紫色土区土地利用类型与降水变化对水土流失的影响

Effect of Land Use and Rainfall Factors on Soil and Water Loss in Purple Soil Region

以川中丘陵区鹤鸣观小流域及其3个试验小区2个试验阶段(1983-1986年,1989-2000年)为研究对象,分析了不同土地利用类型水土流失特征、径流侵蚀对降水变化的响应及小流域综合治理后的效益。结果表明:对于第一阶段,不同雨强下的径流深变化依次是荒地>草地>坡耕地;侵蚀模数的变化依次为坡耕地>荒地>草地。对于第二阶段,其径流深变化依次是梯地>草地>林地;侵蚀模数的变化依次为梯地>草地>林地。荒地、低覆盖草地、坡耕地径流量、侵蚀量与降水变量相关系数较高,土壤侵蚀主要受降水变化影响。林地、高覆盖草地、梯地径流量、侵蚀与降水变量的相关系数较小且没有显著性,可能是植被覆盖、土壤特性对减缓径流和侵蚀过程具有重要作用,说明土地利用/覆被变化具有明显分异的水土流失效应。由于水土保持综合治理的作用,1990-2004年小流域多年平均径流量比1985-1989年多年平均径流量减少30.67%,多年平均输沙量减少91.29%,多年平均含沙量减少76.05%。

This study was carried out in Hemingguan small watershed and its 3 experiment plots in which the observation time were divided into 2 periods（ from 1983 to 1986 and from 1989 to 2000） in hilly region of the central Sichuan, and the characteristics of soil and water loss of different land uses, the response of runoff and soil erosion on rainfall factors and benefits of comprehensive control measures in small watershed were analyzed. The results show as follows： In first period, runoff depth in different rainfall intensities in turn was wasteland 〉 grassland 〉 slopeland, but erosion modulus in order slopeland 〉 wasteland 〉 grassland. In second period, runoff depth successively was terrace land 〉 grassland 〉 forestry, and erosion modulus terrace land 〉 grassland 〉 forestry. The correlation degree among runoff on slopeland, soil erosion, low covered grassland and precipitation was much high, which showed that soil erosion was mainly influenced by rainfall factors. The correlation coefficient among precipitation erosion in forestry, high covered grassland and terrace land was much low, it may be that vegetative cover and soil characteristic play an important role on retarding runoff and erosion processes, which showed land use or vegetative cover had obvious effect on soil and water loss. Owing to the action of comprehensive control measures of soil and water conservation, long-tern average runoff amount from 1990 to 2004 had reduced by 30.67% , average sediment transportation by 91.29% and average sediment content by 76.05% than those parameters from 1985 to 1989 respectively.