甘肃省暴雨洪水时空分布及风险评估

Spatiotemporal pattern and risk assessment of storm flood in Gansu Province

利用甘肃省1951-2008年的降雨资料,基于GIS平台进行了暴雨洪水灾害的时空分布特征分析,基于层次分析法建立了区域暴雨洪水灾害风险评估指标体系,对甘肃省暴雨洪水灾害进行了风险评价。研究结果表明:(1)甘肃省58 a中只有3 a没有暴雨记录,其他年份均有暴雨发生,甘肃省记录的日最大降雨量为167 mm,发生在平凉市;(2)近60 a来甘肃省暴雨量在空间上呈现从西向东逐渐增大的态势,累计暴雨量以庆阳市为最高,依次为平凉市、天水市和陇南市;(3)甘肃省暴雨洪水灾害综合风险最高的地区为临夏州、天水市、平凉市、庆阳市部分地区、兰州市局部地区和陇南市部分地区,其面积为2.95万km^2,百分比为6.77%;中等及较高风险地区面积分别为6.57万km^2和4.64万km^2,其面积百分比为15.05%与10.62%;较低和低风险区所占面积为29.51万km^2,所占面积百分比为67.56%。(4)甘肃省暴雨洪水灾害高风险区面积不大,但危害性较高,这些区域为该省主要的人口聚集地和重要的农业生产基地,对社会经济发展的影响较大,而综合风险较低的区域则多为戈壁滩和沙漠,人类活动较少,对社会经济影响较小。

Using rainfall data of Gansu Province from 1951 to 2008, spatiotemporal distribution characteristics anal- ysis of rainstorm and flood disaster was carded out based on GIS platform. The index system of regional rainstorm and flood disaster risk assessment was established on the basis of analytic hierarchy process, and risk assessment of the rainstorm and flood disasters in Gansu Province was conducted. The results show that ： （ 1 ） Except three years without rainstorm, the latter oceurrs almost every year during past 58 years in Gansu Province. The daily maximum rainfall recorded is 167 mm, which occurrs in Pingliang City. （2）In recent 60 years, the rainstorm amount in Gan- su Province increases gradually from west to east, with the highest volume in Qingyang City, then Pingliang City, Tianshui City and Longnan City in turn. （3）The comprehensive risk of rainstorm and flood disaster is highest in Linxia Prefecture, Tianshui City, Pingliang City, and parts of Qingyang City, Lanzhou City and Longnan City, their areas are 2.95 × 10^4 km^2, accounting for 6.77% of total area. Regions with middle and high risk are 6.57× 10^4 km^2 and 4.64 × 10^4 km^2, accounting for 15.05% and 10.62%, respectively. Regions with lower and the low- est risk covers 29.51 × 10^4 km^2, accounting for 67.56%. （4）Land area with high risk of rainstorm and flood dis-asters in Gansu Province are limited, but the danger is higher, because these areas are main population centers and major agricultural production bases, and have large effects on the socio-economic development. Lower risk area are mainly distributed in the gobi and desert, with fewer human activities and less impact on social economy.