极端暴雨下典型小流域重力侵蚀的分布及影响因素

Distribution and Influencing Factors of Gravitational Erosion in Typical Small Watershed Under Extreme Rainstorm

为探究极端暴雨下重力侵蚀分布规律及其环境条件,以2019年“利奇马”台风引发的特大暴雨事件为对象,采用无人机航拍、室内解译等方法,研究了位于暴雨中心的山东省临朐县曾家沟小流域内不同类型重力侵蚀的数量、空间分布特征及其影响因素。结果表明:(1)小流域内发生的重力侵蚀共70处,主要类型为滑坡(49处),其次为泥石流(14处)和崩塌(7处)。(2)重力侵蚀面积、侵蚀量分别与坡度变率、坡度、坡位、高程、坡向和坡向变率呈正相关,与距梯田距离、距道路距离和土地利用类型呈负相关。(3)坡度是影响重力侵蚀的最重要因素,侵蚀易发生在坡度为30°~50°的斜坡。(4)人类活动对重力侵蚀的影响较大,特大暴雨下的严重重力侵蚀多发生在梯田田坎、道路边坡等位置,需将重力侵蚀防治的重心放在加强道路两侧边坡、梯田田坎和坡度>30°的陡坡边坡防护上。研究结果可为应对和预防重力侵蚀灾害提供科学依据。

To explore the distribution of gravitational erosion and its environmental conditions under extreme rainstorm.The extremely rainstorm event caused by Typhoon“Lekima”in 2019 was chosen as the target.Using UAV aerial imagery and remote sensing interpretation,the quantities,spatial distribution characteristic and influencing factors of various gravitational erosion in Zengjiagou small watershed of Linqu County,Shandong Province,where the center of extremely rainstorm was located.The results showed that:(1)There were a total of 70 gravitational erosions in Zengjiagou.Among which,the predominant type was Landslide(49 sites),followed by debris flow(14 sites)and collapse(7 sites).(2)Gravitational erosion area and erosion amount were positively correlated with slope variation,slope,slope position,elevation,slope direction and slope direction variation,respectively,and negatively correlated with distance to terrace,distance to road and land use type.(3)Slope was the most important factor affecting gravitational erosion,which was prone to occur on slopes ranging from 30°to 50°.(4)Gravitational erosion had been profoundly influenced by human activities.Under heavy rainstorm,severe gravity erosion mostly occurred in terraced field and road slopes.The gravitational erosion prevention and control should be focused on strengthening the protection on both sides of the slope road,terraced field,and steep slopes with slope>30°.The results can provide scientific basis for coping with and preventing gravitational erosion disasters.