喜马拉雅山南、北坡滑坡泥石流发育规律对比研究

Geologically and tectonically active Himalayan Range is characterized by highly elevated mountains and deep river valleys. Because of steep slopes, and dynamic geological condition, landslides and debris flows are very common in Himalayan Range area, where as one of the most active area for geo-hazards in the world. Because of the location and elevation, the Himalayan Range becomes the climate boundary for atmospheric circulation. Precipitation and temperature change with the altitude, and also show many differences in the south slopes with the north slopes of Himalayan Range. So it leads to differences of the distribution and activities for landslides and debris flows between the south range and north range of Himalaya. And for the Himalayan Range measures 2,500km in the length and the climates different in the west section and east section, so landslides and debris flows also show corresponding differences in each section of Himalayan Range. In this study remote sensing technology will be utilized to extracted landslides and debris flows in Himalayan area, then relationships of landslides and debris flows with background factors, such as geology factors, topographical factors and climate factors would be analyzed by GIS. Three belt zones perpendicular to the Himalayan Range will be chosen, to contrast the differences of distribution and activities for landslides and debris flows in south range and north range of Himalaya. Besides, two belt zones parallel to the Himalayan Range will be chosen, to find the characteristics of landslides and debris flows change with the longitude. So as to discuss distribution, characteristics and activities of the landslides and debris flows in the Himalayan area, to analyze the tendency of landslides and debris flows, and also to give suggestions for hazards control in this area.

喜马拉雅山为世界上最高、最年轻，也是最活跃的山脉，其地形起伏大，地质构造复杂，新构造运动活跃，使得该地区成为滑坡、泥石流最为发育的区域之一。由于位置和海拔的原因，喜马拉雅山成为影响大气循环的气候分界线，气候随高程梯度变化明显，南北坡气候差异显著，加之东西纵横长逾2,500km，东西段气候差异，这使得滑坡、泥石流在喜马拉雅山呈现出独特的发育特征。本研究利用遥感技术对滑坡、泥石流在喜马拉雅山区的分布进行调查，在全区尺度下分析滑坡、泥石流与地质、地形、气候等孕灾因子之间的关系；选取垂直于喜马拉雅山的南北向条带，研究喜马拉雅山滑坡、泥石流活动特征随高程梯度变化规律，对比分析南、北坡滑坡、泥石流发育的差异；选取平行于喜马拉雅山的东西向条带，研究滑坡、泥石流发育的经度地带性分异规律。从而全面的了解滑坡、泥石流在喜马拉雅山区的分布规律与活动特征，对其发展趋势进行分析，为这一地区的减灾防灾提供参考。

喜马拉雅山区山地灾害发育，种类较多，包括雪崩、冰湖溃决、崩塌、滑坡、泥石流、山洪等，危害严重。本项目利用多源遥感影像，建立滑坡、泥石流解译标志，对滑坡、泥石流开展遥感解译，并开展考察工作，对山地灾害数据进行校验。研究发现，喜马拉雅山地形呈典型的两阶地形特征，使得该地区的降雨也呈现出两阶的特征，在Lesser Himalaya和Transition Belt山区，形成两个强降雨带，为滑坡的发生提供了激发条件，形成两个滑坡密集分布区，经过分析，将其命名为构造岩性控制区和地形控制区；对滑坡的数量按照南、北坡进行统计，喜马拉雅山南坡分布的滑坡占整个流域的99%以下，而北坡的滑坡仅占1%。基于滑坡、泥石流的分布数据，利用信息量法统计分析了滑坡与地形、坡度、坡向、岩性等因子的关系，进而将关键因子两两组合，分析了滑坡与高程-坡度，高程-坡向，高程-断裂带，岩性-坡度的关系。地震诱发滑坡和降雨诱发滑坡在空间上呈现出不同的分布特征，研究对比了地震诱发滑坡和降雨诱发滑坡不同敏感性等级的空间分布的差异，对比了不同规模的滑坡不同敏感性等级的空间分布差异，发现不同类型滑坡分布受激发因子分布模式的影响，不同规模的降雨型滑坡空间分布具有差异性。该项目的研究为喜马拉雅山区滑坡、泥石流的空间分布规律和活动特征提供了初步的认识，其研究数据和发现的规律，可以为喜马拉雅山区减灾防灾工作提供参考，为该区域的国际公路建设过程的灾害防护提供依据，在此基础之上，可以对山地灾害的演化与跨境风险开展进一步研究。