Study On Fuzzy Set And Risk Analysis Theory For Reservoir Forecasted Flood Operations And Application

As one of the main structural flood control measures, reservoir plays an important role in national economic development and social stability. Rational reservoir forecasted flood operations may effectively handle or mitigate the main contradictions existed in reservoir flood operations, and may favor the effective integration of flood control and beneficial functions of reservoirs.Based on a summary of the task, classification and main characteristics of reservoir flood operations, the applications of fuzzy set and risk analysis theory to reservoir flood operations are first generalized in this paper, and then the tendency of reservoir flood operations is pointed out. Aiming at the information complexity, the fuzzy phenomena and risk analysis problems are mainly investigated, and the research results are listed as follows.(1) With a brief review of fuzzy clustering theory development and an introduction of fuzzy clustering iterative algorithm, correlated coefficient-based cluster validity functional is presented, and then the followed experimental analysis and flood clustering analysis testify the efficacy and applicability of the proposed functional.(2) On the basis of the analysis of the existing problems in the design for reservoir flood operations, the classified design method for reservoir forecasted flood operations is proposed. Founded upon the observed hydrological data, floods are analyzed in an integral way. Taken the weather system and rainfall intension into consideration, the classified dispatching rules are determined for reservoir forecasted flood operations through regulating the forecasted floods with different weather systems. Taken Biliuhe reservoir as an example, the flow for determining the classified dispatching rules is systematically illustrated, and the applicability of the proposed method is testified.(3) Aiming at the group decision making characteristic of reservoir flood operations, and on the basis of multiobjective semi-structural decision-making theory proposed by Professor Chen Shouyu, a mathematical transformation is introduced to convert thefuzzy judgment matrices provided by the decision makers into those with complete consistency, and then a simple weighted method is applied to integrate group decision makings into decision makings with single decision maker, and tries to extend the decision making theory proposed by Chen into group decision making environment.(4) With a summary of the existing problems in reservoir flood operation risk analysis and the current research of fuzzy risk analysis, possibility-probability risk analysis method is introduced for reservoir flood operation risk analysis, and the precision analysis of rainfall forecast for Baiguishan reservoir is provided as an example to illustrate the application of the presented method. With a feature of simple concept, clear mathematical logic and easy computation, possibility-probability risk analysis method is particularly suitable for small sample problems with scant history data.(5) With the method proposed by Professor Wang Bende for the computation of the limiting risk rate, the concept of the allowable limiting forecast errors in design manner is given, and the quantified formulae for the risk degrees of both reservoir and downstream area are yielded. Meanwhile, the basic flow for reservoir flood operation risk analysis and the principle and method for the allowable limiting forecast errors in design manner are presented. Taken Biliuhe reservoir as an example, flood operation risk of both reservoir and downstream area is calculated, and the computation results are discussed, too.Finally, the concluding part is given, and some problems to be further investigated are discussed.