Poster

Modelling river discharge at sub-daily time-step:
Comparison of the performances of the conceptual SWAT model and
the process-oriented MARINE model
Laurie BOITHIAS a,*, Anneli LENICA b, Hélène ROUX b, Kévin LARNIER b, Sabine
a
a,*
SAUVAGE , José-Miguel SANCHEZ-PEREZ
Context and objectives
Due to global change, the frequency of intense rainfall events and consequent flash floods are expected to increase in the next decades across the
Mediterranean coastal basins. To date, few distributed models are able to simulate hydrological processes at basin-scale at a reasonable time scale to
describe these flash events with accurate details.
The MARINE model is one of them: it is a process-oriented fully distributed model operating dynamically at the rainfall event time-scale. Both
infiltration and saturation excess are represented along with subsurface, overland and channel flows. It does not describe ground-water processes
since the model's purpose is to simulate individual flood events during which ground-water processes are considered negligible.
The SWAT model is a conceptual semi-distributed model assuming several simplifications in equations that dynamically simulates above- and belowground processes. It has been recently upgraded to sub-daily time-step calculations.
The objective of this study was to assess and compare the performances of these two models when simulating the discharge at sub-daily time-step.
Study site
1380 km², shallow sandy soils
Typical flash flood prone coastal Mediterranean basin
Modelling approach
SWAT model
Slope
Critical zone
Soil
Land use
Toulouse
River
Hydrological Response Unit
Sub-basin
Basin
outlet
HRU
Sub-daily time-step simulation : Green & Ampt equation
Pula
Têt river
Catllar
Perpignan
MARINE model
Marquixanes
•
•
•
•
Regionalization for flash floods
Physically interpretable parameters to facilitate estimation
Adaptive time-step (typical range: 1-5 min.)
Mesh resolution < rainfall resolution (typical range: 200-500 m.)
Precipitation
Initial soil water content
Network reach width / depth
France
Slope, downhill direction
Representing flow components
with short response time
predominant in Mediterranean
flash flood genesis
Soil
outlet
Land use
Spain
Infiltration
Exfiltration
Cell
Overland cell
Drainage network cell
200
Discharge (m3/s)
Têt discharge at Marquixanes
150
Calibration
100
Validation
Cell model speicifcs
Selection of the flood events :
Soil
50
Input data
0
J-09 A-09 J-09 O-09 J-10 A-10 J-10 O-10 J-11 A-11 J-11 O-11 J-12 A-12 J-12 O-12 J-13 A-13 J-13 O-13 J-14 A-14 J-14 O-14
Surface runoff
(saturation
dynamics)
Subsurface flow
DEM : SRTM 90 m
Land use : Corine Land Cover
Soil : FAO classes, INRA soil properties
Sub-daily rainfall : Measured from rain
gauges (OBS) / SAFRAN model (SAF)
First results
350
300
250
200
150
100
50
0
10/7
10/12
10/17
10/22
180
350
160
300
Sub-daily discharge (m3/s)
SIM SWAT OBS
SIM SWAT SAF
SIM MARINE OBS
SIM MARINE SAF
Observed discharge
400
Sub-daily discharge (m3/s)
Sub-daily discharge (m3/s)
450
140
120
100
10/27
Flood of October 2010
80
60
40
20
0
3/11
3/16
3/21
Flood of March 2011
Nash efficiencies :
250
Oct 2010
200
MARINE
Rain gauges
0.90
SAFRAN
0.20
Mar 2011 Rain gauges
SAFRAN
Nov 2011 Rain gauges
SAFRAN
150
100
50
0
11/2
11/7
0.86
0.25
0.54
-0.63
SWAT
-1.64
0.42
0.39
0.12
-3.02
0.05
11/12
Flood of November 2011
Conclusions & perspectives
The MARINE model gives better results than SWAT, especially when using the rain gauge spatial distribution. The spatial distribution of the gauges
(whether measured or simulated) seems to have little effect on the quality of the SWAT simulations. They are however preliminary results. Once
improved, the suspended sediments and the soil water content simulated by SWAT will be used as MARINE inputs.
a University
of Toulouse; INPT, UPS; Laboratoire Ecologie Fonctionnelle et Environnement (EcoLab), Avenue de l’Agrobiopole, 31326
Castanet Tolosan Cedex, France. CNRS, EcoLab, 31326 Castanet Tolosan Cedex, France
b Université de Toulouse; INPT, UPS; Institut de Mécanique des Fluides de Toulouse (IMFT), Allée Camille Soula, 31400 Toulouse,
France. CNRS, IMFT, 31400 Toulouse, France
* Corresponding authors: [email protected] and [email protected]