中国科学院水利部水土保持研究所机构知识库

为了研究极端降雨条件下流域径流泥沙对不同水土保持措施的响应，揭示水土保持对暴雨洪沙的作用，为极端降雨引发的洪灾和防治土壤侵蚀提供理论支撑。采用 Mann-Kendall 和线性回归方法对大理河流域绥德水文站1964—2017 年实测水沙数据进行趋势分析，并采用时间对比分析法，对比分析 1964 年 7 月、1977 年 8 月和 2017 年7 月 3 个月份暴雨的水沙变化特征。结果表明:大理河流域在区域降水量未出现明显变化趋势的条件下，流域控站绥德水文站 1964—2017 年径流量和输沙量呈显著减少趋势。3 个月份暴雨场次降雨量基本相同，2017 年 7 月和1977 年 8 月径流相较于 1964 年 7 月，分别高 308%和 120%;输沙量分别高 66% 和 131%。但与 1977 年 8 月暴相比，2017 年 7 月径流高 85%，输沙低 39%。2017 年 7 月洪峰流量、洪量显著增大，输沙量随径流的增大而明显减少。1964 年 7 月和 1977 年 8 月洪水表现为陡涨陡落、洪水历时短;2017 年 7 月洪水表现为陡涨缓落，洪峰历时明显延长。大理河流域水土保持措施有效地改变了下垫面情况，减流减沙作用明显;但遭遇极端降雨情况，水土保持工程措施难以发挥良好的水土保持效益，未来若发生大范围强降雨，仍可能产生大水大沙的现象。

［Background］This paper is to study the responses of runoff and sediment characteristics under extreme precipitation conditions in different soil and water conservation measures in the Dali Ｒiver Basin as an example． To reveal the role of soil and water conservation would provide a reliable theoretical support for floods caused by extreme rainstorm and for prevention of water loss and soil erosion．
［Methods］Based on the precipitation data，runoff data，and sediment yield data of Suide station of the Dali Ｒiver Basin from 1964 to 2017，we used Mann-Kendall trend test and linear regression method to analyze the changes in trends． In addition，we used statistical methods to analyze runoff and sedimencharacteristics in rainstorm floods of July 1964，August 1977 and July 2017 with different periods of soil and water conservation. [Results］Under the condition of no obvious change trend of precipitation，the runoff amount and sediment yield of the basin observed from the Suide station in 1964 －2017 showed a declining trend． However，different effects were shown on the characteristics of runoff and sediment yield under extreme rainstorm conditions． Under the three extreme rainstorm conditions，the precipitation was basically the same． Compared with July 1964，the runoff in July 2017 and August 1977 was greater than 308% and 120%，respectively，and the sediment yield was greater than 66% and 131%，respectively．However，the runoff in July 2017 compared with the rainstorm in August 1977 was higher than 85% and the sediment yield was lower than 39%． In July 2017，the flood peak flow and flood amount increased significantly，while the sediment yield decreased significantly with the increase of runoff． Flooding in July 1964 and August 1977 were characterized by steep rise and fall of water and a very short duration． In July 2017，the flood showed a steep rise and slow fall of water，and the duration of flood peak significantly prolonged．Conclusions］Soil and water conservation measures in the Dali Ｒiver Basin have effectively changed the underlying surface conditions and played an obvious role in reducing runoff and sediment yield． However，for soil and water conservation engineering measures，it is difficult to play good benefits of soil and water conservation． These findings indicate that soil and water conservation engineering measures may exert good soil and water conservation benefits within a certain range; while encountering heavy rainfall and flood，soil and water conservation has a limited effect． If a large scale extreme rainfall occurs in the future，the runoff and sediment yield would be also big．