基于Flow-R模型的八一沟泥石流危险性评价

Hazard assessment of Bayi Gully debris flow based on Flow-R model

目前泥石流危险性评价方法通常是一条泥石流沟对应一个危险等级。Flow-R模型将泥石流源区识别与泥石流运动相结合计算泥石流的危险概率,能够评价一条泥石流沟内不同部位的危险性。为丰富泥石流评价方法的应用研究及探究单沟内泥石流危险分布特征,以八一沟为研究区,在确定八一沟泥石流源区识别阈值和运动参数的基础上,用Flow-R模型对泥石流可能的危害范围进行模拟计算,并用混淆矩阵对模拟结果进行评估,最后对八一沟流域不同部位进行了泥石流危险性评价。结果表明:(1)泥石流源区主要分布于沟道20°～50°坡度范围和1 400～1 600 m高程范围内,沟顶细小汇水沟道为泥石流提供了丰富的活动物质;(2)泥石流危险区域大致分布在沟道左右40 m范围,占整个研究区域的20.06%;极高危险区分布于沟道中心,危险性由沟道中心向两边逐渐降低;(3)Flow-R应用于研究区的正确率为84.18%,给出的泥石流危险区图合理,能够反映研究区泥石流的基本危险特征。

At present, debris flow hazard assessment method is usually a debris flow gully corresponding to a hazard level. Flow-R model calculates hazard probability by combining the identification of debris flow source areas and the propagation of debris flow, which can assess the hazard of different parts in a debris flow gully. In order to enrich the application research of debris flow assessment method and explore the characteristics of hazard distribution in single-channel debris flows, taking Bayi Gully as study area, on the basis of determining the threshold value of sources identification and the parameters of propagation, Flow-R model is used to simulate the potential hazard range of debris flow, and then use confusion matrix to evaluate the simulation results. Finally, it assesses the debris flow hazard of Bayi Gully in different parts. The results show:(1) Debris flow source areas are mostly distributed in the gullies which the slope range from 20 to 50 degrees and the elevation range from 1 400 to 1 600 meters. The small catchment channels in the top of the gullies provide rich sources to debris flow.(2) The hazard areas are distributed roughly within the range of 40 m both sides of the channel, accounting for 20.06% of the entire study area. The high hazard areas are distributed in the center of the channel and the hazard gradually decreases from the channel center to both sides.(3) The efficiency of Flow-R model applied to the study area is 84.18% and the hazard zonation is reasonable, which can reflect the basic hazard characteristics of debris flow in the study area.