关键词: SCS模型; 曲线数CN值优化; 坡度; 土地利用类型; 径流场; 小流域;

Abstract: Due to its simple structure, few parameters and easy access, the SCS model is widely used in runoff estimation in areas with insufficient hydrological data.As the main parameter, the runoff curve number(CN) in the SCS model has an important influence on the runoff simulation results, but the CN values provided by the existing hydrologic and soil classification standards cannot be well applied to basins with complex topography.In this paper, CN value was optimized by slope and land use type, and the accuracy of model optimization was verified and analyzed by using runoff test field data of Tiansi and Tanghekou sites, etc.The SCS model was applied to the Changyucheng small watershed in Beijing, and the CN value was optimized according to the topographic features and treatment measures of the small watershed, so as to obtain the runoff situation before and after treatment to evaluate the benefit of water conservation.The results show that the optimized SCS model can be well applied to the calculation of runoff in different runoff fields, and the simulation accuracy of the model can be improved by 3.6%～11.4%.The simulation in runoff field cannot be directly applied to the whole small watershed.CN values should be optimized based on the field situation and existing hydrological data to improve the calculation accuracy of SCS model, so as to provide reference for water conservation benefit assessment in the comprehensive management evaluation of small watersheds.

Key words: SCS model; curve number(CN) optimization; slope; land use type; runoff field; small watershed;