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| Contribution rate of driving factors on the rainfall-sediment relationship of Longhe River watershed in the Three Gorges Reservoir region |
| Liu Huiying1, Gao Qiang2,3 |
| 1.College of Hydraulic and Ecological Engineering, Nanchang Institute of Technology,330099,Nanchang,China;2.College of Environrnent,Hohai University,210098, Nanjing, China;3.Yangtze River Scientific Research Institute,430010,Wuhan,China |
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Abstract In order to elucidate the contribution rate of remarkable decline of sediment load in the Three Gorges Reservoir region, this study took the Longhe River watershed, the center of the Three Gorges Reservoir in the upper Yangtze River basin,as an example, revealed the changing trends and mutation points of annual precipitation, rainfall erosivity and sediment load from 1963 to 2010 with the help of universal soil loss equation, simplified model of rainfall erosivity and Pettitt test. The contribution rate of the human intervention to increasing sediment was analyzed when the rainfall erosivity was taken as the indicator of natural factor in whole period with double cumulative curve method. The result showed that there were some mutation points of annual precipitation in 1982, sediment load in 1990 and rainfall erosivity in 2000, respectively. Using the double accumulative curve based on rainfall erosivity vs.sediment, the whole period was divided into four phases: 1963-1981, 1982-1990, 1991-1999 and 2000-2010. The result also showed that the contribution rates of human activity to increasing sediment in the Long River watershed during 1982-1990 and decreasing sediment during 1991-1999 and 2000-2010 were obtained based on the period of 1963-1981. The contribution rates of the human intervention were 106.5% during 1982-1990, 78.4% during 1991-1999 and 67.8% during 2000-2010,compared to that during 1963-1981. While taking rainfall as the natural factor, the contribution rates of human intervention to increasing sediment in the three periods mentioned above were 99.7%, 97.1%and 85.9% compared with that during 1963-1981. Our research proves that human activities such as conservation of water and soil, and water conservancy project, have a significant impact on rainfall-sediment relationship at the Longhe River watershed. The result is useful in correctly evaluating the benefit of of soil and water conservation measures in the similar watersheds.
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Received: 15 January 2015
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