Sources of uncertainty in the validation of a coupled hydrological-hydraulic simulation model with sediment transport

Arnas and Araguas are two well-instrumented basins located in the Spanish Pyrenees. Experimental data of water discharge from different rainfall events, together with precipitation, temperature and soil humidity have been used in order to calibrate a distributed numerical model of hydrological and hydraulic processes based on a two-dimensional approximation of the shallow water equations. The hydrological model is based on simple but physically-based laws to calculate the evapotranspiration and the infiltration. The surface runoff is modelled by means of a 2D diffusive-wave model. Sediment transport phenomena are simulated by means of a hillslope erosion model. All the differential equations involved in the processes have been discretized using an explicit scheme on quadrilateral meshes. The work is focused on the influence of the choice of the empirical parameters on the model results concerning solid and liquid discharges.