Simulation Of The Flood Of Fenhe In The Middle And Lower And Analysis For Ecological Water Demand

Fenhe river in the middle and lower is located in the loess plateau in China, belongs to the arid and semiarid regions, interannual variation and seasonal changes of the runoff of Fen river are larger, flood period generally happens in7-9months, has the large flow of flood peak and short duration characteristics. Therefore, using numerical simulation to forecast the process of flood evolution, is of great significance for flood control and disaster mitigation. In order to meet the requirements of flood control and irrigation, after the liberation, people carried out a large scale management on fen river, established Fenhe Reservoir, Wenyuhe reservoir, a dam, two dam irrigation water conservancy project project, at the same time, utilization of water resources of fen river has been greatly improved.With the rapid development of social economy, the speeding up of the process of urbanization, human activities have serious effect on the fenhe river and the surrounding wetland habitat, leading to discontinuous flow, deterioration of water quality. In the development of economy, at the same time, the protection of the ecological environment is a problem that needs urgently to be solutioned, the estimation of the river ecological water demand is the basic research.In this paper, according to the characteristics of the middle and lower reaches of fenhe, basing on flow continuity equation and motion equation, the one-dimensional flood model is established. lancun-YiTang Of fenhe has carried on the numerical simulation, and combining the ecological indicators, using the hydraulics model, analysising the river ecological water demand from different angles. The specific work and the main conclusions are as follows:1、Retrieving and reading related literature, comprehensing research of one-dimensional flood routing simulation, summarizing and reviewing the ecological water demand estimation method. And on this basis, the analysis of ecological water demand combining with the water dynamics model and the ecological index is proposed;2、Establishing a one-dimensional flow numerical model, the motion simulation and one dimensional model of fenhe river flood routing LanCun YiTang148km river on the flood numerical simulation of the process, and are compared with those of the hydrological stations of the flood process analysis, to verify this model; establish the numerical model of one-dimensional water movement simulation, and using the one-dimensional flood routing model for numerical simulation of the148km reach LAN Cun-Yitang of Fenhe in flood process and, analysising the result and the flood process of hydrological observation stations,and the model is verified;3、Analysising the flow characteristics of the process of the typical flood, changes of the beach area, and the change of average flow velocity of the section etc.,the results slow that it can ensure diverse habitats of water variations in the river during the flood;4、Applicating the one-dimensional numerical model, in order to reach the indicator ecological flow, the outlet section of the channel does not block having0.1m as control condition, ecological water demand of the fenhe is2.65m3/s;5、Combining ecological flow velocity and water depth, using water depth of80%of the river is greater than0.1m and90%of average flow velocity is greater than0.3m/s as control condition, by using the model to analysis the ecological water demand, calculating the ecological water demand of the river is5.00m3/s;6、The analysis results are close to the results of estimation method of the current ecological water demand needed to maintain aquatic ecological stability. the method of calculation of ecological water demand of the river is credible. Especially for specific protection goals,the ecological water demand analysis is more scientific.