摘要
地处川西南的德昌县近年来由局地暴雨诱发的泥石流造成了严重的经济损失。通过德昌群发性泥石流事件中局地暴雨过程和地面条件的分析,探讨了泥石流形成过程中的雨地耦合关系。根据TM遥感影像(30m)解译,德昌泥石流分布具有明显的区域规律,以安宁河及其支流茨达河流域最为集中,安宁河支流老碾河流域次之。根据泥石流的分布特征,结合流域的高程、坡度、地层岩性等信息,分析了泥石流易发区域的流域坡度以及NDVI特点,并将两者结合起来进行泥石流易发区的判别,准确率达92%。因此,遥感影像的光谱差异可以作为识别群发性泥石流地区的遥感标志之一。此类泥石流易发区的下垫面判别准则有两条:(1)流域平均坡度大于20°;(2)NDVI介于0.1～0.3。将泥石流易发区的下垫面识别与诱发泥石流的局地暴雨过程结合起来分析,泥石流灾害的时空分布取决于暴雨中心落点及移动路径,以德昌2004-08-24群发性泥石流进行了实例验证,结果表明泥石流最终的暴发相对于局地暴雨的峰值过程约有1h的滞后时间,此时段正是实施临灾预警的关键时间。据此,提出了群发性泥石流的减灾思路。
Rainfall-induced debris flows in recent years have brought about tremendous damages to Dechang County,the southwest of Sichuan.This paper explores the coupling of rainfall and the surface conditions that impacts the formation of debris flow.Interpretation of TM images（30 m）reveals the concentration of debris flow in rivers of Anning,Cida,Yalong,and Laonian.It is shown that debris flow is closely related to the slope of valley and the NDVI,among the factors including elevation,slope,strata and rock.And combination of slope and rock can be used to identify debris flow valley at accuracy up to 92%.For the study area of Dechang with high vegetation cover rate,the valley prone to debris flow satisfies the following conditions：（1）the average slope is bigger than 20;（2）NDVI is between 0.1 and 0.3.Combining the surface conditions and the local rainstorm processes reveals that debris flow depends on the center and route of rainfall.This is well confirmed by the event group on August 24,2004.It is also shown that the occurrence had a one hour lag after the rainfall peak,which is crucial for the forecasting.Finally,a new mitigation idea is proposed for group-occurring debris flow of Dechang county.
出处
《山地学报》
CSCD
北大核心
2010年第5期593-606,共14页
Mountain Research
基金
国家科技支撑计划课题(2008BAK50B04)
公益性行业(气象)专项(GYHY201006039)资助
科技部国际合作项目(09B2420420)资助~~
关键词
局地暴雨
群发性
泥石流
成因
local rainstorm
group-occurring
debris flow
causes
