震后泥石流活跃期的新认识——以四川汶川"8·20"灾害事件为例  

A New Understanding of the Activity Behavior of Post-earthquake Debris Flow——Taking the“8·20”Event in Wenchuan,Sichuan,China as an Example

作　　者：靳文 张国涛 邹强[1] 崔鹏[1] 王昊 JIN Wen;ZHANG Guotao;ZOU Qiang;CUI Peng;WANG Hao(Key Laboratory of Mountain Hazards and Surface Process,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;University of Chinese Academy of Sciences,Beijing 100049,China;Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]中国科学院、水利部成都山地灾害与环境研究所山地灾害与地表过程重点实验室,成都610041 [2]中国科学院大学,北京100049 [3]中国科学院青藏高原研究所,北京100101

出　　处：《山地学报》2019年第5期787-796,共10页Mountain Research

基　　金：中国科学院前沿科学重点研究项目(QYZDY-SSW-DQC006);四川省科技计划资助(2019YFH0040)。

摘　　要：受2019年8月19—20日强降雨影响,位于汶川地震灾区的都江堰和汶川地区(简称"都汶地区")暴发群发性山洪泥石流灾害(简称"8·20"灾害),造成12人遇难,26人失联,直接经济损失约36.26亿元.通过遥感解译、野外现场调查等手段,结合气象、地形、物源等数据分析,对本次岷江流域泥石流成因与特征有了初步认识:(1)汶川灾区泥石流活动性由震前低频非群发特征,在震后5年内,经历了高频、特大型、群发、粘性泥石流活动性发展阶段,在震后5~15年间,已经演化成低频、大中型、群发、粘-过渡性泥石流并伴生山洪,震后15~20年,汶川灾区泥石流将恢复或接近震前活动状态;(2)"8·20"灾害具有群发性特征,涉及沟谷多达23条,主要沿人类或工程活动相对集中的岷江河谷、都汶公路沿线呈条带状分布;(3)"8·20"灾害的激发雨强和有效降雨分别为24.2 mm/h和116.4 mm,高于震后初期激发雨强,但略低于震前泥石流激发雨强;(4)受控于主河水动力条件和泥石流体搬运能力,"8·20"灾害中泥石流以侵蚀作用和堆积作用两种方式形成危害,洪水表现为冲蚀破坏."8·20"灾害活动是汶川"5·12"强震10年后出现的一次区域性山洪泥石流灾害,加强对此次灾害的认识,有助于为地震灾区灾害防治和减灾规划提供科学支撑.Due to heavy rainfall from August 19 to 20,2019 in the Wenchuan area(Dujiangyan City and Wenchuan County,Aba Prefecture,Sichuan Province,China),a well-known place stricken by mega earthquake in 2008(the 5·12 Wenchuan Earthquake),it broke out massive debris flows and flash floods(referred to as"8·20"Event).Twelve people were killed and 26 people missing,with a direct economic loss about 3.626 billion Chinese Yuan.It is quite concerned that the"8·20"Event occurred at the time of a decade after the Quake,which has been widely recognized as a watershed time for differentiating post-quake debris flow activity.In order to understand the activity behavior of post-earthquake debris flow,the"8.20"Event was taken as a case study.By remote sensing interpretation,field survey,meteorological and geophysical data analysis,a preliminary understanding of debris flow situation in the Wenchuan area was achieved.(1)The activity of debris flow in the Wenchuan area before the Quake was characterized by low-frequency and non-clustered occurrence.In the ensuing5 years of 2008,Wenchuan subjected to massive outbreak of viscous debris flows,characteristic of high-frequency,mega-scale,clustered occurring.In the 5~15 years of the Earthquake,debris flows has evolved into a pattern of low frequency,medium-large-scale,viscous-transitional combined geophysical property,accompanying by simultaneous flash floods.It suggests that in the 15~20 years after the Quake,debris flows in the region would be gradually recovering to the pre-earthquake state;(2)The"8·20"Event behaved in a collective formation,involving up to 23 river basins mainly distributed along the Minjiang River valley and the Dujiangyan—Wenchuan Highway,where human or engineering activities are relatively concentrated;(3)The critical rainfall intensity and effective rainfall in the 8.20 Event were 24.2 mm/h and 116.4 mm respectively,which are higher than the values obtained in the early days after the Earthquake,but slightly lower than the value before the Earthquake;(4)Controlle

关 键 词：泥石流 山洪 群发性 低频大规模 震后效应 都江堰 汶川 

分 类 号：P931.1[天文地球—自然地理学]