新疆雪灾空间格局和年际变化特征分析

Spatial pattern and interannual variation characteristics of snow disaster in Xinjiang

利用1961—2018年新疆雪灾事件的7个灾情要素(出现次数、死亡人数、倒塌房屋数、倒塌棚圈数、倒塌温室大棚数、牲畜死亡数、受灾面积)数据,采用比值权重法和无量纲化线性求和方法构建了雪灾灾损指数,雪灾灾损指数与7个灾情要素显著相关,且大小能够代表雪灾灾损的强弱。依据灾损指数的伽玛分布,将雪灾的危害性划分为一般、较重、严重、特重4个等级。结果表明,新疆雪灾北疆多于南疆,主要分布在农牧区,主要出现在11月至次年4月,特重等级的雪灾出现在伊犁河谷、阿勒泰市、托里县、阿图什市、巴音布鲁克、巴里坤县。新疆雪灾的年际变化波动性加剧,并且年灾损指数(雪灾强度)呈线性增强趋势,特重等级的雪灾出现在1985、1990、2001、2006、2008、2010年。在风速、气温、水汽压、降雪量、积雪深度这5个气候要素中,雪灾集中期11月至次年4月的新疆雪灾年际变化的主要气候影响因子是降雪量和平均积雪深度。总体来看,新疆雪灾的空间差异性明显,年际变化呈增强的变化趋势。

Based on seven disaster factors:number of snow disasters,deaths,collapsed houses,collapsed sheds,collapsed greenhouses,livestock deaths,and affected area in Xinjiang from 1961 to 2018,the ratio weighting method and linear dimensionless method were used to construct the snow disaster damage index,which is significantly correlated with seven disaster factors.Its size could represent the strength of snow disaster damage.According to the gamma distribution of disaster damage index,snow disaster is divided into four grades of harmfulness:mild,moderate,severe,and extra severe.The frequency of snow disaster in winter,spring,autumn,and summer is 46.5%,39.5%,10.8%,and 3.2%,respectively.Snow disaster mainly occurs from November to April of the next year,accounting for 89%of the whole year,mainly due to the heavy snowfall and thick snow depth in this period.The spatial differences in snow disasters in Xinjiang are obvious.According to the disaster damage index,the top five prefectures(cities)ranked from large to small are:Kizilsu Kirgiz Autonomous Prefecture,Ili Prefecture,Altay region,Tacheng region,Urumqi City,and Hami City.The high value areas of disaster damage index are mainly concentrated in northern and northwestern Xinjiang and pastoral areas in southwestern Xinjiang,while the low value areas are mainly concentrated in the oasis plain.The extra severe snow disasters take place in Nilka County,Xinyuan County,Yining County,Huocheng County,Altay City,Toli County,Artux City,Bayinbuluk,and Barkol County.These counties and cities are the difficult and key areas for disaster prevention and relief.The interannual variability of snow disasters in Xinjiang from 1961 to 2018 is intensifying,and the annual disaster damage index(intensity of snow disasters)shows an increasing linear trend,with an increase of 0.25 every 10 years.The extra severe snow disasters occur in 1985,1990,2001,2006,2008,and 2010,indicating that after entering the 21 st century,the frequency of extra severe snow disasters increases significantly.Among the five climatic factors of wind speed,temperature,vapor pressure,snowfall,and snow depth,the snowfall and average snow depth from November to April of the next year are the main climatic factors affecting the interannual variation of snow disasters in Xinjiang.In summary,the spatial difference in snow disasters in Xinjiang is obvious,and the interannual variation shows an increasing trend.