The River Water Division And Study Of Flood Utilization

Since 1980s, with the development of the social economy, the water crisis has been appearing in many regions in China. Especially at the North of China, the status is more serious. The water shortage not only affects the socioeconomic development, but brings many ecological environment problems. The austere water resources crisis compels people to find resolutions to alter this status. Thus rational arrangement the limited water resources become the first selection, and the broaden sources of income and reduce expenditure of the water is taken into account at the same time. Under this case, the flood water is bringing into the exploitable object. Despite the flood water possesses the property of the water resources, it has the special characteristics different with the common water resources, sometimes which can bring impossible economic losses for the society, as a result the flood water is not the traditional water resources. It has been realized by the academe that flood water can be utilized under certain conditions. And correlation researches have been carried out aiming at the reservoir; many research productions have been obtained for controlling the limited elevation of reservoir. These theory and method have significant importance on the reservoir utilization to realize the application of flood water. However, in some regions, such as the plain country, there is a lack of natural conditions to build reservoirs. The existing theory and method about the application of flood water are not appropriate for such areas. In order to address this issue, this paper presents the new means to realize the application of flood water in the Songnen Plain country. The major contents and research results are as follows:(1) At the point of the river ecosystem balance, river water utilization and flood protection, the theory of the River Water Structure(RWS) can be introduced. The method divides the whole volume of river water into four parts: namely environment water portion (EWP), safety water portion(SWP), risk water portion(RWP) and disaster water portion (DWP). The limit boundaries between the different water portions are the vital factors in the RWS, which can be determined by different methods according to the function and characteristic of different water portions. This theory can quantitatively classify river flood water, and which can provide theoretical source for utilization the flood water.(2) Basing on the theory of the RWS, the river reach RWS model is presented out. Then the calculation methods of flood runoff are put forward, which can evaluate the quantity of the fiver reach flood runoff. And the flood runoff of the whole fiver basin can be evaluated if the fundamental data is sufficient. (3) Basing on the river water resources structural division, the impounding model of utilization flood water for plain region is proposed. Considering the water requirement, potential impoundage and the degree of risk, two modes of the flood water utilization are developed, full impounding and partial impounding. The assessment method of the risk is put forward according to variation of the flood storage capacity before and after impounding water.(4) The runoff forecasting has the important action for utilization the flood water and reducing the flood risk at the same time. Making Use of the software(Mike 11) to simulate the flood hydrograph between the Jiangqiao and Dalai hydrological station, the flood forecasting model can be developed by simulating the course of the measured discharge. This model has a high accuracy standard, which can better simulate the flood course of the Nenjiang River. Many helpful information can be provided be by simulating the flood course of the Dalai hydrological station, which can be acted as the decision parameters during the course of utilization the flood water.(5) Aiming at the risk losses and possible profits during the course of utilization the flood water, the risk-return analysis model can be presented. Using this model to analyze the effect of utilization flood water in Songnen Plain, the results indicate that utilization flood water can bring considerable economic profits for this region.