Study On Spatio - Temporal Symmetry Of Drought And Flood Disasters In Huaihe River Basin

There is a natural dividing line between north and south in our country, the line is named Qinling-Huaihe River. The climate between the north and the south boundary is significantly different. Huaihe river basin is located in the special geographic location, so it is sensitive to climate change. Nearly a century, global warming has brought the change of the atmospheric circulation and precipitation. Affected by it, the situation of drought and flood in the Huai River bring huge effects to the industry and agriculture. Therefore, the study the time and space distribution of drought and flood is necessary. The judgment of occurrence of drought and flood disasters in the future has important practical significance.Based on the daily mean temperature and precipitation data of30meteorological stations from1961-2012, Using the mathematical statistics analysis, trend fitting, Mann-Kendall mutation testing and Commensurability calculations and so on, this paper reveals the climate change characteristics, changes of drought and flood of huaihe river in recent52years from the large, medium and small three dimensions, as well as the time window period of drought and flood disasters. And its influence factors are analyzed. The main conclusions are as follows:(1) The temperature of huaihe river is rising fluctuate, the growth rate was0.2℃/10a. The area didn’t have a warming trend in summer, spring, autumn and winter are obviously warming. The summer temperatures didn’t mutate in different scales, spring, autumn and winter’s temperatures have already mutated. And the winter warming is the fastest. The temperature shows a zonal change. The whole district is characterized by consistent warming trend, but regional differences are big. Annual mean temperature and the temperature change reverse tendency rates.(2) The precipitation mainly concentrated in the summer in different scales of study area. Precipitation didn’t mutate in the study period. It is unconspicuous of the precipitation change trend of the area. Precipitation change led to dry-wet alternate change more obvious. The spring and autumn precipitation decreases in medium and small dimensions, summer and winter precipitations have an increasing trend (except Linyi). The precipitation diminishes from south to north on the space, but regional differences are big. The region of precipitation increased has a slower rate of warming, and the region of precipitation decreased has a higher rate of warming. (3) Huaihe River basin has a tendency of transfer from waterlogging to drought since1961. Waterlogging and drought are frequent in Huaihe River, and show the characteristic of "drought and flood sharp turn", Huaihe River turns from waterlogging to drought in spring and autumn, from drought to waterlogging in summer and winter. Drought and flood changes are the same as the whole area in medium and small scales (except Linyi). The high occurrence frequencies of drought areas have a low frequency of waterlogging in spatial distribution. Drought and waterlogging frequency of four seasons are phase relationship in space. In the21st century, it is increased greatly of "drought and flood sharp turn" in Huaihe River.(4) On the disaster time window of judgment, the middle and lower reaches of the Ruaihe River both show the stronger regularity of drought; Yi, Shu and Si River show the stronger regularity of waterlogging. The study area shows a strong regularity of "drought and flood sharp turn"—the randomness of the probability of57.1%in2016, so, in the year of2016, there will be a "drought and flood sharp turn" in Huaihe River.(5) The flood and drought of Huaihe River are tending to occur in single cycle of extremum area and it’s nearby of sunspot activity. In recent52years, drought and flood occurred near the extremum areais about63.9%of the total. During El Nino year, drought and flood occurrence frequency is equal; flood occurred more often inLa Nina years.This paper provides the basis for rich the research to determine trends in disasters, increase the cases of disaster, and guide the disaster prevention and mitigation.