【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5~10 m,顶冲挤占使河道一般变窄20~30 m,最窄处仅为原河道的1/3(30~40 m)。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10~20 a,尤其震后5 a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。更多还原

【Abstract】 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 dam 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.更多还原