石羊河流域干旱特征及其灾度和危险度分析

Drought Characteristics and Its Disaster Degree and Risk Degree over the Shiyang River Basin

使用石羊河流域1960—2019年的气温、降水资料和2000—2019年干旱灾情资料,采用统计学、灰色理论等综合评判方法分析了石羊河流域各地干旱的时空变化和强度特征,并对干旱灾害灾度和危险度进行计算和定量评价。结果表明:石羊河流域干旱年频次从高到低基本为中游永昌和凉州、上游天祝和古浪、下游民勤,随年代呈先减少后明显增多趋势。各等级干旱频次的变率较大,干旱频次总体随强度加重而减少。各地最大灾度与出现的干旱频次不太一致,干旱灾害均为轻灾,救灾以县级为主。该流域没有极重度危险区和重度危险区,凉州、古浪、民勤为中重度危险区,全流域及永昌、天祝为中度危险区。干旱灾害的灾度和危险度的分析结果不完全一致。

Using temperature and precipitation data from 1960—2019 and drought disaster data from 2000—2019 over the Shiyang River basin,the tempo-spatial variation and intensity characteristics of drought were analyzed by comprehensive evaluation methods including statistical and grey scale theory,further,the disaster degree and risk degree of drought disaster were calculated and evaluated quantitatively in various counties.The results showed that the annual frequencies of drought over the Shiyang River basin ranged from high to low and were basically in the middle reaches of Yongchang and Liangzhou,upstream of Tianzhu and Gulang,and downstream of Minqin,with a trend of decreasing first and then increasing obviously.Variation rates of annual drought frequencies in various levels were large,total drought frequency decreased with the aggravation of drought grade.The maximum disaster degrees were not consistent with drought frequencies in various counties,all of the drought disasters were light and the disaster relief was mainly at the county level.Extremely severe and severe risk areas had not occurred;Liangzhou,Gulang,and Minqin were middle and severe risk areas;the whole river basin,Yongchang,and Tianzhu were moderate risk areas.The analysis results of the disaster degree and risk degree for drought disasters were not completely consistent.