The impact of different elevation steps on simulation of snow covered area and the resulting runoff variance

摘要

This study analyses the impact of vertical model discretisation on modellingsnow covered area and the consequential effects on runoff formation of thesemi-distributed water balance model HQsim. Therefore, the parametersrelevant for snow modelling are varied within the frame of a uniformlydistributed Monte Carlo Simulation (MCS). Since the model is based on thehydrological response unit (HRU) approach, the effect of building the HRUswith different elevation steps (250 m and 500 m) is tested for two alpinecatchments. In total 5000 parameter combinations were generated forsimulation. The results of modelled snow covered area were compared withthirty MODIS (Moderate Resolution Imaging Spectroradiometer) snow cover mapsfor the melting periods in 2003–2011. Based on a contingency table thecomparisons were evaluated by different skill measures. Finally, the paretooptimal parameter settings of each skill measure were detected. Evaluationof runoff variability within the MCS and their pareto optimal runs showreduced variances of model output resulting from an improved simulation ofthe snow covered area.