土地沙化或荒漠化会造成重大经济损失,基于机载激光雷达(LiDAR)技术获得的点云数据在监测沙丘变形和研究其规律方面有着重要意义。将获取的沙漠地区的两期机载LiDAR点云数据分别处理并生成数字高程模型(DEM)和坡度图,结合面向地理对象和基于像元的变化检测技术实现对沙丘的变化及移动情况的精准监测。从不同时期坡度图上提取的沙丘背风坡坡脚线可用于反映沙丘的水平位移,两期DEM的差值分析则反映了沙丘的垂直位移,结合了主要风向的插值线分析则可以量化沙丘的地形变化及移动规律。分析结果显示整个实验区出现了总体沉降,即沙物质搬移,沙丘变形规律与主要风向相关;沙丘迎风坡主要为沉降,沙丘背风坡由于易滑塌,所以顶部发生沉降,底部发生沙物质沉积。

Land desertification can cause significant economic losses. The point cloud data obtained by airborne light detection and ranging (LiDAR) technology is of great significance in monitoring the deformation of sand dunes and studying its laws. The acquired two-period airborne LiDAR data from desert area are processed to generate digital elevation model (DEM) and slope maps, and the combination of geographic object-based and pixel-based change detection methods is used to accurately monitor the deformation of dune and its movement. The toe lines of dunes extracted from multi-temporal slope maps provide horizontal deformation of dunes. Difference analysis of two-period DEM can be used to analyze vertical movement of dunes. The interpolate lines analysis combined with the dominant wind direction can quantify the topographic deformation and movement laws of dunes. The analysis results show that there is an overall settlement in the whole study area, which is the movement of sand material. The deformation law of dunes is highly related to the main wind direction. The stoss slope of dune is mainly subsidence, and the leeward slope of dune is prone to slip-off, so settlement occurs at the top and sand material deposition occurs at the bottom.