中国泥石流形成环境剖析

ON THE FORMATIONAL FACTORS OF DEBRIS FLOW IN CHINA

丰富的松散固体物质、充沛的水源和陡峻的地形,作为泥石流形成的三个基本条件,已得到学者们的认同。就本质而言,这三者可归纳为能量和物质两大因素。本文从中国泥石流区域分布着眼,从不同尺度的自然环境因素和人为活动,探讨中国泥石流形成发展的基本规律。研究结果表明,大尺度的区域地质背景、大地貌单元和犬气候系统是控制泥石流形成发育的主导因素;不稳定斜坡因子、小尺度水文气象因子、流域形态因子、森林植被因子等,在大尺度因素的基础上,对泥石流的形成有重要影响;历史上,特别是近期人类经济活动对环境的不良影响,加剧了泥石流的发展。泥石流灾害非单一因子所致,而是诸多因子综合作用的结果,是山地环境退化的产物。泥石流活动具有开放性、内外营力作用的共同性以及自然因素和人为因素的复合性这三大特点。

China is a country that two thirds of its land covers by mountains. Affected by the Pacific and Indian monsoon, and western mountain glaciers, debris flows have damaged much to the development and construction of mountain regions. Recognizing the formational environments of debris flow is significant to mitigate the disasters. It is well know that three conditions are contributed to initiate debris flow, which'are enough debris material, steep relief and plentiful water. Based on the distribution of debris flow in China, the authors discussed the formational factors according to the natural environments of varies scales and human activies. Several conclusions are obtained as follows: 1. the essential causes to the formation of debris flow in China are the regional geological background, large scale geomorphol ogica and climatic factor, all those control the regional distribution of debris flow; 2. based on the above regional factors, there are four of small-scale significantly to the formation of debris flow, those are unstable hillsiope, small-scale hydrolgy and climate, morphology of basin, and forest and vegetation. 3. irrational human activities in history and much more within the'recent scores of years, have been accelerating the debris flow. 4. the debris flow is a processes of interaction of many factors, the effect may be positive or negative, long-term or short-term, reversible or irreversible; 5. there are three characteristics of the activity of debris flow: openness, interaction of internal and external geological forces, and complexity geodogical of nature and human activities.