Research Of Flood Control Forecast Operation Mode Of Biliuhe Reservoir In Consideration Of The Impact Of Water Conservancy Project In Upstream Basin

At present,China is facing the problems of conflict between supply and demand of water resources and low utilization rate of water resources.It is a way to alleviate water resources problems in China by reasonably regulating natural runoff according to control and application methods through reservoir forecasting and dispatching,and giving full play to the benefits of flood control in reservoirs Important means.At present,the Biliuhe Reservoir has implemented the flood control forecasting and dispatching method.However,with the completion of the Yushi Reservoir in the upper reaches of the watershed,the underlying surface conditions of the watershed have undergone tremendous changes.The original flood forecasting methods and methods of forecasting and scheduling do not conform to the actual conditions of the watershed.Therefore,it is necessary to study and develop the flood forecasting method considering the influence of upstream water conservancy projects according to the characteristics of the basin's runoff generation and confluence,and on this basis to re-study the reservoir's flood forecasting and dispatching methods and analyze the risks of the flood control and forecasting dispatching methods.The main research contents and research results of this article are as follows:(1)Divide the 24 historical flood data of the Biliuhe Reservoir into two parts with the construction time of the Yushi Reservoir as the boundary The results of 15 floods in Xin'an River show that the simulation prediction of the sub-unit model of Xin'an River is good,and the passing rates of runoff and confluence simulation have reached 100% and 86.7%,respectively.By analyzing the simulation results of 9 floods after the construction of the Yushi Reservoir,the Xin'anjiang model was improved according to the interception and storage effect of the Yushi Reservoir,and the 9 floods after the construction of the Yushi Reservoir were re-simulated.The qualified rate of current forecast is increased from 77.8% to 88.9%,and the qualified rate of confluence forecast is increased from 55.6% to 77.8%.The forecast accuracy can meet the needs of the flood control forecast dispatch of Biliuhe Reservoir.(2)Through the improved flood forecasting model in Chapter 3,the design flood process considering the influence of upstream water conservancy projects was deduced using the net rain information,on the basis of which the rules for flood forecasting and dispatching were improved and the improved flood forecasting and dispatching methods were developed.Comparative analysis of the scheduling results.The results show that the improved forecasting scheduling method in this paper can effectively increase the profit-making benefits of Biliuhe Reservoir while not reducing the flood control benefits of the reservoir dam and the downstream flood control targets.The flood-limiting water level of Biliuhe Reservoir can be increased from the original 68.8m to 69.0m.Under the circumstances of ensuring flood control safety and post-flood storage,the reservoir's water storage capacity can be increased by 11.08 million m3 compared with before.(3)Based on the principle of maximum entropy,study and analyze the distribution law of the net rain forecast error in Biliuhe Reservoir,determine the error domain of the net rain forecast,and use this as the basis to calculate that the reservoir encounters different sizes in the forecast information.When the error occurs,when the reservoir conducts flood control operation for design floods with different frequencies through the flood control and dispatching method developed in this paper,the maximum risk level of the reservoir water level during the flood adjustment process exceeds the original design characteristic water level risk rate.The results show that it is safe for the Biliuhe Reservoir to adopt the forecasting and scheduling method improved and formulated in this paper for the flood control operation with the starting water level of 69.0m.When the flood control and scheduling method is improved and formulated in this paper,the highest water level of the reservoir during the flood control process is used.The risk rate of each characteristic water level exceeding the original design is lower than the designed risk rate,and compared with the original design of the dispatching method,the flood control risk of the downstream protected objects will not increase.