泥石流沟危险度定量评价研究——以白龙江陇南两河口镇至桔柑乡段为例

泥石流的危险度是认识、防控泥石流的重要因素,针对反映泥石流危险度的特征函数进行分析,运用量纲分析方法,建立了基于泥石流势能的单沟危险度计算模型。同时考虑到防治工程的减危效果,增加了拦砂坝和排导槽对泥石流的拦挡排疏功能来修正模型,并以白龙江陇南两河口镇至桔柑乡段138条泥石流沟为例来验证模型的有效性,得到了研究区域单沟泥石流危险度值。结果表明:修正模型能计算增加防治工程后单沟泥石流的危险度,具有较好的实用性;沿白龙江流域的泥石流沟中,极高危险区占研究区范围的17.39%,高度危险区占研究区范围的21.74%,且危险区大多集中于白龙江北岸,计算值与野外实际情况基本吻合;然而由于防治工程减危值受历史条件的影响,对于极高危险区的泥石流沟,应及时做好防范。

Quantitative risk degree evaluation on debris flow gully: a case study of Lianghekou-Jugan reach of Bailong River,South Gansu Province

The risk degree of debris flow is an important factor to understand, prevent and control debris flows. According to the characteristic function reflecting debris flow risk degree and the dimensional analysis method, a single gully debris flow risk degree calculation model based on debris flow potential energy is established. At the same time, considering the risk reduction effect of controlling projects, the blocking and drainage function of sediment retaining dam and drainage canal for debris flow is considered to modify the model. Taking 138 debris flow gullies from Lianghekou Town to Jugan Township by Bailong River as examples, the effectiveness of the model has been verified and the single-gully debris flow risk values are obtained. The results show that the model could calculate the risk value of single-gully debris flow considering the control projects, and has good practicability. In the debris flow gullies in the Bailong River Basin, the extremely high risk area accounts for 17.39%, and the high dangerous area accounts for 21.74%, and most of the dangerous areas are concentrated on the north bank of the Bailong River. The calculated values are in reasonably good agreement with the actual situation in the field. The risk reduction value of prevention and control project is affected by historical conditions. For debris flow gullies in extremely high risk areas, prevention should be done in a timely manner.