Assessment And Regionalization Of Drought Disaster Risk In Yunnan Province

Drought disaster is one of the most severe natural disasters in the word. The drought frequency, drought duration, drought area and the damage is at the top over all kinds of natural disasters. Under the global climatic warming, the extreme climatic events such as heat, drought and heavy rainfall occurred more frequently, the damage is more serious, and the drought area is more widely. The annual economic losses of drought disaster are S6-8 billion all over the world, much more than other meteorological disasters. As the increasing impact of drought disaster and attention to the food security, the risk assessment of drought disaster is becoming the hot topic in research of water resources management and disaster.Yunnan complex geographical environment of low latitude plateau, a variety of local climate, special vegetation, and affected interactively by the southwest monsoon and the southeast monsoon, resulted in significant characteristics of regional drought disaster. Recently, the losses of drought disaster is more serious in Yunnan Province, especially in 2010. This study constructed a model of drought disaster risk to evaluate the risk of drought disaster in Yunnan Province based on the theory of natural disaster risk, to reveal the spatial distribution characteristics of drought disaster risk, which will provide a scientific basis for risk management of drought disaster.This study investigated spatial and temporal variations of drought frequency, intensity and the influence areas of drought over Yunnan Province during 1961-2012. On the basis of dataset from 122 meteorological stations covering the region, the standardized precipitation index derived from monthly precipitation was computed and analyzed. Then based on the risk theory of natural disaster, a risk assessment model of drought disaster was developed.15 indicators were selected from the four sub-systems of risk system, including the dangerous of the disaster-causing factors, sensitivity of disaster-formative environments, vulnerability of disaster-bearing body and the capabilities of disaster prevention and mitigation. The model was then used to assess the drought disaster risk for Yunnan Province using the meteorological, socioeconomic statistical and GIS data of 129 counties. Finally, regionalized the risk of drought disaster in Yunnan Province by integrating natural disaster regionalization principle.(1) The standardized precipitation index was used as a drought index, to analysis the spatial and temporal variation characteristics in Yunnan Province. Our results indicated that the drought intensity increased in annual scale. A notable feature for drought intensity was that approximately 82% of the stations had increasing trend, and these stations mainly distributed in eastern Yunnan. The drought frequency in the northwestern, central, southeastern and southwestern regions was relatively high. The eastern and northeastern regions were prone to experience extremely drought. The influence area of drought was significant increase in the past 30 years.(2) According to the theory of natural disaster risk, combing with the characteristics of drought disaster, the natural environment in Yunnan Province and data availability,15 indicators were selected from the four sub-systems of risk system. The dangerousness of drought disaster factors is analysis by drought frequency and drought intensity. The sensitivity of disaster-formative environments is studied by terrain, type of land use, drainage density and per capita water resources. The vulnerability of disaster-bearing body includes the density of population, the density of economic, the density of agricultural output, land area proportion and the per unit area yield of grain. The drought disaster prevention and mitigation capabilities consisted of financial revenue, reservoir capacity, water conservancy infrastructure spending and effective irrigation area.(3) Respectively to evaluate four factors by the AHP and weighted comprehensive evaluation method, (a) The evaluation result indicated that the higher risk areas for disaster-including factors were mainly in Lijiang the northwest of Yunnan, Dali the west of Yunnan, Qujing the east of Yunnan, Zhaotong the northeast of Yunnan and Honghe the southeast of Yunnan. The lower risk areas of disaster-including factors were in Dehong the west of Yunnan and Xishuangbanna the southwest of Yunnan, (b) The evaluation result indicated that the higher risk areas for sensitivity of disaster-formative environments were in Qujing the east of Yunnan, Honghe and Wenshan the southeast of Yunnan, part region of Weixin and Zhaoyang the northeast, and Baoshan the west of Yunnan. The lower risk areas for sensitivity of disaster-formative environments were in northwest and southwest in Yunnan, (c) The evaluation result indicated that the higher risk areas for the vulnerability of disaster-bearing body were mainly in Qujing the east in Yunnan, Kunming and Yuxi the middle of Yunnan, Zhaotong the northeast, and Dali the west in Yunnan. Lower risk areas for the vulnerability of disaster-bearing body were in Nujiang, Diqing and Lijiang the northwest, Ninger and Jiangcheng the southwest in Yunnan, (d) The evaluation result indicated that the higher risk areas for the capabilities of disaster prevention and mitigation were partly distributed in Yunnan Province. Lower risk areas for the capabilities of disaster prevention and mitigation were mainly in Nujiang, Diqing the northwest, Wenshan the southeast in Yunnan, and Puer the southwest in Yunnan.(4) The drought disaster risk index method was used in assessment of drought disaster risk in Yunnan Province. The results showed that the area of low, sub-low, medium, sub-high and high drought disaster risk account for 13.4%,29.8%,28.2%, 19.6% and 9.1% of Yunnan Province. The spatial distribution of drought disaster risk presents the characteristics of complexity In general, Yunnan Province could be divided coarsely into two parts, along the zone of Haba Mountain-Diancang Mountain-Ailao Mountain, the most areas of eastern part showed the high risk of drought disaster while the majority of regions in western parts present low risk of drought disaster. The regions with high drought disaster risk were mainly in Qujing the east in Yunnan, Kunming and Yuxi the middle of Yunnan, Wenshan and Honghe the southeast in Yunnan, Zhaotong the northeast. The regions with low drought disaster risk were found mainly in Diqing and Nujiang. The assessment result was verified through comparing with historical data of drought disaster, which indicated that the model could reflect the situation of drought disaster risk over Yunnan Province.(5) Based on the comprehensive assessment of drought disaster risk and according to the natural disaster regionalization principles, Yunnan Province could be divided into five regions:high risk area of middle, eastern and southeastern Yunnan; high and middle risk area of northeastern Yunnan; middle risk area of western Yunnan; middle and low risk area of southwestern Yunnan; low risk area of northwestern Yunnan.