坡面水土保持措施的减沙水代价分析

Analysis of the runoff cost for sediment control by slope soil and water conservation measures

水土保持措施在减少土壤侵蚀的同时也会减少地表径流,减沙水代价可以直观说明不同措施同步影响径流和泥沙的差异。根据黄土高原沟壑区西峰、天水的农地径流场多年观测资料,统计分析不同耕作措施及生物措施的减沙水代价。结果表明:不同耕作措施和生物措施减沙水代价受最大30 min降雨强度(I30)和坡度影响较大,呈显著负相关;对于耕作措施和生物措施,当I30分别大于0.29和0.48 mm/min时,坡度与措施减沙水代价表现出较好的指数函数关系;耕作措施减沙水代价表现为防冲沟>浅耕>深耕,防冲沟较深耕高33.8%;各生物措施减沙水代价表现为低秆作物和高秆作物玉米/黄豆间作>单作低秆作物扁豆>中高秆作物冬小麦/荞麦轮作。

Runoff cost for sediment control,shown as ratio of detained runoff and sediment（Rrs） of different soil and water conservation measures is an important integrated indicator to intuitive evaluate the impact of different soil and water conservation measures on runoff and sediment synchronously.Based on the experimental data measured in runoff plots in Xifeng and Tianshui stations for many years,the runoff cost for sediment control under different tillage measures and biological measures were analyzed.The results showed that the Rrs of different tillage and biological measures were greatly impacted by I30 and slope,and the RRS was negatively correlated to the two factors.As to the tillage measures and biological measures,the relationship between Rrs and slope appeared as a exponential function as I30 was more than 0.29 mm/min and 0.48 mm/min respectively.The orders of runoff cost for sediment control for different tillage measures were：level ditch tillageshallow plowingdeep plowing,and Rrs of level ditch tillage is higher than that of deep plowing by 33.8%.As to biological measures the orders of runoff cost for sediment control were：intercropping between low-stem and high-stem crops（corn/soybean）monoculture of low-stem crops（lentils）rotation between middle-stem crops（winter wheat/buckwheat）.