Evaluation of the water storage capacity of soil management practices in basin scale

Abstract: Soil management practices, such as Terrace (TE), Contour Ridge (CR), Conservation Tillage (CT), Green Manure (GM) and Straw Mulching (SM), have been widely applied all over the word, due to their positive effects on enhancing Water Storage Capacity (WSC for short) of soil and improving the effectiveness of local precipitation.  However, there are few studies focus on the assessment of WSC of soil management practices in basin scale. In this study, a series of empirical equations for evaluating the WSC of different types of soil management practices were established, based on the fundamental assumption of SCS-CN model, and the geometric parameters of TE and CR. Taking the Sihe River Basin as an example, the current construction area of soil management practices and the potential of the design scenarios were input into the equations, to calculate the existing and potential WSC of various soil management practices. The results show that the construction area of soil management practices in the basin was 679.73 km² in 2015, and the WSC reached 61.85 Million m³. Thereinto, the WSC of the SM was the largest, which was 19.83 Million m³; that of the GM was the smallest, which was 2.08 Million m³. The total potential construction area of soil management practices in each design scenario was 1797.13 km². Scenario I gave priority to the TE and the CR construction, the WSC of soil management practices in the basin was 174.84 Million m³, which was 182.68% higher than that of in 2015. The WSC of soil management practices in Scenario II who gave priority to the SM, CT and CR construction, was 171.84 Million m³, which was 177.84% higher than that of in 2015. This research further compared the water storage efficiency of various soil management practices and discussed the uncertainty of the equations. The results could provide some references for integrated soil water management.