| Under the background of global climate change,the hydrological cycle process of the basin has changed,resulting in frequent occurrence of extreme precipitation events,which can easily cause major natural disasters and casualties,and pose a serious threat to social and economic development,which has attracted great attention from relevant departments.,the hydrological frequency analysis research under the condition of climate change has become a hot issue to be solved urgently.Based on this,this paper takes the Liuyang River Basin as the research object,and carries out the analysis of extreme precipitation frequency and future change trend under climate change conditions,in order to provide scientific basis for the basin management department to deal with extreme climate and drought and flood disasters,and at the same time for future water resources planning and management Provide some reference.The main contents and achievements are as follows:(1)The variation characteristics of hydrometeorological elements in the Liuyang River Basin were studied by means of trend,mutation and period testing.The results show that under the conditions of climate change,the hydrometeorological elements of Liuyang River have different degrees of variation,among which the precipitation sequence shows moderate variation,and the extreme precipitation sequence abrupt year is 1992;the evaporation and temperature sequences have detected trend variation,and the degree of variation is Severe variation and weak variation,respectively;period test shows that,except for the annual average temperature series,the other series have detected obvious main period changes,of which the first and second main periods of the extreme precipitation series are 28 a and 10 a respectively.(2)Based on the extreme precipitation abrupt year,the extreme precipitation sequence is reconstructed to obtain Sn,Sp and Sw series,which represent the extreme precipitation series not affected by climate change,partially affected by climate change,and completely affected by climate change,using GEV and GPD The model performs fitting optimization and frequency analysis for each extreme precipitation sequence.The results show that the fitting effect of GPD model on each extreme precipitation series is better than that of GEV model,and it has strong anti-interference ability.The best fitting effect of a single model is the Sw series of GPD.The extreme precipitation in the basin has an obvious upward trend.Taking the GPD model as an example,the extreme precipitation of the 10-year,100-year and1000-year extreme precipitation increased by 35.9%,64.7% and 103.6% in the Sw series compared with the Sn series.(3)By constructing the future extreme precipitation index time series in the Liuyang River Basin under the SSP1-2.6,SSP2-4.5 and SSP5-8.5 scenarios of the UKESM1-0-LL model,the decadal and interannual variation characteristics were analyzed.The results show that: the extreme precipitation events in the basin will increase in a long time in the future,and the future extreme precipitation index will show an increasing trend compared with the base year.Under the SSP5-8.5 scenario,RX1 D and R95 p increase significantly,while under the SSP1-2.6 scenario,SSDII and R95 p increase significantly.The increase of R30 mm is obvious;the analysis of inter-annual variation shows that the mid-term 2051-2080 is the main period for the growth of extreme precipitation indices.(4)Use GEV and GPD models to perform fitting optimization and frequency analysis of extreme precipitation sequences under future climate scenarios.The results show that the fitting effect of the GPD distribution model on the future extreme precipitation sequence is better than that of the GEV model,and the fitting effect of the SSP5-8.5 series is the best.The design value of extreme precipitation once in 1000 is the largest.The results of the GEV model are 393.7mm and 680.5mm,which are 80.3% and 64.3% higher than the design value of the original series.The design value of extreme precipitation increased by 112.7% and157.8%. |
