基于人工模拟降雨试验的垄作区田水土保持效益的变化研究

目的]研究垄作区田在不同降雨条件下发生溢流和损毁的情况和水土保持效益的变化,为实施垄作区田的适宜条件评价和水土保持效益的评价提供依据。方法]对垄作区田和顺垄耕作实施不同雨强的人工模拟降雨实验,分析二者的产流产沙过程和水土保持效益变化。结果]雨强大于60mm/h时,区田有溢流产生,但土档不会损毁,水土保持效益略有降低;雨强大于60mm/h时,区田土档在溢流后很快损毁,水土保持效益有明显的下降。区田未损毁情况下的蓄水效益为87.5%,保土效益为88.2%;区田损毁后的蓄水效益降至34.1%,保土效益降至21.0%。结论]垄作区田在60mm/h雨强下具有良好的水土保持效益,超过60mm/h时,由于土档在溢流后容易损毁,从而使其水土保持效益显著下降,丧失了拦蓄径流和泥沙的能力。

Variations of Soil and Water Conservation Efficiency for Basin Tillage Measurement Studied by Rainfall Simulation

Objective] The effects of rainfall intensity on the happening of overflowing and breaking on basin tillage and the relevant variations of basin tillage''s soil and water conservation efficiency were explored to provide references of suitable requirements for the application of basin tillage and for the evaluation of its soil and water conservation efficiency. Methods] Simulated rainfall was applied on two tillage patterns of basin tillage and compared conventional tillage, and to analyze their processes of soil and water production and the variations of soil and water conservation efficiency. Results] When rainfall intensity was under 60 mm/h, there was ridge overflowing occurrence but no damage or breaking for basin tillage, and the efficiency decreased slightly. When rainfall intensity was over 60 mm/h, damage and breaking occurred as soon as overflowing happened, whereafter the efficiency decreased remarkably. Average runoff conservation efficiency was 87.5% and the soil conservation efficiency was 88.2%. When basin tillage was damaged, the above two items decreased to 34.1% and 21.0%, respectively. Conclusions] Basin tillage would remain good efforts on soil and water conservation when rainfall intensity under 60 mm/h. When it is over 60 mm/h, because dams of basin tillage might be broken down easily after overtopping, it would lost its ability of blocking water and soil, and hence relevant conservation efficiency decreased remarkably as well.