Research On The Temporal And Spatial Statistical Law And Risk Management Of Drought Disasters In Northwest China

The continuous warming of the global climate has altered the global hydrological cycle,which greatly increased the rate and intensity of the occurrence of the global drought disaster and further increased the coverage of the drought.The northwest region is the main arid area of China and one of the most arid regions in the same latitude in the world.Since the late twentieth Century,the climate in Northwest China has shown a trend of warming and humidification,but the trend of drought in the eastern part of Northwest China is also very obvious.And from the view of varieties of season,the spring drought in Northwest China has been intensifying.Therefore,the spatio-temporal variation and multi-scale features of the warm humidification in Northwest China are still not clear,and there is still a lot of uncertainty in the trend of drought in Northwest China.Clarifying the characteristics and future trend of drought,and based on that,systematic analysis,scientific assessment and risk zoning for drought risk in Northwest China are related to the specific results of regional water resources management.Based on this,the northwest region is taken as study area,using the improved SPEI index method,linear regression method,inverse distance weighted interpolation method,the natural disaster trend model,entropy method,comprehensive disaster system theory and other methods,we studied the climate change background,the space-time evolution of drought disaster and trend judgement,attribution,risk assessment and zoning of drought in Northwest China.The study mainly obtained the following conclusions:(1)Response characteristics to global climate change in Northwest China:In 1960-2016,the temperature in the northwest region showed a significant upward trend,and the rising rate after 1990 was obviously faster than that before 1990.The precipitation showed an upward trend in the whole,but the autumn precipitation showed a decreasing trend.Spatially,the precipitation in the east of Northwest China reduced.The average wind speed in most areas of the whole region decreased significantly,and the interannual fluctuation was great.The hours of sunshine in the whole region generally reduced,and only the hours of sunshine in the spring increased in the four seasons.Relative humidity in the whole region generally reduced,and the trend of relative humidity around the Tarim Basin is increasing obviously.(2)Characteristics of spatio-temporal evolution of drought in Northwest China:Over the years,the SPEI in the northwest and three climatic zones shows an increasing trend,and the SPEI in the eastern monsoon region generally reduced.On a seasonal scale,the spring SPEI index in the northwest region shows a downward trend,while the SPEI index in the rest of the season is on the rise.Spatially,the northwest,central and eastern of Xinjiang,the central of Qinghai,the Yinshan Mountains nearby regions of Inner Mongolia and other places are the main area influenced by wetting trend,and the southwestern of Xinjiang,the eastern Gansu,Ningxia and other places are common with the development trend of drought.(3)Judgement of drought trend in Northwest China:In the annual and seasonal scales,the next few years in the northwest drought and light drought occurrence times more than half of the coverage area,and coverage area of the summer drought in Northwest China is most wide.As for the regional perspective,in the next three years,there will be more disasters in the spring for Qinghai,in the summer for Gansu and Ningxia,in the autumn for the western part of Inner Mongolia and in the autumn and winter for Shaanxi.For the whole region,the annual scale trend year of light and moderate of drought in Northwest China is 2018.The trend year of moderate drought in the western climate zone in spring is 2018.The annual scale drought trend year of the plateau climate zone is 2018 or 2020.The annual scale trend year of moderate and above drought in the southeast climate zone is the year of 2018.From the provinces of China,the annual scale trend year of moderate drought in Qinghai is the year of 2019.The trend year of moderate and above drought in Ningxia and Shaanxi are all in 2018.The annual scale trend year of severe drought and above in Western Inner Mongolia is the year of 2019.The annual scale trend year of severe drought in Xinjiang is the year of 2020.The annual scale trend year of severe drought in Gansu is the year of 2018.(4)The attribution of drought in Northwest China:The drought index of Northwest China is positive sensitivity to precipitation,and it is negative sensitivity to temperature,average wind speed and sunshine hours.The sites where precipitation is the leading factors of drought change,are mainly located in the east of the region,accounting for 71.6%of the point number of the regional total station.The sites where wind speed is the leading factors of drought change,only accounted for only 27%of the total number of total stations,which were basically distributed in the west wind zone.There are only two sites dominated by temperature.The spatial distribution pattern of the dominant factor reacts the characteristics of regional climate change.(5)Construction of drought risk assessment system and risk zoning:High risk area of drought causing factors is in the east of Northwest China.The vulnerability of the disaster environment in the southeast of Northwest China is relatively low,and the vulnerability of the other regions is high.The exposure of disaster bearing bodies in the whole region is low,and the high exposure area is scattered in all provinces and regions.The overall difference in capacity for disaster prevention and reduction between provinces is not significant.For these provinces,the average drought risk in each province is generally higher than 0.40,which indicates that the risk of drought disaster in the northwest region is higher.The arid high risk areas are distributed in the Kunlun Mountains of southern Xinjiang,the Qaidam Basin and Sanjiang source area of Qinghai,the eastern area of Gansu,the southern area of Ningxia,the Alashan of Inner Mongolia,Gansu and Xinjiang at the junction of banner of western area,Qijiaojing station and other places in eastern Xinjiang.(6)Countermeasures for risk management of drought disaster in Northwest China:The risk management system of drought disaster should be improved.Water resources should be allocated and managed rationally.Researcher should formulate scientific and reasonable results of drought risk assessment.The government should implement predisaster intervention on risk factors of drought disaster.According to the actual situation in the region,the government should establish the corresponding management measures,drought contingency plans and drought planning,and local terms.The government should establish long-term effective mechanism of disaster economic input.The government should strengthen the scientific research of disaster management and the level of transformation of scientific research achievements and improve the people's consciousness of disaster,drought resistance and knowledge level.The government should strengthen the construction of ecological civilization and reduce the disaster in the way of ecological protection.The innovation of this study is shown as:(1)It is found that the warming humidification trend in Northwest China has regional difference and scale characteristics.It is considered that there is drought trend in the eastern part of Northwest China on the spatial scale and the degree of drought in the northwest region is increasing in spring on the time scale.(2)On the site scale,we have innovating and improving the trend judgement method of major natural disasters,which enriches the judgement cases of drought disasters in different temporal and spatial scales in Northwest China.(3)The drought evolution in Northwest China is ascribed and it is suggested that precipitation and average wind speed play a leading role in the drought evolution in Northwest China.(4)The drought risk assessment index system in Northwest China has been built and improved.The drought risk in Northwest China has been meticulous evaluated and zoning at grid scale and county scale,respectively.In this paper,the evolution,trend judgment and risk assessment of drought in Northwest China are studied and explored.This work can provide scientific and practical reference for regional disaster management and water resources allocation,and also provide case and framework support for the judgement of major natural disasters trend and integration of disaster risk assessment system.