怒江支流迪麻洛河流域泥石流易发性评价

Susceptibility assessment of debris flow in Dimaluo River,branch of Nujiang River

以往对于怒江流域泥石流的研究大多关注支流泥石流对干流的影响,而对支流内群发性泥石流易发性的研究较少。迪麻洛河为怒江左岸一级支流,因其凸型斜坡地貌、变质软岩分布、断裂剪切破坏及新构造运动间歇性抬升产生的丰富物源等特征在怒江上游具有代表性。野外调查揭示,流域内泥石流主要分为沟谷型、坡面型和沟谷-坡面复合型3种,且多发育于迪麻洛河左岸。基于水文响应单元,从地质、地貌、降雨量、物源条件、人类工程活动等方面选取8项评价因子。针对各因子对不同类型泥石流影响程度的不同,采用层次分析法赋予各因子不同的权重。最后结合信息量法,分类剖析不同类型泥石流的易发性。结果表明:各类泥石流易发性高和极高的地区主要地层为石炭系第四段(C^(d))、第五段(C^(e))等岩性软弱地层;主要沿着道路建设等人类工程活动强烈的地区分布;越靠近断裂带易发性越高。随着易发性等级的提高,泥石流发育比例和相对发育比例也相应增高;各类型泥石流AUC达83.34%、90.07%和84.39%,评价结果合理,可为怒江支流泥石流防治规划与预测预报提供科学依据,为西南深切峡谷变质软岩区群发性泥石流防灾减灾提供理论和技术参考。

The research on debris flow in Nujiang River mostly focused on the influence of tributary debris flow on the main stream,but ignored the tributary debris flow.Dimaluo river is a tributary on the left bank of Nujiang River.It is representative in the upper reaches of Nujiang River(Yunnan)because of its convex slope landform,distribution of metamorphic soft rock,fault shear failure and abundant provenance caused by intermittent uplift of Neotectonic movement.Field investigation shows that debris flow can be divided into three types,gully type,slope type and composite type.Based on the hydrological response unit,8 evaluation factors are selected.This paper analyzes the susceptibility of different types of debris flow by using AHP and information method.The results show that the areas with high and extremely high susceptibility to all kinds of debris flow are mainly weak strata such as C^(d) and C^(e),and they are mainly distributed along the areas with strong human engineering activities,such as road construction,with the closer to the fault zone,the higher the susceptibility.The AUC of all types of debris flow reaches 83.34%,90.07%and 84.39%,so the evaluation results are reasonable,which can provide scientific basis for the prevention and control planning and prediction of debris flow in Nujiang River,and provide theoretical and technical reference for disaster prevention and mitigation of mass debris flow in southwest deep canyon metamorphic soft rock area.