中文摘要：

为了探究降水变化和水土保持措施对黄土高原地区产流产沙的影响,选择我国水土流失最为严重的区域——甘肃省庆阳市的砚瓦川流域为研究区,对该流域1981—2012年的年降水量、年径流量和年输沙量进行趋势分析及突变检验,分析黄土高原沟壑区水土流失治理背景下流域水沙的演变规律,定量评价降水和水土保持措施对流域水沙变化的贡献程度。结果表明：在1981—2012年期间年降水量和年径流量均没有发生显著变化,而年输沙量呈现显著减少趋势,年径流量和年输沙量的突变时间分别在1996和1997年,具有很好的同步性。与基准期（1981—1996年）相比,变化期（1997—2012年）的年径流量和年输沙量分别减少了17.0%和76.0%,分析径流和输沙历时曲线发现流域丰水期和平水期的径流量逐时段减少,而枯水期径流量却持续增加,输沙量在整个时段则大幅度减少。该流域降水和水土保持措施对年径流减少的贡献率分别为-37.9%和137.9%,而对年输沙量减少的贡献率为-35.0%和135.0%,因此,水土保持措施的实施是该流域年径流量和年输沙量减少的主要原因。其中,植被措施（林地和草地）对径流影响显著,占径流减少总量的61.04%;工程措施（梯田和坝地）对产沙影响显著,占产沙减少总量的102.84%。研究结果表明,黄土高原地区水土流失治理已在区域尺度上表现出一定程度上削洪补枯和减少侵蚀产沙的水文效应特征。同时在水土保持措施建设过程中,合理配置植被措施和工程措施比例,充分发挥各项水土保持措施的优势,是开展适应性流域管理的关键。

英文摘要：

To fully explore the effects of precipitation variation and soil and water conservation（SWC）measures on the runoff and sediment yield on the Loess Plateau,the trend analysis and mutation analysis were carried out based on the data of annual precipitation,annual runoff amount and annual sediment yield from1981 to 2012of Yanwachuan basin,which was located in Qingyang city,Gansu province.Yanwachuan basin was the typical meso-scale region on the Loess Plateau and was the most seriously eroded region in China.Therefore,it was of great importance for studying the evolution characteristics of runoff and sediment yield and quantitatively evaluating the effects of runoff and SWC measures on the runoff and sediment yield in this basin.The results showed that there was no significant change in annual precipitation and annual runoff from1981 to 2012,but the annual sediment yield showed a decreasing trend from 1981 to 2012.The change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively,which had a good synchronism.Compared with baseline period（1981—1996）,annual runoff and annual sediment yield of the changing period（1997—2012）reduced by 17.0% and 76.0%,respectively.The duration curves of annual precipitation and annual sediment yield showed that runoff decreased in the flood season and normal season but increased in the dry season in the watershed,while sediment yield significantly increased in the whole study period.In Yanwachuan basin,the contribution rates of precipitation and SWC measures were-37.9%and 137.9%,respectively,to the annual runoff reduction,while they were-35.0%and 135%,respectively,to annual sediment yield reduction.Therefore,SWC measures were the main factor for the reduction of annual runoff and sediment yield in Yanwachuan basin.Impacts of vegetation measures（forestland and grassland）on runoff were significant,accounting for 61.04% of total runoff reduction,while engineering measures（terrace and dam land）had significant effects on sediment yield,a