植被覆盖对暴雨型滑坡影响的初步分析

根据遥感资料、地形数据和历史观测资料等,以江西省为例,分析了森林植被覆盖率、森林生物量和暴雨型滑坡的空间分布,以及森林植被类型对大气降水的截留作用。分析结果初步揭示了植被覆盖对滑坡的影响,认为植被覆盖程度高、生物量多和植被覆盖差、生物量低的中低山区,都可能发生滑坡灾害。不同林冠对降水的截留作用,减缓了降水对斜坡的冲刷,但当降水强度达到或超过暴雨强度时,森林对降水的截留率减小。同等地质环境条件下,植被覆盖率低,滑坡较易发生,但当降水强度较大时,特别是达到诱发滑坡灾害发生的临界值时,植被对滑坡体的重力作用则更加重了滑坡的发生。植被覆盖对滑坡的影响主要取决于降水强度。高森林覆盖区发生滑坡的雨量临界值大于森林覆盖率差的区域。

Preliminary Analysis Of The Impact Of Forest Cover On Landslide Triggered By Torrential Rainfall

Based on data from remote sensing,topography,ground observation and etc.,choosing Jiangxi as cases,the spatial distribution of forest cover,biological amount and landslides triggered by torrential rainfall are studied.The interception amount of different vegetation types to precipitation is discussed.The impact of forest cover on landslide is revealed,with conclusion that landslides can take place in different vegetation cover regions and various biological amount distribution areas in middle and lower mountainous.The interception action of forest cover to precipitation can mitigate the water rushing on slope,but if the precipitation intensity is over 50mm a day,the interception rate may reduce visibly.At the same geological environment,the landslide is easy to happen in sparse forest cover area,but the weight function of vegetation on slope body will strength the landslide events occurring when rainfall amount approaching critical value that will induce landslide.The impact of forest cover on landslide is decided by precipitation intensity.The precipitation threshold value that will trigger landslide is higher in dense vegetation areas than in sparse regions.