基于遥感解译的典型强震区泥石流物源发育及演化--以四川都汶高速沿线为例

Distribution and evolution of debris flow in a typic meizoseismal area based on remote sensing:A case study of the Sichuan Duwen expressway

四川都汶高速位于2008年汶川地震强震区内,震后泥石流灾害异常活跃,对人类财产造成严重损失、人居安全构成重大威胁。为了查清山体斜坡物源空间分布规律,探讨汶川震区泥石流物源成因,选择区内震前DEM、震后Landsat TM多波段融合数据及典型泥石流沟2期全色波段遥感数据,进行泥石流物源发育特征及演化分析。结果表明:①汶川地震强震区物源发育受地形坡向、坡度、高程及水系的共同控制。在坡向上具有背坡面放大效应和逆冲(错动)方向放大效应,高程和坡度选择与山体斜坡发育的动力过程相关;②地震能量释放是物源发育基础,建立了强震区物源发育密度与地震烈度的指数关系模型,并认为研究区断层的存在可能促进了泥石流物源的进一步发育;③物源演化具有面积缩小、大型物源解体为多个小型物源、小型物源汇聚而致规模增大、物源迁移、出现新物源等特征。

Duwen highway in Sichuan province is located in the strong earthquake zone of the 2008 Wenchuan earthquake,where postearthquake debris flow disasters are exceptionally active.The debris flow disasters causes serious damage to human property and poses a major threat to human security.In order to find out the spatial distribution pattern of the material sources on the mountain slopes and explore the causes of the mudslide material sources in the earthquake area,pre-earthquake DEM,post-earthquake Landsat TM multiband fusion data,and two-phase full-color band remote sensing data of typical debris flow gullies in the area were selected to analyze the characteristics and evolution of debris flow source development.The results show that the development of debris flow sources is significantly controlled by the combined effects of terrain slope direction,slope gradient,elevation,and water system in the strong earthquake zone of the Wenchuan earthquake.There is a"back slope amplification effect"and"reverse(displacement)direction amplification effect"on the slope direction,and the elevation and slope gradient are related to the dynamic process of mountain slope development.The release of seismic energy is the basis for the development of debris flow sources.An index relationship model between the density of debris flow source development in the strong earthquake zone and seismic intensity was established,and it was believed that the presence of faults in the study area may promote further development of debris flow sources.The evolution of debris sources is characterized by area reduction and disappearance,the disintegration of large sources into multiple small sources,the convergence of small sources leading to an increase in scale,source migration,and the emergence of new sources.