L. BOITHIAS, D. d A. BRESSIANI, S. SAUVAGE, K.C. ABBASPOUR, R. SRINIVASAN, W. LUDWIG, E. RICHARD, J.-M. SANCHEZ-PEREZ

Application of the SWAT model to Mediterranean flash floods Does the use of fine climate stations grid and sub-basins delineation improve the modelling of river discharge and sediments fluxes at hourly time-step? L. BOITHIAS, D. d A. BRESSIANI, S. SAUVAGE, K.C. ABBASPOUR, R. SRINIVASAN, W. LUDWIG, E. RICHARD, J.-M. SANCHEZ-PEREZ 2015 SWAT Conference, Pula, June 24-26 1

Context Global change is expected to increase the frequency of intense rainfall events and consequent flash floods across the Mediterranean coastal basins in the next decades. Some complex physically-based distributed models are able to simulate hydrological processes at the flood time-scale but they do not capture belowground processes. The SWAT model has recently been upgraded to sub-daily time-step calculations. However, its sub-daily module has only been tested in small catchments (~1 km²). 3

Objectives The objectives of this study were : (1) to assess the ability of the SWAT model to simulate discharge at hourly time-step in a ~1400 km² river basin (2) to assess the possible gain of model s performance when using fine grids of climate stations and sub-basins representation. 4

Green&Ampt infiltration equation SOL_K CN2 SOL_CLAY SOL_SAND SOLB_BD SOL_AWC SOLB_BD 5

Toulouse Data for model set up Pula DEM: SRTM 90m Land use: Corine Land Cover -> mostly range land and forests Soil: FAO + associated INRA soil properties -> Mostly shallow (1.4m) sandy soils 6

Data for model set up Daily discharge out of 2 dams - Vinça (irrigation): 24 hm 3, data from 2000 to 2013 - Bouillouses (hydropower): 17 hm 3, waiting for the data from EDF Dams 7

Average monthly rainfall (mm) Data for model set up Climate data - Daily temperature, humidity, wind, radiation (PET): SAFRAN - Hourly rainfall: measured (OBS ) / SAFRAN (SAF ) 120 100 OBS SAF 80 60 40 20 8 km 0 1 2 3 4 5 6 7 8 9 10 11 12 Months 8

2 sub-basin delineations Minimal drainage area: 1500 ha 66 subbasins, 549 HRU Minimal drainage area: 691 subbasins, 2342 HRU 9

Calibration/validation measured data Subdaily discharge in 3 gauging stations (Banque Hydro) -> focus on 3 embeded catchments number of measures 2009-2011: Catl: 14977; Marq: 18765; Perp: 25909 Dams Outlets Catllar: 90 km² Perpignan: 1400 km² Marquixanes: 810 km² Calibration/validation periods for discharge simulation: - warm-up 2005-2009 - calibration 2009-2011 - validation 2012-2015 10

Parameters for SWAT-CUP set up 21 parameters Parameter Min Max CN2.mgt R -0.1 0.1 ALPHA_BF.gw V 0.01 1 GW_DELAY.gw V 0 500 GW_REVAP.gw V 0.02 0.2 GWQMN.gw V 0 5000 RCHRG_DP.gw V 0.01 0.99 REVAPMN.gw V 0 500 CH_K2.rte V 0.01 10 CH_N2.rte V 0.025 0.15 CH_K1.sub V 0.01 10 CH_N1.sub V 0.025 0.15 ESCO.hru V 0.7 0.9 EPCO.hru V 0.7 1 LAT_TTIME.hru V 0 180 CANMX.hru V 0 100 OV_N.hru V 0.01 0.6 SOL_K.sol R 0 9 SOL_AWC.sol R -0.1 0.1 SOL_BD.sol R -0.1 0.1 SOL_CBN.sol R -0.1 0.1 SURLAG.bsn V 0.05 24 -> daily and hourly autocalibration 11

Experimental design Rain gauges 90 km² 2 rainfall data sets 1500 ha 2 time-steps Daily SAFRAN 2 sub-basin delineations Hourly 3 outlets 810 km² 1400 km² 24 combinations -> 24 calibrations (2009-2011) 12

Daily discharge (m3/s) Daily discharge in Catllar (90 km²) 25 20 15 10 Simulated 100ha SAF Simulated 100ha OBS Simulated 1500ha SAF Simulated 1500ha OBS Observed 5 0 1/17/2009 8/5/2009 2/21/2010 9/9/2010 3/28/2011 10/14/2011 13

Daily discharge (m3/s) Daily discharge (m3/s) Daily discharge in Catllar (90 km²) 25 20 15 10 Simulated 100ha SAF Simulated 100ha OBS Simulated 1500ha SAF Simulated 1500ha OBS Observed 5 0 1/17/2009 8/5/2009 2/21/2010 9/9/2010 3/28/2011 10/14/2011 25 20 12 20 15 10 15 8 10 10 6 5 5 4 2 0 0 0 9/29 10/19 11/8 2/26 3/18 4/7 10/24 11/13 12/3 12/23 NASH OBS SAF 0.65 0.59 1500 ha 0.65 0.64 NASH OBS SAF 0.56 0.22 1500 ha 0.64 0.40 NASH OBS SAF 0.48 0.28 14 1500 ha 0.50 0.55

Horuly discharge (m3/s) Hourly disch. (m3/s) Hourly discharge in Catllar (90 km²) 70 60 50 40 30 20 10 Simulated 100ha SAF Simulated 100ha OBS Simulated 1500ha SAF Simulated 1500ha OBS Observed 0 1/17 70 8/5 2/21 50 9/9 3/28 10/14 60 50 40 30 20 10 0 10/9 10/14 10/19 NASH OBS SAF -0.97-0.02 1500 ha -0.13-0.41 40 30 20 10 0 3/13 3/18 3/23 NASH OBS SAF -0.11-0.14 1500 ha 0.36 0.23 15 10 5 0 11/3 11/13 11/23 12/3 NASH OBS SAF 0.06 0.18 15 1500 ha 0.28 0.40

Summary of the performances 2009-2011 Outlet Meteo data Min. drain. area Daily NS Hourly NS 90 km² SAF 1500 ha 0.50 0.38 0.45 0.29 OBS 1500 ha 0.55 0.40 0.52 0.14 810 km² SAF 1500 ha -0.86-1.00 0.46 0.18 OBS 1500 ha -0.55-1.12-0.75-0.93 1400 km² SAF 1500 ha 0.35 0.24 0.78 0.68 OBS 1500 ha 0.56 0.38 0.62 0.52 16

Summary of the performances Outlet Meteo data Min. drain. area Daily NS Hourly NS 90 km² SAF 1500 ha 0.50 0.38 0.45 0.29 OBS 1500 ha 0.55 0.40 0.52 0.14 810 km² SAF 1500 ha -0.86-1.00 Missing upstream dam data? 2009-2011 0.46 0.18 OBS 1500 ha -0.55-1.12-0.75-0.93 1400 km² SAF 1500 ha 0.35 0.24 0.78 0.68 OBS 1500 ha 0.56 0.38 0.62 0.52 18

Summary of the performances Outlet Meteo data Min. drain. area Daily NS Hourly NS 90 km² SAF 1500 ha 0.50 0.38 0.45 0.29 OBS 1500 ha 0.55 0.40 0.52 0.14 810 km² SAF 1500 ha -0.86-1.00 0.46 0.18 OBS 1500 ha -0.55-1.12-0.75-0.93 1400 km² SAF 1500 ha 0.35 0.24 Daily discharge out of dam controls the discharge d/h 2009-2011 0.78 0.68 OBS 1500 ha 0.56 0.38 0.62 0.52 19

Most sensitive parameters Outlet Meteo data Min. drain. area Daily Hourly 90 km² SAF 1500 ha OBS 1500 ha 810 km² SAF 1500 ha OBS 1500 ha 1400 km² SAF 1500 ha OBS 1500 ha LATTIME (116) CN2 (0.06) GWQMN (475) LATTIME (6) CN2 (0.06) GWQMN (3875) SOL_K (8) LATTIME (6) SOL_AWC (0.04) SOL_K (8) LATTIME (6) GWQMN (3875) CN2 (-0.05) SOL_AWC (0.06) GWQMN (625) ALPHA_BF (0.69) CN2 (-0.05) CH_N2 (0.14) CN2 (0.01) SOL_BD (0.04) RCHRG_DP (0.50) GWQMN (625) SOL_K (3) CH_N2 (0.05) RCHRG_DP (0.04) CH_N2 (0.05) SOL_K (0.05) GWQMN (2375) CH_N2 (0.15) LATTIME (26) SOL_BD (0.04) 9 parameters out of 21 CN2 (0.06) SOL_K (0.31) LATTIME (116) CN2 (0.08) LATTIME (2.7) SOL_K (3) CH_N2 (0.13) SURLAG (16) CN2 (-0.04) SURLAG (16) CH_N2 (0.14) CN2 (-0.05) SURLAG (9) ALPHA_BF (0.72) CH_N2 (0.14) CN2 (-0.05) CN2 (0.01) SOL_BD (0.04) CH_N2 (0.13) RCHRG_DP (0.28) GWQMN (4775) CH_N2 (0.15) RCHRG_DP (0.09) CN2 (-0.02) CH_N2 (0.11) RCHRG_DP (0.64) GWQMN (4275) CH_N2 (0.11) LATTIME (33) SOL_K (8) 20

Most sensitive parameters Outlet Meteo data Min. drain. area Daily Hourly 90 km² SAF 1500 ha OBS 1500 ha 810 km² SAF 1500 ha OBS 1500 ha 1400 km² SAF 1500 ha OBS 1500 ha LATTIME (116) CN2 (0.06) GWQMN (475) LATTIME (6) CN2 (0.06) GWQMN (3875) SOL_K (8) LATTIME (6) SOL_AWC (0.04) SOL_K (8) LATTIME (6) GWQMN (3875) CN2 (-0.05) SOL_AWC (0.06) GWQMN (625) ALPHA_BF (0.69) CN2 (-0.05) CH_N2 (0.14) CN2 (0.01) SOL_BD (0.04) RCHRG_DP (0.50) GWQMN (625) SOL_K (3) CH_N2 (0.05) RCHRG_DP (0.04) CH_N2 (0.05) SOL_K (0.05) GWQMN (2375) CH_N2 (0.15) LATTIME (26) SOL_BD (0.04) SOL_K > CN2 > CH_N2 CN2 (0.06) SOL_K (0.31) LATTIME (116) CN2 (0.08) LATTIME (2.7) SOL_K (3) CH_N2 (0.13) SURLAG (16) CN2 (-0.04) SURLAG (16) CH_N2 (0.14) CN2 (-0.05) SURLAG (9) ALPHA_BF (0.72) CH_N2 (0.14) CN2 (-0.05) CN2 (0.01) SOL_BD (0.04) CH_N2 (0.13) RCHRG_DP (0.28) GWQMN (4775) CH_N2 (0.15) RCHRG_DP (0.09) CN2 (-0.02) CH_N2 (0.11) RCHRG_DP (0.64) GWQMN (4275) CH_N2 (0.11) LATTIME (33) SOL_K (8) 21

Most sensitive parameters Outlet Meteo data Min. drain. area Daily Hourly 90 km² SAF 1500 ha OBS SOL_K > LAT_TTIME > CN2 1500 ha 810 km² SAF 1500 ha OBS SOL_K > 100 LAT_TTIME ha 1500 ha 1400 km² SAF 1500 ha OBS CH_N2 > RCHRG_DP 1500 ha LATTIME (116) CN2 (0.06) GWQMN (475) LATTIME (6) CN2 (0.06) GWQMN (3875) SOL_K (8) LATTIME (6) SOL_AWC (0.04) SOL_K (8) LATTIME (6) GWQMN (3875) CN2 (-0.05) SOL_AWC (0.06) GWQMN (625) ALPHA_BF (0.69) CN2 (-0.05) CH_N2 (0.14) CN2 (0.01) SOL_BD (0.04) RCHRG_DP (0.50) GWQMN (625) SOL_K (3) CH_N2 (0.05) RCHRG_DP (0.04) CH_N2 (0.05) SOL_K (0.05) GWQMN (2375) CH_N2 (0.15) LATTIME (26) SOL_BD (0.04) CN2 (0.06) SOL_K (0.31) LATTIME (116) CN2 (0.08) LATTIME (2.7) SOL_K (3) CH_N2 (0.13) SURLAG (16) CN2 (-0.04) SURLAG (16) CH_N2 (0.14) CN2 (-0.05) SURLAG (9) ALPHA_BF (0.72) CH_N2 (0.14) CN2 (-0.05) CN2 (0.01) SOL_BD (0.04) CH_N2 (0.13) RCHRG_DP (0.28) GWQMN (4775) CH_N2 (0.15) RCHRG_DP (0.09) CN2 (-0.02) CH_N2 (0.11) RCHRG_DP (0.64) GWQMN (4275) CH_N2 (0.11) LATTIME (33) SOL_K (8) 22

Conclusions For a 90 km 2 basin without dam: Hourly simulations catch sub-daily peaks but Nash are lower than daily Nash Rainfall distribution and sub-basin delineation are sensitive model inputs Simulations with PCP from rain gauges seems more reliable than modelled PCP grids It seems there is no need to discretize the basin at SOL_K appears to be the most sensitive parameter and needs to be accurately estimated For bigger basins with dams: The quality of the hourly simulation depends on the quality of the daily out-of-dam discharge data (*.day file) 23

Simulation of suspended sediments Coupling with the process oriented MARINE model Comparison of the hourly simulated discharge. If ok: Soil water content to initialize the MARINE model Later also suspended sediments in runoff Come and see the posters this afternoon! Perspectives Application to the other coastal flash-flood prone basins of the Lion Gulf Lion Gulf 24

Thank you for your attention! l.boithias@gmail.com 25

1/1/2009 2/1/2009 3/1/2009 4/1/2009 5/1/2009 6/1/2009 7/1/2009 8/1/2009 9/1/2009 10/1/2009 11/1/2009 12/1/2009 1/1/2010 2/1/2010 3/1/2010 4/1/2010 5/1/2010 6/1/2010 7/1/2010 8/1/2010 9/1/2010 10/1/2010 11/1/2010 12/1/2010 1/1/2011 2/1/2011 3/1/2011 4/1/2011 5/1/2011 6/1/2011 7/1/2011 8/1/2011 9/1/2011 10/1/2011 11/1/2011 12/1/2011 Débit (m3/s) Effect of the daily discharge out of the Vinça dam on the discharge in Perpignan 400 350 300 250 200 150 100 50 débit sortant Vinça (m3/s) Q observed Perpi 0 The calibration on Perpignan does not make much sense! 26