摘要
深圳市坪山2014年“5.17”泥石流发生于植被茂盛的林地,具有频率低、触发雨强大、突发性强等特征,在广东省具有很强的代表性。通过地面调查,结合区内植被、土壤研究成果,总结坪山“5.17”泥石流的主要形成过程和发育特征,分析其形成机制;然后基于区内2013—2022年的卫星光学影像和归一化植被指数(NDVI)数据,结合泥石流遗留痕迹现状调查,研究该泥石流沟损伤恢复的进程,探索该区是否具有复发的可能性。研究认为,该泥石流是在前期充分降雨条件下,由局地短时超百年一遇降雨诱发的,物质主要源于谷坡的浅层滑塌和沟床侵蚀,泥石流物质未能冲出沟口;泥石流区植被在强降雨条件下对浅层滑塌无明显的抑制作用。基于泥石流区NDVI数据与同期卫星光学影像对比,发现区内各NDVI像元年最大值的平均值(简称NDVI平均值)的变化可以反映地表恢复程度,把泥石流区植被恢复过程划分为窗口期(2014—2015年,NDVI平均值小幅下降)、愈合期(2015—2019年,NDVI平均值逐年平稳上升)、痊愈期(2019—2020年,NDVI平均值恢复到发生年水平);痊愈期后该区NDVI平均值逐年大幅增长,可能又开始了新一轮的泥石流孕育期。本文研究的是低频泥石流爆发→恢复→孕育→再爆发循环过程的前两环,成果可以为广东省低频泥石流灾害的深入研究提供案例与参考。
The Pingshan“5.17”debris flow in Shenzhen City in 2014 occurred in an abundant vegetation area.The debris flow has characteristics such as low frequency,strong triggering rain,and strong suddennes,which is very representative in Guangdong Province.Through ground investigation,combined with the research results of vegetation and soil in the area,the main formation process and development characteristics of Pingshan“5.17”debris flow were summarized,and its formation mechanism was analyzed.Then,based on the optical images and normalized difference vegetation index(NDVI)data from 2013 to 2022 in the area,combined with the investigation of the status quo of debris flow traces,the process of damage recovery of the debris flow gully was studied to explore whether there was a possibility of recurrence in the area.Studies suggest that,the debris flow was induced by local short-term rainfall exceeding one hundred years under sufficient rainfall conditions in the early stage.The material mainly originated from shallow landslides and erosion of the valley,and the debris flow material failed to flush out of the gully mouth.Vegetation in debris flow areas has no significant inhibitory effect on shallow landslides under heavy rainfall conditions.Based on the comparison between the NDVI and the satellite optical image in the same period,it is found that the change of the average annual maximum value of each NDVI pixel in the area(referred to as the average NDVI)can reflect the degree of surface restoration.The vegetation restoration process in the debris flow area is divided into window period(2014-2015,the average NDVI decreased slightly),healing period(2015-2019,the average NDVI increased steadily year by year),and recovery period(2019-2020,the average NDVI returned to the level of the occurrence year).After the recovery period,the average NDVI value of the area increased significantly,so a new round of debris flow incubation period may have begun.This article studies the first two cycles of low-frequency debris flow(occurrence→recovery→incubation→outbreak).The results can provide case studies and references for in-depth research on low-frequency debris flow disasters in Guangdong Province.
作者
王平
程磊
赖安锋
Wang Ping;Cheng Lei;Lai Anfeng(Shenzhen Geokey Group Co.,Ltd.,Shenzhen 518057,China)
出处
《资源环境与工程》
2025年第6期727-736,共10页
Resources Environment & Engineering
基金
深圳市财政专项基金项目(SZCG2021199695)。
