| Drought is one of the major natural disasters as well as the most serious disaster of all kinds of meteorological disasters.Drought disaster has the characteristics of high frequency,wide influence,long lasting time and great economic loss,not only can cause crop production,water security threats,deterioration of ecological environment,but also lead to serious livestock deaths and deaths of catastrophic drought disaster.Guizhou Province locates in the Yunnan-Guizhou Plateau that is the core area of the southwest Karst landform.The ecological environment is very fragile and landform types are complex and diverse.There are 4 types of landforms,the plateau,the mountains,hills and basins.It has a large population,less arable land and uneven temporal and spatial distribution of water resources.The dought characteristic in Guizhou is that "drought occurs every year,light drought occurs once every three years,moderately drought occurs once every fiveyears,severely drought occurs once every tenyears".During 2009?2013,Guizhou Province has suffered severe droughts which has caused great losses.The temporal and spatial variation characteristics and intensity characteristics of drought at different time scales,different ages,different seasons and different grades were analyzed by using drought index(RDIst),standardized precipitation index(SPI)and K index,According to the advantages and disadvantages of the three drought indices,a new drought index SRDI,which is more suitable for drought monitoring in Guizhou Province,was established in order to get a better understanding of the occurrence and development of drought in Guizhou Province.On this basis,according to the theory of natural disaster system and the principle of disaster risk assessment,the SRDI drought index is used as the index of disaster risk factors in Guizhou Province;At the same time,combined with the Guizhou province in 2010 the county administrative area,at the end of the end of the total population,cultivated area,animal husbandry and fishery output value,per capita GDP,production GDP,per capita net income of farmers,budget revenue and expenditure of social economic data,Construction of 10km grid drought hazard factor,disaster-breeding environment,disaster-bearing body,disaster prevention and mitigation evaluation system;the risk assessment model and ArcGIS technology were used to evaluate the drought risk in Guizhou Province,so as to provide a scientific reference for drought relief and disaster reduction in Guizhou Province.The main results are as follows:(1)From the time variation characteristics,by comparing the SPI index,RDIst index and K index in different regions of Guizhou Province,the drought characteristics showed that a increasing trend of annual,seasonal and monthly the drought index of the 3 kinds of drought index during 1960?2013.The annual and seasonal drought intensity of the 3 drought indices had the same quasi 2?4 annual cycle.The drought stations proportion and moderate drought stations proportion showed a downward trend in addition to K,the RDIst index of summer drought,the drought stations proportion and moderate drought stations proportion showed an upward trend of annual and seasonal drought.The annual drought stations proportion of SPI index,K index and RDIst index occurrence in the whole region of Guizhou Province respectively 10?14 years,17?30 years,21?24 years and annual moderate drought stations proportion occurrence 2?4 years,0-20 years,2-7 years(2)From the perspective of spatial change,Annual and seasonal drought intensity showed an increasing trend of three drought indices during 1960-2013.The spatial distribution of drought intensity is different.The spatial distribution of drought intensity of SPI12 index showed the characteristic "the west of Guizhou Province is stronger than the eastern Guizhou Province".In spring,the eastern Guizhou Province is stronger than western Guizhou Province.Summer is consistent with the annual,and the drought intensity is stronger in the southwest and northeast of Guizhou Province in autumn.The drought intensity is stronger in the southwest of Guizhou Province in winter.The drought intensity of K index was "strong in the middle and low in east and west sides",the drought intensity is stronger in western part of Guizhou Province in spring and winter,while the drought intensity was stronger in the eastern part of Guizhou Province in summer and stronger in the south of Guizhou Province in winter.The drought intensity of RDIst index is stronger in the west and northeast of Guizhou Province,the drought intensity is stronger in the west of Guizhou Province in spring and it is stronger in the northern of Guizhou Province in summer.The drought intensity is stronger in northwest of Guizhou Province in autumn and stronger in southeast of Guizhou Province in winter.The drought intensity of SPI12 has an around4 year cycle.There is a consistent with abour 2 years period for K index and RDIst index.In term of season,SPI3 index was consistent with a quasi 2-year cycle.In spring,summer and winter are consistent with a quasi 2-year cycle of K index and RDIst index.In addition,K index has a quasi periodic variation of 4-6 years in autumn,but the RDIst index do not change significantly in the autumn.(3)By comparising with the "The meteorological disaster ceremony of Guizhou Province ",the K index and RDIst index describing drought are better than SPI index in annual,seasonal and monthly drought,but it is more reasonable to describe the non-drought event than K index and RDIst index;The K index was more objective and reasonable in the spring,summer,but it is not good for autumn and winter.The RDIst inde is more objective and reasonable the RDIst index describing the annual,seasonal and monthly scale drought were reasonable.At the same time,RDIst index and K index are overweight depict the no drought.In addition,there is a phenomenon the drought intensity was reflected by the 3 drought index indices inconsistent with the drought affected area,in some years,the drought affected area is large while the intensity is low,in some years,the drought affected area is small but the drought intensity is strong.The drought events of in the SRDI index reflected are consistent with meteorological disasters ceremony recorded in the annual,and spring and summer scales,although we could not completely overcome the shortcomings of the three drought index,but more reasonable than application a single of drought index.(4)According to the drought risk assessment model,combination the drought hazard factor risk,vulnerability of disaster-breeding environment,exposure disaster-bearing body and disaster prevention and mitigation capabilities are obtained:The high drought disaster risk area are distribute in western Guizhou Province,especial the Bijie city and Liupanshui city that suffers the greatest risk of drought disaster.The low drought risk area is mainly distributed in the eastern part of Guizhou Province. |
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