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WaSiM (Water Balance Simulation Model)

The Water balance Simulation Model WaSiM (Schulla & Jasper 2006) uses a mixture of conceptual approaches and physically based algorithms to describe hydrological processes. Infiltration of water into the soil and the surface runoff generation is computed after Green & Ampt (1911) using the two step model approach after Peschke (1987). The calculation of the vertical water fluxes in the unsaturated zone is done by the discrete Richards Equation. Soil moisture content is parameterized considering suction head and hydraulic conductivity according to van Genuchten (1976). Interflow is generated in defined different soil layers depending on drainable water content, suction, the hydraulic conductivity and gradient. Surface runoff is routed using a subdivision of the basin into flow time zones. Interception is considered using a simple bucket approach with a leaf area index dependent storage capacity. Evapotranspiration is calculated following the approach of Penman-Monteith (Monteith 1975). WaSiM contains a simple 2D groundwater model which is dynamically coupled to the unsaturated zone.


At the IMK-IFU, WaSiM is applied for catchments of sizes between 200 - 2300 km2 for regions in central Europe (Ammer and Alz catchment), West Africa (Volta Basin) and the Middle East (Jordan River). For the assessment of climate change on the water balance and for flood forecasting, coupling interfaces to the meteorological model MM5 and WRF were developed at IMK-IFU. For the investigation of rainfall fields, WaSiM was driven with radar reflectivity data. The effect of satellite based albedo and LAI-values in hydrological simulations was investigated.  



Mean surface runoff  in northeast Ghana for  the decade 1960-69


Flood forecasting for the century flood 2005 in the Ammer catchment     


Selected References:

Kunstmann, H.; Jung, G.; Wagner, S.; Clottey, H.: Integration of atmospheric sciences and hydrology for the development of decision support systems in sustainable water management. Physics and Chemistry of the Earth, A/B/C, 33 1-2, S. 165-174. Doi:10.1016/j.pce.2007.04.010, 2008.

Marx, A.; Kunstmann, H.; Bardossy, A.; Seltmann, J.: Radar rainfall estimates in an alpine environment using inverse hydrological modelling. Advances in Geosciences, 9, pp. 25-29, 2006.

Kunstmann, H.; Stadler, C.  High resolution distributed atmospheric-hydrological modelling of an alpine catchment High resolution distributed atmospheric-hydrological modelling for Alpine catchments. Journal of Hydrology, 314, S.105-124. doi: 10.1016/j.jhydrol.2005.03.033, 2005.