基于流域单元的泥石流区域危险性评价

进行泥石流区域危险性评价时,首先要选取合适的单元作为评价单元。在前人的研究成果中已有多种评价单元,如栅格单元、斜坡单元、单一条件单元等。作者认为国内评价工作中常采用的栅格单元、行政区划单元都没有体现泥石流发生特定的地貌条件,故提出以流域为评价单元的思路。根据水文学D8方法,介绍了在计算机协助下基于DEM数据自动完成流域单元划分的方法,并以辽宁省鞍山市岫岩满族自治县作为实例,将全区划分为1024个流域单元。将流域划分结果与历史灾害点位置相对比,每个流域内基本上只包含一个灾害点,该情况说明流域划分精度满足研究工作需要。在此基础上利用人工神经网络进行泥石流区域危险性评价。结果显示,以流域作为评价单元能充分体现泥石流发生的地貌特征和物理机制,利于评价指标取值,而且危险性结果与实际情况吻合较好,可为政府部门制定减灾防灾决策提供参考。

Debris Flow Hazard Zonation Based on Cathment-unit

The selection of evaluating unit is very important during the debris flow assessment. There are many kinds of units used in debris flow hazard zonation, such as grid-unit, slope-unit, unique-condition unit, and district-unit etc. Author regards that grid-unit and district-unit, which were used widely in assessment of debris flow in china, don't reflect the geographical and spatial characters of debris flow. So this article proposes to assess debris flow based on catchment-unit. This research provides the method to get catchments use digital elevation model data by computer automatically. On the other hand, we took Xiuyan County in Liaoning province as target region, where occurred a lot of debris flow in 1982, 1987and 1989, and divide the region into 102 4 catchment-units. Comparing with the position of debris flows, there is almost one debris flow in one cathment and this condition shows that the division of cathment-unit is suitable to the assessment of debris flow. Based on the cathment-units, the work of debris flow hazard zonation was done by the artificial neural network. As the result, the cathment-unit has an explicit topographical and geological meaning of debris flow, based on cathment-units the computing of evaluating factors is simple and correct. According to our verification, the hazard mapping based on cathmnet-units accords with the distribution of debris flow in field and is helpful for planning to reduce the damage by government.