西南山区短时强降雨诱发型低频泥石流成因机制分析——以四川省宝兴县冷木沟泥石流为例
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摘要
以四川省雅安市宝兴县城后山冷木沟为例,通过野外调查及降雨数据分析,对冷木沟2012年8月18日泥石流的特征、成因及可能发展趋势进行了评估。结果显示:冷木沟此次泥石流过程具有隐蔽性强、暴发突然及强输沙能力的特征;前期累计降雨量对该次冷木沟泥石流过程贡献较小,而短时强降雨尤其是泥石流发生前55.9 mm/h降雨量是诱发泥石流的最主要原因;2012年泥石流发生前,冷木沟流域内崩滑等不良地质现象轻微,泥石流的物源主要来自于流域沟道内堆积的松散崩坡积物与早期山洪泥石流堆积物,泥石流物源在高速沟道洪水的揭底和侧蚀作用下启动形成泥石流。此外,由于2012年冷木沟泥石流在中、下游沟道内形成的大量的松散堆积物,加之2013年"4.20"芦山7.0级地震的影响,流域内潜在崩滑体的发育数量增多,冷木沟泥石流极有可能会由低频转化成高频泥石流,需要提出针对性的防治对策。
Based on field survey and rainfall data analysis,this paper takes Lengmu debris flow which occurred debris flow on 18 August 2012 in Baoxing city Sichuan province as an example,and analyzed it's characteristics,formation and trend in development.Results show that the debris flow has characteristics as concealment,sudden running out and strong sediment transportation.The accumulative precipitation had a little influence to the occurrence of debris flow,but the short-time heavy rainfall,especially the precipitation with 55.9mm in one hour before the debris flow running out is the main cause of the debris flow formation.There is no large volume of landslides in Lengmu gully,the loose source of debris flow are form the deposit which accumulate in gully from erosion.These loose sources initiate because of the flood and form the debris flow.In addition,in the process of debris flow on 18 August 2012,there have a large number of deposit in middle and low location gully from debris flow,and the Lushan earthquake occur on 20 April 2013 enlarged the potential landslides in basin,Lengmu debris flow will change low frequency to high frequency in the future,and this need corresponding measures to reduce the risk from debris flow.
Based on field survey and rainfall data analysis,this paper takes Lengmu debris flow which occurred debris flow on 18 August 2012 in Baoxing city Sichuan province as an example,and analyzed it's characteristics,formation and trend in development.Results show that the debris flow has characteristics as concealment,sudden running out and strong sediment transportation.The accumulative precipitation had a little influence to the occurrence of debris flow,but the short-time heavy rainfall,especially the precipitation with 55.9mm in one hour before the debris flow running out is the main cause of the debris flow formation.There is no large volume of landslides in Lengmu gully,the loose source of debris flow are form the deposit which accumulate in gully from erosion.These loose sources initiate because of the flood and form the debris flow.In addition,in the process of debris flow on 18 August 2012,there have a large number of deposit in middle and low location gully from debris flow,and the Lushan earthquake occur on 20 April 2013 enlarged the potential landslides in basin,Lengmu debris flow will change low frequency to high frequency in the future,and this need corresponding measures to reduce the risk from debris flow.
引文
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[2]崔鹏,韦方强,谢洪,等.中国西部泥石流及其减灾对策[J].第四纪研究,2003,23(2):142-151.
[3]陈晓清,崔鹏,韦方强.良好植被区泥石流防治初探[J].山地学报,2006,24(3):333-339.
[4]林明安,王士革,范晓岭,等.川西地区低频率泥石流的特征[J].水土保持通报,2010,30(1):227-231.
[5]John L Innes.Magnitude-Frequency Relations of Debris Flows in Northwest Europe[J].Geografiska Annaler.Series A,Physical Geography,1985,67(1/2):23-32.
[6]宗德孝,高必春.1997年5月云南昭通两次大型泥石流灾害及防御对策[J].灾害学,1998,13(2):67-70.
[7]余斌,杨永红,苏永超,等.甘肃省舟曲8.7特大泥石流调查研究[J].工程地质学报,2010,18(4):437-444.
[8]韦方强,谢洪,Jose L Lopez,等.委内瑞拉1999年特大泥石流灾害[J].山地学报,2000,18(6):580-582.
[9]四川省地质工程勘察院.宝兴县城周围地质灾害(冷木沟“8.18”泥石流)治理工程补充勘查报告[R].成都:四川省地质工程勘察院,2012.
[10]费莱施曼.泥石流[M].姚德基,译.北京:科学出版社,1985:44-50.
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