Influence of soil moisture content and soil and water conservation measures on time to runoff initiation under different rainfall intensities

Abstract

Time to runoff initiation (TRI) is an important factor related to water infiltration, runoff generation, and hillslope erosion. This study assesses TRI values for six different plots and investigates the effects of rainfall intensity, surface soil moisture content at depths of 0–5 cm, soil and water conservation measures (longitudinal ridges, cross ridges, grass, forest, and flat field under fruit trees), and vegetation on TRI for bare soil, longitudinal ridges under maize, cross ridges under peanut crops, grass, forest, and flat field under fruit trees. Results showed that bare soil exhibited the shortest TRI, followed by the longitudinal ridges under maize and cross ridges under peanut crops. The remaining three plots did not generate runoff. The first principal component affecting TRI was soil moisture content, which contributed 69.87%, 64.88%, and 85.73% to the TRI of bare soil, longitudinal ridges under maize, and cross ridges under peanut crops, respectively. The second major component of these three plots were combined rainfall intensity, comprehensive rainfall and vegetation factors, and vegetation factors, which contributed 27.98%, 33.73%, and 14.27%, respectively. Maximum load factor was generated during runoff with maximum rainfall intensity (0.969), stalk diameter (0.985), and maize height (0.864). In conclusion, soil moisture content are the main factors influencing TRI, and soil and water conservation measures provided key benefits for improving the time to runoff initiation and reduction of runoff erosion in the farmlands.