Team F Jiwon JUNG Kamilia HABOUB Baptiste TRUBERT

Team F Ji-won JUNG, Kamilia HABOUB, Baptiste TRUBERT, Ayalew Shura KASA, Bibhab Mani PANTHI, Rayner FERNANDEZ DIEZ, Cecilia Sandra MUHIRIRWE Grégoire GALLOT-LAVALLEE

Issue What is the impact of grid refinement on hydrological simulations? 2

Overview • Grid refinement approach • Importance and limitations • Case of study: Var catchment • Hydrological modelling using different grid sizes • Results and conclusion • Teamwork progress 3

Grid refinement approach Grid refinement Local Refinement Traditional Mesh refinement Global Refinement Telescopic Mesh refinement 4

Importance and limitations Importance: • Better representation of the reality • Improving results accuracy Limitations: • Heavy calculations ⇒ Time consuming + More expensive Balance 5

Case Study : Var catchment Land use statistic of Var catchment in km² using 75 m grid Land use statistic of Var catchment in km² using 300 m grid Land use distribution in km² for 300 m/75 m resolution grid Area: 2, 832 km² Slope: Steep 6

Arcgis Results Comparison of 4 DEMS: 1000 m, 300 m, 75 m and 25 m 1000 m 300 m 75 m 25 m - Lowest elevation: 10 m - Lowest elevation: 4 m - Lowest elevation: 1 m - Max elevation: 2, 944 m - Max elevation: 3, 001 m - Max elevation: 3, 045 m - Max elevation: 3, 132 m - 0. 1%<slope<61% - 0. 1%<slope<66% - 0 %<slope<69% - 0 %<slope<79% 7

River Networks with different grid resolutions at the outlet of the catchment 8

Comparison between 75 m and 300 m DEM 9

Comparison of the hydrographs with different grid sizes 10

Difference in elevation detailing Branch: VAR - Chainage: 99367. 94 300 m DEM 98404. 48 75 m DEM 11

Difference in discharge simulation 75 m DEM is more precise -> Better resolution Still need calibration to have better results 12

Results and conclusions • • The impact of grid refinement on hydrological modelling is high Simulation time increases at higher DEM resolution High resolution data describe more the real topography, but it requires more data storage Grid refinement ⇒ Affect the slope ⇒ Water exchange between cells (Mike She) Considering the “Accuracy” and time required for simulations with different data resolutions, the 75 m DEM is recommended by our group for simulating the flood event of 1994 in the Var River Basin. 13

Teamwork progress Tasks Progress Hydrological analysis Rainfall distribution GIS analysis Done Hydrological modelling Mike she Hec- Hms Calibration Done 1 D Hydraulic modelling Hec-Ras Mike 11 In progress 2 D Hydraulic modelling Iber In progress Flood resilience FRI In progress 14

Thank you for your attention The experience is still going on! : twitter. com/Hydro. Europe. Team. F : facebook. com/Hydro. Europe-Team. F : 16 he. F@aquacloud. net 15