Influence of the representation of the groundwater component in hydrological catchment models on evapotranspiration (et) estimation.

Aklilu Teklesadik, Ann van Griensven, Marijke Huysmans, Christian Anibas, Olkeba Tolessa Leta

Thursday 2 july 2015

12:00 - 12:15h at Oceania Foyer (level 0)

Themes: (T) Water resources and hydro informatics (WRHI), (ST) Surface and subsurface flow interactions

Parallel session: 11L. Water resources - Flow interactions

ET is an important component of the hydrological cycle and it completes the energy balance of the cycle in the vegetation-soil and atmosphere interface. ET is a combination of evaporation from land surface, open water, soil zone and transpiration from vegetation. The proportion of the ET flux in the water balance varies and it could be as high as 90% in some river basins. The representation of the ground water component in hydrological models influences the water distribution in the basin, affecting the runoff and evapotranspiration components. In this study we investigate how the representation of groundwater in the hydrological model influences the ET component by comparing different model structures. We made the comparison for monthly ET estimations at pixel and at a catchment scale. Monthly average ET from SWAT, Water and Energy Transfer between Soil, Plants and Atmosphere (WetSpass), Precipitation and runoff simulation model (PRMS) and MODIS were compared. The ET results from the different models were validated using values derived from MODIS16. The monthly average ET from these models is different, moreover as expected the spatial variation is better represented in semi distributed models. ET estimation of the SWAT model is the lowest compared to estimation from the other models. When we look at the ground water contribution for ET the variation of the result from the models is more significant, time series plot of monthly average ground water ET contribution results from SWAT and PRMS have different shape. Result from WetSpass models, in which spatial variation of ground water depth is represented, show very sensitive ET to groundwater level representation