成都龙门山地震区波状剥蚀过程及其成因

The Wave Denudation and Its Mechanisms in the Chengdu Longmenshan Earthquake Region

针对2008年汶川震后湿润成都龙门山剥蚀与山地灾害发生的巨大变化问题,锁定龙溪-白沙河流域,通过对2009-2014年间具体的山洪泥石流事件引发的剥蚀数量展开调查,并参考震前的区域剥蚀研究成果和其他地震山区剥蚀特征来剖析该震区波状剥蚀过程及其成因。研究发现:(1)区域的剥蚀变化是一个先增后降的波状过程,其峰值变化呈现双曲线衰减趋势,这预示出成都龙门山为代表的区域经过81年后,剥蚀速率将回到地震以前的0. 3 mm,震后26年以后(即2034年后)难以暴发泥石流灾害;(2)震后剥蚀的变化受松散固体物质数量和降水的联合控制。松散固体物质决定了区域内总体的剥蚀变化趋势,而其本身受剥蚀数量、植被覆盖率与土体固结的影响。降水的变化则导致了剥蚀波动。

In view of the huge changes of erosion and mountain disasters in Chengdu Longmenshan after the Wenchuan earthquake in 2008,the Longxi-Baisha River Basin is locked,and the number of denudation caused by the specific mountain torrents and debris flow events in 2009-2014 was investigated and referenced.The corrugated erosion process and its origin in the seismic region are analyzed by referring to the regional erosion research results before the earthquake and the erosion characteristics of other seismic mountain areas.The study found that:(1)the denudation change of the region is a wave-like process with increasing and then decreasing,and its peak value change shows a hyperbolic decay trend,which indicates that the region represented by the Longmenshan in Chengdu is 81 years later.The denudation rate will return to 26 years after the 0.3 mm,earthquake after the earthquake(that is,after 2034),and it is difficult to break out debris flow disaster.(2)the variation of denudation after earthquake is controlled by the amount of loose solid matter and precipitation.Loose solid matter determines the overall trend of denudation in the region,which is affected by the amount of denudation,vegetation coverage and soil consolidation.The change of precipitation results in erosion fluctuation.