Impacts of topographical factors on debris flows and weight analysis at the Gansu segment of the Bailongjiang River Basin
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摘要: 白龙江流域甘肃段是我国四大泥石流灾害多发地区之一，其中地形条件是形成泥石流的关键因素。文章在实地调查研究区内发育的1 008条泥石流沟的基础上，通过统计分析沟床比降、沟坡坡度、流域面积和相对高差4个主要地形因素数据与泥石流灾害的类型及易发程度的关系，研究其对泥石流灾害形成的影响。通过熵权法计算4个因素的权重，由权重大小排序分析了它们对泥石流灾害形成的贡献程度。结果表明：在200‰~400‰区间内的沟床比降、坡度大于30°的沟坡、相对高差大于300 m的山体、小于10 km2的流域面积对泥石流的形成和运动最为有利；对泥石流灾害形成贡献程度最大的为沟床比降，其次为相对高差和流域面积，最小的为沟坡坡度。该研究结果对此区域内泥石流灾害的监测预警及防治有一定指导意义。Abstract: The Gansu segment of the Bailongjiang River is one of the four major debris flow disaster areas in China. Topography is the key factor for the formation of debris flows. In this paper, the impacts of topographical factors on debris flows at the Gansu segment of the Bailongjiang River Basin are examined based on a statistical analysis of the relationship between the main topographical factors, such as the groove gradient, gully slope, relative elevation difference, drainage area and the debris flows’ types, and the susceptibility by investigation of 1 008 debris flows in the study area. The contribution degree to the formation of debris flows is analyzed by ranking the weights of the 4 factors which are calculated by the entropy method. The results show that the groove gradient in the range of 200‰-400‰, slope greater than 30 degrees, relative elevation difference greater than 300 m, less than 10 km2 of drainage area are beneficial to the formation and movement of debris flows. The greatest contribution degree to the formation of debris flows is the groove gradient, followed by the relative elevation difference and drainage area, and the smallest is the gully slope. The results of this study are of guided significances for the monitoring, warning and prevention of debris flow disasters in this area.
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Key words:
- topography /
- Bailongjiang River Basin /
- debris flow /
- entropy method /
- geological hazard
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