A GENERALIZED URBAN STORAGE FUNCTION MODEL CONSIDERING SPATIAL RAINFALL DISTRIBUTION

Abstract

 The rainfall spatial variability has not been considered in the Storage Function (SF) models so far even though there exist various SF models including the Urban SF (USF) model, a relatively new SF model mainly for urban watersheds. Therefore, in this study, we aim to propose a generalized USF (GUSF) model for the storm runoff analysis by considering the spatial rainfall distribution in the basin. This was achieved by the introduction of a new parameter named as rainfall distribution factor (𝛾) in the USF model. The GUSF and USF models were examined and the results revealed that the GUSF model with 𝛾 exhibited higher hydrograph reproducibility associated with the lowest error evaluation criteria which emphasize the effect of parameter 𝛾. Further, the Akaike information criterion (AIC) was used to establish the best model among two based on the number of optimized model parameters. The GUSF model received the lowest AIC score in calibration and validation which indicate that the inclusion of a single parameter, rainfall distribution factor, can substantially improve the performance of a model by representing the spatial rainfall distribution of basin in a better way.