大理河流域水土保持减沙趋势分析及其成因

在1960～1999年长系列的水文资料和降雨量资料的基础上,分析了大理河流域输沙量和年降雨量的时间变化趋势,发现在1972年以来产沙量减少的总体背景之下,出现了1986～1999年间产沙量增加的近期趋势,分析表明,这一增加趋势与20世纪80年代以后淤地坝修建量大为减少,70年代修建的淤地坝已大部分淤满失效密切相关.此外,90年代人为增沙量大幅度增加,已占水土保持减沙量的20%左右,部分抵消了水土保持措施的减沙效益,这也是90年代产沙量增加的重要原因.因此,要重视该地区淤地坝的后续建设,配合坡面各种措施进行综合治理,实现该流域拦沙效益的持续性,同时还应关注新增水土流失问题.

Tendency of Water and Sediment Reduction through Soil and Water Conservation and Its Cause of Formation in Dalihe River Basin

Based on the study of long series hydrological and precipitation data from 1960 to 1999 and analysis on time variation tendency of annual sediment delivery and annual precipitation of the Dalihe river basin,the paper finds that sediment yield has been increased in the period of 1986~1999 based on the overall condition of reduction in the region since 1972.The increasing tendency is closely related with the situation of the reduction of check-dams building since 1980's and lost effectiveness of most reservoirs for sediment retaining built in 1970's.In addition,the man-made sediment increase is great in 1990's,making up about 20% of sediment reduction through soil and water conservation measures and partially counter acting sediment reduction benefits gained through soil and water conservation measures.This is an important reason why the sediment yield is increased in 1990's.Therefore the paper puts forward some counter measures and suggestions in accordance with existing issue such as putting stress on the sustainable construction of the check-dams,cooperating with all kinds of ramp measures,paying attention to new added soil and water problems and so on.