A Modified Distributed CN-VSA Method for Mapping of the Seasonally Variable Source Areas

Many watershed models employ the Soil Conservation Service Curve Number (SCS-CN) approach for runoff simulation based on soil and land use information. These implicitly assume that is generated by Hortonian process and; therefore, cannot correctly account effects of topography, variable source area (VSA) and/or moisture distribution in a watershed. This paper presents new distributed CN-VSA method SCS-CN to estimate amount uses topographic wetness index (TWI) distribute runoff-generating areas within spatially. The size saturated-watershed their spatial locations are simulated assuming an average annual value potential maximum retention. However, literature indicates significant seasonal variation retention which can considerably effect water balance nonpoint pollution. focuses developing modified accounts changes results indicate better than simulate areas. Overall, study improved understanding hydrological response where factors describe retention, and, thus, saturation excess generation