| As one of the most influential and major meteorological disasters on the Qinghai-Tibet Plateau,snowstorms have long brought serious economic losses not only to local livestock production,but also threatened plateau traffic safety and social stability.Recent studies have found that with the increase in frequency and intensity of extreme precipitation in the context of global climate change,snowstorms on the Qinghai-Tibet Plateau have become more frequent,bringing great impact on local livestock production and people's lives.Therefore,it is urgent to identify the snow disaster vulnerability areas on the Tibetan Plateau,analyze the spatial and temporal changes of the vulnerability areas and identify the dominant factors of the snow disaster vulnerability areas,so as to provide a scientific basis for realizing the transformation of snow disaster management on the Tibetan Plateau from crisis management to risk management and from post-disaster emergency response to risk prevention.In this study,firstly,the spatial and temporal variation characteristics of snowfall on the Qinghai-Tibet Plateau from 1960 to 2019 were calculated using daily data of temperature,precipitation,relative humidity and barometric pressure at meteorological stations,and the spatial and temporal variation characteristics of historical snowstorms on the Qinghai-Tibet Plateau from 1960 to 2019 were analyzed using county disaster data;secondly,different levels of snowstorm vulnerable areas on the Qinghai-Tibet Plateau were identified by establishing a snowstorm vulnerable area assessment model and index system,and the spatial and temporal variation characteristics of snowstorm vulnerable areas on the Qinghai-Tibet Plateau from 1990 to 2019 were analyzed;finally,the dominant factors of snowstorm vulnerable areas were diagnosed using a geographic probe.The following conclusions were drawn from the analysis:(1)The overall annual average snowfall on the Tibetan Plateau from 1960 to2019 showed a slightly decreasing trend,but the intra-year distribution was uneven,showing an increase in snowfall in winter and spring and a decrease in snowfall in summer and autumn.The analysis of the changes in the average snowfall per 30 years shows that the snowfall shows a trend of increasing and then decreasing,with more than 70% of the sites showing an increasing trend from 1960 to 2000,and more than70% of the sites turning into decreasing snowfall after 2000.(2)The frequency of snowstorms during 1960-2019 showed an overall fluctuating trend,with the greatest increase in winter snowstorms and the highest frequency of spring snowstorms.1960-2019 snowstorm high frequency areas on the Tibetan Plateau were mainly in the southern Qinghai,the Transverse Mountains and the area around Mount Everest,in addition to the higher frequency of snowstorms in the northern Nyingchi Tanggula.The high frequency of snowstorms in spring was mainly in the Hengduan Mountains,southeastern Qinghai and the area around Mount Everest;in summer,snowstorms occurred only in Qinghai,around Mount Everest and a small part of northwestern China;in autumn,snowstorms were mainly in the central part of the plateau and the southern edge of the plateau;in winter,snowstorms mainly occurred in the southern Qinghai and the area around Mount Everest.(3)This paper identifies snow disaster vulnerability zones on the Tibetan Plateau from three aspects: disaster-causing vulnerability,disaster-bearing vulnerability and defense vulnerability.The high vulnerability area is mainly distributed in the Huanghuang Valley,the border between Qinghai and Sichuan,and scattered in the Hengduan Mountains and the Nianqing Tanggula Mountains,accounting for 0.89% of the area of the Tibetan Plateau;the high vulnerability area is mainly distributed in the Hengduan Mountains,the border between Qinghai and Sichuan,the area around the Huanghuang Valley and between the Tanggula Mountains and the Nianqing Tanggula Mountains,accounting for 15.91% of the area of the Tibetan Plateau;the medium vulnerability area is scattered.The medium fragile area is scattered,mainly in the periphery of the higher fragile area,with a total area of 18.74% of the Tibetan Plateau;the lower fragile area is larger,accounting for 27.35% of the Tibetan Plateau,mainly in the Himalayas,Kunlun Mountains and parts of the Qaidam Basin;the low fragile area is the largest,accounting for 37.12% of the Tibetan Plateau,mainly in the Cocosili,Qaidam Basin and the northern Tibetan Plateau.(4)From the analysis of the spatial and temporal changes of snowstorm vulnerable areas,it is concluded that: over the whole time period,the area of low vulnerable areas was the smallest in 1991-1995,accounting for only 14.53% of the plateau area,mainly in the Qaidam Basin,the Ali region of Tibet and sporadically in the Lhasa Valley and the northern edge of Xinjiang.2006-2010,the area of low vulnerable areas was the largest,accounting for 28.60% of the plateau area,in The lower vulnerable area was the smallest in 2006-2010,accounting for 27.99% of the plateau area,mainly in the Golmud region of Qinghai,the Kunlun Mountains,the northwestern part of the Qaidam Basin,and the border area between Tibet and Sichuan.the lower vulnerable area was the largest in 1991-1995,accounting for38.00% of the plateau area,and was distributed in the One River and Two Rivers region of Tibet,the The middle vulnerable area was the least in 1996-2000,accounting for 19.07% of the plateau area,mainly distributed in the southern region of Nagqu,Changdu region,Himalayan region and the eastern region of Qinghai.2011-2015 the middle vulnerable area was the largest,accounting for 27.98% of the plateau area,widely distributed in the eastern region of Qinghai and eastern Tibet.The area of the higher vulnerable area accounted for the smallest only 11.86% in1996-2000,mainly distributed in the border areas of Qinghai,Tibet and Sichuan provinces(regions),southern and eastern Sichuan,while in 2016-2019 accounted for18.73% of the plateau area,distributed in the border areas of Sichuan,eastern Tibet and southeastern Qinghai;the area of the high vulnerable area in 1991-1995 the largest in 1991-1995,accounting for 13.03% of the plateau area,mainly distributed in the junction of Qinghai,Tibet and Sichuan provinces(regions)as well as the Huanghuang valley area.In 2001-2005 the lowest,accounting for 0.77% of the plateau area,only appeared mainly distributed in the Huanghuang Valley region.(5)The dominant factor diagnostics yielded that the explanatory power of both factors under two-by-two interaction was greater than the explanatory power of the action of a single factor.The single-factor effects of terrain relief(0.615),snowfall(0.611),and livestock inventory(0.471)have the greatest explanatory power for snow-damaged vulnerable areas.Nine pairs of explanatory strengths exceeded 0.7under the interaction,among which snowfall ? topographic relief(0.732),topographic relief ? livestock stock(0.730),and snowfall ? livestock growth(0.724)had the highest explanatory strengths for snow-prone vulnerable areas. |
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