Development and application of an infiltration rate curve for runoff analysis in the North China Plain

According to analysis of rainfall infiltration in the North China Plain we assume that the initial soil moisture and accumulated infiltration in the process of rainfall are the main factors that affect the soil infiltration rate. Based on the soil water dynamics theory, soil water movement is simulated numerically. An empirical formula is developed for infiltration rate estimation based on initial soil moisture and accumulated infiltration in soil of different textures. This so-called infiltration rate curve can be used to simulate runoff and the result is satisfactorily verified by experimental data. The research demonstrates the simplicity, efficiency and accuracy of excess runoff estimation using the infiltration rate curve.