Simulation experiment of effect of antecedent soil moisture content on characteristics of runoff and sediment from two soil sloping lands

The effect of antecedent soil moisture content on the characteristics of infiltration, runoff and sediment was investigated by rainfall simulation experiment of lou soil and sand loess. The results show that, under the controlled conditions with rainfall intensity 80mm/h and slope 10°, the impact of antecedent soil moisture content on initial time of runoff, infiltration process and sediment loss is unapparent for lou soil, while for sand loess, the initial time of runoff is greatly affected by antecedent soil moisture content, which is prolonged firstly and then shorted with the increasing of antecedent soil moisture content. The maximum difference of initial times is 28.91 min. The process of infiltration and surface flow for sand loess has significant discrepancy between two antecedent soil moisture content ranges from air-dried condition to 10% and 15% to 25%. Antecedent soil moisture content might be divided into “three sections” for lou soil and “two sections” for sand loess, based on the characteristics of water infiltration processes. The optimal antecedent soil moisture content values for minimization of soil losses from two soil sloping lands are determined by the approximately parabola relations of soil losses and antecedent soil moisture content, which are 11.25% for lou soil and 12.74% for sand loess. This study provides theoretical principle for the management of soil and water on the sloping land in loess region.