Streamflow simulations reveal the impact of the soil parameterization

Land surface models calculate runoff from the land surface. Therefore they must be coupled to a hydrological model to receive the streamflow which then allows for the comparison to measurements at gauging stations. The land surface model TERRA-ML of the weather forecast model COSMO of the German Weather Service is coupled to a river routing model and applied to the Enz watershed upstream of Höfen (Baden-Württemberg, Germany). The comparison of simulated to measured streamflow revealed, deficiencies in the hydraulic conductivity parameterization and in the applied soil texture data set. Small changes in the vertical soil water fluxes and high resolution soil texture data led to a significant improvement in the streamflow simulation. This resulted in different simulations of evapotranspiration and soil moisture, namely in spring and early summer, i.e. during the most pronounced growing season.