Influence Analysis Of Flood-drought Disasters In Anhui Province Based On Aridity And EI Nino Index

In recent years, global warming accelerates global and regional water cycle, also changes the spatial and temporal distribution of water resources. Regional Climatic dry-wet change, which is a response to global warming, receive extensive attention and research because it has a powerful influence on the local social economic especially agricultural production; Dry-wet change is closely related to occurrence of flood-drought disasters. As a agricultural province, flood-drought disasters of Anhui Province occur frequently. The 1-contour of aridity is the boundary of the humid and semi-humid zones, and its distribution has a well indicator on the dry-wet change of Anhui Province, but the reaserch on relationship between 1-contour of aridity and flood-drought disasters of Anhui Province still has no systematic research. El Nino is an important factor in causing global climate anomaly which significant effect the climate of China, and it has a certain relationship with the flood-drought disasters of Anhui Province. In view of fuzziness problems when the traditonal sea surface temperature and its threshold identify El Nino and period length of El Nino, the accumulation of El Nino index is uesd to analysis relationship with flood-drought disasters of Anhui Province, and a comparative analysis between accumulation of El Nino index and traditonal El Nino is used to reflect the difference and connection on the flood-drought disasters of Anhui Province.The aridity in Anhui province during the period of 1957-2012 is calculated using observed meteorological data. The relationship between the distribution area of 1-contour of aridity based on Arcgis and flood-drought disasters of Anhui province is analyzed, and the contrastive analysis is made between El Nino, accumulation of El Nino index and flood-drought disasters of Anhui province. The results are as follow:(1)Annual average aridity in Anhui Province is 1.08 which Shows a trend of decrease, and aridity in Huaibei Plain, Jianghuai and south of the Yangtze River also reduces. Climate trends to humid. The aridity in each season of Anhui Province is different, which is maximum in autumn, and minimum in winter. Aridity decreases from north to South in space, and it is between 0.41 to 1.55 in each site. Anhui province is divided into humid, semi humid and arid area acoording to aridity index classification. The acreage of humid area is maximum and arid area is minimum. The change of aridity has regional difference in space.(2) 1-contour of aridity moves back and forth between Jianghuai and its distribution area is closely related to the flood-drought disasters of Anhui Province. Contours in different decades all distribute between Jianghuai. The 1-contour of aridity has clear agricultural meaning which is the boundary of the south and north, warm temperate zone and subtropical zone, rice and wheat, dry land in North of Anhui and paddy field in south of Anhui.(3) When El Nino occur, drought occur easily in the current year if El Nino index is slightly larger in spring and summer, and flood occur easily in the next year if El Nino index is slightly larger in autumn and winter in Anhui Province.(4) Point of accumulation of El Nino index has close relation with flood-drought disasters of Anhui Province. Anhui Province is liable to occur flood in the current year when the maximum point of accumulation of El Nino index appear, and occur drought easily in the next year after the minimum point of accumulation of El Nino index appear. Point of accumulation of El Nino index is a supplement on the relationship of flood-drought disasters.