水保所知识产出(1956---)知识库

The effects of slope gradients and antecedent soil water content on the characteristics and interactions of rainfall runoff and sediment on bare land and alfalfa land were investigated under the simulated rainfall experiment of coarse texture soil. The experiment treatment included three slopes（5°, 15° and 25°）and three antecedent soil water content（low, middle and high）.Studying the effects of slope gradients and antecedent soil water content on coarse texture soil erosion is to clarify the efficiency of the project of The Grain to Green. The results show that, the processes of runoff on bare land and alfalfa land were at first increased and then trending to be stable under different slopes and antecedent soil water content, the impact of slopes on runoff volume is unapparent, but sediment losses were greatly increased with the increasing of slopes, which is increased the peak and tending to be stable fluctuations during the process of rainfall, the magnitude of bare land’s fluctuation is higher than alfalfa land. The runoff volume and the mean infiltration were greatly affected by antecedent soil water content. Under the same slope gradient, when antecedent soil water content increased from low to middle, and from low to high, the runoff volume of bare land increased 38.2%~52.8%, 39.7%~42.8%, and the runoff volume of alfalfa land increased 27.3%~77.8%, 45.5%~91.1%. Slope had a significant influence onsediment losses and sediment concentration. Under the same antecedent soil water content, when slope increased from 5° to 15°, and from 15° to 25°, the sediment losses of bare land increased 96.3%~268.7%, 6.9%~40.3%, and the sediment losses of alfalfa land increased 81.1%~384.2%, 61.7%~169.9%. The result showed runoff volume and sediment losses of alfalfa land were significantly lower than bare land at same slope and antecedent soil water content. Antecedent soil water content and slope of coarse texture soil played important roles on the process and amount of soil erosion. The vegetation not only reduces runoff by canopy interception, but also decreases antecedent soil water content through consuming soil moisture.