Study On The Flood Season Staging And Limited Water Level Of Xidayang Reservoir

With the rapid development of social economy,the demand for water resources in our country is increasing.Comprehensive utilization of reservoirs can store and detain floods to protect the lives and properties of people downstream,and at the same time can further solve the problem of regional water shortages through rational dispatch.The Tang River Basin,where the Xidayang Reservoir is located,has obvious seasonal characteristics of precipitation during the year.Floods in the flood season are mostly caused by several typical rainstorms,and the regional flood control risks cannot be ignored.At the same time,the area has a large population and a large demand for water resources.Improving the efficiency of water use and avoiding water waste is the key to coordinating local development.Under the existing conditions,by setting a reasonable staged flood limit water level,achieving the goal of blocking floods at the end of the flood season and increasing the full rate of reservoirs is of great significance to solving the problem of regional water shortages.This paper takes the utilization of flood resources as the research purpose,takes the Xidayang Reservoir as the research object,and controls the flood risk as the scheduling bottom line.It starts with the flood season staging indicators of the Xidayang Reservoir.Analyze and study several aspects of the staged flood limit water level estimation.The main research contents and achievements are as follows:(1)The commonly used flood season staging indicators at the current stage are summarized.Aiming at the complex and redundant relationship between the indicators,the method of index evaluation and screening in the synergy theory is introduced,and ten indicators that can represent the characteristics of the flood season are selected.The maximum irrelevance method is used to analyze and calculate the correlation between each index and the index group,and the key indicators that affect the flood season staging of the Western Dayang Reservoir are obtained.They are: the maximum 1d surface rainfall in ten days,the number of heavy rain days in ten days,and the maximum peak flood discharge in ten days.,The maximum 3d flood volume in ten days,the number of times the maximum flood peak occurs in ten days,and the average inbound flow in ten days.(2)According to the results of index screening,apply the Fisher optimal segmentation method to the filtered staging indicators for flood season staging.At the same time,the fuzzy statistical method was used to calculate the daily precipitation by stages,and the results of the two stages were compared and analyzed.Among them,the Fisher optimal division method divides the flood season into four segments,namely:June 1 to June 30,July 1 to August 10,August 11 to August 31,and September 1.Day to September 30;the flood season based on fuzzy set theory is divided into three sections: June 1to July 17,July 18 to August 14,August 15 to September 30 day.For the attribution difference between early and mid-July between the two methods,statistical analysis of the three indicators of the maximum 3d flood volume in early and mid-July,the number of peaks during the ten-year period,and the average annual runoff in the reservoir was carried out,and the results showed that the first and mid-July The indicators differ slightly from the data in June and can be classified into one period,and the results of the flood season staging are set to be June 1st to July 17,July 18 th to August 14 th,August 15 th to September 30 th.(3)The flood data of Xidayang Reservoir was rechecked.The flood series from 1998 to2012 were added this time,and the results(peak discharge,24 h flood,3d flood,and 6d flood)were all reduced by 20%.The flood data of the last 30 years extended this time is the partial dry flood.It is feasible to analyze the cause.In order to ensure the safety of the dam,the original flood design report is still used to calculate the flood regulation from a disadvantageous point of view of the project.(4)Determine the flood limit water level during the main flood season according to the existing dispatching principles of the reservoir.The typical factors that cause flood control risks are enumerated in detail,and the distribution law of each factor is analyzed,and a "flood-effective wind" over-dam risk model is established.Five initial flood limit water level schemes were preset,and flood control risks were solved.Taking the domestically accepted10-6 flooding risk as the standard,the 133.35 m flood limit water level scheme for the main flood season was selected,which is compared with the current dispatch In the plan,the flood limit water level during the main flood season is increased by 2.5m,and the full exploitation of water resources is realized under the premise of al owable risks.(5)In this paper,the fuzzy set analysis method is used to statistically calculate the fuzzy membership degree in the flood season,and the half-up and half-down curve is used for fitting analysis,thereby determining the fuzzy flood limit water level process line of Xidayang Reservoir,and integrating the existing As a result,a new phased flood limit water level control program was proposed.The new program met the agricultural water demand in1984,1992 and 1998,and increased the agricultural irrigation guarantee rate by 7%.