基于乡镇单元的青海高原果洛地区雪灾致灾风险评估

Township unit-based risk assessment of snowstorm hazard in Guoluo Prefecture of Qinghai Plateau

雪灾是影响青海南部高原牧业生产最主要的自然灾害。通过利用青海、四川两省的气象站点资料,并结合GIS、RS工具,选取积雪深度、积雪持续天数、积雪面积比3个指标,采用层次分析法(AHP)与聚类分析法相结合的方法,对果洛地区44个乡镇的雪灾致灾危险性进行了评估。结果表明:致灾危险性轻度的乡镇数占总乡镇数的9.1%,中度的占31.82%,较重度的占52.27%,重度的占22.6%,其中,致灾危险性程度较重等级以上的乡镇比例占74.87%。因此可以认为,果洛州是一个雪灾致灾风险较高的地区。从空间分布上来看,轻度等级的分布在玛多县的花石峡镇、扎陵湖乡及玛沁县的东倾沟乡和拉加镇;中度、较重度等级的基本上每个县都有分布,但较重度等级的以达日县和甘德县所占乡镇数较多;重度等级的只分布在达日县的桑日麻乡、特合土乡及玛沁县的当洛乡。

Snowstorm is the major natural disaster of the livestock farming production in the southern Qinghai Plateau. With the meteorological station data of Qinghai and Sichuan and the tools of GIS and RS,and selecting the depth of snow,the duration of snow days,the area ratio of snow as three indicators,this paper made an evaluation of snowstorm risk in 44 towns of Guoluo Prefecture by combining the methods of analytic hierarchy process( AHP)and cluster analysis. The results show that,towns with mild hazard account for 9. 1 percent in total number of villages and towns. Those with moderate hazard account for 31. 82 percent,with minor severe hazard account for52. 27 percent,and with severe hazard account for 22. 6 percent. The proportion of severe grade towns( including minor severe) accounts for 74. 87 percent in all. Thus,it can be said that the Guoluo Prefecture is a high snowstorm hazard area. From spatial distribution,it can be seen that the mild grade areas are Huashixia Town in Maduo County,Zhalinghu village and Dongqinggou village,Lajia town in Maqin county; the moderate and minor severe grade areas are basically distributed in every County. However,the minor severe grade areas cover almost every town in Dari county and Gande county; the severe grade areas only distribute in Sanrima Village,Tehetu Village of Dari County and Dangluo Village of Maqin County.