Research And Application On Flood Prevention Forecast Operation And Flood Disaster Evaluation

Not only do severe flood disasters happen frequently, but also there are alarming drought problems in our country. In order to control flood and relieve drought simultaneously, to make good use of the resources of a flood, and to promote the harmonious coexistence between human and nature, our department of water conservancy has recently carried out a series of exploring research on the subject of utilizing flood resources together with some universities and institutes, of which there is one called dynamic control of limited water level of a reservoir. This paper chooses Shenwo reservoir, a typical representative of reservoir group project, as a project background, to study the method of flood prevention forecast operation and the corresponding risks of a reservoir in a group, the optimal choice of limited water level plans in real-time operation, and the integrated evaluation of a disaster. The main contents and achievements are below:(1) Having analyzed whether Shenwo reservoir has the basic conditions to actualize flood prevention forecast operation method or not, through analyzing the hydrological and meteorological forecast decision of Taizihe basin, where Shenwo reservoir is located. The conclusion that control index to Shenwo reservoir operation is flood volume is drawn through analysis and calculation. After analyzing the precision of runoff forecast in Guanshen area and Tanghe reservoir, we draw the conclusion that the information of runoff forecast in Guanshen area and Tanghe reservoir can be utilized in Shenwo reservoir operation. In addition, through the analysis of short-term meteorological forecast data of Shenwo reservoir, we know that the forecast information of flurry or no rain can be used in Shenwo reservoir operation. These two conclusions provide fundamental materials and basis for the following research.(2) After analyzing the areas and flood composition which should be considered to study flood prevention forecast operation rule of Shenwo reservoir, a kind of forecast operation rule which can operate reservoir in a group according to the information of flood composition. In order to guarantee the safety of Shenwo reservoir and its downstream, the rule has considered controlling the discharge by degrees, and adding certain safe leeway to the forecast indices; at the same time, to make sure the safety of the upstream, the rule takes the actual inflow and water level of Shenwo reservoir as the auxiliary indices. Through regulating the reservoir group integrally with Guanyinge reservoir and Tanghe reservoir actualizing the conventional operation method and Shenwo reservoir actualizing flood prevention forecast operation method, the limited water level of Shenwo reservoir can be raised from 86.20 meter to 88.90 meter. After Shenwo reservoir actualizing flood prevention forecast operation method, not only can thewater supply profits be raised, but also the flood prevention standard of downstream city can be raised from a recurrence of 200 years to 300 years. The limited water level of Shenwo reservoir can be raised to 92.10 meter maximally when considering the compensatory storage of the upriver Guanyinge reservoir and regulating the two reservoirs integrally.(3) The risks of reservoir self and its upstream & downstream are studied when reservoir actualizing flood prevention forecast operation method. The risks of limited water level, dam safety and anticipant errors are calculated according to the definition of limited water level and dam safety which is brought forward by Professor Wang Bende. The risks of downstream caused by runoff forecast errors are calculated according to the associated probability distribution of runoff forecast errors and design flood volume. Considering the complexity of combination of flood composition and runoff forecast errors, stochastic simulation method is used to analyze the risks of flood prevention forecast operation method relative to conventional operation method. A method to deal with runoff forecast errors is put forward. To resolve the problem of lack of enough typical flood data, a method which takes the place of several historic typical floods with various flood composition is brought forward.(4) Having studied the permissive control range of limited water level of a reservoir and built up a model of optimal choice of limited water level control plans. The upper limit of permissive control range of limited water level is ascertained according to the restriction of pre-discharge capability- A permissive control range of limited water level has been formed with the limited water level ascertained by flood prevention forecast method as the lower limit and the limited water level calculated by pre-discharge capacity as the upper limit Taking the typical flood for an example, a model of choosing optimal water limited level plan which can consider real-time information, forecasted information and the decision-maker' favor to profits and risks in real-time operation.(5) Having built up an integrated evaluation model of flood disaster based on projection pursuit technique. Projection pursuit is an exploratory data analysis method, which is driven directly by the swatch data, and has the ability of approaching general nonlinear mapping and classifying. An integrated evaluation model of flood disaster based on projection pursuit technology is built up, which takes the decision-maker's personal interference with one or some indexes into consideration. The model can resolve the weight by considering the precision-maker's favor. The optimization problem of objective function of the model is studied emphatically. Since the objective function is multi-peak function and contain some restrictions. It is difficult to get the optimal solution by using the traditional optimization method or regular genetic algorithm. An intermixed algorithm which embeds traditional optimization method inthe regular genetic algorithm is built up. The intermixed algorithm resolves the optimization problem of the model effectively and provides an effective algorithm to resolve the problem which is multi-peak and contains several restrictions.In the last part, having made the summary of the whole paper and brought up some expectations concerning the researches in the paper.