乌江流域1956—2014年降雨特征及输沙效应

Characteristics of Precipitation and Sediment Effect in Wujiang River Basin During 1956-2014

[目的]研究乌江流域的降雨特征及输沙效应,为流域水土保持、生态恢复、防灾减灾、水资源合理利用等提供重要理论参考。[方法]采用累积距平法、双累积曲线法分析了乌江流域年际、年代、汛期降雨特征,以及降雨侵蚀力和人类活动对流域输沙效应的影响。[结果](1)1956—2014年,乌江流域年降雨量和年侵蚀性降雨量均呈现出波动下降趋势。研究时段内大致经历了少雨—多雨—少雨—多雨—少雨5个年际变化阶段。(2)乌江流域在1970—1979,1990—1999年为多雨时期,流域内59a中约有32.57%的降雨为侵蚀性降雨,且多发生于1960—1979年。(3)乌江流域汛期降雨以侵蚀性降雨为主,侵蚀性降雨主要发生在6月。(4)通过建立乌江流域年输沙量和年降雨侵蚀力双累积曲线方程,计算得出1984—1989,1990—1999和2000—2013年降雨侵蚀力的贡献率分别为15.55%,2.84%和12.46%;1990—1999年降雨侵蚀力对输沙变化的影响程度最低。[结论]乌江流域的降雨侵蚀产沙更多地发生在汛期,1983年后人类活动对输沙量的影响占据主导地位。

[Objective] The characteristics investigated, in order to provide theoretic disaster prevention and mitigation, and t precipitation and its sediment effect in Wujiang river basin was reference for soil and water conservation, ecological restoration, rational use of water resources. [Methods] The accumulative anomaly curve methods and double-mass curve were used to analyze rainfall characteristics in interannual, chronological and flood seasons, and to analyze the contribution rate of rainfall erosivity and human activities sediment effect. [Results] ① From 1956 to 2014, the annual precipitation and annual erosive precipitation showed a decreasing trend, and the annual precipitation experienced five wet-dry-alternate periods. ② Rainfall occurred mostly in 1970s and 1990s, and about 32. 570//oo of the precipitation caused soil erosion in the basin during the past 59 years. Erosive precipitation occurred mostly in 1960--1979. ③ The precipitation in flood season was mainly erosive precipitation, and the erosive precipitation mainly occurred in June. ④ According to the double mass curve equation, the contribution of precipitation erosivity to river sediment discharge in the last 6 years of 1980s, 1990s and the first 14 years of the 21st century was 15.55%, 2.84% and 12.46%, respectively. [Conclusion] The rainfall erosion and sediment yield in Wujiang river basin occurred more in flood season. After 1983, the variation of sediment ctischarge was mainly influenced by human activities.