Urban and Human Health
GONG Shengsheng, LI Zimo, XIE Haichao, WANG Xiaowei, ZHANG Tao, SHI Guoning, CHEN Fahu
Epidemics are one of the most severe events in the human disaster network. On the basis of establishing the epidemic sequence by using historical epidemic data, and using the methods such as historical section analysis, factor correlation analysis, and time sequence analysis, this article examines the spatiotemporal characteristics and causes of the epidemic disasters for the past 2720 years (770 BC-AD 1949) in China. The results show that: (1) The frequency and intensity of epidemic disasters in China have a long-term upward trend, with troughs in the warm periods and peaks in the cold periods. (2) The epidemic prevalence in China generally occurred mainly in summer and autumn, but varied with time, so that since the 1450s, the seasonal difference tended to be less significant due to the increase of the kinds and frequency of epidemics. (3) China's epidemic fluctuation cycles are mainly 620-610 a, 320-310 a, 230-220 a, 170 a, 90 a, etc., which confirms the existence of "Twelve Earthly Branches" cycle and the significant impact of sunspot activity on the epidemic cycles. (4) For the past 3000 years, within the China's territory, the Epidemic Widespread is 93.51%, which indicates the percentage of the number of affected counties to the total number of counties, and the Epidemic Thickness is 16.86 layers, which represents the ratio of cumulative affected counties to the total number of administrative counties. The epidemics in the southeast half of China occurred much more frequently and severely than those in the northwest half. (5) The expansion of the epidemic prevalent areas in China is synchronized with the areal land exploration. The change of the epidemic centers of gravity is obviously affected by the spatial changes of the economic centers of gravity. The centers shifted from north to south before the Southern Song Dynasty, and moved from east to west after that. The import of foreign infectious diseases has a great impact on the distribution pattern of epidemics in China. (6) The prevalence of epidemics is not only a natural phenomenon, but also a sociocultural phenomenon. The change in the spatiotemporal distribution of epidemics reflects the change of human-environmental relationship. The densely populated areas, the areas along the traffic line, the surrounding areas of the capital city, the natural foci areas and the disaster-prone areas are all epidemic-prone areas. (7) The geographical environment has a basic impact on the spatial distribution of epidemics, that is, low altitude, warm and humid areas are prone to the prevalence of epidemics. Natural disasters can induce epidemics, so the disaster-prone area is also the epidemic-prone area, and the disaster-prone period is also the epidemic-prone period. Climate change has impacts on epidemic fluctuations, so epidemics are more frequent in the cold periods than in the warm periods. The land excessive development and the conflict between human and land resulting from population growth intensified the epidemic prevalence. Moreover, epidemics always follow wars, that is, the frequent periods of war are also the frequent periods of epidemic.