基于物源特征的白龙江流域泥石流易发性评价

Evaluation of Debris Flow Susceptibility in Bailong River Basin Based on Source Characteristics

白龙江流域是泥石流地质灾害的易发区和高发区,历史上曾发生过多次泥石流灾害。为探讨物源对泥石流的影响,对流域内泥石流物源数量、类型、分布进行了详细地调查分析,进而研究了物源转化泥石流的方式,得出以下认识:①白龙江流域泥石流物源分为重力侵蚀堆积型、坡面侵蚀汇集型、沟道侵蚀堆积型和弃渣侵蚀堆积型,其中物源量最多的为重力侵蚀堆积型,分布面积最广的是坡面侵蚀汇集型;②泥石流的物源多分布于坡度在15°~45°范围内的斜坡上,1000~2500 m的高程范围内,距离断裂500 m范围内,且物源量与植被覆盖率呈较好的负相关性;③流域内物源转化为泥石流的方式主要有崩落冲刷拉槽型、集中堵塞溃决型、沟道揭底铲刮型、坡面径流侵蚀溜滑型。最后,采用确定性模型与灰色关联组合方法,筛选出物源敏感性、坡面侵蚀程度、沟床比降、沟壑密度四个因子,运用层次分析(AHP)模型对区域动态孕灾环境进行泥石流易发性评价,得出高易发区位于白龙江干流左岸物源分布密集区。因评价过程综合了泥石流物源发育及分布特征,尤其考虑了研究区受强烈地震扰动这一因素,故取得了较好的结果,不仅能反映区内发生泥石流可能性的大小,为客观地对该区域进行快速泥石流风险评价提供基础数据,还能为相关部门进行防灾减灾、监测预警提供科学依据。

The Bailong River Basin is a prone and high-incidence area for debris flow geological disasters.There have been many events in history.In order to investigate the influence of provenance on debris flow,the quantity,type and distribution of debris flow sources in the basin were investigated and analyzed in detail.The following conclusions are drawn.The debris flow source in the Bailong River Basin is divided into four types of gravity erosion accumulation type,slope erosion collection type,channel erosion accumulation type and waste slag erosion accumulation type.Among which,the most abundant source is the gravity erosion accumulation type,and the most widely distributed source is the slope erosion collection type.The source of the debris flow is mostly distributed on the slope with the gradient in the range of 15°to 45°,in the elevation range of 1000 m to 2500 m,and within the range of 500 m from the fault.And the source quantity has a good negative correlation with the vegetation coverage rate.There are four main modes for the conversion of provenance into debris flow in the basin.Finally,the deterministic model and the gray relational combination method were used to screen out the four factors of provenances sensitivity,slope erosion degree,gully bed ratio and gully density.And the analytic hierarchy process model was used to divide the regional debris flow susceptibility.The results show that the highly prone area is located in the left bank of Bailong River main stream with dense provenances distribution.Because the evaluation process integrated the characteristics of debris flow source development and distribution,especially considering the factor of strong earthquake disturbance in the study area.Therefore,a good result was obtained.The research can not only reflect the possibility of debris flow in the area and provide basic data for rapid debris flow risk assessment in this area objectively,but also provide scientific basis for related departments to prevent and reduce disasters,monitor and early warning.