应用三维激光扫描监测崩岗侵蚀地貌变化——以广东五华县莲塘岗崩岗为例

崩岗复杂的地形及其动态发育过程是崩岗监测关注的重点和难点。三维激光扫描技术具有高精度、非接触性、穿透性、快速性等特点，能够突破传统监测手段的空间限制，有效获取崩岗地形的细部特征。在介绍基本原理和应用现状的基础上，利用Leica ScanStation 2三维激光扫描仪，对广东五华县莲塘岗崩岗进行连续3 a共6次实地监测。选择2011-06-03和2012-05-12两次监测结果，通过ArcGIS对数据进行处理分析。结果表明：莲塘岗崩岗体积侵蚀量为1 007 m³/a，年侵蚀量为1 380 t，侵蚀模数为269 268 t/（km²·a），崩岗中下部位侵蚀强度高于上部。侵蚀最强烈地带出现在中下部海拔高度为111~116 m和116~121 m的崩积锥分布部位，侵蚀量分别为202和178 m³/a，崩积锥土体松散，极易在片流和股流作用下出现侵蚀，崩积锥快速侵蚀导致崩壁加高，使得崩岗呈现出越高越陡的态势。此外，在崩岗下部96~101 m和101~106 m两个区段的侵蚀作用也比较强烈，侵蚀量分别为151和157 m³/a，这一高程区为多条支沟汇合后的主沟道段，每年雨季水力侵蚀十分强烈，沟道侧蚀加宽和下切加深，进一步加速崩岗的重力侵蚀过程，致使莲塘岗崩岗仍处于快速侵蚀和崩壁加高变陡的壮年期阶段。三维激光扫描连续监测结果的对比分析，不但能够定量得到崩岗侵蚀量及地形的变动信息，还可进一步探究侵蚀泥沙的来源及其精细的空间分布特征，是崩岗监测较为理想的先进技术。

Application of 3D Laser Scanning to Monitoring the Landform Changes of Collapsing Hill and Gully: A Case Study of Liantanggang Collapsing Hill and Gully in the Wuhua County of Guangdong

The complex topography and dynamic erosion process are the key problems to be taken into consideration for collapsing hill and gully monitoring. 3D laser scanning is a very useful tool which is of high accuracy, non-contact, penetrating and rapidity. This paper has introduced the principles of 3D laser scanning technology and its application. By surveying Liantanggang collapsing hill and gully in the Wuhua County of Guangdong for 6 times during the last 3 years by 3D laser scanner (Leica ScanStation 2), the paper analyzes the data acquired on June 3^rd, 2011 and May 12^th, 2012 by ArcGIS. The results indicate that Liantanggang collapsing hill and gully erosion volume is 1 007 m³/a, i.e. 1 380 t/a, and the erosion modulus is 269 268 t/(km^{2·a). The erosion rate on the middle-lower zones of the collapsing hill and gully is higher than that of the upper, and the intenseerosion zones appear at the elevation between 111~116 m and 116~121 m with the erosion volumes of 202 and 178 m3/a, respectively, where there are collapsing soils which are easily erodible by sheet wash and gully flow. The collapsing soil erosion makes the collapsing hill present such a form that the higher the elevation is, the steeper the headwall would be. The lower zones at the elevation between 96~101 m and 101~106 m also have an intense erosion with the erosion volumes of 151 and 157 m3/a, respectively. In those areas, the main gully with serveral tributary gullies, has intense lateral and down-cutting erosions during rainy season, that can trigger gravitational erosion to make the collapsing hill and gully keep in the mature phrase with a high erosion rate and steep headwall. 3D laser scanning can break through the space limits of traditional monitoring and so can effectively obtain topographic details of collapsing hill and gully. The comparative analyses of continuous monitoring data not only can obtain the information of the collapsing hill and gully erosion rate, but also the quantitative terrain changes, as well as a possible explanation for the erosion sediment sources from the collapsing hill and gully. 3D laser scanning may be a promising technology for collapsing hill and gully monitoring.}