Study On Extreme Precipitation Event Spatial And Temporal And Risk

With increased emissions of greenhouse gases and global warming, watercirculation has speed so that extreme precipitation event frequency is more andmore big. It threats to the safety of the people, cause huge property losses andincreases the instability of the society. In recent years, the frequent occurrence ofextreme rainfall events caused an immeasurable loss to our country. Therefore，extreme rainfall events draw the government attention, also became one of thehot issues of concern and research research.The data from "China meteorological data sharing service network"provided China’s climate daily data. The paper mainly adopts the data whichregards to the site, year, month，day, and each site daily rainfall capacity since1951. By using the matlab software, the paper eliminates invalid data andcalculates the average annual rainfall of each site. At the same time, we extractmore than50mm rainfall data everyday and maximum daily rainfall every year.On this basis, the paper statistics the average annual rainfall each site every tenyears and the number of days more than50mm rainfall each year. We use thePearson-III probability calculation method to calculate maximum rainfall returnperiod. We Use the statistical data to generate distribution or days of the extremerainfall and the average annual rainfall by the methods of spatial interpolation of ArcGIS. The data of return period calculation is classified in order to generateextreme rainfall distribution of Hazard in our country. Based on the presentsituation of land use classification，we divide the vulnerability grade of differentland use types to generate different. We comput grid of the Hazard andvulnerability distribution map in ArcGIS to get risk of extreme rainfalldistribution. We carry on the risk analysis of extreme rainfall and divide higherrisk so that we can provide a basis for disaster prevention and mitigation.Research shows that:(1)Therainfall has increased in north of China, the average annual rainfallof2000-2009move between huaihe river and the Yellow River the region thataverage annual rainfall is increased has enlarged in the tarim basin in xinjiang.(2)In1960-2009，the extreme rainfall days showed an increasing trend in50years.the north of china, extreme rainfall days increase.(3)Extremerainfall space-time distribution is closely related to variousaspects reason. Including: global warming which caused global redistribution ofprecipitation and extreme rainfall events induced; EI nino and la Nina makingabnormal changes in the global climate system. Also specific to the sea and landlocation, factors such as landform, climate and human activities. All the factorsaffect the space-time distribution of extreme precipitation in China.(4)Underdifferent return period, extreme rainfall values are different.Thereturn period is greater, the extreme rainfall is greater. Under the same returnperiod, different regions have different extreme rainfall.(5)Withthe increase of return period，the highest Hazard area which mainlyconcentrated in the southeast coastal area of extreme precipitation in China isexpanding. The areas are extending to the northeast and north of China in100years scene. The areas of high Hazard are mainly in the northeast, central China, southwest. Low Hazard areas are mainly concentrated in the northwest andDaxinganiing Mountains. In100years scenario, only a small area is low Hazard.(6)Thehighest vulnerability areas are mainly distributed Heilongjiang, Jilin,Liaoning Hebei, Beijing, Tianjin, Shanxi Province, Hen an, Hubei, Hunan,Guangdong, and Guangxi. There cities in coastal areas and in the middle andlower reaches of the Yangtze River and Yellow River and the giant cities Beijing,Shanghai, Guangdong have highest vulnerability. The high vulnerability areas areinortheast plain, the north China plain the Sichuan basin, tarim basin in xinjiang,and ZhunGeEr basin. The moderate vulnerability of extreme precipitation areInner Mongolia plateau，the Qinghai-tibet plateau and the Yunnan-guizhouplateau. The low vulnerability area is mainly the northwest region of our country.(7)Thehighest-risk areas of extreme precipitation in our country mainlyconcentrated in the southeast coastal areas, the Yangtze River basin and smallareas along the bohai sea. High risk areas are mainly concentrated in parts of thenortheast, north China and central China region.The moderate risk areas aremainly concentrated in parts of Inner Mongolia, north of shaanxi，shanxi andother places, in the southwest of yunnan, sichuan, Tibet The low risk areas aremainly in northwest and northeast minority area of our country.