Analysis Of Sediment Scour And Deposition And Discussion Of Water Environmental Benefit On Rubber Dam's Reservoir In Yan'an City

To improve the water environment of Yan'An city, two rubber dams will be built up on Yanhe River. Based on the measured data of Yanhe basin and large amount of references, Yanhe riverway's evolution law and conditions of sediment after constructing rubber dams are generally analyzed by the methods of calculating and hydraulic model testing. The main findings of this paper are as follows:1. Riverway's evolution laws of Yanhe and Xi'Chuan are analyzed according to the measured data of drainage basin respectively. Riverway's evolution is a circular process. That is to say that depositions appear after erosion, but the degree of scour and deposition changes with the situation of water and sand, and the tendence of scour and deposition towards balance in a long time. The law of riverway's evolution is also approved by hydraulic model test.2. Different methods and partition of period are adopted to calculate depositing of rubber dam reservoirs in the Yan'he River. The result shows that under the condition of scanty data, the formula of Qihua University is more applicable.3. The calculation of backward erosion and streamwise erosion of reservoir sediment showed that the depositing in low water period is swept away in flood season. Based on the results of calculation of runoff and scour, appropriate run pattern is discussed—the runtime of reservoir accumulating water is from October to May of next year. Environmental benefitof reservoir can be realized by discharging sediment in December.4. The simulation of Yan'He riverway's evolution process by hydraulic model test shows that the evolution process is similar to the measured data of Yan'He station. The simulation under the condition of reservoir filled by sediment deposition shows: sediment is washed out partially by flood after the whole flood process. Compared with the results of model test, the outcome calculated by experiential formula is on the high side.5. Using hedonic price method, the environment benefit of rubber dam reservoirs is basically and quantificationally analyzed. The result shows that this project could achieve better environmental and economical effect.