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Understanding the driving factors (precipitation variation, land use changes and check dams) and mechanisms behind the changes in sediment load of a Loess watershed, China
  • Xiang Zhang,
  • Dongli She,
  • Guangbo Wang
Xiang Zhang
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau
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Dongli She
Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China, Ministry of Education
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Guangbo Wang
Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China, Ministry of Education
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Abstract

Soil and water conservation measures, especially reforestation and check dam construction, have been progressively implemented on the coarse sandy hilly catchment region of the Yellow River basin for several decades, and climate conditions are also dynamic. Therefore, it is very urgent to understand how the precipitation variation, land use changes and check dams affect soil erosion and sediment yield in a large watershed. The sediment delivery distributed (SEDD) model was employed to quantitatively identify the impacts of the three factors on soil erosion and sediment yield in the Kuye River watershed. Significant land use changes, with the conversion of arable land and bare land to vegetation cover and construction land, occurred in the study watershed from 1987 to 2016. In addition, 306 key dams were built in the watershed, with a total storage capacity of 316.64 Mm3, according to the statistical data of 2011. Hot spot analysis showed that the high-risk regions for soil erosion and sediment yield were mainly concentrated in the middle reaches of the watershed. The simulation results showed that the check dams were the dominant factor, reducing total sediment load by 53.77% in 2006. However, from 1987 to 2016, the contribution of these three factors (precipitation variation, land use changes and check dams) to sediment reduction was 29.10%, 40.09% and 30.81%, respectively, which indicated that all of them had significant influence on sediment load. The results can serve as a reference for watershed management and policy implementation.