Spatial and temporal distribution pattern and changing process of major drought in Pre-Qin and Qing Dynasties of China
The major drought records with detailed disaster descriptions from Pre-Qin Dynasty to Qing Dynasty(850 a B.C.-1911 a A.D.)are extracted from historical documents and historical material records.The entropy weight method was used to determine the comprehensive index of major drought,and the spatial autocorrelation,barycentric analysis and standard deviation ellipse were used to study the distribution pattern and change process of major drought in historical period of China.The results show that:1)From Pre-Qin Dynasty to Qing Dynasty,the frequency of major drought in China was 580 times,with an average of once every 4.76 years,showing an overall upward trend.2)On the whole,the frequency of major drought in the north is higher than that in the south,and the highest frequency of drought is in some counties of Shaanxi,Henan and Shandong.3)The Ming Dynasty is the period with the highest cumulative level of major drought,and nearly 56.81％of the areas in China have experienced major drought.The cumulative grade of major drought has significant spatial autocor-relation,and its correlation changes have experienced the process of"increase-decrease-increase-decrease".The Moran index of the whole period is 0.43,which has significant spatial agglomeration.4)The number of counties with major drought accounted for 21.42％of the total number of counties with major drought.Its cen-ter of gravity is always located in Henan Province,moving in the direction of"southwest-northeast-southwest-southeast-northwest".5)The frequency of major drought was significantly negatively correlated with temperat-ure and precipitation.The terrain conditions of high in the west and low in the east of China,temperate contin-ental monsoon climate and unreasonable human activities are related to North China and its surrounding areas becoming the hardest hit-areas.In addition,climate change and population distribution have an important im-pact on the changes in the distribution pattern of major droughts in historical periods.
major droughtseverely affected areasfocus migrationShenyang-Lanzhou-Xishuangbanna Arc
万方数据
