中国西部泥石流及其减灾对策

中国西部多为山区,泥石流异常发育,类型相当齐全,几乎发育着除火山泥石流以外的各种类型泥石流.泥石流严重危害山区城镇、交通、农田、工矿和水利工程等,造成严重灾害.仅已查明的泥石流就有15797条,其中铁路沿线泥石流1294条.有108个县级城镇、19个地(州、市)首府城镇和4个省会城镇受到泥石流的威胁或危害.西部大开发应注重泥石流减灾,特别要加强工程前期减灾预研和减灾知识普及,建立灾害信息系统,实现资料共享,把城市规划和减灾规划结合起来,进一步搞好环境保护和生态建设.

DEBRIS FLOW AND DISASTER REDUCTION STRATEGIES IN WESTERN CHINA

China is a country with abound mountains in the west. With the strong uplifting of the Qinghai Xizang Plateau and its marginal mountains, the western mountain regions have become the area with the largest altitude differences and intensive neotectonic movements in the world; and the marginal mountain regions are in plenty of rainfall controlled by the East Asian monsoon. Under these influences, the west of China is one of regions under threat of the most extensively developed and endangered debris flows in the world. There exist nearly all types of debris flow except volcanic debris flow. The distribution of debris flows is obviously controlled by landforms, geologic structure, rock properties, monsoonic climate and human activities. Most debris flows develop in the transitional areas between the 3 geomorphologic units in China, especially in the second and third geomorphology transitional belts, including the deeply undercut extra high mountains, high mountains and middle mountains. Debris flows often appear in groups and zones, and concentrate on the southeast of Xizang, mountains of the southwestern China, the Loess Plateau and Qinling Mountains. In particular, glacial debris flow mainly distribute in the southeast of Xizang, rain water debris flow in southwest and northwest mountains, and mudflow in loess areas of the northwest. It has been reported that debris flows in China amount to 15 797, among which, 1 294 distribute along railway lines. In some narrow valleys, the conflicts between human beings and debris flows are outstanding. Debris flows always seriously endanger traffic lines, factories, mineral fields, river channels, water conservancies and power stations, gas and electric transports, agricultures, scenic spots and eco environment and other aspects of national economy and society. The preliminary investigation shows that 108 county cities and towns, 19 prefecture capital cities and 4 provincial capital cities are threatened by debris flow hazards. In order to reduce and avoid debris flow hazards in developing the west of China, countermeasures of mitigation and evasion of the hazards are proposed in the paper as follows: (1) the in advance research on disaster reduction should be done in order to grasp the active and dangerous features of debris flow and carry out prevention works scientifically; (2) programs of disaster mitigation should be combined with local construction and reconstruction programs in cities; major buildings can not be constructed in the most dangerous degree zones of debris flow so as to reduce disasters; (3) based on researches and investigation, information system of debris flow in western regions should be set up, which is used for forecasting disaster and planning regional disaster reduction; (4) training programs should be conducted in local inhabitants and officials to increase their level of recognitions in hazard mitigation and prevention; (5) through conserving ecologic system and utilizing natural resources, the mountain environment will be well changed and debris flows will be decreased up to a rather high degree.