Research On Flood Control Operation Of Yingnahe Reservoir Coupled With Weather System

Reservoir operation plays an important role in flood prevention and disaster reduction.With the establishment of a modern flood control system,conventional reservoir dispatching methods have been difficult to meet the needs of reservoir dispatching.For small and medium watersheds,the forecasting and dispatching methods formulated based on the current water and rain conditions have problems such as short forecast periods and low forecast accuracy.In recent years,numerical forecasts have gradually been applied to reservoir dispatching.Although the accuracy of numerical forecasts has been improved,the reliability of the rainfall forecast information alone is still low,so the corresponding analysis should be carried out in conjunction with the rainfall weather system.This paper takes Yingnahe Reservoir as the engineering background,analyzes the availability of rainfall forecast information,summarizes the weather system of the basin and the corresponding rainstorm characteristics,and finally focuses on the weather system and formulates the pre-discharge dispatching strategy of the reservoir based on the rainfall forecast information.The main research contents and results are as follows:(1)The use of rainfall forecast information can effectively extend the flood forecast period,but its error is likely to bring certain risks to the flood control operation of the reservoir.This article focuses on the feasibility of the application of TIGGE rainfall ensemble forecast information to the flood control operation of the reservoir.Select the data released by the two forecast centers of NCEP and ECMWF,and use methods such as TS score and Bias score to analyze the forecasting skills and accuracy of the forecast center.Taking the forecast information of the ECMWF Forecast Center with higher forecasting skills and accuracy as the research object,the availability of rainfall forecast information at different time scales in different rainfall stages is analyzed from the aspects of error characteristics,actual rainfall probability analysis,and weather energy release rules.The results show that the 24-hour forecast rainfall in the short-term forecast rainfall can be used to guide the decision-making of the reservoir,but the availability is general,and further consideration should be given to combining the weather system.(2)Since only considering rainfall forecast information does not meet the requirements of flood control and dispatching of reservoirs in small and medium-sized river basins,this paper focuses on analyzing the weather system and the characteristics of the rainstorm affecting the Yingna River Basin,and studying the relationship between the characteristics of the rainstorm and the weather system.The main weather systems that affect rainfall in the Yingna River Basin are summarized,and the similarity method is used to determine the weather system that has the main influence when multiple weather systems are combined.Based on this,the characteristics of rainstorms in different weather systems are analyzed,and the high-altitude situation,water vapor conditions,and dynamic conditions during rainfall are analyzed in combination with examples.The results show that meteorological conditions are closely related to rainfall,and this factor needs to be considered when analyzing rainfall.(3)In order to further improve the flood control capacity of the reservoir,based on the use of rainfall forecast information,this paper focuses on coupling the weather system that affects the rainstorm to guide the decision-making of the reservoir.Analyzing the error between the forecast rainfall and the actual rainfall under different weather systems,the results show that the forecast rainfall is too large.Combine meteorological elements to determine meteorological factors,analyze whether it is beneficial to rain,and determine four different pre-discharge rainfall amounts based on meteorological factors,weather systems,and forecast rainfall.Based on the analysis results,a decision tree that considers the weather system,meteorological conditions,accumulated rainfall,pre-release water,24 h forecast rainfall,and 4d forecast rainfall,is formulated,and five different rainfall scheduling methods are pre-released.The results show that the new dispatch method is used to guide reservoir dispatch,compared with conventional dispatch,it can extend the forecast period,lower the maximum reservoir water level,and reduce flood control pressure.The coupled weather system has a more significant effect in guiding reservoir decision-making.Finally,the full text is summarized,and the issues that need to be further studied are prospected.