Frequency Estimation Of Hydrological Curves And Its Empirical Analysis

Hydrological frequency analysis is a crucial part in hydrological research.Through hydrological frequency analysis,the relationship between the numerical value of hydrological events and their occurrence frequency can be accurately revealed,which plays a key role in planing water conservancy projects and optimizing water resources allocation.In order to carry out indepth research on hydrological frequency analysis,the dissertation first collects a large number of relevant domestic and foreign research literature to read,grasps the research status of hydrological frequency analysis and makes a concrete exposition,and at thesame time the current hydrological frequency distribution model and its parameter estimation method are determined,and a set of general parameter estimation methods for hydrological frequency analysis are compiled including normal classes,log normal classes,Pearson type three distribution model and nonparametric estimation methods based on nucleardensity,ARIMA,ARCH,TGARCH are used as time series analysis and prediction methods.Later,based on the daily runoff series of Boluo Hydrological Station from 2017 to2019,the hydrological curve distribution and trend of the sample hydrological station were calculated in combination with the constructed analysis system.Finally,the main conclusion is drawn: compared with the normal class and log-normal class parameter estimation method,the results of P-Ⅲ are more significant and the application value is higher.Compared with the traditional research on the average value of hydrological frequency,this dissertation innovatively analyzes hydrological frequency from multiple dimensions,not only considering the average value of hydrological frequency,but also analyzing its variance and skewness,thus describing the nature of hydrological frequency more comprehensively;At thesame time,time series method is used in this dissertation to analyze hydrological frequency,which can describe the regularity of hydrological frequency change with time more accurately,so as to have a more precise grasp of the changing trend of hydrological frequency.In addition,this dissertation decomposes the change of hydrological frequency by period-trend,thus better describing its long-term trend and short-term fluctuation,providing a more accurate basis for subsequntanalysis.TGARCH model is introduced to describe the extreme asymmetry of hydrological frequency,which can better describe the probability and impact of extreme events and provideamore detailed method for hydrological disaster early warning and risk assessment.