Variation Law Of Runoff And Sediment And Its Response To Climate Change And Human Activities In Xiangjiang River

River Basin is an ecosystem that is sensitive to climate change and human activities, and the runoff and sediment are the most active part. Along with the global climate change and human activities, the runoff and sediment in the Xiangjiang River has the characteristics of uneven distribution of seasonal and large inter annual variation. The Xiangjiang River Basin as the research object by analysis of runoff and sediment variation and its influencing factors, in-depth understanding of the variation of the basin water cycle, can provide with Xiangjiang River Basin water resources development, utilization and management of important theoretical basis and practical support holders.Using 1951-2014 years of Xian Tan Railway Station hydrological data,1957-2014 years of Changsha Railway Station, Zhuzhou Railway Station, Yong Zhou Railway Station, Xiang Tan Railway Station meteorological data by moving average method, Mann Kendall mutation test, wavelet analysis method and cumulative amount of the rate of change of slope and method analysis the Xiangjiang River basin runoff and sediment of the annual and interannual variation, draws the following conclusion:(1)The regularity of annual distribution of runoff and sediment.The regularity of annual distribution of runoff and sediment was analyzed by using the percentage of distribution,the percentage of annual variation amplitude,the variation of the year, the distribution process and the uneven coefficient, The results show that the distribution of runoff and sediment in the Xiangjiang river basin is uneven in the year, runoff is mainly concentrated in 4-6 months, sediment concentration is mainly concentrated in 4-8 months;The seasonal variation of runoff and sediment is large, and the distribution of uneven coefficient and Cv is 0.59 and 1.09 respectively;In spring and summer, the runoff and sediment yield were the most, and there was less in autumn and winter;The interannual annual variation of runoff is little and Cv is 0.25, the interannual variation of sediment transport capacity is larger and Cv 0.52;There is a certain correlation between the sediment discharge and runoff in the Xiangjiang River Basin, which is satisfied with the rule of "the water is big, the sand is big, the water is small, the sand is small".(2)Variation trend of runoff and sediment time series.The trend, abrupt change and periodicity of runoff sediment were analyzed by the moving average method, M-K mutation testing method, accumulative anomaly method and wavelet analysis method.The overall rising trend of the runoff is weak, the mutation occurred in 1991, there are 4-6 years, 9-13 years, 30-35 years, 3 types of scale cycle changes. The sediment yield was significantly decreased, and the abrupt change points were in 1984 or so, and there existed 4 kinds of scale periodic changes of 3-5, 9-13, 18-22 and 30-35.(3)Analysis of influencing factors on variation of runoff and sediment in the Xiangjiang River Basin.There are many reasons for the change of runoff and sediment in the river basin, the most important one is climate change and human activities in two aspects.Climate change is mainly the precipitation and air temperature, while the precipitation plays a decisive role in the process of runoff and sediment variation;Human factors mainly include three aspects: production and living water, water and soil conservation measures, and water conservancy projects. The contribution rate of climate change and human activities are separated by the rate of change of accumulation slope. The results showed that the contribution of climate change and human activities to the runoff change in Xiangjiang basin was 56.94% and 43.06% respectively, and the contribution rate of the change of sediment transport rate was 9.6% and 90.4% respectively.