Investigating the effect of catchment characteristics on the response time scale using a distributed model and weather radar information

The response time scale (RTS) is a characteristic time scale of the catchment that represents the amount of smoothing performed by the hydrological system in transforming the rainfall input into runoff. Previous studies using catchments in Israel and Panama indicate that the RTS is stable for a given catchment and it depends on the catchment characteristics. In order to study the relationship between catchment characteristics and the RTS, a physically-based, non-calibrated distributed hydrological model is applied to a 24-km² rural catchment in Israel. The radar rainfall data are used to obtain the computed runoff hydrographs, and these computed data are then used to derive the RTS of the modelled catchment. The effect of catchment parameters (such as length and roughness of hillslopes and channels) on the RTS is examined by changing parameter values and deriving the RTS for each case. Special emphasis is placed in distinguishing the effects of hillslope vs channel processes. The results indicate that the effect of hillslope processes on the response time scale is greater than the effect of the channel processes for the study catchment.