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不同的水土保持措施在减少侵蚀泥沙的同时对径流量的影响不同。以裸坡地水土流失为对照,分析了不同水土保持措施减水减沙比(Rrs),并以其作为减沙水代价指标,根据黄土高原土壤侵蚀严重的丘陵沟壑区(西峰、绥德、天水等3个典型区)的农地径流小区多年观测资料,分析了不同耕作措施及生物措施的减沙水代价(Rrs)。结果表明,不同耕作方式Rrs差异很大,变化幅度在8.5～36.4m3/t;在耕作措施上,横向耕作的Rrs大于防冲沟和浅耕,深耕Rrs最小;生物措施方面,低秆与高秆作物间作措施Rrs大于单作低秆作物和中高秆作物轮作,牧草(草木樨、苜蓿)轮作的Rrs较农作物轮作大,且草木樨与农作物轮作的Rrs大于苜蓿与农作物轮作。随着雨量的增加和坡度的增大,耕作措施和生物措施Rrs呈减小趋势。Rrs较大的措施在减少相同的坡面侵蚀泥沙时,有利于增加土壤水分,但是不利于径流形成。
Different soil and water conservation measures have different impacts on runoff while reducing sediment erosion. Taking the loss of soil and water on the bare slope as a contrast, the paper analyzed the water and sand reducing ratio (Rrs) of different soil and water conservation measures, and took it as the indicator of the cost of reducing sediment. According to the indexes of gully areas (Xifeng, Suide and Tianshui) And other three typical areas) of agricultural runoff plot for many years to observe the data, analysis of different tillage measures and biological measures of sand reduction cost (Rrs). The results showed that there were significant differences in Rrs between different tillage methods, with a variation range of 8.5 ~ 36.4m3 / t. In the tillage measures, the Rrs of lateral tillage was greater than that of anti-gully and shallow tillage, and the lowest of deep tillage Rrs. In terms of biological measures, The Rrs of stalk intercropping was higher than that of monoculture stubble and middle-high stalk crop rotations. The Rrs of forages (herbaceous plants, alfalfa) was larger than that of crop rotation, and Rrs of rotation of shrubs and crop was higher than that of alfalfa and crop rotation. Rrs of tillage and biological measures decreased with the increase of rainfall and slope. Rrs larger measures to reduce the erosion of sediment on the same slope, is conducive to increasing soil moisture, but not conducive to the formation of runoff.