大渡河干旱河谷区横垄坡面产流产沙特征及水保效益

为弄清干旱河谷区横垄坡面水土流失特征及水保效益,采用野外调查与室内人工模拟降雨相结合的方法,以坡耕地平作坡面为对照,开展了4种降雨强度(30,60,90,120 mm/h)和4种坡度(10°,15°,20°,25°)条件下横垄坡面产流产沙特征及减流减沙效益。结果表明:(1)横垄坡面产流时间随降雨强度和坡度的增大而提前,且受坡度影响远小于降雨强度;同等条件下,横垄坡面产流时间滞后平作坡面8.14%~55.60%。(2)随着降雨强度和坡度的增大,横垄坡面产流率和产沙率均表现为增加趋势。(3)坡度与横垄坡面减流减沙效益随降雨强度的增大由正相关关系转变为负相关关系,而降雨强度与横垄坡面减流减沙效益关系复杂,无明显变化规律。降雨强度和坡度对横垄坡面产流产沙过程和减流减沙效益有重要影响,横垄坡面能够延长坡面径流形成时间,有效减少坡面产沙率,但横垄坡面减流减沙作用存在临界条件。研究结果可为区域坡耕地横垄措施合理布设和水土流失有效防控提供数据支撑和理论依据。

Runoff and Sediment Yield Characteristics and Soil and Water Conservation Benefits of Cross Ridge Slope in Arid Valley of Dadu River

In order to understand the characteristics of soil and water loss and benefit of soil and water conservation on the cross ridge slope in arid valley area, field investigation and indoor artificial rainfall simulation were carried out, and the characteristics of runoff and sediment yield and benefit of runoff and sediment reduction on cross ridge slope were analyzed under four rainfall intensities (30, 60, 90 and 120 mm/h) and four slopes (10°, 15°, 20° and 25°). And the flat sloping farmland was taken as the control. The results showed that: (1) The runoff production time on the cross ridge slope was advanced with the increasing of rainfall intensity and slope gradient, and it was much less affected by slope than by rainfall intensity. Under the same conditions, the runoff production time on cross ridge slope lagged behind that of flat sloping farmland by 8.14%~55.60%. (2) With the increasing of rainfall intensity and slope gradient, both runoff yield and sediment yield on the cross ridge slope showed an increasing trend. (3) With the increasing of rainfall intensity, the relationship between slope gradient and benefit of runoff and sediment reduction on cross ridge slope changed from positive phase to negative phase, while the relationship between rainfall intensity and benefit of runoff and sediment reduction on cross ridge slope was complex without obvious change law. Rainfall intensity and slope gradient had important effect on the process of runoff and sediment yield and the benefit of runoff and sediment reduction on the cross ridge slope, and cross ridge slope could prolong the time of slope runoff formation, effectively reduce the slope sediment production rate, however there were critical conditions for the effect of runoff and sediment reduction on the cross ridge slope. The results could provide data support and theoretical basis for the regional reasonable layout of farmland cross ridge measures and the effective prevention and control of soil erosion.