Soil and Water Conservation Effects of Contour Reverse Slope Terraces on Red Clay Sloping Farmland against Short and Heavy Rainfall

Abstract

To explore the effect and applicability of contour reverse slope terraces in water and soil conservation of karstic red clay soil area in northern Guangxi, rainfall simulation experiments were conducted on bare red clay soil slopes laid with contour reverse slope terraces to find the erosion pattern in response to different rainfall intensities (15, 30, and 50 mm/h) and bedrock porosities (1%, 3%, and 5%). The results showed that contour reverse slope terraces can change the spatial distribution of surface runoff, divert surface runoff to the underground, and increase underground sediment yielding. It is found that contour reverse slope terraces can effectively reduce surface soil erosion though it still remains dominant erosion for red clay terraced farmland, with surface runoff reduced by 71%, 52%, and 46% and surface sediment loss reduced by 70%, 65%, and 63%, respectively, when the rainfall intensity is set at 15 mm/h, 30 mm/h, and 50 mm/h. It is concluded that contour reverse slope terraces can help reduce water and soil erosion of red clay terraced farmland in northern Guangxi.