Jtm)
6
5
.,
.,
"
E
Site 7A soft mud sheet
• Site 7B/C
III
Flandrian clay I--
4
�'0 3
1:
.,
.,
D- 2
!!
1
o
�'?'<> �').'<> ,,9'-' J'
Figure 9
Z
"
,,�
'J.,'?� ",,'?'<> �� ro'?� f»�" ,,'J.,<f'
Sieve size (�m)
,,'0').'0
II
rO-,?ro "",,':of» {J-'?'<> ,<>corf'
Grain size distribution plots for site A (soft mud sheet) and site B/C (Flandrian clay) on
14 January 1998
HR Wallingford
TR 57 06104/98
Colloidal Carbohydrate against Sediment Temperature
7
� 6
.!2'
• Site C
en
5
5
Q)
1'1
4
-g,
.<:
0
-e
tU
()
:§
(iJ
"0
0
()
•
• Site A
.t. Site
•
y = 0.1 965x · 1 .5051
R2 = 0.6384
CD
3
2
•
•
1
0
•
•
0
5
10
15
20
Sediment Temperature (deg
25
30
C)
35
Loss on Ignition against Sediment Temperature
13
• Site A
• Site B
12
;g
(5
�
...J
11
.t. Site
•
CD
•
10
•
9
•
8
•
y=0. 1 1 1 2x+7.583
R2=0.3822
7
6
Figure 10
•
0
5
10
15
20
Sediment Temperature (deg
25
C)
30
35
Colloidal carbohydrate and loss on ignition against sediment temperature
:'PHR Walllngford
.:
TR 57 06/04198
Plates
:JIHR WaUlngford
.:
TR 57 06104198
Plate 1
Z
Peterstone Wentlooge general site
HR WalHngfo,d
TR 57 061G4191
.. ,
, ...
Plate 2
Transition zone, saltmarsh and bund
.
:yHR Walhngford
.::
TR 57 06I0�19S
Plate 3
;!
SedErode at site lC1D1 April 1997, and at site B, looking onshore January 1998
HR Wallingford
TR 57 O6IO-lI9S
•
--'"
?"
Plate 4
�
:.:r':
..
.... ..
�
.-.� .'
Main drainage runnels and banl< collapse on 16 and 18 September 1997
TR S7 06/()..I198
Plate 5
Z
Exposed Flandrian base clay and surface features at station CID and runnel bank
layering.
HR W,IUngford
TR 57 06J04{98
Plate 6
Layering featnres at site CID September 1997, showing exposed Flandrian clay layers,
and soft mnd sheet remnant
.
::JIHR Walhngford
.:
TR 57 06/0�/98
Plate 7
Surface features at station A in January 1998, showing scour erosion marks and bird
footprint patterns in soft mud
Z
HR Wallingford
TR 51 06/04(98
Plate 8
�
Station A onshore and offshore view in September 1997
HR Waltingford
TR 57 O6IOms
Plate 9
Station A s urface features in April and September 1997
.
::JIHR Walhngford
.:
TR S7 06/0419&
"
.� ' f"
-.:.;"::: �---:..� --,.
.•
...
Plate 10
�
� ��"
Station C s urface features in Juue and September 1997
HR Wallingford
TR 57 06/0H98
Station C
Plate 1 1
:..HR Walhngford
..:
.
surface features in May alld September 1997
TR 57 06104/98
Plate 12
Z
Station CID surface features in May and June 1997
HR Wallingford
TR57 O�f98
Appendices
Z
HR Wal!;ngford
TR 57 06104198
App endix 1
Sediment analysis methods
Z
HR Wallingford
TR S7 06I00'9i
Appendix 1 Sediment Analysis Methods
1. Water Content B.S. 1377 (1975)
-
1 . 1 Basic method
The samples were placed in pre-weighed dishes, weighed wet and then placed in an oven at
1 1 0°C for 24 hours. After this period the samples were allowed to cool in a dessicator and then
weighed dry. The water content (wc) was then calculated using the following equation :
Water Content (wc)
where :
Md
=
Mw
(%)
=
mass of dry sediment (g)
=
mass of wet sediment (g)
1 . 2 Salinity Correction
As the samples contain salt water there must be a correction due to the salt weight in the
interstitial water. The corrected sediment water content (wc') is calculated after Noornay ( 1 984)
as follows:
wc' =
wc
---
l - r - r . wc
where:
r
=
salinity of interstitial water (0.025)
2. Loss On Ignition
This method yields the % mass loss of the dry sediment when it is burnt to combust the
components containing carbon within the sediment.
It represents all of the carbon within the
sediment which includes biologically derived organic material and inorganic material of a non
biogenic origin . It is a crude indicator of the biological activity of the sediment, but does include
non-biological material as well, so care must be taken when interpreting the results.
The sediment samples were dried at 1 10°C for 24 hours to remove water and then ground using
an agate pestle and mortar. Approximately 2g of sample is placed into a pre-weighed crucible
and then ignited in a furnace for 4 hours at 450°C. The crucible and contents are then removed
from the furnace and put into a vacuum dessicator to cool. The loss on ignition (LOI i n %) is
calculated as follows:
loss on ignition (L01)
WI - W2
=
WI - WO
.100 %
where:
LOI
W1
W2
WO
Z
HR Wallingford
=
=
=
=
loss on ignition (%)
mass of the crucible
mass ofthe crucible
+
sediment before ignition (g)
+ sediment after ignition (g)
mass of the crucible (g)
TR 57 06/04198
3. Grain size analysis
Samples were analysed for grain size using wet sieving at 90J-tm and a Micrometrics Sedigraph™
5 1 00 to produce the grain size distribution of the <90J-tm fraction. The pre-weighed dried samples
was disaggreated in 0 . 1 % Calgon solution for 24 hours before wet sieving.
The >90J-tm was
retained from the sieve and dried at 1 1 0°C for 24 hours, this allowed the <90J-tm fraction as a
percentage of the total sample mass to be entered into the sedigraph. The <90J-tm fraction was
dispersed for 2mins in an ultrasonic bath to reduce the effects of flocculation before being loaded
into the sedigraph. One possible source of elTor when using the sedigraph™ is that its analysis is
based on stokes law, which assumes that the particles are spherical whereas in reality the
particles are far from spherical.
4. Colloidal Carbohydrate
1 ml of distilled H20 was added to the sediment sample to extract the colloidal fraction.
After
mixing, the sample was stored at 20°C for 15 minutes. The samples were then centrifuged at
8000rpm for 1 0 minutes. 400J-t1 of the supernatant was recovered and placed in a glass test tube
to which 400J-t1 of 5% aqueous phenol added.
The solution was vortexed and 2ml of
concentrated H2S04 was added using a pump dispenser this resulted in an exothelTnic reaction.
After 35 minutes at room temperature the solutions were transfelTed into semi-micro cuvettes and
the sample absorbancies were read using a 'Cecil 300' scanning spectrophotometer at 486.5nm
(Dubois
et al.,
1956).
Calibration was via a standard curve of absorption vs. glucose
concentration to give results in microgram glucose equivalents.
and its applications are found in Underwood
5. References
DUBOIS, M.,
GILLES,
et al.
FUt1her details of the method
( 1 995).
KA .. HAMILTON, J.K., REBER, P.A.
356.
INTRMUD PROTOCOLS ( 1 997).
Anal. Chem. 28:
and SMITH, F.
Colorimetric method for determination of sugars and related substances.
1 956.
350-
Guide document compiled for INTRMUD partners, by
SERG (Severn Estuary Research Group), Gatty Marine Laboratory, St Andrews, Scotland, UK.
February 1 997.
NOORNAY, I.
1984
Phase relations in marine soils.
Journal of Geotechnical Engineering
Vol. 1 l O, No.4, pp.539-543.
UNDERWOOD, G,J.C., PATERSON, D.M. AND PARKES, RJ. 1995.
The measurement of
microbial carbohydrate exopolymers from intertidal sediments. Limnol. Oceanogr. Vol.40 No.7,
pp. 1243-1253.
Z
HR Wallingford
TR 57 06104/<)8
Appendix 2
SedErode Data Plots
Z
HR Wallingford
TR 57 06104/98
SedErode Data Plots
Cardiff April 1997
:.HR Wa1l1ngford
.:
TR S7 0711)(191
Cardiff
t OOO
.s
c
o
i8
'0
"
2214/97
��------
0.8
--Shear stress
concentration
-- Mud
800
�
1A1
0.6
..
i
'"
'"
600
0.4
400
f.
:;;
=
�
1;)
..
�
"
�
'"
:¥
0.25Nm�2
0.2
200
is.
Il.
<t
o ��--�-+--�--��-+-�- o
11 :10
11 :20
11 :25
11 :15
Local time
Site:
Cardiff seasonal survey April
11 :12
TiDate:
me: 22/04/96
Operator: H.J.Mitchener
texture:
colour:
coveri
ng:
topography:
biologicomposi
cally actitvioitn:y:
other features:
Site description:
soft I medium
Comments:
Data file:
Path:
surface water
(fromcontent:
top 5mm) -238DOB2 of dry weight
Water
3
Bulk density: 1235
kgm·
9.65 micbyronsweight
Carbon Medi
(loss aonn siigznietd50:
ion): 3.09
gghtht
1.95 byby wei
Sand
content:
wei
57.
Si
l
t
content:
Mud content: 40.6 by weight
Mud Temperature: 15.6
(localSalicolnityle:cted22.19
at HW)
Film: 21
Time: 11:05 Number:
%
%
flat with Hydrobia
ragworms + Hydrobia
mud I silV snails · homogeneous
dewalering, sunny, calm
(downl
rrel data flt\capr001.IOl
ogger)
..\sedimoaded
entslhelfromenliSqui
ntrmud\cardi
Surface sample:
medium red-brown
33mm
vane
Observer:
Damon
Measurements (kPa): 0.1
0.0 O'Brien
0.0.22
Average: 0.0.23
Shear vane:
1997
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'A & <.
<A =
0.00
Average =
0.13
<. =
10103/98
0.25
Nm-''
NmNm"
1
at.xls
Cardiff
0.03
1 A1
2214/97
h�}.'i!�lA.
---
Shear stress
--- Erosion rate
0.02
J"J
"
Cl!
•
E
'"
c
�
0.01
c:
0
'iii
0
k
0.8
0.6
0.4 �
Cl!
Cl!
Cl!
..
"
k
.c:
Cl!
'0
.�
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UJ
0
1
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__
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__
�
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�
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__
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__
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-0.Q1
11 :10
11 :15
Local
TiSite:
me:
Date:
Operator:
10103/98
Cardi
ff seasonal survey April 1997
11:
12
22104/96
H.J.Mitchener
11:20
0
11 25
:
time
Film:
Photographs:
Time: 11:05 Number:
1
2
1 a 1.xls
Cardlfl l A1 2214197
1000
�
.5.
c
!
8c
8
800
H
,
"
200
0
0
0.1
0.2
c
0.5
...
�
-
100
0.6
0.7
0.6
O.S
...
0.7
0.6
0.0
0.7
0.6
0.9
.-
tl
0
0
0.01
0.006
0.006
0.004
:; 0.002
� 0
�
� -0.002
� -0.004
-0.006
-0.008
-0.01
1.t
Applied shear stress (Nm"t)
1000
1
-H
Cardifl l A1 2214197
.5.
•
u
c
0
u
�
,
"
0.4
0.3
10000
1
f&
t.++
400
�
�
\<1
600
;!
t..+
0.1
0.2
+
0.3
0.4
0.5
0.6
Applied shear stress ("m"t)
Cardlfl l A1 2214197
0
0.1
0.2
�
H
..
c
0.3
0.4
0.5
�
0.6
Applied shear stress (Nm-t)
*
1000
----------- ----
800
g
�
c
0
Cardiff 1 A 2 2214/97
-- Shear stress
-concentration
[J:,,17
<- " o r,m '
Mud
600
�
c
�
"
u
c
0
u
."
"
:;;
400
- -- - -------
- - _ ..
r¥..JNvI
�
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tA=0.3SNm
0.8
0.6
�
Cl)
il
1i)
..
"
�
0.4
�
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Cl)
:ll
0.2
200
..r
'li
co«
Erosion
o �--�--��--�- o
11:40
11:35
11:45
Local time
Site:
11:28
TiDate:
me: 22104/96
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Site description:
1997
soft / medium
mud I sitV snails · homogeneous
dewatering, sunny, calm
%
%
flat with Hydrobla
ragworms + Hydrobia
(from top 2S0
Srnm) - DOBS
Water content:
of 3dry weight
Bul
k
densi
t
y:
1227
kgm'
9.83 micbyronsweight
Carbon Medi
(loss aonn siigznietdSO:
ion): 2.68
2.S byby wei
Sand
content: S2.9
weigghtht
Si
l
t
content:
Temperature:
IS.8 DC
Mud
(localSalicolnitly:ected22.19
at HW)
Film: 31
2
7
TiTimme:e: 11:
Number:
11:27 Number: 4
Surface sample:
surface water
33mmvane
Observer:
Damon O'Brien
Measurements (kPa): O.S
0.8
0.4
0.0.43
Average: O.S
Comments:
aded fromen�ntrmud\cardi
Squirrel data flof\capr002.
gger) IOl
Path: il (downl
..\sedimoents\hel
medium red·brown
near drainage channel
Shear vane:
Data f e :
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between tA & tB
tA =
tB =
Average
10/03/98
0.35
0.48
0.42
Nm"
Nm"
Nm"
la2.xls
Cardiff 1 A2 22/4/97
0.8
0.01
--
Shear stress
-- Erosion rate
0.6
�U)
1
w
w
E
Cl
�
�
0.4
0
E
�
1ii
"
•
•
'"
w
0
c
'(;j
e
w
0.2
"0
.�
C.
Co
<I:
-0.01 �-�------�---�--� o
1 1 :45
1 1 :40
1 1 :35
Local time
TiSiDate:
mte:e: Cardiff seasonal survey April
1 1 :28
22/04/96
1 0103/98
1 997
Photographs:
TiTimme:e:
1 1 :27
1 1 :27
Film
Number:
Number: 4
1
3
1 a2.xls
Cardiff 1 A2 2214/97
1000
t
800
�
g
e
�
e
•
u
e
0
u
+f
".
;t-
600
400
�
=
"
2O{l
-
0
0
0.1
0.3
0.2
.• +
0.4
#j.4lI:
tt
�
t-t
++
pt
0.5
0.6
0.•
0.7
0.8
0.7
0.8
0.•
0.7
0.8
0.•
Applied shear stress (Nm-f)
Cardiff 1 A2 22/4/97
1000
�
g
100
1
•+ +
e
�
•
u
e
0
u
�
=
"
++
++
++
+
10
0
0.1
*�
*+
++*
It
h
:j!"
0.3
0.2
«
ft
If:t
0.4
Cardiff
0.Q1
0.5
0.6
Applied shear stress (Nm-l)
1 A2 2214/97
0._
0.006
'.
)
�
c
.n
.�
*'!j.
0.004
..
0,002
0
"""" +
+
-0.002
-0,004
(1ft.
..
�
.(l.aoe
-0.008
-O.G1
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm'2)
1000
--------- -
- -----
-------
-----
0,8
Shear stress
--Mud concentration
-
800
0,6
g
600
8
400
�
c
o
I
c
'C
�
:;;
0,2
200
O f-�-�-�-�----cI--�-�-�-�__+-�-�-��-__j O
11:55
12:00 Local time 12:05
12:10
Site:
11:50
TiDate:
me: 22/04/96
Operator: H,J,Mitchener
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Site description:
soft I medium
(from top 205
5mm) - DOB8
of-3dry weight
Water content:
1264
kgm
Bul
k
densi
t
y:
9,95 micbyronsweight
Carbon (lMedi
ossaonn siigznietd50:
ion): 3,09
weigghtht
3.4 byby wei
Sand
content: 54,8
Si
l
t
content:
Mud Temperature: 18,8
(localSalicolnity:lected22,19
at HW)
Film: 51
Time: 11:50 Number:
%
%
flat under snails
ragworms + Hydrobia
clayl silV snails - homogeneous
hardening under sunny dry
aded fromenliSqui
rrel data flflcapr003,I
ogger) Ol
"(downt
Isedimoentslhel
ntrmudlcardi
Surface sample:
Hydrobia snails!
33mm
vane
Observer:
Damon
Measurements (kPa): 0,8
0,9 O'Brien
0,8
0,8
0,8
Average: 0,8
Comments:
Data file:
Path:
medium red-brown
conditions
Shear vane:
1997
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'A & '8
Nm-2
' =
A
'te =
Average =
10103/98
0,27
0.42
0.34
Nm-2
Nm-2
la3,xls
0.01
0.008
0.006
"
'"
"
E
'"
�
�
C
0
'iij
Shear stress
--Erosion rate
i;,��
0.002
0
-0.002
0
�
w
--
0.004
�
-0.004
0.8
rAfo�
0.6
�
"E'
'"
'"
0.4
�
1ii
�
�
�
.t:
'"
"
-Wi/o'MWI/,iJ,IAW
.�
c.
0.2
coo:
-0.006
-0.008
-0.01
1 1 :55
1 2:00
12:05
0
1 2:10
Local time
TiSiDate:
mte:e:
Operalor:
10103/98
Cardi
1122/04/96
:50ff seasonal survey Aprl1 1997
H.J.Mitchener
Film:
Photographs:
Time: 11:50 Number:
51
la3.xls
Cardiff lA3 2214/97
1000
800
�
s
c
1
8
c
0
u
�
=
:):....
800
+
400
"
200
".
+
•
+
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ii
it
+
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0.1
0.2
0.4
0.3
0.5
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�
S
c
!
100
•
u
c
8
•
"
�
10
�
0."
Appl ied shear stress (Nm·2)
+
•
"
..
0.7
0.6
0.•
1
Cardiff 1 C1 2214/97
000
0.8
-- Shear stress
800
.§.
'§;
c
0
600
Erosion
�
�
�
c
..
"
c
0
0
Ar!-L
-- Mud concentration
400
Mixing
"
"
:;
fNhIv",J
fa
�
fA =
=
0.6
�"
......
"
!!
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0.4 1;;
co
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..
"
"
J::
0.32Nm-2
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ii
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D.
«
0.2
200
o
15:45
�-�--�--�-�--4---�-�--�--�-�
0
15:55
15:50
Local time
Site:
Cardiff seasonal survey April 1997
15:47
TiDate:
me: 22104/96
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Site description:
medium lsoft
10/03/98
(from top 5mm)
231 DOB23
of-3dry weight
Water content:
Bul
k
densi
t
y:
1241
kgm
byronsweight
Carbon Medi
ion): 10_98
2.11
mi
c
2.83 byby wei
Sand
content:
gghtht
wei
Si
l
t
content:
48.
(localSalcol
at HW)
inityle:cted22.19
Film : 141
Time: 15:35 Number:
•
%
%
flat uner snails
ragworms and Hydrobia
clay/silVsnails - homogeneous
worm holes - 2nd attempt
aded fromenliSqui
rrel data floflcaprOl0.I
gger) Ol
\sedimoentslhel
ntrmud\cardi
..(downl
Surface sample:
Hydrobia snails
33mm
vane
Observer:
Damon
0.1 O'Brien
0.1
0.2
Average: 0.2
0.1
Comments:
Path:
medium redlbrown
cloudy dull raining
Shear vane:
Data file:
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between <A & <a
2
Nm0.32
<. =
2
Nm0.43
<a =
2
Average =
0.37
Nm-
lc1.xls
Cardiff 1 C1 2214/97
0.01
--
--
Shear
Erosion rate
stress
0.8
IMMt'I
,--w,w1J
0.6
...
-
��
E
Cl
Co
�
0
0
';;
e
w
i
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rJ
0
1!
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0.
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..:
�-�--�-�--�--�-�-----�--�-�
-0.01
15:45
15:50
time
0
15:55
Local
TiSiDate:
mte:e:
Operator:
10103/98
Cardi47 ff seasonal survey April 1997
15:
22/04/96
H.J.Mitehener
Film: 141
Photographs:
Time: 15:35 Number:
lel.xls
Cardiff
1000
1
Cl 2214/97
�...
+
800
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g
"
i
8"
8
+
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400
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0.5
0.7
0.8
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0.8
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Applied shear stress (Nm-r)
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10000
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1000
8
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100
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14:10
14:20
1 4: 1 5
1 4:25
Local time
Site:
Cardiff seasonal survey April 1997
14:07
TiDate:
me: 22104/96
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y:
other features:
Site description:
soft/medium
Hydrobia snails
flat under snails
ragworms + Hydrobia
0.9
Comments:
(downt
aded fromenliSqui
rrel data flotlcapr007.
gger) 101
..lsedimoentslhel
ntrmudlcardi
(from top 212
5mm) - DOBof dry14 weight
Water content:
3
Bul
k
densi
t
y:
1258
kgm'
Carbon (lMedi
ossaonn ignitd50:
ion): 10.2.3339 micbyronsweight
Sand content: 47.5.82 byby wei
weigghtht
Si
l
t
content:
Mud Temperature: 22 ·C
(localSalicolnity:lected22.19
at HW)
Film : 101
Time: 14:07 Number:
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'A & tB
'A =
'B =
Average =
10103/98
%
size
clay IsHV snail s · homogeneous
hardening in sunshine, calm
file:
Surface sample:
medium redlbrown
33mm
vane
Observer:
Damon
Measurements (kPa): 0.7 O'Brien
0.5
0.4
Average: 0.8
0.7
Shear vane:
Data
Path:
0.27
0_38
0_33
Nm-'
Nm-'
Nm-2
1cd2.xls
Cardiff 1 C02 22/4/97
0.01
Shear stress
--Erosion rate
--
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E
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=$
0
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0
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o
14:25
14:20
14:15
Local time
TiSite:
e:
Date:
Operator:
m
10103/98
Cardiff
seasonal survey April 1997
14:07
22/04/96
H.J.Mitchener
Photographs:
Time: 14:07
Film:
N mb :
u er
101
2l
lcd x s
.
Cardiff 1 C02 2214197
1000
800
�
S
=
.2
i!
8
=
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0
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'0
0
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600
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400
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. tl*-
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0
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0.4
0.3
0.5
0.8
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0.7
0.8
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1000
�
S
0.2
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.
-
--
....
•
+
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=
•
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8
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0
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10
0
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0.2
0.4
0.3
0.5
0.6
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0.7
0.8
0."
0.8
0.•
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0.01
0.008
0.006
}
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e
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1
oli
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•
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0
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•
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0
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0.2
0.3
0.4
0.5
0.6
Applied sheaI stress (Nm"l)
0.7
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1000
0.8
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----Shear stress
Mud concentration
800
--
600
400
0.2
200
Erosion
0 f---�-�-��--+--��-�-�--j-�-�-�--1 0
t4:30
14:35
14:40
14:45
..
Local time
Site:
14:25
TiDate:
me: 22104/96
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Site description:
1997
soWmedium
medium redlbrown
scant Hydrobia, worm holes
flat under snails
ragworms + Hydrobla
hardening in sunshine, calm
vane: Observer: 33mm
vane
Damon
0.3 O'Brien
0.3
0.2
0.1
Average: 0.2
Comments:
Surface sample:
%
%
%
%
%
°c
clay IsUV snails - homogeneous
drained, many wormholes
Shear
rrel data flf\capr007.I
ogger) Ol
..\sedimoaded
ents\helfromenliSqui
ntrmud\cardi
Path: (downl
CHANGED FILLING PROCEDURE
(from top 5mm)
217 - DOB17
Water content:
of 3dry weight
Bulk
densi
t
y:
1253
kgm·
Carbon (lMedi
gghtht
Sand
content:
3.4 byby wei
48.7
wei
Si
l
t
content:
(localSalcol
at HW)
inity:lected22.19
Film : 111
Time: 14:27 Number:
Data file:
Eroding Water:
Photographs:
0.23
Nm-2
tA =
tB =
Average
10103/98
0.26
0.24
Nm-2
Nm-2
lcd3.xls
Cardiff 1 CD3 2214/97
0.01
0.8
--
Shear stress
--Erosion rate
0.6
,
'"
•
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e
g
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E
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-
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1 4:30
..
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w
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1ii
14:40
1 4:35
14:45
Local time
Site:
TiDate:
me:
Operator:
1 0103/98
Cardiff seasonal survey April 1 997
14:25
22/04/96
H.J.Mitchener
Photographs:
Time:
14:27
Film:
Number:
1
11
1cd3.xls
++t +
Cardiff 1 CD3 22/4/97
1000
'ii:
.s
i
c
u
c
0
u
�
(,
BOO
'V
+
++
+++
+++++
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'00
+
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+
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0
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0.1
0.2
0.3
+
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+
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•
0.5
0.4
0.7
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0.8
0.'
0.8
0.'
0.8
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Applied shear stress (Nm-2)
10000
'ii:
++
1000
.s
c
�
8
c
.....
+�
100
0
u
�
•
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:t-
-
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+
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,
-0.006
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0.1
0.2
0.3
0.4
0.5
0.'
0.7
SedErode Data Plots
Cardiff May 1997
Z
HR Walling/o,d
TR S7
07104198
1 000
-
800
.§.
�
c
.2
----.-- --------
- --
.
.-
-
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. _- _._----- --
_
---- Shear stress
concentration
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0.8
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400
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:;
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�
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c
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ii
c.
<I;
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0.2
o ��--��--�-+--�-�--�_+-�� o
1 1 :4 0
1 1 :45
Cardiff seasonal survey May 1 997
Site:
11:38
Time: 22105/97
Date:
Site description:
Comments:
10103/98
1 2:00
time
Data file:
Path:
texture:
medium. soft fjel y like)
colour: mid
brown
coveri
n
g:
Tiny shell fragments
no algae, but worm tracks
biologicomposi
ctopography:
ally actitvioity:n: worm
holes, few hydrobia snails
smooth mud, no sand, homogeneous
other features: TIny
pits on surface (approx 5/1Qcm
dIameter) Situated approx Q,5m from
drainage runnels
33mm
vane
Measurements (kPa):Observer: 0.0.Damon
37 O'Brien
0.0.0.973
Average: 0.6
Shear vane:
1 1 :55
1 1 :50
local
(down
aded fromen\iSqui
rrel dataflf\cmay\cmay001.
ogger)
. \sedimloentslhel
ntrmud\cardi
101
(from top 5mm)
Water content:
172 - SM2of3dry weight
9.3.330 mikgm'cbyronsweight
Carbon Medi
(lossBulaonn ksiigdensi
nizetd50:
ion):ty: 1303
ghtht
Sand
content: 59,0.81 byby wei
Si
l
t
content:
wei
g
Clay content: 40.1 by weight
(localSalicolnitylected
: 20.at 3HW)
6
Film: 81 Before erosion
Time: 11:35 Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Nm-2
<. =
0.00
Nm·2
<. =
0.26
Average
0.13
Nm·2
2a1.xls
0.01
0.008
0.006
0.004
0.002
� 0
-0.002
-0.004
-0.006
-0.008
-0.0111 :40
---
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0.8
"
�
"
0.6
E
'"
6
��
�
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..
"
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11:45
11 :50
11 :55
12:00
local lime
Site:
Cardiff seasonal survey May
11:38
TiDate:
me: 22105/97
Operalor: H.J.Mitchener
10/03/9a
1997
Film: a Before erosion
Time: 11 :35 Number:
Photographs:
21
a
. x15
1000
'i>
Cardiff 2A1 2215197
600
S-
e 600
1e
8
0
0
�
,
"
'00
2
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..
t
200
0
0
0.1
0.2
•
0.3
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i
e
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8
�
,
"
0.6
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0.7
0.8
0.7
0.8
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0.7
0.8
D."
D."
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-
100
li
•
0
e
�.
-�
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1000
S-
+
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�M
.
.-
10
0
0.01
0.008
0.006
0.004
�
j 0.0002
i
ie -0.002
ill
.{).004
".006
".008
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0.1
0.2
0.4
0.3
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0.6
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....
0
0.1
0.2
....,..,..
0.3
....... .
D.'
D.'
...
0.6
Cardiff 2A2 2215/97
1000
800
.s
�
c:
!i\
W
J""'
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--- Shear stress
r
r/lIJ,W{fii,l� '
600
.�
o
'8
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5
400
u
'A =
..,
"
::;
200
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0.8
£
�
..
0.6
=
"
"
�
0.44 Nm0.31 Nm-'
0.4
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«
0.2
o
��--��--�-r----�--�-4--�-4-�-� 0
12:15
12:20
12:00
1 2:05
12:10
local time
Site:
Cardiff seasonal survey May 1997
Data file:
TiDate:
me: 22105/97
12:00
medium, soft Gaily like)
texture:
colour:
coveri
ng:
topography:
biologicomposi
cally actitvioity:n:
other features:
33mmvane
Observer:
Measurements (kPa): Damon
1.1.00 O'Brten
0.1.08
Average: 0.0.89
Site description:
Path:
worm holes, few hydrobia
Tiny plls on surface {approx 5110cm
Shear vane:
Comments:
10103/98
%
%
diameter) 1 m upshore of site A 1,
(from top 5mm)
Water content:
136 - SM5of-3dry weight
byronsweight
7.6.139 kgm
Carbon Medi
nizetd50:
ion):ty: 1360
mi
c
gghtht
Sand
content: 67.2.26 byby wei
wei
Si
l
t
content:
Mud Temperature: 10.7 QC
(localSalcolinity:lected20.at3HW)
6
Number:
Surface sample:
mid brown
O.Srn from drainage runnel
(downl
aded fromen\iSqui
rrel data fllo\cmay\cmay002.
gger)
. \sedimoents\hel
ntrmud\cardi
101
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'lA & 'TB
0.31
'A =
0.44
'CB =
Average
0.38
Nm·2
2a2.xls
Cardiff 2A2 2215/97
0.01
0.008
--
--
0.006
Shear stress
Erosion rate
0.8
0.004
"�
E
0.002
J!l
0
Cl
:.
t'!
0
0
.�
�
0.6
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�
�
•
�
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•
'"
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0.4
-0.002
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.�
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0.2
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__
__
__
__
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__
�
�
__
�
_L
__
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__
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__
�
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__
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__
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__
1 2:00
1 2 :05
12:10
1 2: 1 5
1 2 : 20
Local time
Site:
1 2:00
i e:
22105/97
Date:
Tm
1 0103/98
1997
Photographs:
Film: 91
Number:
Before erosion
2a2.xls
Cardiff 2A2 22/5/97
1000 ,--
'§;
oS
.�
i
c
3
�
800
600
400
200
0.8
F-----
1000
0.9
Cardiff 2A2 22/5/97
.
-
��
0.1
o�
0.3
0.2
0.4
0.5
0.6
0.7
0.9
0.8
�
0.6
0.7
Applied s hear stress (Nml)
Cardiff 2A2 2215/97
0.D1 r--
0.008
0.006
0.004
0.002
�
·i
�
- -
0
.0.002
-0.006
-o.OOS
0.2
0.3
0.4
05
'
Applied shear slress (Nml)
0.8
0.9
Cardiff 2A3 2215/97
1 000
--, Shear stress
Mud concentration
---
800
.s
�
c
�
.2
8
c
8
'tJ
�
:;;
0.8
'"
�
�
0.6 �
"
600
�
400
0.4
200
o
"'"'--� -v;,
� Slight erosion
�--�--�---r----�
1 2:35
Cardiff seasonat survey May
TiDate:
me: 22105/97
12:30
local
1997
time
Data file:
Path:
0
1 2:45
1 2:40
(downl
aded fromenliSqui
rrel data mlocmaylcmay003.
gger)
ntrmud\cardi
IOl
..lsedimoentslhel
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
0.7 O'Brien
Measurements (kPa):
0.0.89
1.90
0.
Average: 0.9
Surface sample:
Comments:
Nm,2
0.26
tA =
Nm'2
0.35
tB =
Average
0.30
Nm,2
Site description:
medium, soft Gaily like)
mid brown
Tiny pits on surface {approx 5/10cm
diameter). Approx. 1 m upshore of site A2,
O.Srn from drainage runnel
10103/98
(from top 5mm)
142 - SM8of dry weight
Water content:
Carbon Medi
nizetd50:
ion):ty: 1350
7.6.405 kgm"
byronsweight
mi
c
Sand
content:
1.85 byby wei
weigghtht
67.
Si
l
t
content:
(localSalicolnity:lected20.at 3HW)
6
Number:
%
%
worm holes, few hydrobla
Shear vane:
"
'tJ
.!!
0.
a.
'"
0.2
xing
�_,..,.Mi�;:..
12:30
Site:
�
.c
%
%
%
Eroding Water:
Photographs:
2a3.xls
0.01
0.008
0.006
0.004
0.002
0
�
-0.002
-0.004
-0.006
-0.008
-0.0112:30
Cardiff 2A3 2215/97
--
Shear stress
-- Erosion
rate
0.8
,
'"
,
0.6
E
Cl
6
§:!:.
'"
'"
�
�
�
c
m
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_
�
_
�
_
__
_
__
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__
_
_
�
_
12:35
12:40
12:45
Local time
Simte:e:
TiDate:
Operator:
Cardi
12:22105/97
30ff seasonal survey May 1997
H.J.Mitchener
10/03/98
Photographs:
Number:
2a3.xls
1000
�
Cardiff 2A3 22/5/97
600
Se 600
.2
�
11
•
u
e
8
,
MlO
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..
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,.
0
0
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0.2
0.4
0.3
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8
,
+- + �
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100
u
e
�
0.6
...
0.7
0.6
0.•
0.6
0.•
0.•
0.•
Cardiff 2A3 22/5/97
11
•
..
O.S
Applied shear stress (Hmt)
1000
Se
.,,+�
...+�....
10
0
0.1
0.2
0.4
0.3
0.6
0.'
AppUed shear stress (Hmt)
0.7
Cardiff 2A3 22/5/97
0.01
0.006
0.006
'E
';
E
�
e
�
e
w
0.004
0.002
....
0
+- +
-
-0.002
�+.-...
-0.004
-0,006
..{l.GOS
-0.01
0
0.1
0.2
0.3
0.4
O.S
0.6
Applied shear &tress (Hmt)
0.7
------- -
1000
- ----------
--------
Cardiff 2C1 2215/97
-- Shear stress
800
.§.
�
600
"
'1
"
"
"
TB =
0
0.45 Nm-2
400
"
�A,"'
��A
�
�
..
0.6
"
"
�
"
"
"
�
0.4 '0
..
'0
0.8
.!!
0.
0.
"
:;
..:
,
Mixing
200
0
13:50
0.2
Slight erosion
0
1 4:05
14:00
1 3:55
Local time
Site:
TiDate:
me: 22105/97
13:45
1997
Data file:
Path:
rrel dataflflcmaylcmay004.
(downl
aded fromenliSqui
ogger)
..lsedimoents\hel
ntrmudlcardi
IOl
texture:
um, gelatinous
(from top 5mm)
178 - SM11
colour: medi
pale brown
of-3dry weight
Water content:
coveri
n
g:
worm pits and feeding marks
Bul
k
densi
t
y:
1295
kgm
Carbon (lMedi
1mm
biologicomposi
ctopography:
ally actitvioitn:y: clworms
tracks, hydrobia, no algae
1.49 byby wei
ay, sil , no sand, homogeneous
gghtht
Sand
content:
58.
other features: surface,
m to left of runnel, deeper worms under
Si
l
t
content:
wei
diam, odd hydrobla
on surface,
diameter
Mud
Temperature:
11.5 °c
33mm
vane
(localSalcolinitylected
33 O'Brien
: 20.at3HW)
6
0.0.14
Number:
Number: 16 After erosion
Average: 0.0.33
Site description:
Surface sample:
%
%
*
&
%
%
%
1
5·10 pitS/1Ocm
10-20/1 Ocm
Shear vane:
Eroding Water:
Photographs:
Comments:
10/03198
Critical erosion shear stress between 'fA & 'rB
TA =
TB =
Average
0.41 Nm-'2
0.45 Nm"
0.43 Nm-2
2cl.xls
Cardiff 2C1 22/5/97
0.01
0.008
0.006
..
�
"
E
'"
---
Shear stress
Erosion rate
0.8
0.004
Slighl erosion
0.002
�
�
'l..
0
c
0
.� -0.002
�
.s
�
..
,
"
0.6 �
�
�
1;;
�
�
'"
�
"
�
0.4
.�
0.
c.
..
-0.004
·0.006
0.2
-0.008
-0.01 L-_�_�_�_�_�_�_�_�_�_�_� 0
13:50
1 3:55
14:00
1 4:05
Local time
Site:
Time: 22105/97
13:45
1997
Photographs:
Date:
Number:
S H i I O \,' (1
'l'l{S \91
\ . 'tu
10103/98
2c1.xls
-- ''' 1 -- ----'"""" ''''Cardiff
1000
'1l
s
t
c
8
800
2Cl 2215/97
-
600
400
�
200
��' � -�-;��:;��':""��-+��°�
o
heat stress (Nm1
LI
1000
'1l
S
��
0.1
0.3
0.2
0.4
Applied 5
0.5
0.6
0.7
0.8
0.•
0.7
0.8
O.
0.8
0.•
)
__
Cardiff 2Cl 2215/97
� 2 215/9
�
-
r-i
100
c
•
u
c
0
u
�
,
::;
10
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm1)
f
Cardiff 2Cl 2215/97
0.005 ..-0.004
0.003
"
."
'.
�
2
e
�
.�
c
0.002
0.001
�
0
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-0.002
+�.�l!litl
+
·0.003
..0.004
-0.005
�
0
0.1
0.2
0.3
0.4
0.5
0.6
-+ �
0.7
I
Cardiff 2C2 2215/97
1000
�--.
BOO
'§;
s§
�
8
1:
c
"
"
--
Shear stress
Mud concentration
O.B
600
400
:;
Mixing Slight erosion �
200
0.2
0
0
14:15
14:20
Local
Site:
TiDate:
me: 22105/97
14:11
Operator: H.J.Milchener
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
Measurements (kPa):
0.0.52 O'Brien
0.0.0.532
Average: 0.3
Site description:
medium, gelatlnous
time
Data file:
Path:
worm pits and feeding marks, watery
'mm
worms & tracks, hydrobia, no algae
clay, silt, no sand, homogeneous
between runnels. worms/pits S·10/1Dem
diameter, hydrobia 10-20/10cm diamater.
Approx 2m from C1
Shear vane:
Comments:
10/03/98
14:30
aded fromenliSqui
rrel data flo\cmaylcmay005.
gger)
..(down
lsedimloentslhel
ntrmudlcardi
IOl
(from top 5mm)
of 3dry weight
184 - SM14
Water content:
Bul
k
densi
t
y:
1287
kgm'
byronsweight
Carbon Medi
(lossaonn siigznietd50:
ion): 9.51
2.
6
mi
c
Sand
gghtht
Si
l
t
content:
wei
6
Number:
Surface sample:
pale brown
±
1 4:25
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'TB
Nm'2
tA =
0,37
tB =
0,42
Nm,2
Average =
0,39
Nm"
2c2.xls
Cardiff 2C2 22/5/97
0.01
0.008
Shear stress
-- Erosion rate
--
0.006
��E
E
'§
0.8
..
0.004
0.002
�
Slight erosion
0
"4.
0.6
AM
��
�
�
"
0
0
.� -0.002
e
w
-0.004
0.4
-0.006
�
�
.t:
�
"
.�
0.
0«
0.2
-0.008
-0.Q1
14:15
14:20
o
14:25
14:30
Local time
Site:
Photographs:
TiDate:
me:
14:1 1
22105/97
Film:
Number:
1
15
Before erosion
S I,I T/C,\
2Jlf17
1 4- : 10
1 0103/98
2c2.xls
1000
Cardiff 2C2 2V5197
800
�
g
�
c
c
•
u
c
8
600
400
;,
:i
�
=
'"
+
...... + � +
200
�
0
0
0.1
0.2
++l
0.3
0.4
0.'
t
0.7
O.S
0.8
0.•
0.8
0.•
0.8
a."
Applied shear stress (Nmt)
Cardiff 2C2 2V5197
1000
�
g
i"
8c
100
.-
c
0
u
�
=
'"
;J
+� +
�
..� +
*
10
0
0.1
0.2
0.3
0.'
0.4
O.S
0.7
Cardiff 2C2 2V5197
0.01
0.008
.;;
"
E
�
•
e
.ll
0.006
0.004
0.002
�
0
c
�
_ ...
+
-
�
-0.002
.{).004
-0.006
-0.008
-0.01
0
0.1
0.2
0.3
0.4
0.'
O.S
Applied shear stress (Nmf)
0.7
1000
BOO
.s
�
r:
0
�
8
u
r:
Cardiff 2C3 2215/97
----- ----
- - - -------
O.B
-- Shear stress
0.6 �
......
�
600
"
"
:0
..
"0
0.4
400
"
::;
200
f'Jf
Slight erosion
'1..
'A =
0.25 Nm-2
..
"
"
"0
.!!
"ii.
D.
«
0.2
0
14:55
15:050
15:00
Local time
Site:
14:48
TiDate:
me: 22105/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
Measurements (kPa): 0.0.32 O'Brien
0.0.23
Average: 0.10.2
Site description:
medium, gelatinous
Data file:
Path:
scant water, pits, feeding marks
day/sill, no sand, homogeneous
raining, grey sediment under surface
Comments:
%
%
1 mm
worms & hydrobia
Shear vane:
(from top 5mm)
Water content:
179 - SM17
of-3dry weight
Bul
k
densi
t
y:
1294
kgm
Carbon Medi
(lossaonn siIgznietd50:
Sand
gghtht
wei
Si
l
t
content:
(localSalcolinitly:ected20.at3HW)
6
Number:
19
Surface sample:
pale brown
±
(downl
Squirrel data flfo\cmay\cmay006.
gger)
..\sedimoents\hel
IOl
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 't'A & 'tB
'A =
0.25
'. =
Average =
10/03/98
Nm·2
0.36 Nm"
Nm"
0.31
2c3.xls
Cardiff 2C3 2215/97
0.01
0.008
--
Shear stress
-- Erosion rate
0.006
"
0.8
"
0
0.6
E 0.002
'"
�
�
0
0
�
"
1;;
"
0
c
0
.� -0.002
�
.s
1;
.r
0.004
0.4
�
�
se:
0
"
.�
ii
a.
'"
-0.004
0.2
-0.006
-0.008
-0.01 L14:55
__
__
�
__
__
�
__
__
�
__
__
�
__
__
�
�
__
__
�
�
__
__
�
__
__
�
__
__
0
1 5:05
_
_
Site:
TiDate:
me: 22105/97
14:48
15:00
Local time
Photographs:
S f,I T k
... !"
'1.2 /'/'1 7
Number:
1
(3
1 4- . 5e
10103/98
2c3.xls
Cardiff 2C3 2215/97
1000
'<l;g
�
c
c
•
u
c
0
u
�
•
+ ..
+'W
++
�+
\�+ +++
f++
800
600
+
'00
� + � +++$ � ,
"
200
0
0
0.1
0.2
0.'
0.3
0.6
0.7
0.8
0.9
0.8
0.9
0.8
0.9
Cardiff 2C3 2215/97
1000
'<l;g
0.5
Applied shear stress (Nm�)
� + � ++.-
100
.2
c
�
nJi
•
u
c
8
�
•
"
10
0
0.1
0.2
0.'
0.3
0.5
0.6
0.7
Cardiff 2C3 2215/97
0.01
0.008
�
E
•
�c
'.
.ll
.�
0.006
0.004
0.002
.....
0
·0.002
..0.004
+ � +- *' �
+
-0.006
-0.008
-0.01
0
0.1
0.2
0.3
0.'
0.5
0.6
0.7
Cardiff 2CD1 22/5/97
1000
--
800
--
Shear stress
concentration
Mud
0.8
�
200
0.2
Erosion
o
��-��-��-��-�-+-��-r-� O
15:25
15:30
1 5:35
15:40
1 5:45
Local time
Site:
TiDate:
me: 22105/97
15:20
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioity:n:
other features:
33mm
vane
Observer:
Damon
1.1.12
Average: 1.2
1.2
Site description:
medium
mid brown
worm pits, few hydrobia, no algae
±
1mm
1-2 hydrobla/10cm diamaler
clay/sill, homogenous
positioned on a stiffer outcrop,
close to drainage runnel.
Raining
Shear vane:
Comments:
10103/98
Data file:
Path:
(downl
aded fromenliSqui
rrel data flf\cmay\cmay007.
ogger)
..\sedimoents\hel
ntrmud\cardi
101
(from top 5mm)
Water content:
161 - SM20
of3dry weight
Bul
k
densi
t
y:
1319
kgm·
Carbon (lMedi
0.12 byby wei
weigghtht
Sand
content:
58.
Si
l
t
content:
: 20.at3HW)
6
Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'TA & 'TB
Nm"
0.38
<A =
<. =
Nm"
0.53
Average =
0.46
Nm"
2cd1.xls
0.Q1
0.008
0.006
0.004
�
0.002
� 0
-0.002
-0.004
-0.006
-0.008
-0.0115:25
Cardiff 2CD1 2215/97
---
Shear stress
Erosion rate
tWN"/'r�1
"
b
E
en
�
c
.2
'"
E
W
./
f(�I'"1iII'
\I ",f
Erosion /f
\tMI.\,,\'�J
�
15:30
15:35
tA =
ts
0.38
=
0.8
0.6 1�
'"
10
�
�
.c
'"
�
0.53
Nm'2
0.4
Nm·2
"
.�
a.
c.
'"
0.2
15:40
15:450
Local time
Sile:
TiDate:
me: 22105/97
15:20
1997
Photographs:
� o "f \C.
Number:
�
').'l /Shl
10/03/98
2cd1.xls
Cardiff 2CDl 2215197
1000
g
�
!
c
8
,
8
c
600
600
400
�
..
'"
200
�
0
0
0.1
0.2
0.3
0.'
�"", ,,.
-. .
O.S
0.6
0.7
t\
0.8
�
•.\
0.'
AppUed shear stress (Hm')
1000
�
g
�
c
....
..".,
"'"
.,.. +*" flNlt"
..... .
.. . ....
.
100
8
c
c
0
0
�
0
"
10
0
0.1
0.2
0.3
0.4
Applied
O.S
0.6
0.7
0.8
0.'
shear stress (Hm!)
0.01
0.008
0.006
)i
c
i
W
0.004
0.002
.....
0
.,...
�.
•ll�i"' M-
-0.002
... ....
-0.004
-0.006
-0.008
-0.01
0
0.1
0.2
0.3
0.'
O.S
0.6
Applied shear stress (Hm')
0.7
0.8
0.'
1000
800
oS
�
c
�
------- -
-- Shear stress
0.8
600
0.6
0
"
"0
�
'"
'"
�
1;;
c
"
"
c
�e
400
TA =
:;;
=
0.43 Nm"
0.37 Nm"
TB
0.4
li;
"
'"
.c
"0
.!!
Q.
Q.
..:
200
0
15:50
0.2
,
Erosion
16:00
15:55
0
16:10
16:05
local time
C.rdiff se.son.1 survey M.y
Site:
15:47
TiDate:
me: 22105/97
1997
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
Measurements (kPa): 1.1.20 O'Boen
1.11.1
Average: 1.11.1
Site description:
mediumthard on ridge
mid brown
worm pits
± 1 mm
worm holes. no hydrobla or algae
clay/sit!. homogeneous
on ridge approx 1 0cm above a
draInage runnel. SUffer outcrop
Shear vane:
Comments:
aded fromenliSqui
rrel dalaflf\cmaylcmayOOa.
ogger)
Palh: i ..(downl
lsedimoenls\hel
nlrmudlcardi
101
Oat. f le:
(from top 5mm)
165 - SM23
Water content:
of3dry weight
Bul
k
densi
t
y:
1313
kgm·
Carbon (lMedi
Sand
content:
1.40 byby wei
gghtht
57.
Si
l
l
eonlent:
wei
(localSalicolnity:lected20.al 3HW)
6
Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between lA & 'tB
TA =
'tB =
Average =
0.37 Nm"2
0.43 Nm"2
0.40 Nm"
10103/9a
2ed2.xls
0.01
0.008
-- Shear stress
-- Erosion rate
0.006
�E�
Cl
0.004
Erosion ""
0.002
�
�
0
0
.� ·0.002
e
w
·0.004
c
·0.006
�
M.....
·0.008
·0.01
15:50
:
15:47
TDate:
mee 22105/97
Operalor: H.J.Milchener
Sit
i
:
/VIrJANr
l
:f\;J'"
tN,�\�.Ir�1
'>1
�V
JwJ
�
V
.5
��
�
"
�
�
=
1 6:00
Local time
1997
Photographs:
\fAn0�
Tim,,'
10/03/98
�
'"
0.4
"
�
"
.�
ii
c.
"
0.2
1 5:55
0.8
0.6
0.43 Nm"
0.37 Nm·2
TB
TA =
r"
1Y\,{,�\'\'1I1
f'AN
NfN'N'
'),']
(s.1 '17
1<; 4-)
1 6:05
0
16:10
Number:
riD 1
i!
2cd2.xls
1000
800
�
S
i
c
•
u
c
0
u
"
=
"
800
.00
200
� +
0
0
0.1
0.2
0.3
s
1
....�4t\o"';W
...
0.4
0.5
0.8
AppUed shear siress (Nm2)
0.7
0.8
0.9
1000
�
W�
Jtl
., +
100
c
W·XCp"
�411t4t\o*;W
�.
8
c
0
u
"
=
"
10
0
0.1
0.2
0.3
0.'
0.5
0.•
Applied shear s1ress (Nm2)
0.7
0.8
0.9
Cardifl2CD2 22/5/97
0.01
0.008
�
)
•
l!
.ll
.2
c
•
0.006
0.004
0.002
�
0
+
�ur!tMlt .�I_I"".iI:!$.""
i
�-
-0.002
-0.004
-0.006
-O.OOB
-0.01
0
0.1
0.2
0.3
0.'
0.5
0.•
0.7
0.8
0.9
1 000
-�-.
800
.s
'§;
c
.2
...
�
"
"
"
c
0
"
"C
Shear stress
concentration
-- Mud
t!i�\
r,YIVIllli'�)i:
600
400
::>
:;;
200
rhf{?;)
'8
=
0.35 Nm" ..
tV
{;"'It''v/V'V '\, ..
Erosion '>I.
o
'A =
!!" H)
V
0.8
lNNViJlit
.§
�
..
ny-·,
0.6 '"
'"
�
�
0.4
0.26 Nm"
"
.c
'"
"C
.�
C.
Q.
«
0.2
��-�-��-4--��-�-�-+-�-��-�-r-�- 0
16:10
16:15
1 6:20
1 6:25
1 6:30
Local time
Site:
16:11
TiDate:
me: 22105/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mmvane
Observer:
1.1.10 O'Brien
1.11.2
Average: 1.11.1
Site description:
mediunVhard on ridge
mid brown
worm pits
±
1mm
worm holes, no hydrobia or algae
clay/silt, homogeneous
on ridge approx lm upshore
from C02
Shear vane:
Comments:
1 0/03/98
Data
Path:
file:
aded fromenliSqui
rrel dataflflcmaylcmay009.
ogger)
..(downl
lsedimoentslhel
ntrmudlcardi
IOl
(from top 5mm)
of3dry weight
Water content:
152 - SM26
Bul
k
densi
t
y:
1332
kgm,
Carbon (lMedi
gghtht
Sand
wei
Si
l
t
content:
: 20.at3HW)
6
Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & 'tB
Nm"
0.26
'A =
Nm"
'8 =
0.35
0.30
Nm"
Average =
2cd3.xls
0.01
0.008
0.006
.�E
"
Cl
-- Shear stress
-- Erosion rate
0.8
N"
0.004
0.002
�
�
0.6
��
�
�
�
..
..
0
c
0
.� -0.002
e
w
-0.004
�
"
.c
0.4
-0.006
.�
ii
Dot
0.2
-0.008
-0.01 L-�_��_��_��_�_L-�_��_�-" O
16:10
16:15
1 6:20
1 6:25
16:30
local time
SUe:
TiDate:
me:
Operator: H.J.M itchener
Photographs:
16:1 1
22105/97
Film:
Number:
Number:
1
22
Before erosion
24
sn-rIC." (/D3
rn/5 197
/6 :10
1 0/03/98
2cd3.xls
1000
'ii
g
800
c
600
u
c
0
u
�
0
400
�
i;
•
�
U+
++
�
+�+
W'fft
"
...
200
0
0
0.1
0.2
+�
0.4
0.3
0.'
0.'
Applied shear stress (Nmt)
0.7
0.8
0."
0.8
0 .•
0.8
0."
Cardiff 2CD3 2215197
1000
'ii
gc
!
8c
0
u
�
0
"
:m �
.. +v.
lOO
-
10
0
0.1
0.2
0.3
0.4
0.'
0.'
Applied shear stress (Nm�
0.7
0.01
0.008
0.006
f
s
�
c
i
oll
0.004
..
0.002
0
-0.002
+-
�
.1<.....
-0.004
-0.006
.{l.oos
-0.01
0
0.1
0.2
0.3
0.4
0.'
0.'
0.7
SedErode Data Plots
Cardiff June 1997
:.HR Walllngfo,d
.::;
TR 51 07104/9&
Cardiff 3A 1 1 9/6/97
1000
Shear stress
--- Mud concentration
800
�
E"
.2
0.8
600
E
c
"
"
"
0
"
"
"
:;
400
'Ta
=
0.25 Nm-2
200
Erosion
...
.r
�
�
fIr/��
0.6 �
�
�
�
.t:
"
�
0.4 "
.�
C.
"..:
l IlNMIJ,lJ!tj
rV1,,;vIWr'l"WlIi
0.2
o �--�--�--��;---�---+1 1 :40
1 1 :45
0
1 1 :55
1 1 :50
Local time
Site:
Cardiff seasonal survey June
TiDate:
me: 11:19/06/97
32
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
medium
mid brown
water, as raining, pitted
.1·2mm
very UlUe, no worm holes
rainy, clay, scant sand
Rainy and windy
33mm
vane
Observer:
Damon
0.1.09
Average: 0.1.19
Shear vane:
comments:
1997
Data file:
Path:
(downl
rrel data flf\cj
ogger)
..lsedimoaded
entslhelfromenliSqui
ntrmud\cardi
unlcjun001.101
(from top 209
5mm) · SM1·3
Water content:
of dry weight
Bul
k
densi
t
y:
1260
kgm"
Carbon (lMedi
ossaonn siigznietid50:
on): 8.2.908 micbyronsweight
Sand
content:
weigghtht
1.23 byby wei
Si
l
t
content:
60.
7
Film:
Time: 11:30 Number:
2 Before erosion
Surface sample:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & tB
Nm·2
tA =
Nm·2
t. =
Average =
Nm>2
0.00
0.25
0.13
11103/98
3a1.xls
Cardiff 3A 1 1 9/6/97
0.005
0.003
,
'"
"
E
'"
6
�
c
,2
'"
--Shear stress
-- Erosion rale
0.8
..
�
�
Erosion ......
0.6 '"
'"
0,001
·0.001
e
w
tB
-0.003
=
0.25 Nm" •
�
•
�
.c
"" r·j\�v.J1
rtl{'V1W\N,'J.I.\\\V!I.i,\�\\r'
' w'
'"
0.4 '0
.�
a.
Cl.
""
0.2
�
-�
---�
-�
�
--�
-�
-------�
-0.005 L----1 1 :40
1 1 :45
1 1 :50
Local lime
_" o
__
Site:
Time:
11:19/06/97
32
1997
Photographs:
Time
11 :30
1 1 :55
Number:
Date:
I"
sviJE" t"\ ' P
, , : 30
11/03/98
3a1.xls
Cardifl 3A1 19/6197
1000
800
�
...
I
c
600
•
u
c
0
u
�
,
"
400
Mass erosion
200
11
+
0
0
0.1
0.2
0.3
..,
�
0.'
.\ �
f
�
0.6
0.'
Appned shear stress (Nm-t)
0.7
0.6
0.•
0.8
0.9
0.6
0.9
Cardlfl 3A1 1916197
1000
�
...
,p
c
�
+
b
�
u
c
8
�
,
"
Wo
+i>.
t+ +
1 00
�
.�
... -
+
+
10
+
0
0.1
0.2
0.3
0.4
0.'
0.6
Applied shear stress ("m-t)
0.7
Cardiff 3A1 1 9/61197
0.006
0.004
�
"E
E.
�
0.003
0.002
+.
" +
0,001
0
� -0.001
e
w
.().O02
c
*- it w "
ift
-0.003
-0.004
-0.005
0
0.1
0.2
0.3
0.'
0.5
0.6
Applied sheat stress (Nm't)
0.7
Cardiff 3A2 1 9/6/97
1000
800
.s
�
c
0
i
"
u
c
0
u
--
600
400
"
"
:;
200
o
12:05
Shear stress
concentration
!W
lll
�v
Mud
r
rJV'
'" -" "�l
'A =
0.36
.,
Nm �
;lffj(',\",�
12:10
/V
0.8
0.6 �
..
0.4
..
..
�
10
�
..
"
'"
..
"
.!!
C.
a.
«
�
0.2
Erosion
Local12:15
12:25o
12:20
time
Cardiff seasonal survey June 1997
Site:
TiDate:
me: 12:
06
19/06/97
Data file:
Path:
aded fromenliSqui
rrel data flflcjunlcjun002.
ogger) 101
..(down
lsedimloentslhel
ntrrnudlcardi
texture:
um
(from top 223
5mm) - SM4-6
Water content:
colour: mimedid brown
of3dry weight
Bul
k
densi
t
y:
1248
kgmcoveri
n
g:
fl
u
i
d
i
s
ed
wi
t
h
rai
n
byronsweight
±1-2mm
Carbon (lMedi
ion): 8.18
3.
0
mi
c
biologicomposi
ctopography:
ally actitvioity:n: very
l
i
t
tl
e
,
no
worm
hol
e
s
2.0 byby wei
rainy, clraiay,n scant
content:
weigghtht
Si
l
t
content:
other features: Heavy
61.5
and wisand
ndy, 0.5 m from channel Sand
33mm
vane
(localSalcolinitly:ected24.at 9HW)
79 O'Brien
7
0.0.98
Film: 31
Ti
m
e
12:
0
4
Number:
Average: 0.1.09
Site description:
Surface sample:
%
%
%
%
%
°c
Shear vane:
Eroding Water:
Photographs:
Comments:
Critical erosion shear stress between 'fA & 'rB
fA =
0.36
0.45
'fB =
Average =
0.40
Nm"
Nm-22
Nm-
11/03/98
3a2.xls
0.005
Shear stress
--Erosion rale
--
0.003
�
E
�
.�
c
Jl
0.8
0.001
·0.001
0.2
-0.003
-0.005
1 2:05
TiSiDate:
mte:e:
Operator:
1 2:10
Cardi
ff seasonal survey June 1997
12:
0
6
H.19/06/97
J.Mitchener
11/03/98
12:15
time
o
12:20
12:25
Local
TiPhotographs:
me 12:04
:
Film 31
Number:
382.xls
Cardiff 3A2 19/6/97
1000
'§;
g
c
�
c
•
u
c
0
u
�
0
800
400
"
200
0
0
0.1
0.2
�,
0.3
g
'"
1
,
tOO
c
•
u
c
8
�
0
"
!t
�
++ �
* � ffll: +
W
0.4
O.S
0.5
Applied shear slress (Nm-2)
0.7
0.'
0.8
1000
=
.�
600
"" ... -�
....+.. � "t4
�
10
0
0.1
0.2
0.3
0.4
0.5
O.S
Applied shear stress {Nm-l)
0.7
0.'
0.8
0.005
0.004
�
•
E
�
�
c
�
e
w
0.003
0.002
0.001
•
0
-0,001
t)t+
� ·*� \ *b ...
·0,002
-0,003
t�
+
-0.004
-0.005
0
0.1
0.2
0.3
0.4
0.5
O.S
0.7
0.8
0.'
1 000
800
�
Et:
�
.2
8
-g
1l
t:
---- Shear stress
Mud concentration
--
0.8
.§
1E-
.-
600
0.6
�
0
0
�
�
"
.t:
0
0.4 ..,
400
.�
ii
c.
:;;
..:
200
0.2
o �-�-�-�-�--+--�----�-+--�-�-��-�-� 0
1 2:30
1 2:35
1 2:40
1 2:45
Local time
Site:
TiDate:
me: 12:19/06/97
27
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
1997
medium
mid brown
fluidised and pitted with rain
.'·2mm
very IIlIle, no worm holes
rainy, clay, scant sand
RaIny and windy, 2m to
edge of channel
33mm
vane
Observer:
Damon
0.0.0.599
Average: 0.9
Shear vane:
Comments:
Data file:
Path:
(down
rrel data flfolcjunlcjun003.
gger) 101
. lsedimloenladedslhelfromenliSqui
ntrmud\cardi
(from top 217
5mm) - SM7-9
Water content:
of3dry weight
Bul
k
densi
t
y:
1254
kgm·
byronsweight
Carbon (lMedi
ion): 8.11
3.
2
mi
c
Sand
content:
gghtht
3.6 byby wei
Si
l
t
content:
wei
55.1
7
Film: 61
Time: 12:25 Number:
Surface sample:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'TA & 'tB
Nm·2
'A =
Nm-2
'B =
0.34
Average =
0.30
Nm·2
0.25
11/03/98
3a3.xls
0.005
--
Shear stress
-- Erosion rate
0.003
0.8
�
N
-
.5
,
�
"
0.6 �
�
�
E 0.001
'"
�
�
0
.� ·0.001
e
w
c
·0.003
18
=
0.34
'
Nm· .
"
JI"'"J"
f
vvV(\IJIi/lr\Mt.I'AAW oil
lA
�
�
0.4
= 0.25 Nm"
'"
�
u
.�
'li
"..
0.2
·0.005 �-�-�-�-�-+----�-�-�-�-�-� 0
1 2:30
12:35
1 2:40
1 2:45
Local time
Site:
TiDate:
me: 12:19/06/97
27
11/03/98
1997
Photographs:
Time 12:25
Film: 61
Number:
3a3.xls
Cardiff 3A3 1 9/6197
1000
It�
+
800
�
s
1
c
•
"
c
0
u
..,
t\
+T+
600
400
-+)#'+
0
"
200
0
0
0.1
0.2
,
0.'
0.4
++
.. l...
0.5
0.7
0.6
Appned shear stress (Nm";
0.8
0.'
0.8
0.'
0.8
0."
Cardlfl 3A3 19/6197
1000
�
S
.ff!tIt+ �+
fI+
100
..
c
i
•
��
"
c
8
..,
0
10
"
0
0.1
0.2
0.'
0.4
0.5
0.7
0.6
AppUed shear stress (Nmo2)
Cardlfl3A3 1 9/6197
0.005
0.004
0.003
.;;
•
0.002
•
0
i
i!
�
+++
l*+jt+
'If
0.001
.. -0.001
•
c
-0.002
*
+ +
w.
r
+
-0.003
-0.004
-0.005
0
0.1
0.2
0.'
0.4
0.5
0.6
0.7
Cardiff 3C1 1 9/6/97
-- ---------
--------
-- - - -
1000
-- Shear stress
800
g
�
c
0
�
u
c
0
u
0.8
.s
i!S
.r
0.6
800
�
400
'TB
..,
�
=
0.35 Nm'2
0.4
•
:;
' Eroslon
.
•
200
'lA = 0.26 Nm-2
�
.,
�
1;;
�
.r:
.,
..,
.!!
Q.
<l.
«
0.2
O f-�-��-�-+--��--"'I---��--+-�-��-�--l o
13:30
13:35
13:45
1 3:40
1 3:50
Local time
Site:
11:25
TiDate:
me: 19/06/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obsel
V
er:
Damon
O'Brien
Measurements (kPa):
0.5
0.6
0.0.77
0.6
Average: 0.6
Site description:
1997
medium hard gelatinous
Data file:
Path:
few worm holes, no hydrob!a
worms coming out now
clay, scant sand
Drainage noise. LW now.
Slight rain after 0.75 hour of dry weather.
1 1/03/98
%
%
lumpy - . 2mm
Comments:
(from top 220
5mm) - SM10-12
Water content:
of3dry weight
Bul
k
densi
t
y:
1250
kgm·
Carbon (lMedi
Sand
2.59 by weight
content:
Si
l
t
content:
52.
Clay content: 44.6 byby wei
weigghtht
(localSalcolinitiy:ected24.at 9HW)
7
Film: 71
Time: 13:24 Number:
Surface sample:
mid brown
Shear vane:
(down
aded fromen\iSqui
rrel dataflflcjun\cjun004.
ogger) IOl
..lsedimloentslhel
ntrrnud\cardi
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & tn
0.26
Nm-2
'A =
Nm-2
0.35
'TB =
Average =
0.31
Nm-2
3cl.xls
0.005 ,-----
0.003
�E�
E
�
,�
c
-- Shear stress
-- Erosion rate
0.8
..
�
�
0.6 �
�
0.001
�
�
�
.c
-0.001
1a
e
w
0.4
=
0.35 Nm'2
0.2
·0.003
·0.005
1 3:30
�
'C
.�
Q.
Co
"
13:35
1 3:45
1 3:40
o
13:50
local time
Site:
TiDate:
me: 1119/06/97
:25
11/03/98
1997
Photographs:
Time: 13:24
Film: 7
Number:
3cl.xls
Cardiff 3C1 1 916197
1000
800
�
S
]
�
8e
0
u
�
,
"
600
400
.
+
200
0
0
0.1
0.3
0.2
0.4
0.6
0.5
0.8
0.9
0.7
0.8
0.9
0.7
0.8
0.9
0.7
Cardiff 3C1 1 916197
�-..
1000
�
S
+�
... ��
-
100
1
e
•
u
e
8
�
,
"
10
o
0.1
0.2
0.3
0.4
0,5
0.6
Applied shear stress (Um'l)
Cardill 3C1 1 916197
0.005
0.004
.;;
"
ED
C
$E
e
!
0.003
0.002
0.001
0
-0.001
·0.002
·0.003
·0,004
-0.005
0
0.1
0.2
0.3
0.4
0.5
0.6
1000
BOO
.§.
f§;
c
�
.2
"
u
c
8
"
�
::;
O.B
----- Shear stress
-concentralion
Mud
I
0.6 �
�
�
600
:"
�
J:
0.4 "
400
.�
a.
c.
..
0.2
200
o ��-�----�-+----�-�--+-�--�-��r-�-�---�� 0
13:55
14:00
14:05
14:10
14:15
local time
Site:
TiDate:
me: 13:19106197
50
1997
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm vane
Observer:
Damon
0.0.57
Average: 0.0.66
Site description:
mid brown
few worm holes, no hydrobla
lumpy - ± 2mm
clay, scant sand
O.Sm to E of 3C1, midway between
runnels, lumpy bed
Shear vane:
Comments:
11103198
Data file:
Path:
aded fromenliSqui
rrel data mlocjgger)
..(downl
\sedimoentslhel
ntrmudlcardi
un\cjun005.101
(from top 5mm)
194 - SM13-15
Water content:
of·3dry weight
Bul
k
densi
t
y:
1276
kgm
Carbon (lMedi
Sand
content:
1.97 byby wei
gghtht
Si
l
t
content:
54.
wei
7
Film: 8
Time: 13:48 Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & to
Nm-2
'A =
0.25
Nm"2
0.30
'fB =
Average =
0.28
Nm"2
3c2.xls
Cardiff 3C2 22/5/97
0.005
--
0.003
--
Shear stress
rate
Erosion
0.8
�
"
0.6
E 0.001
�
�
�
0
0
.;;;
e
"§1:<h
<h
�
�
�
�
<:
.
0
-0.001
4
<h
"
.�
0.
0.
w
'"
0.2
-0.003
-0.005
13:55
14:00
14:10
14:05
o
14:15
Local time
S te :
ime: 13:50
TiDate:
Operator: 19106/97
H.J.Mitchener
1997
Photographs:
Time: 13:48
Dato,
Tlmo,
1 1/03/98
Film: 8
Number:
3 c.. a
\
9 :rU >i E 1 '\ 9 1
1 3 : l+ f
3c2.xls
Cardiff 3C2 1 9/6197
1000
'1l;
g
c
�
600
'1
600
tf4
'*
jl
E
0
u
c
0
u
�
0
"
400
200
0
0
0.1
0.2
W!! + � .1tI*'
0.3
0.4
O.S
0."
Applied shear stress (Um-,
0.7
0.8
0."
Cardiff 3C2 1 9/6197
1000
'1l;
g
c
1
+ "'1=
�+l + ,j*
+ ft'
100
.....
0
u
c
8
�
=
"
�ttl ,"
10
0
0.1
0.2
+
0.3
0.4
0.5
0."
Apptled shear stress (Um-t)
0.7
0.8
0."
0.8
0.•
Cardiff 3C2 19/6197
0.005
0.004
�
,
i
o
e
c
�
�
0.003
0.002
..+�. + � .t� .t<\<-
0.001
0
++
-0.001
-0.002
-0.003
-0.004
-0.005
0
0.1
0.2
0.3
0.4
0.5
0."
0.7
1000
BOO
-�
--
Shear stress
Mud concentration
.
�J""
rm'
rVl"
rl�r
rl,M
600
400
TB =
200
;:;;:;P
0'29
Slight erosion
0
14:15
""-
1 4:20
tA
....
0,6
��
�r
..
O.B
�I!/M,<
=
!
..
�
"
"
z:
..
�
0.4
Jl
'li
Q.
..
0.25 Nm-2
0.2
1 4:30
14:25
0
1 4:40
1 4:35
Local time
Site:
TiDame:e: 14:15
H.J.Mitchener
Operator: 19/06/97
1997
Data file:
Path:
aded fromenliSqui
rrel data llfolcjunlcjun006.
gger) 101
.(downt
,lsedimoentslhel
ntrrnudlcardi
t
texture:
colour:
coveri
ng: topography:
composi
tion:
other
features:
33mm
vane
Observer:
Damon
Measurements (kPa):
0,0.78 O'Srien
0,0.86
0,0,77
Site description:
mid brown
few worm holes, no hydrobia
lumpy
biologically activity:
± 2mm
clay, scant sand
1 m downstream from 3C2.
Sunny now, surface drying,
worm trails on surface.
Shear vane:
(from top 5mm)
207 - SM16-18
dry weight
Water content:
Sul
k
densi
t
y:
1263
kgm"
Carbon (lMedi
ion): 8,1.899 micbyronsweight
wei
gghtht
Sand
content: 48.1.21
Si
l
t
content:
wei
Clay content: 50.7
weight
Mud Temperature: 22,1 QC
: 24,9HW)
7
Film: 101
Time: 14:13 Number:
Surface sample:
% of
%
% by
% by
% by
Eroding Water:
at
Photographs:
Average:
Comments:
Critical erosion shear stress between 'tA & 't8
'to =
Average =
11/03/98
0,25 Nm,22
0.29 Nm"2
0.27 Nm-
3c3.xls
0.005
-- Shear stress
-- Erosion rate
0.003
�E�
'"
=-
0.001
Slighl erosion
S
0.8
'a.
0.6
�
c
t.
=
-0.003
��
�
"
�
0
.� ·0.001
e
w
"i�
lYII!.�
/fil
(�
' r\)ti
jY,IJi.'Pi.'NI/'"'
0.29 Nm·' ----.
..
�
�
lA
=
0.4
.,
�
"
.!!!
0.
a.
""
0.25 Nm-2
0. 2
-0.005 I-��-��-f-��-��--j-�-+-��-�--{ 0
14:15
14:20
14:25
1 4:30
14:35
14:40
local time
Site:
Time:
Dale:
1 4: 1 5
1 9/06197
1 1 103/98
Photographs:
Time: 1 4 : 1 3
ilm :
Number:
F
10
3c3.xls
c
�
!l
c
•
u
c
0
u
�
=
1000
800
600
400
1
3C3 1 9/6/97
�
�Cardiff
-
"
:wo
o
0.1
0.9
0.4 �
0,5 0.5 �
0.2�.3�
0.7 0.8 �
Applied shear stress (Nm't)
"",,,
",,
---"""
1000 �--","
I
'i> 100
.§.
�"'''� , ...,
_
_
c
.2
�
•
u
c
0
u
�
=
"
10
o
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
0.9
0.005 r-----··
0.003
.-. 0.002
i 0.001
E 0
·0,001
.l: -0,002
-0.003
-0.004
.0.0Q5 �
.7 0.8 0.9
0.5 0.6 0�
0.1 �
0.2 0.3 0.4�
S
1ii
Applied sh ear stress (Nm'l)
Cardiff 3CD1 1 9/6/97
1000
.�-.-.
BOO
E..
c
600
5
400
'J;
I
o
u
"tI
:>
:;;
Shear stress
O.B
,
200
o
1 4:55
0.2
Mass erosion
1 5:00
o
15:10
1 5:05
local time
Site:
Cardiff seasonat survey June
TiDate:
me: 19106/97
14:47
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioity:n:
other features:
33mm
vane
Observer:
Damon
Measurements (kPa):
1.11.2 O'Brien
1.11.1
Average: 1.11.2
Site description:
1997
mid brown
irregular, pits, worm holes
± 2mm
less than in May, lew hydrobla
clay, scant sand
sunny and windy now, drying
Shear vane:
Comments:
11/03/98
Data file:
Path:
aded fromenliSqui
..(downl
lsedimoentslhel
ntrmudlcardi
unlcjun007.IOl
(from top 5mm)
Water content:
of 3dry weight
140 - SM19-21
Bul
k
densi
t
y:
1353
kgmCarbon Medi
Sand
ghtht
Si
l
t
content:
wei
g
(localSalicolnity:lected24.at9HW)
7
Film: 121
Time: 14:45 Number:
Surface sample:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'CB
Nm-2
0.32
fA =
Nm·2
fa =
0.41
Average =
0.36
Nm·2
3cdl.xls
0.005
0.003
:
-;"
E
0>
0.001
6
�
0
...
c
-- Shear stress
--Erosion rale
Slight erosion
'A
-0.003
=
It'
�
ta
-0.001
e
w
0.8
0.32
=
jv � j'AI\N
0.41
Nm-2
Nm·2
JVlI!lMW;,J,"v-J/,
Mass erosion
�
f'\�"
lv/,!'
, M!I/vIMI
rMYtJ'o.VN
1
rN.VI)
. t'. I��
fAA /V
'"
0.6
.5
�
00
00
�
"
�
"
�
0.4
00
"
.
�
C.
c.
"
0.2
-+--�-�-�-�--+---l o
-0.00514:I--�-�-�-�
55
15:00
15:05
15:10
Local time
Site:
Time:
Date:
14:19/06/97
47
11/03/98
Photographs:
Time:
14:45
Film:
Number:
121
3cd1.xts
Cardiff 3CDl 1 9/6197
1000
600
�
s.
c
!
•
u
c
8
"
0
..
i
if.*
600
400
�
.",. -+
200
00
0.1
S.
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0
.•
Applied shear stress (Nrn-')
Cardiff 3CDl 19/6197
1000
�
K�
tr'
�-+
100
f
c
�K'*
.
.,.
li
u
c
8
"
0
"
10
0
0.005
0.004
0.003
0.002
�� 0.0001
-0.001
�
-0.003
-0.004
.(l.G05 0
0.1
0.2 0.3 0.'
O.S
0.8 0.7 0.8 0
Applied shear stress (Um-2)
.•
... ..+... .-ikt
c
0
..
;" \\1
..(}.OO2
0.1
0.2 0.3 0.4
O.S
0.6 0.7 0.8 0
Applied shear stress (Nm-i)
.•
1000
800
S
'§;
�
�
0
�
"
u
�
0
u
"
"
::;;
-- Shear stress
0.8
600
18
400
200
=
0.49 Nm-2
�
rr
�J
.�
,;,JWN,'i/'
_/
..
'A
=
..
�
0.6 "
"
E
<;;
�
"
"
"
0.4 "
�
0.42 Nm·2
.�
i5.
Q.
..
0.2
/f
Slight erosion
��--��--�4---��--�-4--�-�----4-� 0
1 5:25
1 5:30
15:10
15:15
15:20
o
Local time
Cardiff seasonal survey June 1 997
Site:
15:10
TiDate:
me: 19/06/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mmvane
Observer:
Damon
Measurements (kPa):
1.11.1 O'Brien
1.2
1.19
0.
Average: 1.1
Site description:
mid brown
irregular, pits, worm holes
± 2mm
less than in May, few hydrobia
clay, scant sand
1m to East of C01
Tide coming In fast - 200m away
Shear vane:
Comments:
11/03/98
Data file:
Path:
(downl
aded fromenliSqui
rrel dala flfo\cjgger)
. \sedimoentslhel
ntrmudlcardi
un\cjun008.101
(from top 5mm)
139 - SM22-24
Water content:
of3dry weight
Bul
k
densi
t
y:
1355
kgm·
Carbon (lMedi
oss aonn siIgznietd50:
Sand
content:
ghtht
3.29 byby wei
wei
g
59.
Si
l
t
content:
7
Film: 131
Time: 15:03 Number:
Surface sample:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & fa
0.42
Nm·2
tA =
Nm-2
0.49
tB =
Average =
0.45
Nm-2
3cd2.xls
---
0.005
0.003
-- Shear stress
-- Erosion rate
0.8
"
"�E
Cl
:'!'.
0.001
�
Slight erosion
"
lS
0
.�
·0.001
E
UJ
·0.003
·0,005
15:10
Site:
15:15
11/03/98
1997
,I\'k'
0.6
I
Nm-2�'K
,[
t
J
0.49
fti�'»)''A''''WW1J''�
TiDate:
me: 15:10
Operator: H.19/06/97
J.Mitchener
=
'-..
Mass erosion
§1':.
��
e
1;;
"
,J-
�
�
0.4
�"'.
"
"
�
"
,�
a.
c.
"
0.2
1 5:20
Local time
Photographs:
Time: 15:03
1 5:25
o
15:30
Film: 131
Number:
3cd2,xls
1000
800
�
.§.
�
c
600
c
•
u
c
0
u
�
400
+ t'�J8
.-. + �- - ..
•
"
200
0
0
0.1
0.2
0.3
0.4
0.6
0.5
vl
i
0.7
0.8
0.•
0.•
0.•
0.8
0.•
toaD
�
.§.
jj
� ..
�. � �
�+
100
c
.2
•
u
c
g
•
"
�
10
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress {Nm-l)
0.7
0.005
0.004
�
"E
�•
il
Jl
0.003
0.002
t- +
0.001
0
c
.2 -0.001
•
�� l tt�liA
+
-0.002
·0.003
.(}.OO4
.0,005
0
0.1
0.2
0.3
0.4
0.5
0.8
0.7
SedErode Data Plots
Cardiff July 1997
:7'HR WallJngford
.:
TR S7 07/1W9&
1000
800
§.
'd;
c
�
�
o
u
"
,
:;
.
. . . ._ --_ .•
-
.
---- - ---
---Shear stress
0.8
1
600
0.6 �
400
ii
�
�
0.4 "
.�
0.
Cl.
<>:
0.2
o fC---�--�-�--�----t--l o
14:15
14:20
14:25
Local time
Cardiff seasonal survey July
Site:
13:41
TiDate:
me: 22107197
texture:
colour:
coveri
ng:
10pography:
biologiccomposi
ally actitvioitn:y:
other features:
33mm
vane
Observer:
Damon
0.0.79
Average: 0.1.09
Site description:
Data
Path:
1997
pale brown
worms, hydrobia
±'mm worm tracks
20-30 worms, 20 hydroblaJ10cm diam.
mud, virtually no sand
Tide just oul, drying Qui, very hot + sunny,
-
approx 1cm - new deposit (last tide)
Shear vane:
Comments:
11103/98
aded lromenliSqui
rrel dataflfo\cjgger)
..(downl
lsedimoentslhel
ntrmudlcardi
ullcjuI001.IOl
(from top 251
5mm) - SMl-3
Water content:
of-3dry weight
Bul
k
densi
t
y:
1226
kgm
Carbon (lMedi
weigghtht
Sand
content:
1.85 byby wei
47.
Si
l
t
content:
: 24.at3HW)
4
Film: 111
Time: 13:40 Number:
Surface sample:
medium soft
slight breeze. Thin surface layer
file:
%
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 'rB
Nm-2
0.00
<A =
Nm-2
0.22
<. =
Average =
0.11
Nm-2
4al.xls
0.01
0.008
0.8
0.006
0.004
�
0.6 1
0.002
�
� 0
. -0.002
0.4
-0.004
0
-0.006
-0.008
-0.01 �--�----�--+---�--� o
---
Shear stress
Erosion rale
"
�
�
E
'"
�
"
�
•
.<:
�
'"
c
0
;;;
e
.�
Q.
0<
w
.
14:25
14:20
14:15
2
Local time
Site:
Time:
Date:
Operator:
13:41
22107/97
H.J.Mitchener
11/03/98
1997
Photographs:
Time:
13:40
Film:
Number:
11
4a1.xls
{t+
Cardiff 4Al 2W197
1000
'&
800
I�
t!
s
c 600
I
•
u
c
0
u
"
0
"
400
+
200
00
0.1
W
:t:
0.2 0.3
s
c
.2
�c
8
c
0
u
"
0
"
0
.-
1000
!t
lOO
�
1;+
t\
10
+
+
+
0.1 0.2 0.3 0.4 0.' 0.6 0.7 0.8 0
0.1
0.01
0.008
0.006
0.004
�
'E 0.002
g
� 0
-0.002
-0.004
-0.006
-0,008
-0.01 0
.•
Cardiff 4Al 2W197
I_
'&
0.4 0.' 0.6 0.7 0.8
Applied shear stress (Um'!)
.•
Applied shear stress (Nm'�
Cardiff 4Al 2W197
"'++
+
.-
c
�
e
w
0.1
�
0.2 0.3 0.4 0.' 0.6 0.7 0.8 0
.•
Cardiff 4A2 2217/97
1 000
800
.s
�
c
i
8
c
u
0
"
�
�
�
-- �
-----
-- Shear stress
0.8
..
800
�
dr:: 0.31 Nm�2
�t ..
400
�
:E
..
00
2
'II'If'I1!A-
=
f�Ji""
0.6
:.
"
'"
"
0.4 "
.�
'li
Q.
'"
�,
'tA = O.29 Nm
Erosion
0.2
0
0
14:30
i"
"
�
14:35
14:40
1 4:45
Loca time
14:55
1 4:50
l
Cardiff seasonal survey July 1997
Site:
14:29
TiDate:
me: 22107/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
cally actitvioity:n: 30·35
other features:
33mm
vane
Observer:
Damon
1.11.2
Average: 0.1.09
Site description:
medium
Data file:
Path:
worms, tracks and holes
Comments:
%
%
.2mm
Shear vane:
(from top 5mm)
of-'dry weight
Water content:
189 - SM4-6
kgm
Bul
k
densi
t
y:
1282
Carbon (lMedi
gghtht
Sand
content:
2.1 byby wei
Si
l
t
content:
41.7
wei
Mud Temperature: 29 DC
4
Film: 121
Time: 14:27 Number:
Number:
13 After erosion
Surface sample:
pale brown
worms+ 1·2 hydroblal10cm diam.
mud, no sand or shells
aded fromen\iSqui
rrel dataflf\cju�cjuI
ogger) 002.101
..(downl
\sedimoents\hel
ntrmud\cardi
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between fA & to
Nm-2
0.29
tA =
0.31
Nm-2
tB =
Average =
0.30
N �2
m
11/03/98
4a2.xls
Cardiff 4A2 2217/97
0.8
0.01
0.008
0.006
--
Shear stress
-- Erosion rate
0.6
.§
;=..
0.004
.-
E 0.002
�
�
,
�
"
'"
�
�
0
0
.;;;
e
UJ
0.4
0
�
�
�
""
�
"
Mass erosion
-0.002
�
.�
0.
Co
-0.004
0.2
"
-0.006
-0.008
-0.01 ��-r��--�r-��-+��--��+-� O
1 4:55
1 4:50
1 4:45
1 4:40
1 4:35
1 4:30
Local time
Site:
Photographs:
1997
Time: 14:27
TiDate:
me:
Operator: H.J.M itchener
14:29
22107/97
22
Film:
Number:
Number:
12
13
After erosion
T U L'I
I t..- · '1 71
if- A 'J-
( " I� D I PF PLTI_ :(S
1 :-1 r'� �\IJ D
1 1 /03/98
T() 'IE
4a2.x15
Cardiff 4A2 22f7197
1000
'ii;
.E-
�0
o
u0u
�
800
600
.Eft>
400
,.+
•
"
,J +
• nti ;) 41ft tIf if
200
0
0
0.1
0.3
0.2
0.4
0.5
0.6
0.7
0.8
0.'
0.7
0.8
0.•
0.8
0 .•
Cardiff 4A2 22f7197
10000
'ii;
1000
.E-
j0u0
�u
+ ;j 4lft .
f
'
" ;.m
t:*t1
,
o
100
•
"
10
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm,l)
Cardiff 4A2 22f7197
0.01
0.008
0.006
��
0
1)
E
0
]
0.004
0.002
.. � �.$1t
0
-0.002
·0.004
"i;�+ �
+
·0.006
-0,008
-0,01
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
------ ---------
Cardiff 4A3 2217/97
---
1000
--
-�-
800
--
---
-
-
Shear stress
Mud concentration
0.8
..
0.6
0.4
200
o
1 5:05
0
0
e
1il
�
'"
"
"
0
'C
.�
'ii
a.
<I:
0.2
, Slight erosion
1 5:20
15:15
15:10
t
o
1 5:30
1 5:25
Local time
Site:
15:01
TiDate:
me: 22107/97
1997
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y: other features:
33mm
vane
Observer:
Damon
1.3
1.11.1
Average: 1.1
Site description:
medium · getting harder
mid brown
worm holes, no hydrobia
.1mm
25 wormsf1 Ocm diam.
mud, worms, no sand
on rid g e · drying out In sunshine ·
very hot
Shear vane:
Comments:
Data file:
Path:
(downl
aded fromenliSqui
rrel data llflcj
ogger)
..lsedimoentslhel
ntrmudlcardi
ullcjuI003.IOl
(Irom top 5mm)
161 - SM7-9-'dry weight
Water content:
1318 kgmby weight
Carbon Medi
(lossBulaonnksiigdensi
nizetd50:
ion):ty: 10.11
1.9 micbyronsweight
1.4
Sand
content:
47.4 byby wei
ClSiaylt content:
content: 51.2
weigghtht
: 24.at3HW)
4
Film: 141
Time: 14:58 Number:
Surface sample:
% 01
%
%
%
%
°c
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'fB
Nm·2
TA =
Nm·2
'fB=
Average =
Nm'2
0.31
0.36
0.33
11/03/98
4a3.xls
Cardiff 4A3 2217/97
0.Q1
0.008
0.006
"
�
"
E
C>
=-
�c
0.004
0 .002
--
--
Shear stress
Erosion
rate
0.8
¥ Slight erosion
0.6
0
I/)
"
m
•
0 ·0.002
';;
�
I
�
0.4
·0.004
0.2
·0.006
]�
-"
C.
"
..
·0.008
·0.01
1 5:05
15:15
15:10
1 5:20
Local time
Site:
Photographs:
Cardiff seasonal survey July 1997
Time: 14:58
15:01
TiDame:e: 22107/97
Operator: H.J. Mitchener
t
15:25
o
1 5:30
Film: 14
Number:
--
2 2 JUL.'f
SITE
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0.7
Cardiff 4C1 2217/97
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I
c
.2
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O.B
1
�
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400
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1 6:00
16:05
15:55
Local time
Site:
15:51
TiDate:
me: 22107/97
1997
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
Measurements (kPa): 0.0.76 O'Srien
0.0.53
Average: 0.0.54
Site description:
medium soft
pale brown
worms and hydrobla, water around
± 2mm
20 worms+20 hydroblaJ10<:m diam.
watery mud
Drying out, soft surface deposit
Shear vane:
Comments:
1 1/03/98
Data file:
Path:
(downl
aded fromen\iSqui
rrel data flolcjgger)
..\sedimoents\hel
ntrmud\cardi
u�cjuI004.101
194 - SM10-12
of·3dry weight
Water conl(from
ent: top 5mm)
Sul
k
densi
t
y:
1276
kgm
Carbon Medi
weigghtht
2.53 byby wei
Sand
content:
45.
Si
l
t
content:
Mud Temperature: 27 °C
: 24.at 3HW)
4
Film: 161
Time: 15:50 Number:
Surface sample:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'fB
Nm·2
0.30
'A =
Nm·2
0.34
'fB =
Average =
0.32
Nm'2
4c1 .xls
Cardiff 4C1 22nt97
0.02
0.018
0.016
0.014
---
Shear stress
--- Erosion rate
0.8
0.012
,
�
"
""
0.01
E 0.008
0.6
'"
�
� 0.006
c
0
i
�
�
�
�
�
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.c
0.004
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2
0
w
0.4
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·0,004
�
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,�
a.
c.
..
0,2
·0,006
·0,008
·0,01 �----�--� o
1 5:55
16:00
1 6:05
Local time
Site:
TiDale:
me: 15:51
Operalor: H,J,Mitchener
1997
Photographs:
Time:
1 5 :50
Fi m
Number:
l
:
16
22107/97
1 1 /03/98
4c1.xls
Cardiff 4C1 2217/97
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0.7
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1000
800
.§..
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0
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1 6:20
16:25
16:15
local time
Site:
TiDate:
me: 22107/97
16:15
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
1997
medium soft
pale brown
very scant water
±
2mm, worm tracks, hydrobia
no hydrobia, 1 5 worms/10cm dia
mud, worms, hydrobia snails
2nd attempt. Moved to side of dip
lnlo runnel · appears harder
33mm
vane
Observer:
Damon
Measurements (kPa):
0.0.83 O'Brien
0.8
0.5
0.2
Average: 0.5
Shear vane:
Comments:
Data file:
Path:
aded fromenliSqui
rrel datamlocjgger)
..(downl
lsedimoentslhel
ntrmudlcardi
ullcjuI005.IOl
(from top 5mm)
184 - SM13-15
Water content:
3dry weight
Bul
k
densi
t
y:
1287
kgmCarbon (lMedi
gghtht
Sand
Si
l
t
content:
wei
Mud Temperature: 27 °C
: 24.at3HW)
4
Film: 18
Time: 16:13 Number:
Surface sample:
% 01
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA
2
N m'
'fA =
2
'B =
N m2
Average =
N m-
0.23
0.31
0.27
11/03/98
& 'fa
4c2b.xls
Cardiff 4C2 22n197
0.Q1
0.008
0.006
"
�
"
-- Shear stress
--Erosion rate
0.4
§1E.
0.004
�
�
�
E 0.002
'"
6
�
0
�
�
�
<:
c
0
0.2
•• -0.002
e
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�
"0
.�
C.
"..
-0.006
-0.008
-0.01
16:15
o
1 6:25
1 6:20
local time
Site:
Cardiff seasonal su rvey July
16:15
TiDate:
me: 22107/97
Operator: H.J. Milchener
11103/98
1997
Photographs:
Time: 16:13
Film: 18
Number:
4c2b.xls
�
�
u
c
8
,
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600
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;It t *
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Cardiff 4C2 2217/97
1000
�
200
0
0
0.05
0.1
0.15
0.2
0.3
0.25
0.35
Applied shear stress (Nm-�
0.45
0.4
0.5
Cardiff 4C2 2217/97
10000
+
1000
10
0
0.05
0.1
0.15
0.2
0.3
0.25
0.35
Applied shear &tress (Nm"1
0.45
0.4
0.5
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0._
0.006
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+
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·{tOl
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0.2
0.25
0.3
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0.35
0.4
0.45
0.5
Cardiff 4C3 2217/97
1000
---- Shear stress
800
.s
�
c:
0
�
E
"
"
c:
"
'0
"
:;
0
600
0.8
"
"
Slight erosion 'It.
400
0.6 �
i
�W/!triIMVIIM
'"
"
"
"
�
0.4 II
Q.
<l.
-0:
�TB=0'30Nm'2
� TA = 0.23 Nm·2
'�Ji\)'JJJM
200
o
16:40
..
0.2
�--�--�--�r---�--� O
16:55
16:50
16:45
Local time
Site:
16:40
TiDate:
me: 22107/97
1997
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioity:n:
other features:
33mm
vane
Observer:
Hel
e
n
Mi
Measurements (kPa):
0.1.83 tchener
0.1.1.129
Average: 1.1
Site description:
medium
mid brown
worm tracks, pits, dry
± 2mm,
tracks
no hydrooia, 1 5 worms/1Ocm dia
mud, worms
30 worm holes/1Ocm dlam. Slight
drainage
Shear vane:
Comments:
11/03/98
Data file:
Path:
Squirrel data flflocgger)
..(downl
\sedimoents\hel
ju�cjuI006.IOl
(from top 5mm)
Water content:
131 - SM16-18
of3dry weight
Bul
k
densi
t
y:
1370
kgm'
byronsweight
Carbon (lMedi
ion): 9.16
2.
0
mi
c
Sand
gghtht
Si
l
t
content:
wei
Mud Temperature: 27 BC
4
Film: 20
Time: 16:39 Number:
Surface sampte:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & 'ta
Nm"
"A =
0.23
Nm"
0.30
TB =
Average =
0.26
Nm"
4c3b.xls
Cardiff 4C3 22nt97
0.01
0.008
0.006
"
1-- She�r stress I
1--- Erosion rate I
0.8
0.004
"'"
E 0.002
'"
6
�
0
c
Slight
.l
0
'iii -0.002
e
w
-0.004
erosion
��-I..
..1
0.2
-0.006
-0.008
-0.01 �-�--�--�--+---�-----r--� O
1 6:50
1 6:55
16:40
1 6:45
Local time
Site:
Cardiff seasonal survey Juty
TiDate:
me: 22107/97
16:40
11/03/98
1997
Photographs:
Time: 16:39
Film: 20
Number:
4c3b.xls
1000
000
�
g
600
�
400
200
00
Cardiff 4C3 22f7/97
c
it
�.•
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•
u
c
0
u
,.
+
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•
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0.1
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Applied shear stress (Nm-:)
Cardiff 4C3 2217197
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-""*.....,..
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Mud concentralion
0.8
--
0.6
I
�
(f)
�
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�
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�
.�
200
o�
S ight erosion "».
l
itme: 18:05
TiDate:
Operator: 22107197
H.J.Milchener
S e:
Cardiff seasonat survey
�� o
local time
�
18:10
�
1 8:05
0.2
July
1 997
18:15
Data file:
Path:
1 8:20
Squirrel data flfo\cjul
gger)\cjuIOl1.IOl
..(downl
\sedimoents\hel
texture:
hard
(from top 5mm)
123 - SM25-27
Water content:
colour: very
mid brown
of3dry weight
kgm1388
Bul
k
densi
t
y:
coveri
n
g:
many
worm
hol
e
s
topography:
Carbon
(lMedi
biologiccomposi
ally actitvioitn:y: -mud,303mmworm
hol
e
S/
l
0cm
di
a
m.
No
hydrobi
a
weigghtht
Sand
wormson flat part
Si
l
t
content:
other features: 7th attempt
Clay content: 35.3 Q by weight
Mud
Temperature:
27 C
33mm
vane
O'Brien
(IocatSalicolnity:lected24.at3HW)
Measurements (kPa):Observer: Damon
1.8
4
1.1.89
Film: 22
2.11.9
Time: 15:28 Number:
Average: 1.9
Site description:
Surface sample:
%
%
±
%
%
%
Shear vane:
Eroding Water:
Photographs:
Comments:
11/03/98
Critical erosion shear stress between tA
Nm-2
'A =
0.23
0.26
Nm·2
'B=
Average =
0.24
Nm-2
& 'tB
4cdlg.xls
Card iff 4CDl 22fl197
0.01 r-------�--___,
0.008
0.006
�0
E
0>
--
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-- Erosion
rate
0.004
�
0.6
�--��
.�
�
,
..
0
0
.0 -0.002
;;;
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0.002
:.
0.8
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-0.004
0.2
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1 8:10
18:15
18:20
1 8:05
Local time
Site:
Cardiff seasonal survey
18:05
Time: 22107/97
Ju 1997
ly
Photographs:
Time: 15:28
Film: 22
Number:
1
Dale:
r
11/03/98
4cd1
g.xls
1000
800
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g
c
600
8
400
1
c
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.•
SedErode Data Plots
Cardiff August 1997
ZHR Walllngford
TR S7 07/0(/98
Cardiff SA 1 1 9/8/97
1000
--
800
§.
'§;
�
1
o
�
8
--
Shear stress
concentration
Mud
0.8
600
0.6
400
0.4
"
1
�
(/)
�
�
'0
.�
8:
'0
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o �_�_�_�L-�_�_�_�_�_�__�_�_�_�_�_�
o
1 4:25
14:20
14:15
14:10
Local time
Cardiff seasonal survey August
Site:
TiDate:
me: 13:37
J.Mitchener
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
1997
medium soft
Data file:
Path:
hydrobla, water, worms
fta! wfth sHgh!ridge, ± .mm
mud, no sand, hydrobla
saturated mud drainIng down. -5mm very
layer. -Srn E of drainage channel
Comments:
%
%
15·20 hydrobla & 15·20 worm holes I 10cm diam
33mm
vane
Observer:
Damon
O'Srien
1.2
1.2
Average: 1.1.64
I .B
(from top 301
5mm) - of dry weight
Water content:
1196 kgmby,3weight
Carbon (lMedi
ossBulaonn ksiigdensi
nizetd50:
iotn):y: 10.93
1.1.17 micbyronsweight
Sand
content:
weigghtht
ClSialyt content:
content: 45.
53.63 byby wei
Mud Temperature: 30
3
Film:
Time: 13:35 Number:
Surface sampfe:
mid brown
saturated deposll (last Udal over harder
Shear vane:
Squirrel data mlocaug\caug001.
gger)
..(downl
\sedimoents\hel
101
%
%
%
·c
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 1'a
Nm-2
fA =
Nmo2
ta =
Average =
Nm-2
0.00
0.19
0.10
09/03/98
581.xls
Cardiff 5A 1 1 9/8/97
0.01
0.008
0.006
;
-
- Shear stress
Erosion rale
--
0.8
0.004
":"
"
E 0.002
E
�
0
�
t
c
.0
� ·0.002
e
w
-0.004
-0.006
0.2
-0.008
-0.01
14:10
14:15
o
14:25
14:20
local time
Site:
37
TiDate:
me: 13:19/08/97
1997
Photographs:
Time: 13:35
, ... .... .... T!.
,' rt.,.:
IH'.
09/03/98
-
, �\ '�1r 11 1.
j:H
!o fl t
f n r"'�" ,l>
, ,,�,,,
..
Film:
Number:
. .. ."
. ..
"
'.
.,
5a1.xls
Cardiff SAl 1 9/8197
,t!.,
1000
g
�
!
c
800
�*
#
+\
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c
8
c
0
u
�
ff
"
.00
,
'"
200
0
0
0.1
0.2
0.3
0.'
0.'
0.6
0.7
0.•
0.9
0.'
0.6
0.7
0.•
0.•
0.'
0.6
0.7
0.•
0.•
Applied shear stress (Um-!)
10000
gc
�
�
IIc
1000
,
.2
,
100
0
......
u
�
+
'"
10
0
0.1
0.2
,�
0.3
0.'
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0.01
0.008
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"E
!
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0.004
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c
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0
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0.1
0.2
0.3
0.'
Applied shear stress (Um·l)
Sal.xls
1000
800
.s
�
"
E
"
.2
--- -----
--- ---- ------
-- Shear stress
concentration
--
Mud
0.8
.r
�
600
0.6 "
"
400
Iii
"
"
0.4 "
e
1ii
,.
U
"
u
0
.t:
�J�;
"
"
:;
.�
0.
Q.
«
tB = O
200
'"
0
14:30
lA =
0.23 Nm
0.2
Erosion
0
14:45
14:40
14:35
Local time
aded fromenliSqui
rrel data flflcauglcaug002.
ogger)
Path: file: (down
..lsedimloentslhel
ntrmudlcardi
IOl
Data
Cardiff seasonal survey August 1 997
Site:
TiDate:
me: 14:19/08/97
27
Site description:
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y:
other features:
•
lmm, flallsh, hydrobia on lop
hydrobla, worms under surface
mud, no sand
harder surface than Ai. on ridge top
33mm
vane
Obsel
V
er:
Damon
Measurements (kPa):
1.11.3 O'Brien
1.1.46
Average: 1.1.44
Comments:
%
hydrobla 20/1Ocm, worms 311Ocm, 15-20 worm holes
soft layer. Dry. humid. very warm
Shear vane:
(from top 247
Water content:
1228 kgmby-3weight
Carbon (lMedi
nizetd50:
ion):ty: 11.15
Sand
content:
gghtht
70.52 byby wei
wei
ClSialyt content:
content: 28.
3
Film: 2
TiTimme:e: 14:25 Number:
Number: 4
Surface sample:
medium soft
pale brown
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 't8
Nm-2
0.23
<A =
N 2
0.27
'tB ::
0.25
Average =
Nm-2
m-
09/03/98
5a2.xls
0.01
O.OOB
0.006
"
�
•
---
Shear stress
Erosion rate
O.B
0.004
0.6
E 0.002
'"
�
�
0
�1:�
�
�
1;;
�
ro
�
c
.0
� -0.002
e
UJ
0.4
-0.006
0.2
-0.004
"
�
'0
.�
C.
c.
"
-O.OOB
-0.01
14:30
14:40
1 4:35
Local time
Site:
Cardiff seasonal s u rvey August
27
TiDate:
me: 14:19/08/97
1997
Photographs:
TiTimme:e: 14:25
DATE:
T/I1E:
'ITE :
Film: 21
Number:
Number: 4
,q 1\U&uST I�fn
SA il
1 4- : � S
( , \ '� lJ ' , F
09/03/98
FI· rh<,!. 10":(
{ 1'J T R f1 U U
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+
1000
'§;
g
�
c
c
•
u
c
0
u
�
"
'"
�H
h
.�+
600
400
200
00
+t
f
BOO
+�
++
0.1
0.2 0.3 0.4
0.5 0.6 0.7 0.8
Applied shear slress (Nm-1)
o.g
10000
'§;
1000
g
c
.2
1;
�
ii
u
100
c
8
�
"
'"
09/03/9B
10
+
+.... �
++
tIt�
5a2.xls
-------- ------ ------ -
1000
800
.§.
�
�
c
0
C
�
u
c
0
u
"
�
:;
------ Shear stress
concenlration
-- Mud
0.8
.§
�
""
0.6 '"
'"
�
600
400
200
fi
0
14:50
Site:
.e
"
la
,Erosion
Comments:
09/03/98
.�
0.
0.
'"
0.2
0.19 Nm·2
0
15:05
1 5:00
v, soft lop layer, medium soft
Dala file:
Path:
hydrobia 20/1Ocm, worms -10/10cmdlam
*
lmm. hydrobia on ftat mud
hydrobia
mud
soft mud. -2m from a1 & A2
(downl
aded fromenliSqui
rrel dala flflcaug\caug003.
ogger)
. \sedimoents\hel
nlrmud\cardi
IOl
(from top 5mm)Water content:
289 of-3dry weight
Bul
k
densi
t
y:
1202
byronsweight
Carbon (lMedi
ion): 14.3.740 kgm
mi
c
1.59 byby wei
gghtht
Sand
conlent:
Si
l
t
content:
wei
68.
Clay conlent: 29.6 by weight
Mud Temperature: 30
3
Film: 31
Number:
Surface sample:
pale brown
33mm
vane
Observer:
Damon
1.1.10
Average: 1.1.13
Shear vane:
'"
0.4 "
local time
Cardiff seasonal survey Augusl 1 997
texture:
colonur:g:
coveri
biologicomposi
clopography:
ally actitvioity:n:
other features:
lA =
(W'"v.p,fF'o.-.._J'
=
1 4:55
TiDate:
me: 14:51
J.Mitchener
Site description:
rM'NN-NN
W
r
,AA. 0.22 Nm-2
�
m
�
.<:
%
%
%
%
%
·c
Eroding Waler:
Pholographs:
Critical erosion shear stress between 'tA & 'ta
Nm'2
0.19
'A =
0.22
Nm-2
'ra =
Average :::.
0.21
Nm'2
5a3.xls
0,01
0.008
0.006
E
.s
e-
.r
0.6
��
�
C.
w
0.8
0.002
Cl
c
.0
..
Shear stress
--Erosion rate
0.004
��E
�
--
1;;
�
0
�
�
�
004
-0.002
·0.004
-"
�
"
.�
D.
Il.
..
0.2
-0.006
-0.008
-0,01
14:50
o
15:05
15:00
1 4:55
Local time
Sile:
Cardiff seasonal survey August 1 997
Time:
14:51
Dale:
Operalor:
Photographs:
Film:
1
Number:
3
1 9/08/97
H.J .Milchener
bAn . 1 11 l\l' {;- UST I
III i
r l /'II, : 1 4 : 5 0
5 1 1'E :
SAJ
( .l ' ( !J t r,·
09/03/98
p� rc ... )
I {lJ r R ('1 v tJ
''' '''1
5a3.xls
Cardiff 5A3 1 9/8197
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+
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�
S
!
c
i
,
u
c
8
*,-+
+ l -i'+
600
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400
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200
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f
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+
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0.2
0.3
0.4
0.'
0.7
0.8
0."
O.B
0.7
0.8
0.•
0.6
0.7
0.6
0.•
0.6
Applied shear stress {"m'�
1 0000
�
1000
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+
s
!
c
8c
."0
100
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U
"
.
'
10
0
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0.4
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l
•
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0
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0.3
0.4
0.'
09/03/98
5a3.xls
'-
- - - --_...
1000
-- Shear stress
BOO
.§.
'§;
:8
E:c
c
�
u
c
u
0
--
Mud
concentration
O.B
�
....
E
0.6 "
"
600
e
1;;
�
.c
:;;
4
00
""'%�
0.36 Nm-2
Erosion
"
�
:;
0.4
"-
«
Ta =
lA = 0.23 Nm-2
200
"
"
.!!
i5.
0.2
-+--�-�-�--�-+--�--4500
15:�-�_-u��-�35
15:40
15:
4
5
15:
Local
o
time
Site:
30
TiDate:
me: 15:19/08/97
1997
Data lile:
Path:
rrel cdata
ogger)
aded fromenliSqui
..(down
lsedimloentslhel
ntrmudl
ardillflcauglcaug004.
101
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
Measurements (kPa): 0.0.58 O'Srien
0.0.72
Average: 0.0.86
Surface sample:
Comments:
Critical erosion shear stress between 'tA & tB
Site description:
medium soft - hardish, less water
pale brown
hydrobla, fewworffiS
± lmm on flat ridge
(from top 224
Water content:
3
81.99 mikgm·cbyronsweight
Carbon (lMedi
ossSulaonn ksiigdensi
nizetd50:
ion):ty: 11.1247
ghtht
Sand
content:
0.79 byby wei
wei
g
Si
l
t
content:
47.
Mud Temperature: 29.25 ·C
(localSalicolnitly:ected25.at 6HW)
3
Film: 5
Time: 15:27 Number:
%
%
hydrobla -20/1Ocm, wormholes -10!1Ocmdiam
mUd, no sand
audible draining sound
warm, hot, muggy
Shear vane:
09/03/98
%
%
%
Eroding Water:
Photographs:
1A=
0,23
tB=
0.36
Average =
0.30
Nm"2
Nm-2
Nm-
5cl.xls
0.01
0.008
0.8
0.006
.:;
0.004
"
E 0.002
'"
�
.'!l
0
�
0
0
.� -0.002
e
"'
-0.004
0.2
-0.006
-0.008
-0.01
15:35
o
1 5:50
1 5:45
15:40
Local time
Site:
30
TiDate:
me: 15:19108/97
1997
Photographs:
Time: 15:27
... : , , --
"
;"
' • ••
09/03/98
.1
•
•
•'
....
.
.
;
.:
,., 0(
. .'.
Film: 51
Number:
,,"re 1 ' 1 1ll'(;-lI�r
-,
" /1110:
�In: .
I, J 7
, '/lt7.
5(1
5c1.xls
1000
800
'§;
S
600
1
400
,
200
00
Cardiff 5Cl 1 9/8/97
it++
c
u
c
0
u
�
"
�
0.1 0.2 0.3
+
+
+�
+
+
100
c
j
ft
J
�
0.4 0.5 0.6 0.7 0.8
1000
'§;
S
+ +
+
.,.++
++
�.,p
0.9
��
c
•
u
c
, 10
8
�
"
0
0.01
0.008
0.004
�� 0.002
!
·�a ·0,002
-0.004
·0,006
-0,008
-0.01 0
0.005
�
c
09/03/98
0
0.1
0.4
0.2 0.3 Applied
0.5
0.6 0.7 0.8
0.9
shear stress (Nm-1)
+
..
+
+
+
'-
.�1I41111"
+
r
;Q
0.1 0.2 0.3 Appl0.4ied
0.5
0.6 0.7 0.8 0
.•
shear stress (Nm'l)
5c1.xls
0.01B
0.016
0.014
0.012
�E�
-- Shear stress
--
Erosion rale
�
0
.;;;
�:!S
0.01
O.OOB
'" 0.006
=-
0.8
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0.004
c
0.002
e
w
0
-0.002
-0.004
-0.006
0.6 '"
'"
�
�
..
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"
'"
0.4 "
�
.�
ii
Q.
r'"
''''''''' ''"'''�NA'�MAilJ;�:
=
<
0.20 Nn'-'
0.2
-O.OOB
0
-0.01
16:00
Site:
Cardiff season at survey August 1 997
TiDate:
me:
1 5:58
1 9/08/97
09/03/98
16:10
16:05
local
time
Photographs:
Time:
15:53
Film: 6
Number:
after
Number:
1
7
erosion
5c2.xls
1500
-�,,--�.
--
Shear stress
Mud concentralion
0.8
""
0.6
�
�
�
�
'"
�
'"
�
"
.<:
0.4
v/,v'NVVY'-_..J\tv\rV\';'Vv�,
\:,\\"'"_�j
�""N\AA��i""
Erosion
o
f---f ----.L
1 6:00
Site:
"
{A
"f-_-
Jlf\._'! -"'4
te =
0,20 Nm·2
0.2
��----+-�
-�� 0
16:05
16:10
Local time
TiDate:
me: 15:19/08/97
58
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obsel
V
er:
Damon
0.1.90
Average: 0.1.09
Site description:
�
1997
soft gelatinous surface
Data file:
Path:
hydrobia
±
2mm
hydrobia 20/10cm, worms S/10cm diam
mud, no sand
(downl
aded fromenliSqui
rrel data mlogger)
. lsedimoentslhel
nlrmudlcardi
cauglcaug005.101
(from top 5mm)
Water content:
221 kgm·of3dry weight
Bul
k
densi
t
y:
1250
Carbon Medi
weigghtht
Sand
Si
l
t
content:
Clay content: 29.6 · by weight
Mud Temperature: 29 C
: 25.at6HW)
3
Film: 6
Time: 15:53 Number:
Number: 7 after erosion
Surface sample:
pale brown
�
surface. Draining
Comments:
%
%
%
%
%
dry, sunny. hot, lots of worms & hydrobia on
Shear vane:
.!!!
C.
c.
<l:
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 'CB
Nm"
<A =
Nm"
<8 =
Average =
Nm"
0.00
0.20
0.10
09/03/98
5c2.xls
f++
1500
'ii
.s
�
+
+
1000
+
c
+
ii
u
c
8
,
'"
�
500
0
Cardifl 5C2 1 9/S197
0
0.1
l!
+
0.2
0.3
0.4
O.S
0.•
0.7
0.8
0.•
0.4
O.S
0.6
0.7
0.8
0.•
0.4
O.S
0.6
0.7
0.8
0.•
10000
'ii
1000
t
.s
c
�
1:
•
1 00
+
8
�
+
0.1
0.2
0.3
0.02
+
0,015
l
0.01
�
0,005
w
0
+
*+
c
�
e
+
+
++
10
0
�
·E
+
�
u
c
,
'"
.
+ +<+
Applied shear &tress ("m,l)
+
++
++
+
+
li
f,$ t +
0.2
0.3
-0,005
-0.01
09/03199
0
0.1
Applied shear stress (Nm·l)
5c2.xfs
- ---------- ---
1000
800
�
.E-
---- Shear stress
concentration
--
E
"
"
400
0
"C
0.8
0.6 �
�
::;
..
200
I/)
I/)
�
"J/'i.
JM
;!i(IIN
#>
J
'
ri
,J-IIM.JAf\..
0.21
��
0
0
Mud
..
600
"
.2
,.
�
"
"
z;
0.4
D.
1B = 0.31 Nm·2
...:
Nm·2
"A =
I/)
"C
.!!
0.
0.2
o ��--��--�-�--�_+- o
16:35
16:30
16:25
16:20
16:40
Local time
Cardiff seasonal survey August 1997
Site:
TiDate:
me: 16:19
H.J.Mitchener
Operator: 19/08/97
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
gelatinous, medium soft
.!·2mm
hydrobia 20/1Ocm. worms 5110cm dlam
mud, no sand
on ridge, drained slightly on filling.
09/03/98
aded fromenliSqui
rrel data flollgger)
..(downl
lsedimoentslhel
ntrmudlcardi
cauglcaug006.IOl
(from top 218
Water content:
3
Bul
k
densi
t
y:
1253
kgm·
Carbon Medi
Sand
content:
gghtht
1.87 byby wei
wei
Si
l
t
content:
55.
: 25.at6HW)
3
Film: 7
Time: 16:17 Number:
Surface sample:
hydrobla
33mm
vane
Observer:
Damon
0.9
1.11.1
Average: 1.0
Comments:
Path:
pale brown
Cooler now, some light breeze
Shear vane:
Data file:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & 't8
Nm·2
'A =
0.21
'B =
0.31
Nm·2
Average =
0.26
Nm"2
5c3.xls
0.01
O.ooB
0.006
E'"
�
"
�
e
w
O.B
0.002
0.6
§;:.
�
�
�
1;;
"
0
�
c
0
Shear stress
-- Erosion rate
0.004
�
.;;;
--
�
�
J:
-0.002
0.4
-0.004
-0.006
�
"
.�
a.
0.
"
0.2
-O.OOB
-om L-�--��--�� O
1 6:35
1 6:30
6 :40
16:25
1 6:20
Local time
1
Site:
TiDalmee:: 16:19
Operalor: H.19/08/97
J .Milchener
09/03/98
1997
Photographs:
Time: 16:17
Fi m: 7
Number:
l
5c3.xls
Cardiff 5Ca 19/8/97
*t
1000
'§;
s
!
c
c
•
u
c
0
u
�
?
j
..tf
800
..
+t't
600
ii*
�
400
,
"
200
0
0
0.1
�
0.2
��
tr'"'
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0.7
0.8
0.9
0.7
0.8
0.9
Applied shear stress (Nm'f)
10000
'§;
1000
S
c
••
d
c
•
u
c
0
u
�
�
,
"
�
100
10
0
0.1
0.2
�
��
0.3
0.4
0.5
0.6
Applied shear slress (Nm'f)
0.01
0,008
*
0,005
�I'I
'.
�
c
�
c
�
.�
+
0.004
0.002
....
+
0
+
·0,002
*!
+
.1';Ull" .�IMf_
+
.0.004
-0.006
-0,008
·0.01
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm'!)
09/03/98
Sc3.xls
Cardiff 5CD1 1 9/8197
1000
-
----- Shear stress
Mud concentration
800
.§.
�
c
.�
0
c
�
u
c
0
u
."
0.8
--
0.6
600
400
�
::;
200
004
/ .PVlm
0.2
I
Erosion
o
��--��--+-�-��-�-�--�-�� ·0.2
16:50
16:55
1 7:00
17:05
17:10
local time
o
Site:
Cardiff seasonal s urvey August 1 997
TiDate:
me: 16:19/08/97
49
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
Measurements (kPa):
1.1.74 O'Brien
1.1.36
Average: 1.1.24
Site description:
gelatinous, medium hard
Data file:
Path:
scant hydrobla, worm holes
2mm, pitted In parts, worm holes
no hydrobla, rag worms 20-30/10cm dlam
mud no sand
hydrobla only In water, not at our site.
Hard surface
Shear vane:
Comments:
09/03/98
(from top 5mm)
Water content:
147 - of 3dry weight
Carbon Medi
nizetid50:
on):ty: 10.1340
byronsweight
52.1 0 kgm·
mi
c
weigghtht
Sand
Si
l
t
content:
: 25.at6HW)
3
Film: 91
Time: 16:46 Number:
Surface sample:
pale brown
±
(downl
aded fromenliSqui
rrel data mlogger)
..lsedimoentslhel
ntrmudlcardi
cauglcaug007.101
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between '"CA & 'tB
'A =
0.35
Nm-2
Nm-2
'B =
0.38
Average =
0.37
Nm-2
5cd1.xls
0.01
0.008
--
Shear stress
-- Erosion rate
0.006
0.8
,,v\V/""'1'
0.004
�
"
E
'"
c
.2
�
£
0
-0.002
-0.004
. �..w'-" ,
\vcJ,/,F!
J\M�.f
..
,
\
�
�
'J)I
\
TA =
ta
�e.
�
�
0.002
Co
�
0.6
0.4
�
:;;
"
�
=
0.35 Nm.2
�
0.38 Nm"
'0
0.2
-0.006
.�
0.
a.
«
0
-0.008
-om
1 6:50
Cardiff seasonat su rvey August
Site:
Date:
16:19/08/97
49
Operator:
H.J.Mitchener
Time:
1997
-0.2
17:10
1 7:05
1 7:00
Local time
16:55
Photographs:
Time: 16:46
Film:
Number:
91
DAT E : I q ,\U&UST 1 (1(j '�1_
T H'IE :
1 6 : 4- <>
SITE : 5 ( 0 I
( t\4H.q:"r. j.'t- p :..! � ro.'I(
I N T R (1 l) U
09/03/98
5cdl .xls
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+
+
600
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c
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8
400
b
c
•
u
c
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=
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)
+
+
III,..M.o> ""
200
+
o
0.1
0.2
0.3
0.4
0.5
0.7
0.6
0.8
0.9
Applied shear &1ress {Nm'�
1 0000 ,-------,
1000
�_....III
+
10
0
0.1
0.2
0.3
0.'
0.5
0.6
0.7
0.8
0.9
0.7
0.8
0.9
0.01
0.008
�
l•
0.004
".
0.002
1!
0
c
�
0
.n
\+
0.006
+
+
+
+ +
+
+
.� ""I"��*�
...
-0.002
-0.004
-0,006
-0.008
-0.01
0
0.1
0.2
0.3
0.'
0.5
0.6
Applied shear stress (Nm·J)
09/03/98
5cd1.xls
1000
-------- ---- -
--Shear stress
800
.s
�
c
�
0.8
0.6
600
..
c
u
0
"
..
..
�
1ii
�
c
u
.!l
2:.
.r
0.4
400
�
"
..
..
'"
"
.�
0.
D«
:lE
.1/
200
0.2
Erosion
0
17:10
17:15
Cardiff seasonal survey August 1997
Site:
TiDate:
me: 17:12
J.Mitchener
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
medium hard, gelatinous
(downl
aded fromenliSqui
rrel datallf\caug\caug008.
ogger)
. \sedimoentslhel
ntrmudlcardi
101
(from top 5mm)
145 - of3dry weight
Water content:
1344 kgm-by weight
Carbon Medi
nizetd50:
ion):ty: 10.31
Sand
content:
weigghtht
ClSialyt content:
content: 50.9
48.1 · byby wei
Mud Temperature: 26.5 C
3
Film: 101
Time: 17:10 Number:
Surface sample:
± 'mm
worms -20-30/1Ocm d!am
mud, no sand
firm gelatinous mud · on dry patch :. no
33mm
vane
Observer:
Damon
1.1.96
Average: 1.1.97
Comments:
Path:
worms, v scant hydrobla � dry surface
hydrobla. Cooler but stilt hot
Shear vane:
Data file:
pale brown
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & tB
'fA =
'. =
Average =
09/03/98
0
1 7:30
1 7:25
17:20
Local time
0.34 Nm-2
0.37 Nm"-'
0.36 Nm
5cd2.xls
TiSiDate:
mte:e: 17:12
Operator: 19108/97
H.J.Mitchener
1997
Photographs:
Time: 17: 1 0
Film: 101
Number:
1 '1 IIV{� L!�T 1 1<1 7, " : /0
S C D J_
( H' (� j r ,· I�/;- r,- , � 1<:.,:/
f N r l< r'1 u u
09103/98
5cd2.xls
Cardiff SCD2 19/6/97
1000
.. <;:
+
...
eg;
s
c
.2
�
8
c
0
u
�
1
!I'
800
+
+
}
600
,
"
•
200
+
0
�:.
+
400
0
0.1
0.2
..
.. ....� �
0.3
0.4
0.5
0.•
0.7
0.8
0.•
0.7
0.8
0.•
0.7
0.8
0.9
Applied shear stress (Nm-I)
10000
1000
+
100
10
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm-')
0.Q1
0,008
0.006
��
!E
�
c
�
'\I'
0.004
+
0.002
.,.
0
·0.002
...
*'*.
-0.004
�¥-.,Jt,
+
·0.006
-0.008
-0.01
0
0.1
0.2
0.3
0.4
0.5
0.•
Applied shear stress (NmOz)
09/03/98
Scd2.xls
SedErode Data Plots
Cardiff September 1997
Z
HR Walling/ord
TR 51 0711)4198
Cardiff 6A 1 1 8/9/97
1 200
1000
.s
'§;
0.6
------ Shear stress
J\MMJV�-tJ
�
�
0
�
u
�
0
U
"0
�
"
:;
600
�
LB =
400
�
0.4 �.s
""
�tV\fJ'I
Mf
l
;V\j\f'N\AJ\�/\IIN/lf.,A"yJ""J
800
<i)
�
<i)
�
"
"
<i)
"0
.�
0.2 i'i.
O.2SNm 2
0.
..:
Massive erosion at slart
200
O �� o
1 2:54
1 2:54
1 2:55
12:56
1 2 :56
1 2:57
12:58
12:59
1 3:00
12:59
time
Local
Cardiff seasonat survey September 1997
Site:
54
TiDate:
me: 12:18/09/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
Measurements (kPa):
0.0.67 O'Brien
0.4
0.8
Average: 0.6
Neph. 150 model used
Site description:
Very soft
Data file:
Path:
Water & Hydrobia
%
%
+/- 1 mm (flat as fluid deposit)
Hydrobia -25-30/10cm diameter
Mud I Hydrobia
Very soft surface
1 .Scm fluid mud from last spring tide
Shear vane:
(from top 5mm)
Water content:
kgm'by weight
Carbon (lMedi
nizetd50:
ion):ty: 10.1174
8
9
Sand
content:
weigghtht
54,46 byby wei
ClSiaylt content:
content: 43.
Mud Temperature: 22
: 24.at9HW)
7
Film: 2
Time: 12:10 Number:
Surface sample:
Pale brown
Very sunny
(downl
aded fromenliSqui
rrel data mlogger)
..lsedimoentslhel
ntrmudlcardi
csep001.101
%
%
%
·c
Eroding Water:
Photographs:
0.7
Comments:
11/03/98
Critical erosion shear stress between 'tA & ta
0.00
Nm'2
'A =
Nm'2
'. =
0.25
Average =
0.13
Nm-2
6al.xls
Cardiff 6A 1 1 8/9/97
:I
0 025
�
Shear Slres
.--- Erosion rate
0.02
� o.015
,
E
�
� o.01
c
.2
�
rNv�\
/
/"'vVV�/\J..Jv"V'NvVIN�V'JV\0;1N
J/IfJ
'6
e
w 0.005
o
0.6
=
0.25 Nm·2
Erosion al slart
2 54
1 2:54
"",/
12:55
12:56
1 2:56
12:57
12:5B
12:59
0.2
1 3 00
12:59
o
-0.005
Local time
Site:
Cardiff seasonal survey September 1997
Photographs:
Time:
Date:
Operator:
1 2:54
Time:
H.B/09/97
J.Milchener
0
12:10
Film:
Number:
2
1
6�I
C \RDI
,
FF I� UDFL ATs
I N 1Rl'wD
11/03/98
6al .xls
Cardiff 6A1 1819197
1200
�
1 000
�
.s
!
800
++
c
!i
,
c
0
u
'0
,.
600
200
0
+
+
+
+
+
400
t-t�
+
0
0.05
0.1
0.15
0.2
0.25
0.3
0,35
0.4
0.45
1 0000
�
�,I'I III
1000
1
,
c
•
u
c
+
+
.s
I,IIII
--
+
100
8
'0
,.
10
0
0.05
0.1
0.15
0.2
0.25
Applted shear stress (Nm'l)
0.3
0.35
0.4
0.45
0.3
0.35
0.4
0.
0.025
+
0,02
-;
)
•
11
]
0,015
+
+
0.01
c
0
+
0,005
0
·0.005
0.05
0.1
0.15
0.2
+
i<I>.1:.
+
0.25
Applied shear stress (Nm·l)
"
1000
800
§.
S
�
�
8
Il
"
�
0.1
-- Shear stress
concentration
--
Mud
0.'
600
400
200
o ��-+��+-� O
13:13
Site:
13:14
13:16
13:17
13:19
Local time
TiDate:
me:
13:14
18/09/97
Mitchener
Operator: H.J.
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
Measurements (kPa):
0.0.79 O'Srien
0.1.09
Average: 0.9
0.9
Site description:
Very soft
Data file:
Path:
Water & Hydrobla
+/- 1mm (lIat as fluid deposll)
Hydrobla -25·30/1Ocm diameter
Mud I Hydrobla
Very soft surface
1 .Scm fluid mud from last spring tide
Shear vane:
Comments:
09/03/98
Approx. 1m from 6A1
13:22
1 3:23
(downl
aded fromenliSqui
rrel data llal\l!
..Isedimoentslhel
ntrmudlcardi
(from top 348
Smm) Water content:
610
Carbon Medi
(lossSulaonn ksiigdensi
nizetdSO:
ion):ty: 10.1174
1.
S
Sand
content: 43.1.3S
Si
l
t
content:
Clay content: SS.2
Mud Temperature: 23
: 24.at9HW)
7
Film: 1
Time: 13:09 Number: 3
Surface sample:
Pale brown
Very sunny
13:20
Eroding Water:
Photographs:
Critical erosion shear stress between "tA &
Nm-2
0.00
'A =
Nm-2
0.25
"tB =
Average =
0.13
Nm-2
6a2.xls
0.008
-- Shear stress
0.007
-- Erosion
rale
0.8
0.006
"
00
"
E
0>
0.005
0.6
6
0.004
c
.0
0.003
�
I/)
00
�
1;;
"
ill
0.4
�
�
I
0.002
0.001
J!
<:
00
Ca.
«
0.2
0
13 13
1 3 23
o
-0.001
local time
Site:
Cardiff seasonal survey September
TiDate:
me:
1 3: 1 4
1 8/09/97
09/03/98
1997
Photographs:
Time:
1 3:09
Number: 1
Film:
3
6a2.xls
1000
900
g
c
600
"
500
�
�
c
•
u
c
0
u
u
•
"
�*
600
700
!iJ
+
++f ++
+
400
300
200
100
0
+r J
0
0.1
0.2
+
+t �'"
+ +!it
i+i
..
0.3
0.4
0.5
0.6
0.3
0.4
0.5
0.6
Applied shear stress (Nm"l)
10000
1000
+
10
o
0.008
0.007
0.1
0.2
�
t
-----
++
+ +
0.006
,
,
" 0.005
'S
�
�
�
oll
0.004
0.003
++
0,002
0.00 1
0.1
0.2
+
0.3
Applied shear stress (Nm,2)
+
0.4
0.5
0.6
1 000
800
S
f§;
C
.2
1;;
�
;:
�
"
0
c
"
"
::>
::;;
------- -�--
0.8
- -.--�.----------
-- Shear stress
,
600
�
MNI\J\./W'
M
,v,\,i,i
Wo jW
-j
0.6
..
!'"
'"
�
0.4
t,)
�
ro
�
.c
'"
"
400
18
.�
C.
=O.25Nm-2
c.
«
0.2
200
Erosion
o
��4-��4-�� 0
1 3:33
13:35
1 3:36
13:37
1 3:39
1 3:40
13:42
1 3:43
1 3:45
1 3:46
1 3:48
Local time
Site:
TiDate:
me: 13:18/09/97
35
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Damon
Observer:
1.11.11.1
1.1
Average:
Site description:
1997
Firmer than 6A2
Data file:
Path:
Water & Hydrobia
Mud I Hydrobia
Very soft surface
1 .5cm fluid mud from lasl spring tide
Comments:
Approx. 2mm from 6Al
%
%
+/- 1 mm (flat as fluid deposit)
Hydrobla -25·30/10cm Diameter
Shear vane:
(from top 303
Water content:
3
Bul
k
densi
t
y:
1194
kgm·
Carbon (lMedi
weigghtht
Sand
content:
1.93 byby wei
47.
Si
l
t
content:
Mud Temperature: 24 'C
: 24.at9HW)
7
Film: 41
Time: 13:27 Number:
Surface sample:
Pale brown
Very sunny
(downl
aded fromenliSqui
rrel data mlogger)
. lsedimoentslhel
ntrmudlcardi
csep003.101
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'fa
Nm·2
<A =
Nm"2
'fa =
Average =
Nm·2
0.00
0.25
0.13
11/03/98
6a3.xls
0.004
--
0.003
Shear stress
Erosion rate
0.8
0.4 "C
13:3
.J1i�jlJJ\AfV'''/OJ
1 3:36
I}.. , 13:39
1 3 :37,IJ}
1'8 -
-0.001
_
0 25
'
Nm
·2
1 3:40
1 3:46
0.2
o
-0.002
local
Site:
TiDate:
me: 13:18109197
35
1 997
1 3 48
.�
Q.
Co
«
time
Photographs:
Time:
Film:
3 27 Number:
1 :
1
4
D 43
(.r.1<;\JIFF IWl.w�Ar.s
I N IIU'tu).)
09103198
6a3.xls
1000
600
1 .-
' "",,-_...
,,,
"",
M
fl ·
+0.2
�
1000
.5.
c
�
E
'C
•
u
c
0
u
�
=
"
100
10
o
0.1
0.5
0.6
07
-1-
�il
rglfi
;-.. ��
0.3
0.4
0.1
.200 l..._---....-�
----;;;
10000
...----
----
+
�WIft.
1
+
+
0.7
0.3
0.6
0.4 ��
0.2 ��
Applied shear stress (NmOz)
0.5
_
_
0,004
0.003
:;,; 0.002
I 0.001
;
/
_
_
++
++
+
+
:b;;.
+
+
�
�
�
�
�
��
�
�
°r�0.1 0.2 + 0.+3 0.4 0.5 0.6
.0.001
_
.,t
.£ 1
+
..{}.002
l
1. jjj: t. '. '''''''
H.'1t.
....-<t�
:+
...···' -
07
1000
,-_._,
--
0.6
Shear stress
Mud concentration
800
.§.
�
c
�
c
�
u
c
0
u
"
600
400
�
::E
Iv'
Erosit on
"'-JA1I\J\U"A/vv\V'WvJNv.fv,.Iv\f\J"\
..
l�f�'",A�)
I
..
A/'AM··�j\V;\�
\\ B
=0.27Nm '
200
o �-�--" '---�--1--�---+----��
14:23
14:25
Site:
24
TiDate:
me: 14:18/09/97
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
O'Brien
0.0.1.079
Average: 0.1.09
Site description:
1 4:27
time
Local
1997
Soft new deposit
Pale brown
Hydrobia, surface waler in patches
+/- 1mm, hydrobla snails
Data file:
Path:
aded fromenliSqui
rrel dataflllcsep004.
ogger) 101
..(downl
lsedimoentslhel
ntrmudlcardi
(from top 5mm)
256 of-3dry weight
Water content:
1223
Bul
k
densi
t
y:
byronsweight
Carbon Medi
ion): 11.2.1423 kgm
mi
c
gghtht
0.38 byby wei
Sand
content:
wei
50.
Si
l
t
content:
Mud Temperalure: 23 ·C
(localSalcolinitly:ected24.at9HW)
7
Film: 51
Time: 14:15 Number:
Surface sample:
Hydrobla -1 5·20!10cm, 1 worm'10cm diameter
Mud, no sand
Underconsolidaled
Shear vane:
Comments:
Not as soft as site A
09/03/98
0
14:31
1 4:29
w
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'ta
Nm·2
0.00
<A =
Nm"2
0.27
ta =
Average =
0.14
Nm"2
6e1 .xls
0.6
0.016
0.014
0.012
�
"
0.01
C. O.OOB
E
en
�
c
0
0.006
1-
- Shear stress
Erosion
rale
w 0.004
'Ta
=
0.4
0
14:25
A.
.-
g
�
�
�
"
�
�
.c
0 27 Nm 2
0.2
Erosion at start
0.002
423
�ft'
""VV'W'NIN"'/J�""htw\;lkJ�
/'
.�
e
I
�
'C
.�
Q.
c.
"
.Jv-v,.
:
1 4 27
14:29
143
o
-0.002
Local time
Site:
TiDate:
me:
1 4:24
1 8/09/97
1 1 /03/98
1 997
Photographs:
Time:
1 4: 1 5
Film:
Number:
5
6cl.xls
Cardiff SCl 1 8/9/97
1000
gc
I•cu
0u
�
+'Ii
�
+
�
800
' +"\1-
+ +
600
400
=
�
"
2{)0
0
0
0.05
0.1
0.15
0.25
0.2
0.3
Applied shear stress (Nm'z)
0.35
0.4
0.45
0.5
0.4
0.45
0.5
0.4
0.45
05
10000
gc
�
1000
u
100
Iuc0
+�
.... ....
++lH+
=
�
"
10
0
0,05
0.1
0.15
0.2
0.25
0.014
c
0.3
0.35
+
0,012
.�
e
w
0.35
+
0,016
i1l0
0.3
0.01
0.008
0.008
+
+
+
0.004
0.002
+
0
0.05
-0.002
0.1
0.15
0.2
Applied
"\.......""-tl.25
Jit:c�
shear stress (Nm'l)
-- - ----- ---- --
1000
800
.§.
f§;
c
0
-
-
-
�
---
---
0.8
;/",vv\lIMJ
/o.�.,,"-
j"''''I\\" .vll
600
JVli
1:
"
::>
:;
-------
------ Shear stress
.�
�
u
c
0
u
--
--
0.6
2S
t\Je.I'/,'WL/\AlvIM\
t on
Erosi
.
"
Site:
1 4:46
1 4:44
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Very soft surface deposit
Pale brown
Hydrobia (snails)
Comments:
09/03/98
ii
0«
=O.26Nm-2
+/. 'mm
14:48
local time
14:50
Data file:
Path:
Mud, hydrobia
0
14:54
14:52
aded fromen\iSqui
rrel data flf\csep005.
ogger) IOl
..(down
\sedimloents\hel
ntrmudlcardi
5mm)- of dry weight
Water content: top 243
3
Bul
k
densi
t
y:
1232
kgm·
by
Carbon (lMedi
ion): 10.1.8788 micronsweight
Sand
weigghtht
Si
l
t
content:
7
Film: 71
Time: 14:34 Number:
Surface sample:
Hydrobia -10-1S/10cm, 2 worms/1 0cm diameter
Disturbed soft surface on introduction of water
33mm
vane
Observer:
Damon
0.1.09
Average: 0.0.99
Shear vane:
1"s
0.2
43
TiDate:
me: 14:18109/97
Site description:
"
.�
!
0
14:42
lii
�
.<:
0
;; \
200
�
0
0
0.4
400
.s
..
(from
%
%
%
%
%
·c
Eroding Water:
Photographs:
Critical erosion shear stress between 'lA & 're
Nm·'
<A=
0.00
Nm,2
0.26
1'6 =
Average =
0.13
Nm·'
6c2.xls
-
0.0035
0.003
--
--
Shear stress
Erosion rale
0.0025
"
�
,
E
�
0.0015
0
0
.�
E
w
!;
IVvVlNJ"'\V
0.002
'"
Co
IA..!'}J!'lJWVMI .l1J
J\J\NN
Erosion al slart
0.001
0.0005
0
14 42
0.8
1 4 :44
�l"�A...A
rvV'NV"J'J'I..Ta ::
0.6
�
�
0.4
0.26 Nm-2
0.2
14:46
14:48
1 4:50
14:52
·0.0005
§
�
..
�
�
m
�
.0
�
"
.�
C.
Co
<>:
1 4 54
0
Local time
Site:
Cardiff seasonal su rvey September
TiDalmee:: 14:18/09/97
43
1997
:) ;)lfrr
1 1,. J1t
b o..
11/03/98
Film: 7
14:34 Number:
Photographs:
Time:
,q�-.
6c2.xls
Cardiff 6C2 1819197
1000 ,.-800
•
600
0
u
�
0
400
,g
�
11
8
•
"
+l1!
+
0.5
0.3
0.1
o��
0.2 �
0.4
200
Applied 6hear stress (Nm"1
.•
�
0
0.7
10000
+
1000
lOO
10
o
0.1
0,0035 r-----0.003
0.0025
�
0.002
'E
l.
0,0015
0,001
�
S
�
•
2
0.2
++
+
0.3
0.4
+
0.5
+
.•
0
0.7
1000
BOO
.5
�
"
�
0
"
u
"
0
U
."
"
::;;
- - - --- - -
O.B
-- Shear stress
--
600
400
200
Mud
Ar
i\I
!lV.�V.'
IJV\!I
concentration
"'"
IN
0.6
\ w....r·•
llifl"�.JJ
Jj
��
'8=0.
24
�
If"'/W
0.4 �
0
0
�
�
"
.r:
0
."
!!
.
Q.
Q.
0.2
Slightterosion
0
1 5:05
§�
1 5:10
..
200
15:15
15:
local time
Site:
TiDate:
me: 15:18/09/97
07
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm vane
Observer:
Damon
Measurements (kPa):
1.11.2 O'Brien
1.1.11.12
Average: 1.1
Site description:
1997
Sofl. Drier than 6C2
Data file:
Path:
(downl
aded fromenliSqui
rrel data flflcsep006.
ogger) 101
..\sedimoentslhel
ntrmudlcardi
5mm) (from top 240
Water content:
of3dry weight
y:
t
densi
k
kgmBul
1234
Carbon Medi
Sand
ghtht
content:
t
l
Si
wei
g
Mud Temperature: 24
: 24.at 9HW)
7
Film:
Time: 15:00 Number: 101
Surface sample:
Pale brown
Scant water, hydrobla
+/- 2mm, hydrobla snails
%
%
Hydrobla -20/1Ocm. 3 worms/1Ocm diameter
Mud, hydrobla
Short rain shower, then windy and sunny
Shear vane:
Comments:
Surtacestress
layer erosion at first applied
shear
09/03/98
%
%
%
'c
Eroding Water:
Photographs:
Critical erosion shear stress between 'fA & 'tn
tA =
0.00 Nm-22
NmNm-2
'tB =
0.24
Average =
0.12
6c3.xls
-
0.0045
0.004
0.8
-- Shear stress
-- E osion rate
0.0035
0.6
0.003
��E
1;
i!S
0.0025
'"
C
�
'"
'"
�
0.002
:;;
0.4 '"
�
c
0
0.0015
e
0.001
.�
UJ
�
.c
'"
'C
.�
Q.
0-
0.0005
0
1 5 05
-0.0005
0.2
15:10
..
1520
15:15
0
·0.001
local time
Site:
TiDate:
me:
Operator:
1 5:07
Photographs:
Time:
1 5:00
Film:
Number:
1
10
1 8/09/97
H.J.Mitchener
1 1 /03/98
6c3.x18
Cardiff 6C3 18/9/97
1000 ,--800
600
g
400
200
'"
0.4
0.3
0.2
0.5
0.6
07
·200
Applied shear sIress (Nm'l)
10000
'"
g
.§
i
1000
+
100
u
c
0
u
�
=
"
10
0.4 ��
0.2
0.3�
0.1
0.6
0.7
0 .5
O ��
+
Applied shear stress (Nm.1)
00045 r-----0.004
0.0035
0.003
� 0,0025
0.002
E 0,0015
Wj 0.001
0,0005
0,1
.0.0005
.0.001
_
c
_
+�---
+
*
,,;.
J
+
+
",
+
+
,,
+
+
+
. 03
o[==��+�+ ��
��
I1
#
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0.4
0,5
0,6 '
,
++
U
.
"____________
+
.
t
'"
-n
�+
" '"
•
t
't; t;'ttW+
•
0.8
1000
----Shear stress
800
E.
�
i
c
§"
"
'C
"
600
400
:;;
200
��+-��-r��-+��-,��+-� o
15:49
1 5:44
15:59
1 6:04
15:54
1 5:34
15:39
Local time
o
Site:
Cardiff seasonal survey September 1 997
TiDate:
me: 18/09/97
15:39
Site description:
Shear vane:
Observer: (kPa):
Measurements
Average:
Comments:
11/03/98
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Medium 5011, much harder than C
Pale brown
Dry, few hydrobia & pore holes
+/' lmm, pore holes
Data fite:
Path:
aded fromenliSqui
rrel data flflocgger)
..(downl
lsedimoentslhel
ntrmudlcardi
sep007.IOl
(from top 5mm)
Water content:
Carbon (lMedi
nizetd50:
ion):ty: 1332
9.2.4822 mikgmcbyronsweight
Sand
gghtht
wei
Si
l
t
content:
: 24.at9HW)
7
Film: 151
Number: 17, 18. 19 after erosion
Surface sample:
Hydrobla -15/10cm, 30 worms/10cm diameter
Mud, scant sand
Dry & sunny
33mm
vane
Damon
O'Brien
1.4
1.4
1.1.12
1.1.34
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between tA & te
�A =
0.37
Nm'2
Nm'2
�e =
0.42
Average =
0.40
Nm,2
6cdl.xls
0.003
--
0.0025
i'- Erosion rale
--
0.002
Shear stress
I
0.8
�\JIJ\J\I(
tJ,<d."
l
.
V
J
1
/>.
,yW, N
r
v
I
('MMfA'
J
I
J
W
0.42 Nm-2
rvJ.V.\'/Ju. r
, 4,
� 0.0015
"
E
E
�
c
0
.�
0
�
W
0.001
0.0005
0
·0.0005
5 37
15:
I
. ,.
M,h. " ",,.
. . .
15:40
t
.",t'J\NV
. ,
15:41
15:43
r
TB =
4
TA
=
0.<7 1
5:44
Local
Site:
i
15:18/09197
39
Dale:
Op rat r: H.J.Mitehener
e
,/\
15:50 15:51
,-!-,
Erosion
·0.001
T me :
h.
M ,AA Mf5: V ';5 4r 15:48
n
1997
0.6
�1:�
�
�
ro
•
.<:
�
"C
�
0.4
.!!
Q.
Q.
1556.2
"
o
time
1
15:31 Number:
15
Number: 17, 18. 19 alter erosion
Photographs:
Time:
Time:
Film:
o
1'6 �Grr
/ s : I l/
6 e /o I
1<19-
C M�D I FF MUD Fl.A
Ts
! f\J IR r- 1 v O
11/03/98
6ed1.xls
Cardiff 6CDl 1 8/9197
.� ,-------,
800
+
-
+
o
0.'
0.9
0.2 0.3 0.4 0.5 0.6 0.7 0.8
Applied shear &tress (Nm-1)
.� .-------,
'"
g
-
+
'00
c
.2
i
+
��W4l'tr*-/
. _ � ..Inl' ••�
- --"'
--
c
8
-g
"
10
0
0.003
0.0025
0.002
0.0015
�! 0.001
i 0.0050
0
�
-0.0005
-0.001
·0.0015
-0.002
0.1
0.2 0.3 0.4 0.5
O.S
0.7 0.8
0
.•
+
t
+
+
+
+
+
c
�
0.' 0.2 0.3 0.4
+
+
Applied shear stress (Nm·t)
+
+t
+
+
-
1000
800
§.
!§;
:8
�c
c
�
u
c
0
u
-- Shear stress
Mud concentration
--
1
0.8
I
�
..
0.6
600
0
0
�
�
.c
..
0
0.4 ."
400
.!
"ii.
"
."
"-
::;
..:
0.2
200
��L-�---+--�--4---�--��---+- 0
1 6:24
1 6:27
16:18
16:21
16:15
16:12
Local time
o
Site:
TiDate:
me: 16:13
H.J.Mitchener
Operator: 18/09/97
Site description:
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y:
other features:
Medium
Pale brown
Pore holes, hydrooia
+/. 2mm. pore holes
Comments:
10/03/98
Path:
(from top 5mm)
138 - of-3dry weight
Water content:
8.2.7884 kgm
byronsweight
Carbon (lMedi
nizetd50:
ion):ty: 1356
mi
c
Sand
content: 51.7
3.9 byby wei
gghtht
Si
l
t
content:
wei
Mud Temperature: 23.5 ·C
: 24.at9HW)
7
Film: 161
Number: 22,23 after erosion
Surface sample:
%
%
Hydrobla -20-25, 2 worms, 10 pore holes/1Ocm 0
Mud, scant sand
01)1, sunny & windy
33mm
vane
Obsel
V
er:
Damon
Measurements (kPa):
1.1.70 O'Brien
1.1.77
Average: 1.1.65
Shear vane:
(downl
aded fromenliSqui
rrel dataflflcsep008.
ogger) 101
..lsedimoentslhel
ntrmudlcardi
Data file:
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fa & tb
<a =
0.28
't'b =
0.33
Average =
0.31
Nm·2
6cd2.xls
0.0016
0.0014
0.0012
�0
---
Shear
stress
Erosion
rate
0.8
0.001
E 0.0008
0.6
0>
:.
.'l
�
"
0
.�
e
w
0.0006
Site:
0.4
11/03/98
'"
'"
."
.�
a.
a.
'"
16:15
\
16:18
16:2
0.2
1 6 27
16:24
Erosion
TiDale:
me: 16:13
Operator: H.18109/97
J.Milchener
e
1;;
ro
�
0.0002
-0.0004
'"
'"
�
0.0004
0
1 6 12
-0.0002
�!S
Local
o
time
Film: 16
16:05 Number:
Number: 22,23
Photographs:
TiTimme:e:
1
6cd2.xls
-----'----
1000
800
c
�
Jlc
•
u
c
8
�
=
+
*
600
400
"
200
0.7
0.8
0.7
0.8
1000
S
�
100
c
.g
1l
iJc
8
1l
"
'0
+
, L
0.1
o
0.001 6
0.001 4
0.0012
r
.'�
"
C
�
g
'8
oll
0.001
0.0008
0.0006
0.0004
0.0002
0.2
0.'
0.4
0.5
Applied shear sIress (Nmol )
0.6
1
�
------
'+
+
+
+
+
+
-- ------- , - -
1 000
.�
--
800
.§.
5
�
Shear
stress
Mud concentration
0.8
1
0.6 III
�
600
�
E
Il
8
c
."
"
�
'ii
0.4 ."
.�
Q.
c.
«
400
::;
0.2
200
o
��-�-�-+-�-��-4--��-�-+-�-�-��-�-�
1 6:36
16:44
16:40
Site:
16:37
TiDate:
me:
Operator: 18/09/97
H.J.Mitchener
local
1997
16:48
0
16:56
16:52
time
Data file:
Path:
(down
Squirrel data flflcsep009.
ogger) IOl
. \sedimloents\hel
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Damon
O'Brien
ObseI
V
er:
1.3
Measurements (kPa):
1.1.32
1.1.25
Average:
1.3
Surface sample:
Comments:
Critical erosion shear stress between 'fA & 'ta
Nm'2
0.25
tA =
Nm'2
tB =
0.28
Site description:
Medium
Pale brown
Hydrobia, worm tracks & pore holes
+/. 2mm, pore holes
Hydrobia -20, 3 worms/10cm diameter
Mud, hydrob!a
Feels softer than 6CD2
Shear vane:
(from top 5mm)
137 - of3dry weight
Water content:
byronsweight
8.2.4605 kgm'
Carbon Medi
(lossBulaonnksiigdensi
nizetd50:
ion):ty: 1358
mi
c
3.37 byby wei
Sand
content:
gghtht
Si
l
t
content:
49.
wei
: 24.at9HW)
7
Film: 211
Time: 16:31 Number:
%
%
%
%
Eroding Water:
Photographs:
Average =
10103/98
%
0.27
Nm'2
6cd3,xls
·0.001
Site:
o
local time
TiDate:
me: 18/09/97
16:37
'/ nr1E :
DATe";
Film: 21
16:31 Number:
Photographs:
Time:
h� :;lirr } q ' P
I 6: I I
S I TE : b C /O J
CARDI FF " H JD Fl. A T.s
J N IR (, I V D
10103/98
6cd3.xls
1 000
600
�
.s
i
c
8
600
400
�
:i!
200
1
1
3
�
:E
+
�...
100
+
10
o
0.2
0.1
0.3
0.4
0.7
0.6
0.5
�
Applied shear stress (Nm-')
0.8
J
0.9
_
0.003
_
_
0.0025
0.002
:r
�
+
+
+
0.0015
++
+
+
0.001
+
·0.0015
09
�"-
__�
.0.OO2 -
+
Applied shear stress (Nm"2)
SedErode Data Plots
Cardiff January 1998
:ofHR Wallingford
.::;
TR S1 011041!18
Cardiff 7A1 - 1 4/01198
1000
800
.§.
�
c
�
�
.2
u
'0
::>
0.8
--Shear stress
0.6
'"
�
�
0.4
"'
"'
600
�
ro
�
'"
"'
'0
400
.!!
'li.
0.
:;;
0.2
""
200
o ��-��-��-��-�-��-�-+-��
1 1 :20
1 1 :1 5
Cardiff winter survey January
Site:
58
TiDate:
me: 10:14101198
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Comments:
98
Medium soft � homogenous gritty
1 1 :30
Path:
(from top 215
5mm) - 7Aof1 dry weight
Water content:
-3
Bul
k
densi
t
y:
kgm
1255
10.
0
2
Carbon (lMedi
ion): 4.61 micbyronsweight
Sand
weigghtht
Si
l
t
content:
: at20HW)
Film: 21 7A1 before erosion
Time: 10:57 Number:
45 7A1
7A1 after
after
Surface sample:
scant water, some black debris
+/- 2mm Fladrian clay exposed in places
%
%
%
%
large flock of birds, at this site earlier in day
Eroding Water:
Photographs:
Critical erosion shear stress between tA & ta
Nm·2
tA =
0.13
Nm·2
to =
0.17
Average =
11103198
%
Birds prints t-2/1Ocm diam, no hydrobia,no worms
mud, very scanl fine sand
o
1 1 :35
aded fromenliSqui
..(downl
lsedimoentslhel
ntrmudlcardi
anlcjan001
Data file:
brown with green hue
33mmvane
Observer:
Damon
Measurements (kPa):
1.1.25 O'Brien
1.3
1.1.66
Average: 1.4
SedErode
overl
ying Fldepl
andrioyed
an clonay.soft mud
Shear vane:
1 1 :25
Local time
0.15
Nm·2
7a1.xls
Cardiff 7A1 1 4/01/98
0.0002
--
0.8
Shear stress
-- Erosion
rate
0.6
�U)E
0.0001
Erosion
�1:�
�
'"
�
�
0.4
�
�
�
�
$;
�
."
c
2
�
.
�
.�
Q.
0
c.
0.2
·0.0001
1 1 :15
o
1 1 :20
Site:
Cardiff winter survey January 98
Time:
1 0:58
Date: H.J.Mitchener
Operator:
1 4101 /98
1 1 /03/98
..:
1 1 :30
1 1 :25
Local time
Photographs:
Time:
10:57
1 1 :35
Film: 2
Number:
7A 1
before erosion
after
4
7Al after
5
7Al
7al.xls
1 ooo .-------------------��----��--------------------,
Cardiff 7 A1 - 14/01196
+f.+�:f!t +
800
+++ +
+
i 400
c
600
�
,
"
200
0.4
o
0.5
0.6
1000 r-------��+��--,
+
..... +
+
0.006 ,----,
+
0.005
+
0.004
++ +
+
+
0003
+
++
)
i
!
c
0.002
+
0.001
+
o
-0.001
o
0.8
Cardiff 7A2 -1 4/01198
1000
0.8
- -------
� ---.�
Shear slress
800
.s
�
600
c
E
"
.2
...
"
c
0
"
..,
"
:;
400
'tA =
200
0
11 :41
�
11 :46
r�
r
'fB =
0.22
0.26
�
0.6
�
III
..
0.4
Nm'2
Nm+2
0.2
Slight erosion
11:5 1
.!l
e
...
�
..
"
'"
..
..,
.!!
Q.
c«
12:001
11:56
Local time
Site:
TiDate:
me: 11:
37
14/01/98
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Obser
v
er:
Damon
8.8
5.2
Average: 6.7.17
Site description:
98
Medium soft, homogenous gritty
Data file:
Path:
water, black debris
birds prints.1 ·211Ocm. no worms Of snails
mud, scant sand + debris
cold, windy and sunny
Shear vane:
Comments:
SedErode
overl
ying Fldepl
andrioyed
an clonay.soft mud
11/03/98
(from top 5mm)
Water content:
220 - 7A2of3dry weight
Carbon (lMedi
ossBulaonnksiigdensi
nizetd50:
ion):ty: 1251
9.4.0389 kgm�
byronsweight
mi
c
Sand
content:
0.00 by weight
Si
l
t
content:
76.
Clay content: 24.0 · byby wei
weigghtht
Mud Temperature: 8.5 C
(localSalcolinity:lected at20HW)
Film: 31 before erosion
Time: 11:33 Number:
Surface sample:
brown, some black flecks, green hue
+/. 2mm. undulating
(downl
aded fromenliSqui
rrel data flfo\Cjgger)
..lsedimoentslhel
ntrrnud\cardi
anlcjan002
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'fa & 'tb
Nm·'
0.22
<. =
Nm-2
tb =
0.26
Average =
0.24
Nm"2
7a2.xls
0.0009 ,-. r-
-�
C�
a-�
rd�
i f�
f�
7A
��
2-�
1 4�
/O
�
1�
/9;8,-------_. , �
�
__
__
__
__
__
__
__
__
__
__
0.8
--- Shear stress
--- Erosion rate
�Vl
E
'"
�
�
0.0004
c
0
'iij
e
w
r
"'w-�
/,I
,,«/,,
r
..
;I\ /�
, �'�'�'
I�
'v·
0.6
..
i
0.4 �
�
�
�
�
�
.<:
�
'0
.�
'TB = 0.26 Nm'2
ii
Q.
'tA = 0.22 Nm'2
0.2
'"
L-��--��-�-� o
-0.0001
1 1 :41
1 1 :46
1 1 :51
1 1 :56
1 2:01
Local time
Site:
:37
TiDalmee:: 1114/01/98
Operalor:
Film: 31
11:33 Number:
Photographs:
Time:
H.J.Milchener
11/03/98
7a2.xls
1000
*+ '1+ ++ ++ +++
,...it .,a+ + ++
++0: ::
{
\
+ ��-ttY'++ fA,t
++
Cardiff 7A2 · 14/01/98
r------rr---,
BOO
�
1
s
c
....
4
++
+
+t"'
600
8 400
]
'"
200
:/:
*"
O ��
0.1
o
0.3
0.2
0.5
0.4
0.7
0.6
0.8
0.9
Applied shear stress (Nm-J)
1000
+t �+ :f+
@
,+iJ.t +",++ ++
+ Y+
++ �
++
r-----------------------------------��--------------------,
....++"l�
t
�.,j:
:
0.3
0.2
0.1
o
0.5
0.4
0.6
0.7
0.8
0.9
Applied shear stress (Nm-J)
+
0.003 ,------------,
0.0025
+
0.002
��
!
'{/)
c
0.0015
0.001
++ +
+
0.0005
o
-0,0005
-0.001
o
0.1
+
0.2
0.3
0.4
0.5
0.6
Applied shear stress (Nm't)
0.7
0.8
0.9
1 000
800
.s
'§;
"
0
�
"
�
u
"
0
u
"
"
:;;
Cardiff 7A3 - 1 4/01198
------------ --------
0,5
"--- Shear stress
0.4
.§
e
.-
600
0,3
0
0
�
�
400
0,2
200
0,1
..
�
.t:
0
'C
,�
C.
Cot
o �--�-��--�---�--� o
12:11
Site:
12:16
time
TiDate:
me:
12:14/01/98
02
Operator: H,J,Mitchener
98
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
33mm
vane
Observer:
Damon
7,9,56 O'Brien
Measurements (kPa):
7,8,8,520
Average: 8,2
Site description:
Medium soft, homogenous gritty
brown, black flecks, green hue
debris, water
+/- 2mm. undulating
birds prints 1·2/1 Ocm
mud, scant sand
COld, windy and sunny
Shear vane:
Comments:
SedErode
overl
ying Flwas
andrideplan oclyed
ay, on soft mud
11/03/98
1 2:21
local
Data file:
Path:
(downlmoentsli
aded nIrom
Squirrellflcjdataanlcjan003
logger)
"lsedi
trmudlcardi
(from top 223
5mm) - 7A3of dry weight
Water content:
3
Bul
k
densi
t
y:
1248
kgmCarbon (JMedi
ion): 10,4,6055 micbyronsweight
weigghtht
0 byby wei
Sand
content:
Si
l
t
content:
79
Clay content: 21 by weight
(localSalicolnity:lected at20HW)
Time:
Number:
Surface sample:
%
%
%
%
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 'CB
Nm·2
TA =
0.14
0.25
Nm·2
'tB =
Average =
0.20
Nm"2
7a3,xls
Cardiff 7A3
0.001
.- Shear stress
-- Erosion rate
,
��
- 1 4/01198
--
0.5
0.4
0.0005
0.3
C>
�
�
..§
�
�
�
�
ro
�
.c
. .".�
�
c
0
·in
02
�
0
Q.
a.
�
'CA = 0.14 Nm'2
)
�
0.1
�---�----�---�--� o
-0.0005
1 2: 1 1
12:16
Local time
Site:
Cardiff winter su rvey January 98
Photographs:
Time:
12:02
Time:
Date:
1 4/01/98
Operator:
H.J.Mitchener
1 0/03/98
1 2:21
Film:
1
Number:
7
733.xls
Cardiff 7A3 - 14101196
1000
600
�
Se
!
600
e
8
e
0
u
�
=
,.
400
200
0
0.1
0
0.2
0.5
0.4
0.3
0.6
Applied shear &tress (Nm';
0.7
0.6
0.•
1000 ,-------,
�
S-
+ ...
+
.: +$
+ +
"'04...",.. ril�
A
e
j
e
8
100
e
0
u
�
=
,.
+
10
0.1
0
0.0006
1!
.2
0
e
Jl
•
..
·0.0002
0.6
0.•
...
#"
<,-
...
+
;
+
-0.0004
-0.0006
0.7
++
�
0.0004
0.0002
0.6
Applied shear stress (Nm"f)
++ � + +
+
* ++\+ +-+ ", +
+ ++
++ + +
+ +;(..++ \{t\.t;.-t.t++ +
+J
��
+
+
0.0006
Eo
0.5
0.4
0.3
++
0.001
�
'E
0.2
0
0.1
0.2
0.3
0.4
0.5
0.6
Applied shear stress {Nm,l}
0.7
0.6
0.•
Cardiff 7BC1 - 1 4/01198
1000
-- Shear stress
800
£.
�
c
E"
.2
1ii
"
c
0
"
'0
�
::;
v-.--� 0.8
�
V
0.6 �
or
r
� 0.28 Nm-2
vv!'",..,r;
600
400
�
"
"
0.4
'0
�
Il.
Il.
..
'TB =
..
200
:;;
"
"
.<:
0.2
..
Erosion
0
12:58
13:03
Local13:08
13:13
0
13:18
time
Site:
52
TiDate:
me: 12:14/01/98
Site description:
texture:
colour:
coveri
ng:
topography:
biologicomposi
other features:
Fland"an clay· hard
scant mud, some sand/shell deposits
+/. 2mm pitted
pHted 5·10/10 cm
clay scant sand
less windy, cold, sunny
Comments:
11/03/98
(from top 5mm)
Water content:
100 - %7BClof3dry weight
6.69 kgm'
Carbon Medi
% by weight
nizetd50:
ion):ty: 1448
4.
9
5
mi
cbyronsweight
0.
0
Sand
content:
%
ghtht
75.00 %% byby wei
ClSialyt content:
content: 25.
wei
g
(localSalcolinitly:ected at20HW)
Time: 12:50 Number:
Surface sample:
blue grey- scant brown soft mud on top
33mm
vane
Obser
v
er:
Damon
O'Brien
16.6
16.3
12.9
15.8
Average: 15.5
FlaandndriC.an Sticlaly erodes
exposedslobetween
sites
BSed
wl
y
wi
t
h
Erode
Shear vane:
aded fromen\iSqui
rrel data flto\gger)
Path: file: ..(downl
lsedimoentslhel
ntnnudlcardi
cjan\cjan004
Data
Eroding Water:
Photographs:
Critical erosion shear stress between 'CA & 1'8
Nm·2
0.18
fA =
Nm·2
0.28
'tB =
Average =
0.23
Nm·2
7bc1.xls
Cardiff 7BC1 - 1 4/01198
0.0004
--
--
Shear stress
Erosion rale
0.8
"
�
•
E
'"
0.6
0.0002
�
�
1;
is
�
�
�
"
�
�
.c
c
2
�
0
"
0.4
.
"r8 = 0.28 Nm-2
w
D
�
u
.�
Q.
0
'"-
0.2
�
-0.0002 L-�
1 2:58
l�
__
�
�
�
__
�
� o
__
__
__
�
�
�
�
�
__
__
�
�
�
�
�
__
Simte:e:
TiDate:
Operator:
13:03
Cardi
ff winter survey January 98
12:
5
2
H.14/01198
J.Mitchener
11/03/98
1 3:08
Local time
13:13
13:18
TiPhotographs:
me: 12:50 Number:
7bc1.xls
i
c
'0
:il
600
�
200
;;
0.001
1� 0.0005
j
++
+
-0.0005
+
_0'001 0�
0.' 0.'
0.5 06. 0 �
0.2 0.3 0.4 �
0.1 �
o
Applied 5 h .., .t,ess (Nm-')
.
7
....
Cardiff 7BC2
1000
800
�
El:
I
Il
I:
8
"C
�
:;;
-
. . . - -------- -- _.
1 4/01198
.
._---- -- -------_ . . _ . _ --
----- Shear stress
Mud concentration
--
I
jVJ/'
0.8
0.6
600
§
�
..
·----·�
en
en
�
-
m
�
.t::
en
0.4 "C
.�
C.
400
c.
..:
0.2
200
o �-�-�-�-�--+-�-�--�-�-+_-�-�-�-�-� o
13:50
13:55
1 3:45
1 3:40
local time
Sile:
13:14/01/98
34
TiDate:
me:
Site description:
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y:
other features:
very hard. homogenous
none
none visible
Flandrlan clay
less windy, cold, sunny
FlB aandndriC.an clStialyerodes
exposedslobetween
sites
wl
y
wi
t
h
SedErode
(down
aded fromenliSqui
rrel dataflfolgger)
..lsedimloentslhel
ntrmudlcardi
cjanlcjano05
(from top 5mm)
Water content:
86 - %7BC2
of-3dry weight
Bul
k
densi
t
y:
1497
kgm
Carbon Medi
ion): 6.5.0950 %micbyronsweight
Sand
content: 740 %% byby wei
weigghtht
Si
l
t
content:
Clay content: 26 ·% by weight
C
Mud Temperalure:
: at20HW)
Film:
Time: 13:33 Number: 91 before erosion
Surface sample:
pitted +/. 2mm. 5·10 cml1 0 diameter
33mm
vane
Obser
v
er:
Damon
O'Brien
Measurements (kPa):
16.1
19.5
14.2
20.
9
25.
0
Average: 19.1
11/03/98
Path:
blue. grey, flandrian clay
Shear vane:
Comments:
Data file:
8
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & 'fa
Nm·2
'A =
0.20
m2
'. =
0.29
Average =
0.24
Nm·2
N
-
7bc2.xls
Cardiff 7BC2 - 1 4/01/98
0.0005
-- Shear
--
stress
Erosion rate
0.8
0.0003
�
"
E
'"
�
�
0.6
0.0001
�
�
�
�
�
�
0
.;;
c
�
.s
e
..
,
0.4
=
·0.0001
=
-0.0003 L-_�
�
_
�
_
�
_
�
_
�
_
.�
D-
c.
"
0.29 Nm·'
0.2
0.20 Nm'2
�
�_
�
_
�_
_
�
_
�
_
_
�_
�
---'
0
1 3:55
_
_
13:45
1 3:40
"
�
"0
13:50
Local lime
TiSiDate:
mte:e: Cardiff winter survey January
Photographs:
Time:
98
1 3 :33
13:34
Film:
Number:
1
9
before erosion
1 4/01198
TIME : i J :33
S I TE :
r B/C 2
C Af'-- D IFF PE: rERSTo
\..
1 1/03/98
( N TR
M ub
7bc2.xls
'a
Se
I
8 400
1l
'"
200
0.9
0.0015 ---+
�
1
0001
0.0005
�
j
-{I.OOG5
+
��
,().001 �
0
0.1
0.2
0.3
0.4
0' 5
0.8
0.9
0.6 �
0.
�
7
Applied s hear stress (Nm'z)
1000
----
Cardiff 7BC3 - 1 4/01198
----
. ._ - -
-
-
-- Shear stress
.§.
�
"
0
800
0.8
600
0.6 1
�
C
"
"
"
0
"
"C
400
,I
"
:;
200
014:22
v
Erosion
r.f
�
VI
VI
'tB =
0.45
�
Nm-2
�
"
"
VI
.c
0.4
"C
�
i5.
.
Do
«
0.2
------...
14:27
14:370
14:32
Local time
Site:
TiDate:
me: 14:19
J.Mitchener
Operator: H.14101/98
texture:
colour:
coveri
ng:
topography:
biologiccomposi
ally actitvioitn:y:
other features:
33mm vane
Observer:
O'Brien
15.2
13.1
15.9
20,
1
15,
2
Average: 15,9
Site description:
very hard, homogenous
grey, blue, FlandrJan day
Data file:
Path:
aded fromenliSqui
rrel datamlocjgger)
..(down
lsedimloentslhel
ntrmudlcardi
anlcjano06
(from top 5mm)
Water content:
63 7BC3
of 3dry weight
kgm+
Bul
k
densi
t
y:
1602
Carbon (lMedi
ossaonn siigznield50:
ion): 4.6.3454 %micbyronsweight
Sand
content:
0.00 % byby wei
gghtht
wei
Si
l
t
content:
72.
Clay content: 28.0 % by weight
(localSalcolinilylected
: at20HW)
Time: 14:09 Number:
Surface sample:
-
%
some mud In places- planted on exposed clay
+/- 2mm
pitied, no worms or hydrobia
clay, scant sand
cold, no sun, not as windy
Shear vane:
Comments:
FlandriC.an clay exposed between sites
Band
11103/98
%
Eroding Water:
Photographs:
Critical erosion shear stress between 'tA & ts
'A =
0.37
Nm·2
'B =
0.45
Nm·2
Average =
0.41
Nm·2
7bc3.xls
Cardiff 7BC3
0.002
-- Shear
-
1 4/01198
stress
-- Erosion
rale
O.B
.r
0.6 g
�
�
0.4
�0
I/)
E
Cl
=- 0
�
"
.2
�
E
UJ
't"A
=
0.37
'"
�
"C
.�
C.
c
<
Nm-2
0.2
-0.00214:22
14:27
14:32
o
14:37
Local time
Site:
14:09 Number:
Photographs:
TiDate:
me: 14/01/98
14:19
Time:
r Jl1E
B/C 3
: J 11 (.;' /
S I TE :
7-
C Ai'-- J) " F
PE rERSTo
! N TR �\ LLb
10/03/98
7bc3.xls
Cardiff 7BC3
1000
'§;
800
c
600
g
1
u
c
0
u
- 1 4/01196
�+...�+$Ii
�
+"1$+ +#/ +
*' ..
+
t
""+++..
�*++
�
+
+
t
t
+ � �� tlt::� 'i+ ++
"
t+
+
+
400
�
=
"
++
<\c1t' +ff+
200
0
0
0.2
0.1
A.'
0.5
0.6
2
Applied shear stress (Nm· )
0.3
�
1000
+ p +.+
+
�+t++++
+ *tt""+ +..,..
+++ +++-t+ ++ +
t\++ t++
++�tt+
++++ + ++++
+ ++ + + + +
+
"I4H-
'§;
0.7
0.8
a.•
0.8
0.•
0.8
0 .•
'If
..
g
ii
c
.2
+
ii
u
c
0
+
u
�
=
"
'i-
of
....
.t
100
0
0.2
0.1
A.'
0.5
0.6
2
Applied shear stress (Nm· )
0.3
0.7
0.D1
+
0.008
0.006
�
'E
C
!f
D
]
0
0,004
+
0.002
0
-0.002
-0.004
+
....IIl.... W. �" II,..
+
+
c
*""+
+ �
(I·��t;-1f��'*'# +
+
·0,006
-O.OOB
-0.01
0
0.1
0.2
0.3
0.5
0.6
0.4
2
Applied shear stress (Nm' )
0.7

Seasonal erodibility measurements at Peterstone Wentlooge, Cardiff

Transcription

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