View of Silt Trapping Dam in Middle-reach Area of Yellow River
【摘要】：正 The middle-reach area of Yellow River is totally 640,000 km2 with rising and falling ridges and mountains, sparse vegetations and soft loess. The climate here is drought with less precipitation which is distributed unevenly on time and space. The soil erosion is so serious that the erosion area is up to 454,000 km2 with erosion modulus of 1000 t /(km2·a) , occupied 71 % of its total area. About 1.6 billion tons of sediment are poured into Yellow River from this area every year. The significant erosion features of this area are intensity erosion, centralized erosion area, and the sediment produced mainly in gullies. Heavy erosion made sediment disposition on the river course in lower-reach of Yellow River, which have a negative effect to water resources utilization, eco-environment and social development.The silt trapping dam is one of the soil and water conservation engineering built in the erosion gully for impounding flood-water and retaining eroded soil turning wasted land into cultivated farm land. The earliest dam was formed naturally 400 years ago. Since 1950s, the silt trapping dam construction has gotten a wholly development. Up to 2000, 113,000 dams were built in the middle-reach area of Yellow River with the result of over 21 billion tons of silt checked behind the dams, 300,000 hm2 farm land developed in which 20,000 hm2 have irrigation and other 13,333 hm2 arable land in low-reach area under protection by these silt dams.The silt trapping dams have played a great role in the aspects as follows: stopping eroded soils and reducing the amount sediment to rivers, increasing farm land area grains yields, prompting the water resources utilization and providing waters for farmers, increasing the farmer s income and developing rural economy, currying out the state police of 'turning cultivated land to forestry", benefiting to flooding and disaster protection and lessening, the final one is favorable to transportation by dams instead of roads. The summary of main experiences is that it is necessary and important for dam' s construction to build the dams under systematic planning, enhance the organization, make the property right clearly, complete the running mechanism, which all are regarding to the project running efficient and sustainable development.According to the National Eco-environmental Construction Planning and Recent Development Planning on Important Project, of Yellow River approved by State Council, to step up the silt trapping dam construction is the main strategy in middle-reach area of Yellow River, about 60,000 dams will be built recently, and 180,000 hm2 farm land will be developed, the industrial structure and land utilization will be regulated and be more going rationally, farmers' income will be increased, about 800,000 hm farm land will be turned into forestry, the percent of comprehensive control on soil and water erosion will be to 60 % in this area, the serious erosion situation will be harnessed and the environment will be improved significantly, 0.5 billion tons of silt will be reduced to Yellow River.