The Spatial Resolution of Physiographic Data Simulations in Prealpine and Alpine Catchments

Condensed Abstract: The aggregation of spatial information causes a decrease in efficiency in the gridded simu-lation of catchment hydrology in the alpine region. A method is presented to analyse the sensitivity of the simulated discharge to the change of resolution in the physiographic characteristics. This allows simulations with spatial data having different resolution. One can also identify which characteristics of the catchment physiography is responsi-ble for the decrease in efficiency in model runs at low resolution. The model PREVAH is used to run HRU and grid-based simulations for the prealpine catchment of the Murg and for the high alpine Dischmabach catchment. The results in the Murg catchment indicate that the decrease in simulation performance is more sensitive to the coarsening of the land surface properties than to the resolution reduction of the topography. For the Dischmabach catchment there is a significant performance decrease when the model is run with low resolution topographical information. The sensitivity to changes in the spatial resolution of soil and land surface properties is limited in this case. A 1x1 km grid spacing is a critical resolution for the simulation of catchment hydrology in the Alps