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| Review of the effects researches of soil and water conservation on sediment reduction in the middle reaches of the Yellow River |
| Kang Lingling1,Zhang Shengli1,Wei Yichang2,Liu Xiaoqiang1,2 |
| Kang Lingling1,Zhang Shengli1,Wei Yichang2,Liu Xiaoqiang1,2 |
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Abstract The effects of soil and water conservation on sediment reduction in the middle reaches of the Yellow River relate to the overall strategy of the river harnessing.Review of the effects researches of soil and water conservation on sediment reduction,therefore,has a significant reference value for the ongoing revision of comprehensive planning of the Yellow River.The studies of the role of water projects and soil and water conservation on sediment reduction have shown that about 510 million tons of sediment had been impounded each year during 1996-2000,including 100 million tons(19.6%) impounded by reservoirs of the main stream,120 million tons(23.5%) by reservoirs of tributary treams,60 million tons(11.8%) intercepted by irrigation system,200 million tons(39.16%) by warping dams,and 30 million tons(5.9%) by terrace.This ratio of sediment intercepting had changed in the 1980's and 1990's,the proportion of sediment intercepting of water projects had changed a little,while the proportion of water and soil conservation had reduced.The studies also show that about 300 million tons of sediment was intercepted annually by water projects and water and soil conservation in the middle reaches of the Yellow River during the 1970's-1990's,and the figure is 350 million-450 million tons now.To the effects of water projects and soil and water conservation on sediment reduction,we consider that the storm intensity is decreased in the soil erosion area of the Loess Plateau in recent years,therefore the data of measured incoming sediment cannot be used as main basis in calculation of current sediment reduction effects of soil and water conservation in revision of comprehensive plan of the Yellow River.The main reason for this is that,the changes of incoming sediment in the middle reaches of the Yellow River depends on the combination of many factors.Therefore,the effects of soil and water conservation on sediment reduction should be studied from now on and for a long time.
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Received: 23 June 2009
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