Study On Treatment Direction Of Coarse Sand Area In Middle Reaches Of Yellow River

This paper took the coarse sand area in the middle reaches of Yellow River as study object where the sediment delivery modulus of sand grain size more than 0.1mm is over 1400t/km~2 .a. The area is such an area that soil and water loss is the most serious, the ecological environment is the weakest, and the silting influence to main stream reservoir and channel of the lower reach is the most serious in the Yellow River basin. The coarse sand area is only 18,800 km~2 which takes 2.9% of the loess plateau. While the sediment discharge reaches to 408 million tons by taking 21.7% of the whole basin during the same period (from 1954 to 1969). The coarse sand discharge is 61 million tons by taking 56.5% of the relevant sand grading sediment discharge.This paper considered the environmental factors such as stratum, landform, topographic feature, soil, vegetation, climate, economy, society and erosion force etc. The paper studied and analyzed regional environmental features of soil erosion and sediment yield and put forward the principle, method and result of regional treatment zone. The area is divided into three, loess area, soft rock area and sand-covered area. This study provided scientific basis for regional treatment and coarse sediment control delivering into Yellow River. The paper also studied and analyzes the adaptability of warping dam (system), sediment retention dam and treatment measures on slope land in the different current treatment situation by using the methods of characteristic value analysis, typical analysis and on-the-spot survey. This study provided the scientific basis for the determination of regional treatment direction. According to the regional possible sediment reduction capacity, the paper advanced the treatment target, basic mentality, key measures, layout and disposing ways by aiming to the regions and varied treatment area. The study provided realistic guidance in regional soil conservation planning, treatment measure layout and investment steering; in accelerating regional soil conservation progress; in intercepting and reducing coarse sediment discharging into Yellow River concentratively, quickly and effectively; in slowing down silt deposit in main stream reservoir and river channel of the lower reaches of Yellow River; in mitigating natural disaster and promoting overall improvement of regional ecological environment as well as sustainable economic and social development; and in keeping healthy life of the Yellow River.