Climate and catchment controls on the performance of regional flood simulations

SummaryFlood runoff is simulated for 57 catchments in Austria and Southern Germany. Catchment sizes range from 70 to 25,600 km2, elevations from 200 to 3800 m and mean annual precipitation from 700 to 2000 mm. A semi-distributed conceptual water balance model on an hourly time step is used to examine how model performance (both calibration and validation) is related to the hydroclimatic characteristics of the catchments. Model performance of runoff is measured in terms of four indices, the Nash–Sutcliffe model efficiency, the volume error, the percent absolute peak errors and the error in the timing of the peaks. The simulation results indicate that the model performance in terms of the Nash–Sutcliffe model efficiency has a tendency to increase with mean annual precipitation, mean annual runoff, the long-term ratio of rainfall and total precipitation and catchment size. Peak errors have a tendency to decrease with climatological variables as well as with catchment size. Catchment size is the most important control on the model performance but also the ratio rain/precipitation is an important factor. The hydrograph shapes tend to improve with the spatial scale and magnitude of the precipitation events. Calibration and validation results are consistent in terms of these controls on model performance.

► We assess the model performance as function of climate and catchment controls.
► Model performance increases with area and wetness of catchment.
► Peak errors decrease with area and wetness of catchment.