基于三维激光扫描的崩岗沟道侵蚀与坡向发育及其侵蚀量计算

Erosion Volume Calculation of Benggang Gully and Their Slope Development Based on 3D Laser Scanning

探讨崩岗流域沟道侵蚀及其引起的崩岗坡面的坡向变化,对崩岗流域的科学整治具有重要意义;崩岗沟道侵蚀量的计算,是崩岗流域侵蚀强度划分和崩岗侵蚀方式甄别的主要依据.利用Leica Scan Station 2三维激光扫描仪,以广东五华县莲塘岗崩岗为研究案例,通过3年共计6次定位监测,获取了5个监测周期的高精度地形数据.以此为基础,结合Arc GIS软件,对崩岗沟道发育及其坡向变化进行定量分析.研究结果表明,沟道侵蚀是崩岗流域主要侵蚀方式之一,53.6%的侵蚀量来自切沟和冲沟的沟床下切和沟壁侧蚀,其中下切侵蚀又是沟道侵蚀的主要形式.沟道总长度和流域切割密度出现先增加后减小的阶段性变化,3年平均流域切割密度为158km/km2.沟道走向对崩岗坡面的坡向发育具有控制作用.沟头的细沟和切沟的溯源侵蚀对坡面的坡向具有重塑作用,坡面面积减少的坡向的反方向,即为沟道溯源侵蚀的主方向.侵蚀强度最大的坡向与主沟道发育的走向NNW—SSE一致,这是由当地区域构造应力场的一组剪切应力产生的裂隙走向所决定的.沟道侵蚀作用对崩岗流域演化具有深刻的影响.

To investigate the relationship between slope direction and gully erosion in the drainage basin of Benggang( collapse hill and erosion gully) is of great significance to the basin management. The calculation of erosion amount of gully erosion is the main bases for the division of erosion intensities and the discrimination of erosion patterns. By 3D laser scanner( Scan Station Leica 2) and the case study of Liantanggang Benggang in Wuhua County,Guangdong Province,the high precision terrain data were obtained based on 5 monitoring period during 3 years from 2013- 2015. The variations of gullies and slope directions of the basin were analyzed with Arc GIS. The results show gully erosion is one of the main erosion patterns in the Benggang,and 53. 6% of the erosion materials comes from the incision and lateral erosions of the gullies in the Benggang. The total gully length and the drainage basin density first increases and then decreases periodically. Average density of the drainage basin is 158 km / km2. The gully direction controls the slope direction of the basin. The retreat erosion caused by the rills and gullies at the source area reshapes the basin slopes. The opposite direction of the slope area reduction indicates the principal direction of the headward erosion. The direction with maximum erosion intensity is consistent with the main gully direction in NNW-SSE,which is dominated by the direction of the regional tectonic stress. Gully erosion has a profound effect on the evolution of the Benggang basin.