Study On Long-term Runoff Forecast And Reservoir Benefical Operation

Frequent floods disaster, inadequate water resources and deteriorative water ecological environment are great threat to China. Relying on scientific and technical progress, making the best use of water resources socially, economically and ecologically is an important measure to ease Chinese water crisis.As an important non-engineering measure, reservoir forecast operation can ensure flood control safety to a certian extent. On the other hand, it also can increase water resources utilization rate and maximize the reservoir benefit. At present, most of the traditional operation modes only focus on the benefit of flood control and water supply, but eco-environmental water demand of downstream river is often neglected. With the development of society and economy, eco-environment problem attracts more attention, and the contradiction between benefical water supply and eco-environmental water demand has become more observable. So it is urgent to adjust the current reservoir operation mode to improve the eco-environment of downstream river under the existing hydraulic engineering condition.In this paper, eco-environmental objective is incorporated into reservoir operation goals. Firstly, medium and long-term hydrological classified forecast and quantitative forecast are studied to improve forecast accuracy. Secondly, the choice method of normalization formulae and the ideal and non-ideal plans is studied in the multi-objective decision-making method. Finally, based on the runoff forecast information and the multi-objective decision-making method, reservoir benefical forecast operation mode is studied considering the eco-environment objective. Main contents and results are as follows.(1) The feasibility study of utilizing hydrometeorological information.Firstly, the contradiction between flood control, water supply and ecological water requirement is studied. Secondly, the necessity and feasibility of forecast information in multi-objective reservoir operation is analyzed. The feasibility study of applying flood forecast information, short-term and intermediate-term rainfall forecast information to reservoir operation is researched with emphasis.(2) Study on multi-factor classified runoff forecast model based on rough-fuzzy inference method.To solve the problem of complex factors' selection in classified runoff forecast, a multi-factor classified runoff forecast model based rough-fuzzy inference method is created. Firstly, factors are selected and classified with the attributes' importance and relative classification accuracy. Secondly, reduction solution based on rough set theory is used to generate the minimum decision-making rule set. The results indicate that the model can solve the forecast problem related to complex factors' selection effectively.(3) Study on runoff forecast method based on multi-factor wavelet network.In order to improve accuracy of wavelet network long-term hydrological forecast, a runoff forecast method based on multi-factor wavelet network is proposed. Firstly, the wavelet multi-scale decomposition is carried on the original data of runoff and factors. Secondly, the relative relation between factors and runoff is quantified in the wavelet multi-scale space, and multiparty correlation coefficient is used to amend similar extension mode. Fuzzy enhancement algorithm is also proposed to modify large deviation at mutation point in runoff forecast. Finally, parameters are determined with the wavelet network model and the forecast results are gotten with the multiple iterative calculation. The annual and monthly runoff forecast examples of Dahuofang reservoir show the efficiency in the medium and long-term forecast.(4) Study on choice method of normalization formulae and the ideal and non-ideal plans in the multi-objective fuzzy optimization model.Reservoir operation is a fuzzy multi-objective decision problem. So economic, social, environmental and ecological factors should be considered altogether to establish the multi-objective fuzzy optimization model. The choice of normalization formulae and the ideal and non-ideal plans is analyzed and dispersal indices are established to make the approximate choice criterion for normalization formulae to optimize the satisfying decision alternative.(5) Study on reservoir benefical forecast operation mode considering eco-environment objective.This paper analyzes the current eco-environment situation of reservoir downstream river and the characteristic of ecological water requirement. Hydrologic and weather forecast information, reservoir downstream river eco-environment information and the multi-objective decision method are taken into account in reservoir multi-objective benefical forecast operation research. The case study of Dahuofang reservoir shows that the effect of ecological water requirement on the original water supply can be decreased with the benefical forecast operation mode considering ecological objectives.Finally, a summary is given and some problems to be further studied are discussed.