Study On Ecological Water Requirement Within The Downstream Of Fuhe River Channel Based On Runoff Reduction

The water contradiction is becoming increasingly acute, river ecological waterrequirement is occupied and it result in the destruction of the river ecosystem.Therefore, more and more people pay attention to reasonable use of waterresources, the maximum guarantee on river ecological water requirement, andspontaneously, relevant departments must face how to deal with those problems.There are different degree of water shortage in Fuhe river during the dryseason. This Problem is particularly prominent in downstream of Jiaoshi Dam. Andpresent situations of river are large beach nudity, narrow water surface, riverecosystem destruction and the gradual loss of channel function. Lijiadu station actsthe control station of Fuhe river into Poyang Lake. According to statistics, themeasured flow of Lijiadu station is tiny in typical dry year, such as average flowfor96days in1978is less than2m3/s. Minimum flow in1967was only0.059m3/s,it’s almost in a state of cutoff.The small measured flow of the Lijiadu stationoccurs more in each year, from July to October, which is the peak period for thedrainage of Ganfu Plain Irrigation Area, so the small measured flow of the Lijiadustation has the relevant to the drainage of the East and West Main Canal, and thesmall measured flow directly affects river ecological water requirement ofdownstream of Jiaoshi Dam.Measured flow of the Lijiadu station, which is indownstream of Jiaoshi Dam, does not represent a natural river water. Somescholars calculated ecological water requirement for the downstream of Fuhe Riverbasing on the measured flow of the Lijiadu station, and the calculation result wassmall.Therefore, runoff reduction of Lijiadu station and the analysis, which isaccording to the runoff reduction, on ecological water requirement for thedownstream of Fuhe River has important significance.In this paper, runoff reduction calculation of Lijiadu station adopted4 methods: Xin’anjiang model, BP neural network model, method of flow incorrelation about upstream and downstream and hydrological analogy method.According to runoff statistics of Lijiadu station from1960to2008after runoffreduction, the average annual measured flow of4methods is successively:489m3/s,525m3/s,494m3/s and492m3/s. The results of them approached each other, so thereduction results of calculation is reasonable. Xin’anjiang model is generallythought a hydrological model with higher reduction (forecast) accuracy. Therefore,this paper adopted the result of Xin’anjiang model. Compared with the averageannual measured flow(389m3/s), from1960to2008, the calculated flow (489m3/s)by Xin’anjiang model is increased by25.7%. The average annual calculated flowfrom1953to2008by Xin’anjiang model is491m3/s.To calculate Fuhe river downstream of ecological water requirement in theriver, the study used these methods: frequency calculation method from month tomonth, Tennant method, the minimum monthly average flow method, the most drymonth average flow method nearly a decade, and so on. Basing on the analysis ofFuhe river downstream river mainstream ecological water requirement, waterrequirement of river basin water surface evaporation and leakage of channel waterrequirement, the calculated result of Fuhe river downstream of ecological waterrequirement in the river is67.9×108m3a year, and the minimum month ecologicalwater requirement of flow is67.1m3/s.The result to the river ecological water requirement after runoff reduction forLijiadu station in this study, is more in line with the river ecological waterrequirement in the actual, and it studied the improvement measures and safeguardecological water requirements for the downstream of Fuhe river, providing thebasis for water resource management, reasonable and efficient utilization.