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基于泥石流来源于某些处于特殊演化阶段的分支小流域的理论,分析了面积高程曲线及其参数与泥石流活动的关系。面积高程曲线积分值S表征流域内松散固体物质量,S/2对应的相对高差比值K表征流域源地面积在不同高程的分布,以S和K为参数提出泥石流敏感性分析思路。针对汶川县主要公路(都汶公路和省道303)沿线泥石流敏感性分析,在Arcgis、Matlab等软件的支持下,基于震前1∶50 000地形数据,计算了研究区泥石流流域的S和K。根据计算结果,初步判定了各流域的地貌发育阶段,以及流域源地汇水区的高程位置。并根据震后泥石流实际活动情况,对于S小于0.5但又属于震后频发型,或者S值大于0.5但其面积较大且分支较多泥石流沟,进行了次一级子流域的面积高程值计算,判定其易发生泥石流具体源地。最后,根据流域面积高程值S得出了研究区泥石流敏感性分级图,分析结果基本反应了地貌演化对泥石流发生能力的潜在影响。
Based on the theory that debris flow is derived from some small watersheds in special evolution stage, the relationship between area elevation curve and its parameters and debris flow activity is analyzed. The integral value of area elevation curve S is used to characterize the mass of loose solid matter in the river basin. The relative elevation ratio K corresponding to S / 2 is used to characterize the distribution of source area of the river basin at different elevations, and the idea of debris flow sensitivity is proposed using S and K as parameters. Based on the analysis of the debris flow sensitivity along the major roads in Wenchuan County (Duveruang Highway and Provincial Highway 303), the S and K values of debris flow in the study area were calculated based on the topographic data of 1:50 000 before the earthquake with Arcgis and Matlab software. . According to the calculation results, the geomorphologic development stage of each basin and the elevation position of catchment area of the basin are preliminarily determined. According to the actual activity of debris flow after the earthquake, for S less than 0.5 but also belong to the frequent earthquake type, or S value is greater than 0.5, but its area is larger and the branch more debris flow channel, the sub-watershed area elevation value Calculated to determine the specific source of debris flow prone. Finally, according to the elevation value S of the basin, the grading map of the debris flow sensitivity in the study area is obtained. The analysis results basically reflect the potential impact of the geomorphy evolution on the occurrence capacity of the debris flow.