Operation Rules Of Cascade Reservoirs In Wet Season Considering Flood Forecast And Early Warning

In the context of global warming,with the influence of extreme precipitation events and human activities,the river basin will face more pressure from flood control,especially in the wet season,is a flood-prone period.Cascade reservoir in the area of flood control has a significant role by combining scheduling,which can effectively decrease flood peak and delay flood process,thus,it effectively reduces the risk of flooding.The study takes the upper Yellow River cascade reservoir as an example.Deriving the design flood,building an optimal scheduling model to solve the optimal scheduling process of design flood,based on reservoir real-time conditions,reservoir capacity,optimal scheduling result and other index,define the reservoir warning grade to guide reservoir operation,and combined with flood forecasting model.Finally,realizing flood scheduling of cascade reservoir in floor period which considered flood forecasting and warning.In order to enriched the theory of reservoir operation and provide reference for other cascade reservoir.The main result are as follows:（1）Based on flood peak,volume and shape error indexs,the multi-objective equilibrium optimization method（MOEO）is proposed for deriving the design flood.The MOEO method has a better accuracy than other common methods,the method can satisfy the constraints of peak flow and interval flood volumes.It is unnecessary to manually smooth calculation or adjust the index of the algorithm.The method effectively reduces the complexity and uncertainty in computing design floods.（2）Considering historical meteorological and flow factors,the forecast factors were select by stepwise regression analysis,multiple linear regression（MLR）,support vector machine（SVM）and back propagation（BP）neural network were used to forecast flood in wet season.The evaluation result shows that BP neural network model is the best method for flood forecasting.（3）The joint scheduling model was built,which considered the flood control and profit objectives of cascade reservoir,and the fitness function was improved by step scheduling method.The step scheduling method takes the difference value in outflow volume for each phase as decision variables,which is not only achieve optimization objectives but also ensure the uniform outflow process of cascade reservoir.The model can achieve the effect of stable outflow while ensuring the goal of reservoir flood control and utilizable benefit.（4）Based on reservoir flood control safety factors,a flood control status matrix was established,which can reflect reservoir comprehensive flood control pressure,combined with the optimal scheduling process of design flood to divide the warning grades.The warning grades can guide reservoir to outflow.Finally,flood warning scheduling strategy was established,and combined with flood forecasting model to built the operation rules of cascade reservoirs in wet season.The effect of operation in flood season mainly have been studied.The result shows that:the rules could better play the beneficial role of reservoirs and better than conventional scheduling rules.（5）The real-time flood in wet season were used to confirm the feasibility of operation rules,which consider the uncertainty of reservoir inflow.The result shows that:the rules can ensure the flood control safety of reservoir and achieve benefit objective,which has scientific and operability.It can effectively relieve the contradiction between flood control and profit of cascade reservoir,rational utilization flood resources.