诱发台风暴雨型滑坡的降雨阈值研究——以泰顺县为例

Rainfall thresholds of typhoon rainstorm induce landslides:A case study over Taishun County

在我国东南沿海地区,台风暴雨诱发了大量山体滑坡。建立诱发台风暴雨型滑坡的降雨阈值模型,可为该地区的滑坡预警提供参考依据。基于浙江省泰顺县2007—2022年以来发生的滑坡信息和日降雨量数据,进行了诱发滑坡的台风暴雨事件编目,初步揭示了台风暴雨型滑坡的发育规律和触发降雨特征,通过降雨强度(I)、降雨历时(D)的幂律关系构建了滑坡临界降雨阈值模型,并开展了不同台风降雨雨型的阈值模型对比。结果表明:台风暴雨型滑坡大量发生在与台风登陆方向接近的迎风坡,坡表植被多为乔木和竹林;诱发滑坡的台风降雨一般持续2~3 d,且降雨过程集中,降雨雨型以单峰型为主,总降雨量一般在200 mm以上;台风暴雨诱发滑坡的降雨阈值显著高于一般性的降雨,这种差异与台风降雨模式及大尺度气候环境有关;雨型也会显著影响降雨阈值,随着降雨峰值的后移,阈值逐渐降低,表明台风暴雨型滑坡对长时间降雨后出现的强降雨事件更加敏感。通过降雨阈值模型对9次台风降雨事件是否诱发滑坡进行了预测,预测结果与实际情况比较吻合,证明该模型及研究思路对台汛期东南沿海的滑坡监测预警有较强的参考价值。

In the southeast coast of China,typhoon rainstorms resulted in lots of landslides.Investigating rainfall thresholds and patterns of typhoons is of great importance for the early warning of landslides.In this study,the landslide information obtained from multiple sources and typhoon rainstorm data were used to analyze landslide and rainfall characteristics in Taishun 2007 to 2022;the rainfall threshold of typhoon rainstorm-induce landslides was defined for Taishun area based on the rainfall intensity–duration(I-D)model.It finds that a large number of typhoon rainstorm landslides occur at the windward slope close to the landing direction of the typhoon,where the main vegetation types of the landslide are arbors and herbs with tall trunks and shallow roots.The duration of rainfall events inducing landslides is usually 2~3 days,with concentrated rainfall and total rainfall more than 200 mm.The threshold of typhoon rainstorm-induced landslides is significantly higher than that of rainfall-induced landslides in other regions.With the backward position of rainfall peak in rainfall process,the thresholds become lower and steeper,indicating that more rainfall is needed to trigger landslides when the rainfall peak appears earlier than when it is late.Typhoon rainstorm-induced landslides are more sensitive to the heavy rainfall event after a long rainfall.The threshold model established in this study is consistent with the observation,indicating that it is effective for landslide monitoring during the typhoon season.