Flood hydrograph simulation in ungaged basins: modeling linear-nonlinear storage-discharge relationships in a semiarid mountain region

摘要

For the purpose of flood mitigation in a mountain region, this study aims to evaluate the degree of nonlinearity in the hydrologic storage-discharge relationship. The study area includes a mesoscale catchment, its headwater subcatchment, and its large-scale parent basin in the Zagros mountain region of southwestern Iran. Rainfall events are divided into two variable classes, Low Temporal (LT) and High Temporal (HT), based on their heterogeneity across time. For Low Temporal rainfall events, the mesoscale catchment and its headwater subcatchment show strong nonlinear behavior, but their responses tend to be less nonlinear for High Temporal rainfall events. Meanwhile, for High Temporal events, soil moisture has a dominant role in catchment response. On the other hand, a different perspective is drawn for the larger basin because a strong nonlinear response is obtained for all events regardless of temporal heterogeneities and soil moisture conditions, emphasizing the filtering effect of catchment extent on the rainfall-runoff process.