Study On The Characteristics Of Plum Rains In Anhui Province Based On Set Pair Analysis

Anhui Province crosses the Yangtze River and the Huai River,and is located in the plum rains belt in the middle and lower reaches of the Yangtze River in China.It studies the occurrence characteristics and evolution of the plum rains.It is of great significance to forecast the situation of hydrology and water resources in Anhui Province,formulate effective water resources planning and utilization and flood control Drought programs have important guiding significance.Based on the daily precipitation and temperature of 14 typical stations in Anhui Province during the period from 1957 to 2016,such as temperature and other hydrological and meteorological data,characteristics of plum rains process,such as the beginning,the end,and the length of plum rains process,the amount of plum rains,were identified for each station respectively.Based on the regime of climatic and territorial difference between north and south of China,region of Anhui Province was divided into three sub-regions,namely,the region of north of Huai River,the region of Yangtze-Huai River and the region of south of Yangtze River.Then the characteristics of plum rains processes of three sub-regions were obtained through spatial averaging of characteristics of each station in its own region.The standardization index method was adopted to divide the status of annual precipitation and precipitation during the plum rains period for three sub-regions.Then the set pair analysis method was used to analyze spatial characteristics of the plum rains,annual precipitation as well,between three sub-regions.Meanwhile,the relationship between the annual precipitation and the amount of the plum rains are also studied in each sub-region.Meanwhile,At the same time,set-up analysis is used to predict the status of the plum rains in the three regions respectively,and the two schemes of single-step prediction and multi-step prediction are selected.Research indicates:(1)the beginning and the end of the plum rains period are gradually later from south to north in Anhui Province on the whole.The average beginning of the plum rains period of regions of south of the Yangtze River,Yangtze-Huai River and north of Huai River are June 15,June 21 and July 3 respectively,and the end of the plum rains period are July 9,July 13 and July 20.Correspondingly,the lengths of plum rains period are 24,22 and17 days.(2)The average annual amounts of plum rains in regions of south of the Yangtze River,Yangtze-Huai River and north of Huai River are 322.7 mm,232.1 mm and 193.2 mm,respectively.For the status of annual amount of precipitation and the amount of plum rains,the connection degree value of south of Yangtze River region and north of Huai River region is the smallest,and the identical degree of south of Yangtze River region and Yangtze-Huai River region is the highest.It implies that plum rains and annual precipitation is of geographical gradual variance in Anhui Province.Generally speaking,the identical degree of plum rains and annual precipitation is strong in the three sub-regions,all of them reach over 55%,Among them,the correlation between the plum rains and the annual precipitation in the Yangtze-Huai River region is the largest,at 0.858.(3)Based on the set pair analysis method,the plum rains quantity status of south of Yangtze River region,Yangtze-Huai River region and north of Huai River region was predicted with the pass rates of 70%,50% and 70% respectively.The pass rates of the three regions were analyzed and compared.The prediction of south of Yangtze River region and north of Huai River region better results.