崩岗侵蚀分布特征及其成因

Distribution Characteristics and Causes of Collapse Erosion

崩岗是南方最严重的侵蚀类型。通过分析崩岗侵蚀空间上的分布和成因，表明：崩岗主要分布在淮河以南亚热带湿润地带，主要集中分布在花岗岩母质区，垂直空间上分布在海拔100～500m丘陵地区。崩岗的形成和分布特征主要与以下3点有关：1．亚热带湿润地区高温多雨的气候为崩岗发育提供了深厚的风化壳和侵蚀动力；2．崩岗侵蚀发育与风化壳物理性质密切相关，风化壳颗粒组成决定着其物理性质，是影响崩岗发育的最根本因素之一。花岗岩地区风化壳颗粒组成的特殊性质导致其抗剪强度低，从而容易失稳崩塌；3．丘陵地区土体深厚，同时高强度径流冲刷和重力能量容易引起崩岗。

Collapse erosion is the most serious type of erosion in South China. This paper analyzed the space distri- bution and genesis of collapse erosion. The results show that collapse is mainly distributed in the humid subtropical zones on the south of the Heather River, concentrated in the areas of granite parent materials, and vertically distrib- uted in the hilly regions with a height of 100 ~ 150 meters. The characteristics of formation and distribution are in close connection with the following 3 factors： 1 ） hot and rainy climate in humid subtropical zones provided deep weathering crust and strong erosion dynamic for collapse formation; 2 ）Collapse erosion is closely related to the physical properties of weathering crust. Weathering crust particles determines their physical properties. Weathering crust particles is one of the most fundamental factor affecting collapse erosion. Granite weathering crust particles led to its special nature of low shear strength, which tends to collapse instability ; 3 ） the deep soil, runoff scouring and strong gravitational energy in hilly regions cause consequence that soil is prone to collapse into collapse hill.