Regional Comprehensive Drought Risk Assessment Method And Its Application

In recent years,with the continuous development of China's social and economic conditions,the demand for water resources is increasing everywhere.At the same time,under the background of the continuous intensification of global climate change and frequent extreme weather events,drought and water shortage caused by frequent drought events has become an important issue facing China in the 21st century.It is necessary to evaluate the degree of regional drought and the spatial and temporal distribution of drought,formulate regional drought-resistant countermeasures,and deal with the problem of drought and water shortage.Chang-Zhu-Tan area in Hunan Province,as a key development area,is particularly affected by drought.Therefore,monitoring and evaluating the drought situation in Changsha-Zhuzhou-Tan region and comprehensively understanding the law of drought occurrence in Changsha-Zhuzhou-Tan region have far-reaching significance for the further development of Changsha-Zhuzhou-Tan region.In this paper,the standardized precipitation index(SPI),standardized runoff index(SRI),standardized regional water shortage index(SSDI)are selected from 20 meteorological stations around Chang-Zhu-Tan from 1961 to 2010,including daily precipitation,daily temperature,daily barometric pressure,river water level and discharge,and drought area data of crops,and then synthesized into a comprehensive drought index(MIDI)evaluation.At the same time,the copula function is used to analyze the regional drought characteristics,so as to reasonably reveal the changing trend of climate and drought in Changsha-Zhuzhou-Tan region over the years.The main research contents and results are as follows:(1)Based on the weighted synthesis method,a comprehensive drought index(MIDI)is constructed on the basis of SPI,SRI and SSDI to comprehensively reflect the regional meteorological,hydrological and agricultural drought characteristics.Meteorological drought is weakening year by year,while hydrological drought and agricultural drought are increasing year by year(2)The changes of drought in different regions in the study area are generally consistent.Compared with the Historical Drought process,the comprehensive drought index can better reflect the characteristics and laws of drought.Generally speaking,autumn drought is the main drought,followed by spring and winter drought.The main cycle of drought change in the region is about 39 years,and the secondary cycle is about 4-16 years.Spatial distribution shows that some districts and counties such as Yanling,Chaling,Youxian,Liling and Xiangtan have frequent light drought,but less severe drought,while some districts and counties such as Ningxiang and Wangcheng have relatively frequent heavy drought.(3)Based on the analysis of drought frequency characteristics of each sub-region and the actual situation of the region,a series of drought-resistant measures including the construction of groundwater reservoirs and non-engineering measures including the establishment and improvement of drought early warning mechanism are put forward.