信江流域水沙变化及其对降雨侵蚀力的响应

信江流域是鄱阳湖的第三大入湖流量支流，其水沙变化直接影响鄱阳湖水文情势。本文基于信江流域7个气象站降雨资料和梅港水文站1960-2014年的径流和输沙资料，采用Mannn-Kendall非参数检验、双累积曲线等方法，研究了流域水沙变化及其对降雨侵蚀力的响应。结果表明：信江多年平均径流量为179.8×108m3，年际呈不显著的上升趋势（P>0.05）。多年平均输沙量为198.9×104t，年际呈极显著下降趋势（P<0.01）。多年平均降雨侵蚀力11 270MJ·mm/（hm2·h），年际呈不显著的上升趋势。输沙量与降雨侵蚀力双累积关系曲线在1999年出现拐点，与基准期（1960-1998年）相比，变化期（1999-2014年）降雨侵蚀力使年均输沙量增加14.0×104t，对输沙量变化的影响程度为10.8%；人类活动导致年均输沙量减少143.5×104t，对输沙量变化的影响程度为-110.8%，二者综合作用导致输沙量减少。水库建设和大规模水土保持措施的实施是信江流域输沙量减少的主要原因，研究成果可为流域水土流失防治、水土资源利用提供参考。

Runoff and sediment load change and its response to rainfall erosivity in the Xinjiang river basin

The Xinjiang river basin is the second largest tributary of the Poyang Lake,whose runoff and sediment variation directly affects the hydrological regimes of the Poyang Lake.This paper investigated the runoff and sediment load change and its response to rainfall erosivity in the Xinjiang river basin based on the rainfall data of seven meteorological stations in the Xinjiang river basin and the annual runoff and sediment load data of the Meigang hydrological station from 1960 to 2014 using Mann-Kendall non-parametric test and double cumulative curve methods.The results showed that the annual average runoff of Xinjiang river was 179.8×108 m3with an insignificant increasing trend (P>0.05).The annual average sediment load was 198.9×104t with a significant decreasing trend (P<0.001).The annual average rainfall erosivity was 11 270 MJ·mm/(hm2·h)and showed an insignificant increasing trend.The double mass curve relationship between sediment load and the rainfall erosivity appeared an inflection point in 1999.Compared with the base period(1960-1998),rainfall erosivity made the annual average sediment load increased by 14.0×104t,and its impact degree on the variation of sediment load was 10.8% during change period(1999-2014).The average annual sediment load was reduced by 143.5×104t due to human activities,and the impact degree on the variation of sediment discharge was-110.8%.As a result,the sediment load decreased.The construction of the reservoirs and the implementation of large-scale soil and water conservation measures were the main reasons for the reduction of sediment load in the Xinjiang river basin.The study results can provide reference for the prevention and control of soil and water loss and the utilization of soil and water resources in the basin.