5．12汶川地震对岷江上游河道的影响--以都江堰-汶川河段为例  

River Channel Change of the Upper of Minjiang River by 5.12 Wenchuan Earthquake:A Case Study of the Section of Dujiangyan-Wenchuan

作　　者：葛永刚[1,2,3] 庄建琦[1,2,3] 

机构地区：[1]中国科学院山地灾害与地表过程重点实验室,成都610041 [2]中国科学院成都山地灾害与环境研究所,成都610041 [3]中国科学院研究生院,北京100049

出　　处：《地质科技情报》2009年第2期23-28,共6页Geological Science and Technology Information

基　　金：973项目“汶川地震次生灾害形成机理与风险控制”(2008CB425802);国家自然科学基金项目(40841011);西部交通建设科技项目“震后灾区公路走廊次生灾害危险性评估技术研究”(200831822196)

摘　　要：5．12汶川地震造成灾区地质灾害广泛发育，土壤侵蚀剧烈，极大地破坏了灾区环境，改变了灾区自然环境演化的进程。通过实地调查与观测，并结合遥感资料数据，分析了岷江上游都江堰-汶川河段地质灾害的发育特征，揭示了崩塌、滑坡、泥石流、堰塞湖及工程建设对岷江上游河道的影响形式，分析了上游河道的变化趋势。研究表明，震后崩塌、滑坡单侧挤占河道使岷江干流河宽普遍压缩5～10m，顶冲挤占使河道一般变窄20~30m，最窄处仅为原河道的1／3（30-40m）。泥石流堆积物进入河道而淤积河道，甚至阻断岷江而形成堰塞湖，造成河床上升，河曲加剧，工程建设及灾害．点处置使河宽变窄。在多重因素的共同作用下，今后10-20a，尤其震后5a内，汶川-映秀河段，河道变窄，河曲加剧，河床升高，河床比降呈增大趋势，映秀-紫坪铺河段淤积明显，河床升高。从长期变化来看，地震次生山地灾害加速了岷江上游高山峡谷区河道的自然演化进程，河床升高并展宽，河床比降降低，河谷逐渐向宽谷形态演化，河床趋于稳定。This paper discusses the river channel change of the upper of Minjiang River by geo-hazards induced by 5.12 Wenchuan Earthquake, including collapse, landslide, debris flow, geo-hazard darn lake and so on. It also studies the characteristics of geo-hazards distributed in Dujiangyan-Wenchuan Highway and establishes the mechanisms of river channel change by geo-hazards on the basis of the field observations and the remote sensing image analysis. After this earthquake, most Minjiang River channel width decreased by 5--10 m due to the deposition of collapses and landslides, somewhere by 20--30 m, and the narrowest remaining only 30--40 m. Debris flow delivered quantity of solid materials into the River and deposited on the river channel, blocked the river and generated geo-hazards dam lake, resulting in the rise of the riverbed and the increase of the river curve . Generally, in the coming 10--20 years, especially the next 5 years, the river channel of Wenchuan-Yingxiu would become narrower with more curves and higher riverbed slope. While the riverbed of Yingxiu-Zipingpu would rise rapidly because of the deposition of sediments from the upper Minjiang River. In the long term, the geo-hazards by this earthquake will accelerate the natural evolvement of the upper reaches of the Minjiang River and induce riverbed rise and extension, riverbed slope reduction and gorge expansion.

关 键 词：汶川地震 次生地质灾害 岷江上游 河道变化 

分 类 号：P642.23[天文地球—工程地质学] TP753[天文地球—地质矿产勘探]