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| Effect of soil and water conservation on runoff and sediment in Pianguan River |
| Wang Fei, Mu Xingmin, Zhang Xiaoping, Li Rui |
| Institute of Soil and Water conservation, Chinese Academy of Sciences and Ministry of Water Resources, Northwest Sci-tech University of Agriculture and Forestry, 712100, Yangling, Shaanxi, China |
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Abstract Soil and water conservation is a significant measure to regulate runoff and sediment. The area of soil and water conservation increased from 1万1593hm2 in 1959 to 5万5338hm2 in 1996, accounting for 28.90% of the whole area. The annual runoff amount and constant runoff amount have significantly negative correlation with year and all soil and water conservation measures. The relationships between annual runoff amount and annual precipitation, precipitation in flood period （during May to September） and effective precipitation （daily amount more than 10?mm） are very significantly positive, but the relation of constant runoff amount with annual precipitation, precipitation in flood period and effective precipitation are weak. The water surface evaporation in Pianguan River basin decreased annually, but the trends of runoff and sediment were not increased because of the soil and water conservation. Annual runoff, runoff and sediment in flood period varied in the same trend that they have positive relationship with annual precipitation, precipitation in flood period and effective precipitation, but negative with areas of soil and water conservation measures.
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Received: 05 January 2005
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