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| Change in runoff and sediment in the upper catchment of Beiluo River under the vegetation restoration |
| (1.State Key Laboratory of Soil Erosion and Dry Land Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi; 2.Graduate University of the Chinese Academy of Sciences,100049, Beijing; 3.College of Resources and Environment, Northwest A&F University, 712100, Yangling, Shaanxi: China) |
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Abstract Grain for Green program since 1999 resulted in a great land use/cover changes in the Loess Plateau, China, which fundamentally influenced hydrological cycle and sediment transportation. It is important to understand the impacts of soil and water conservation measures on the streamflow and sediment load in the catchment. The double accumulative curve and Pettit Test method were employed to identify trend and change point in the runoff and sediment in the upper catchment of Beiluo River from 1980 to 2009. Combined with the data of climate change and measures of soil and water conservation, the runoff and sediment process at monthly and yearly scales were analyzed. The result showed that: 1) the change points in 2002 was detected for both runoff and sediment. Compared to period 1(1980—2002), the volume of runoff and the sediment discharge in period 2(2003—2009)decreased by 0.32×108m3, 0.29×108t respectively, and with less fluctuation. 2) At monthly scales, the patterns of monthly rainfall amount and monthly mean volume of runoff in both periods were similar. The relationship between monthly mean volume of runoff and sediment delivery was showed as clockwise 8, but the varying ratio was different.3) Compared to period 1, the annual average rainfall amount and the annual average rainfall erosivity increased by 10.06% and 10.28%. The rainfall has the potential capability of reducing the runoff and the sediment .Regardless of the effect of rainfall, the effect of reducing runoff and sediment by forest and grass measures were about 41% and 81%, respectively.
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Received: 04 July 2012
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