Research On The Features Of Precipitation And Rainfall Storm Pattern In Main Cities Of Hunan Province

In this thesis,the precipitation characteristics and the rainfall storm pattern of the 14 major cities in Hunan Province are analyzed by using the precipitation data provided by the Meteorological Bureau of Hunan Province,precipitation data mainly includes daily precipitation data and minute precipitation data from 1980 to 2015,the results obtained are as follows:(1)The average annual rainfall in the cities is in the range of 1300 mm to 1510 mm.According to the variation coefficient and the annual extreme value ratio,the southern part of Hunan,such as Yongzhou and Chenzhou,the ann ual precipitation changes greatly,and mountain areas more cities,the annual rainfall is also relatively large degree of change;By comparing the monthly precipitation,it is found that the concentration of precipitation more appear in April and May,the precipitation concentrated month appear early,the end is also early.(2)From the statistics of the rainstorm days,the rainstorm days in southwest Hunan is higher than that in other parts of Hunan;Half of the city's annual rainstorm days maximum year occurred in 1990 s,half occurred in twenty-first Century after 00 years;the trend shows that the number of days of rain in the city is basically in a rising trend,the upward trend is more obvious in Zhuzhou.(3)Using the M-K method to test the precipitation trend of the annual maximum rainfall,the results showed annual rainfall in seven cities have an increasing trend,respectively,Jishou,Yueyang,Huaihua,Loudi,Xiangtan,Changsha and Zhuzhou,of which Huaihua annual precipitation has a clear upward trend;The annual precipitation is 36 years,and the annual precipitation data of each city are basically mutated,and there is at least one mutation in the early 1990 s and after the 20 th century.(4)It is found that the samples selected by the annual maximum value method have the best effect by using the Gumbel distribution curve;The calculation accuracy of the least squares method is superior to the Gaussian Newton method in the calculation of the rainstorm formula.(5)From the results of the rain,we can see that the urban rain peak position coefficient is similar,basically at 1/3 points,among them,Zhijiang City,the location of the rain peak are more forward,and the location is more stable;Based on the precipitation data,the calculation method and the influence degr ee of the rain rain intensity,it is recommended to use the Keifer&Chu to design the rain pattern in Hunan province.