Study On Real-time Control Of Water Level In Flood Season Of Shenwo Reservoir

The water shortage problem in north China is very prominent.The distribution of water resources is very uneven in the year,and about 70%of water resources are concentrated in the flood season.Theory and practice show that use of the existing reservoir project,through the real-time dynamic control of reservoir flood season,without additional flood control risk at the same time,improve the efficiency of flood resources utilization,is an important non-engineering measures to improve the utilization ratio of water resources,the core is make full use of short-term rainfall forecast information and flood forecast information.Up to now,there have been three changes in the research and application of dynamic control of reservoir flood control:first,the demand for water resources is increasing;second,the characteristics and conditions of reservoirs(or basins)are changing;third,the acquisition of forecast in formation is more diversified.The research and application of dynamic control of reservoir flood control level should adapt to the above three changes.In this paper,based on the research results of dynamic control of flood limit level in the early stage of The Test with Respect to the changes of The test,the original results of flood control are no longer applicable to the test.At the same time,there are new changes in rainfall forecast products,and the time scale of rate cut forecast information is longer.Firstly,the availability of the forecast products of the ECMWF(European Centre for Medium Range Weather Forecasts)in the Test area is analyzed,and the coupling utilization of rainfall forecast information in different time scales is analyzed.Secondly,the dynamic control domain of flood limit water level of the Test block reservoir is determined by using the improved flood prediction and dispatching method and the improved pre-discharge capacity constraint method.The pre-discharge and recharge method is used to reduce the water level in flood season,and the corresponding dynamic control scheme of flood limit water level is established.Finally,the feasibility of dynamic control scheme of corresponding flood limit level is analyzed with an example of a flood.The main achievements are as follows:(1)Shenwo reservoir sedimentation in the relationship between the capacity of the water level important characteristic curve obvious changes in the status quo,holding characteristics of the reservoir,reservoir downstream in the cross section of the control flow constraints such as the same,using new water capacity curve,review regular of the goddess of mercy pavilion reservoir,Shenwo reservoir scheduling group of flood forecast and reservoir dispatching mode.The results show that,with the silting up of The Reservoir,the original research results of routine dispatching,flood control prediction and regulation of water level in flood season do not meet the requirements of the original design,and the flood limit water level determined by the current conventional flood control dispatching method is too low,resulting in high water supply pressure of the reservoir.Therefore,there is an urgent need to study the new regulation of flood control prediction and operation in order to increase the pre-discharge and raise the flood limit water level in order to meet the new situation of reservoir silting.(2)Analyze the availability and coupling utilization of rainfall forecast information at different scales such as 24h,48h and 72h.Firstly,the length of rainfall sample data series is extended by comparing with the period of May to September of each year in 2008-2015.The period of study is The Period of May to September of each year in 2008-2021.Based on the rainfall forecast information of corresponding periods and regions issued by THE ECMWF,rainfall grades are classified by Using Pearson typeⅲdistribution curve.Secondly,using frequency analysis and error statistics method,three rate analysis of rainfall forecast information under different forecast periods is carried out to quantitatively analyze the accuracy of rainfall forecast.Finally,by analyzing the availability and distribution of rainfall forecast information in different forecast periods,the utilization mode of coupled large-scale rainfall forecast information in different time scales is studied.The results show that with the extension of rainfall sample data,the overall change of rainfall forecast accuracy is not obvious,and the rainfall forecast level in the longer forecast period does not reach the degree of direct utilization.Therefore,it is necessary to study the utilization mode of coupled rainfall forecast information at different time scales.In the actual scheduling stage,when the rainfall forecast for 24h is the"Ⅲ"magnitude rainfall,The reservoir can discharge water in advance according to 5～10mm rainfall;When the predicted rainfall of 24h is the"IV"magnitude rainfall,the reservoir can refer to the rainfall of 10～15 mm in advance.(3)Shenwo reservoir dynamic control original research results is not applicable,first of all,according to the sedimentation Shenwo reservoir,after the reference to forecast flood dispatching rules before deposition,to a certain correction,to forecast flood dispatching rules after sedimentation,and USES the new way of forecasting flood dispatching determine Shenwo adjust the water level of reservoir during flood season high value,An improved pre-discharge capacity constraint method is used to determine the rise value of the initial regulation water level of the block reservoir in flood season.The lower value is taken as the upper limit of the dynamic control domain of the flood limit water level in view of safety,and the dynamic co ntrol domain of the flood limit water level is determined.Secondly,the pre-discharge and recharge method is used to determine the starting regulating water level which can be reduced in the real-time dispatching stage.Finally,a dynamic control scheme of flood limit water level coupled with rainfall forecast information at different time scales was developed,and the scheme was applied to the actual simulation scheduling of"20100819"flood.The results show that the dynamic control scheme of flood control level is feasible.Compared with the conventional control scheme,the maximum flood control level of pre-storage and pre-discharge control scheme is reduced by 1.49m,flood control storage capacity is increased by 16.5×10~6m~3,and the water level at the end of flood control is increased by 1.85m.Finally,the paper summarizes the research results and points out the shortcomings of this research and the problems to be further studied.