汶川地震强震区映秀地区泥石流的危险性  

Risk of Debris Flow in Epicenter of Wenchuan Earthquake,Yingxiu of Sichuan

作　　者：刘清华[1] 唐川[1] 常鸣[1] 余斌[1] 

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《山地学报》2012年第5期592-598,共7页Mountain Research

基　　金：国家科技支撑计划课题"龙门山地震带小流域泥石流滑坡灾害综合风险评价技术研究与示范"(2011BAK12B01)~~

摘　　要：汶川地震震中四川省汶川县映秀镇及附近于2010-08-14暴发群发性泥石流(简称"8.14"泥石流),造成巨大的人员伤亡和财产损失。地震灾区松散固体物源丰富,泥石流灾害相对活跃,估算未来不同降雨频率下泥石流的暴发规模并评价其危险性,是泥石流灾害风险管制的首要工作。在研究四川省部分地区的泥石流和对应降雨频率资料的基础上,得到泥石流规模和降雨频率之间的关系式。以映秀"8.14"泥石流的暴发规模和降雨频率为基础数据,通过泥石流规模和降雨频率之间的关系式推算得到映秀及附近岷江两岸13条泥石流沟在不同降雨频率下的泥石流规模。以泥石流在堆积扇上的平均堆积厚度(泥石流规模/堆积扇面积)、泥石流发生频率、流域面积、主沟长度、流域相对高度、流域切割密度和不稳定沟床比例为危险性判断因子,分别对映秀及邻近地区的13条泥石流沟在100 a、50 a、20 a、10 a和5 a一遇5种不同频率降雨条件下的泥石流危险性进行评价。结果表明:在5种降雨频率下,8条沟的泥石流危险性为高度,4条沟的为中度到高度,1条沟的为中度。Group debris flows occurred on August 14,2010 in Yingxiu area, epicenter of Wenchuan earthquake, Si- chuan province, which caused enormous life and property losses. The debris flows are very active because of the a- bundant loose materials in earthquake-stricken areas, it is the primary work for the management and control of debris flow risk to estimate the scale and hazard under different rainfall frequencies in the future. The empirical formula between debris flow scale and rainfall frequency was obtained by collecting and studying the datum. The scales of 13 debris flows under different rainfall frequencies were calculated i through the empirical formula with the basic da- tum of ＂8.14＂ debris flows scales and rainfall frequency in Yingxiu area along the Minjiang river. Chosen the aver- age deposition thickness of alluvial fan （ scale / alluvial fan area）, oceurrence frequency, drainage area, channel length ,basin relative height ,valley incision density and instability gully cutting proportion as hazard judgment fac- tors,the debris flow hazards of 13 gullies were assessed under the rainfall return period of 100 years,50 years,20 years, 10 years and 5 years in Yingxiu area. The results indicated that debris flow hazards of 8 gullies were high un- der 5 rainfall frequencies, debris flow hazards of 4 gullies were moderate to high under different rainfall frequency, the remaining one was moderate hazard under 5 rainfall frequencies. The method using average deposition thickness on alluvial fan as the variable factor of hazard assessment can better estimate the debris flow hazard in different rain- fall frequency.

关 键 词：汶川地震区 降雨频率 泥石流规模 平均堆积厚度 危险性评价 

分 类 号：P642.23[天文地球—工程地质学]