Flood hydrograph prediction in a semiarid mountain catchment: The role of catchment subdivision

Abstract

Abstract The effect of different degrees of catchment subdivision coupled with the nonlinear storage–discharge relationship on hydrograph prediction is evaluated in a meso‐scale catchment in the Zagros mountain region, southwest of Iran. The catchment is divided into different sets of subcatchments based on catchment geomorphology, and runoff hydrographs are simulated for each set using a network‐based runoff routing model, watershed‐bounded network model. It is shown that, in the absence of fully distributed data, if a semidistribution of storage–discharge is taken into consideration in the modeling process, lumped rainfall data could provide valuable information on the hydrological response of catchment in data‐scarce regions, which are usually found in remote areas, such as mountains. Although the results suggest that catchment subdivision leads to more accurate results, a subcatchment area threshold of about 3% of the catchment extent is found. Below this, no further improvement in simulation accuracy can be achieved, probably because of the limitations of the data interpolation method used by the model.