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    长江流域不同类型山洪灾害易发区划分

    Susceptibility zoning of different types of mountain torrent disasters in the Yangtze River Basin of sourthern China

    • 摘要: 长江流域因其复杂的地质地貌及气候条件成为我国山洪灾害发生最为密集的地区。山洪灾害易发区划分是山洪灾害防治工作的重要内容,针对长江流域大尺度(跨省级)区域的山洪灾害易发性研究可为长江流域及相似区域的山洪灾害评价研究以及规划、部署、实施山洪灾害防治工作提供科学依据。本文综合考虑影响山洪灾害形成的自然地理因素,以县域为评价单元,构建各类山洪灾害易发程度指标体系,基于Matlab,采用层次分析法计算各类山洪灾害易发性指数。据此,利用ArcGIS自然间距分类方案将长江流域划分为4个山洪灾害易发区,即高易发区、中易发区、低易发区和非防治区。结果表明:溪河洪水灾害呈现由东向西灾害易发程度逐渐降低的趋势,分布较为密集的区域在流域的中东部地区;滑坡灾害高易发区主要分布在流域中部,上游干流附近滇北和陇南山地,尤以四川盆地以东地区最为集中;泥石流灾害高易发区主要分布在流域西部,其中以断裂带发育的第一、二阶梯过渡带最为密集。划分结果显示各类山洪灾害在流域内的分布差异较为明显,不同类型山洪灾害的历史发生次数在高易发区的集中程度均在80%以上,表明分区结果能够较好反映各灾害的区域分布特征。

       

      Abstract: The Yangtze River Basin has become the most intensive area of mountain torrent disasters in China because of its complex geological topography and climatic conditions. Susceptibility zoning of the mountain torrent disasters is of significance to the integrated disaster prevention system. The study on the susceptibility of mountain torrent disasters in view of the large-scale(inter-provincial) region of the Yangtze River Basin can provide scientific basis for the study of planning, deployment and implementation of mountain torrent disaster prevention in the Yangtze River Basin and similar areas. The assessment indices were established for the susceptibility evaluation of three kinds of mountain torrent disasters in the Yangtze River Basin, based on the affecting mechanism of natural geographical factors on the formation of the mountain torrent with county as assessment unit. The susceptible indicators for three kinds of mountain torrent disasters were calculated based on the method of analytic hierarchy process (AHP) using Matlab. The Yangtze River Basin was classified into four susceptibility degrees of areas for three kinds of the mountain torrent disasters, i.e. highly-susceptible area, medium-susceptible area, lowly-susceptible area and insusceptible area, using classification scheme by ArcGIS natural spacing. The river flood disaster showed a tendency to decrease gradually from east to west, and centered in the middle and eastern basin. The highly-susceptible area of landslide disaster is mainly in the middle of the basin and certain areas like northern Yunnan and the mountains of Longnan, southern Gansu in the upstream of the river, with the most concentrated area in the east of Sichuan Basin. The highly-susceptible area of debris flow disaster is mainly in the west of the basin, and happened most frequently on fault zones in the first and second ladder transition districts. The results showed obvious differences in the distribution of different mountain torrent disasters in the basin. Over 80% of historical disasters were located in the assessed highly-susceptibility area for all three types of mountain torrent disasters. The assessment results can well indicate the regional distributions of different types of mountain torrents.

       

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