Study on the Influential Factors of SCS-CN Model Parameter S in the Loess Plateau area

摘要

SCS-CN method, developed by the U.S. Department of Agriculture, is simple, effective and can be used inthe area having lack of rainfall process data, thus has been widely used to estimate the runoff. In this study,213 runoff events from 9 plots at Zizhou located on the Loess Plateau area, were studied and applied tocalibrate water storage capability of soil which is donated as S in the SCS-CN method. The influence factorsof S parameter were then analysed. The results show that the main influence factor of S is initial abstractionI a . The initial abstraction ratio (I a / S) at Tuanshangou watershed is 0.03. The maximum 30-minute rainfallintensity, 5-day prior rainfall amount and soil moisture in the top 20 cm soil layer has no influence on the Sparameter.