中国台湾地区位处亚热带地区,夏季受台风暴雨侵袭,加上位处板块运动活跃处,造成地形变化较大,尤其在台风暴雨后河道地形都会产生很大的变化;目前航空激光雷达地形数据,分辨率较高、精度、便利性,并可以滤除建筑物与树木遮蔽,还原原始地面形貌,符合地质与地形分析研究的需要。2008年兰阳溪地区经历海鸥(KALMAEGI)、凤凰(FUNG-WONG)、森拉克(SINLAKU)、蔷薇(JANGMI)等4次重大台风事件,河床地形变化甚剧,因此本研究利用两次航空激光雷达测量地形数据,分析比较台风前后河床地形以及河道输沙的变化。研究成果首次展示空载激光雷达系统,在大流域面积测量河道地形应用效果显著,于台风季节前后产制不同时期的数值地形数据,并应用高程差值的地形计量方法,计算在台风季节前后河道地形的变化,研究结果显示空载激光雷达高解析数值地形模型数据,应用在河道地形变迁与沉积物体积变化量计算,可以得到极佳的成果。

Taiwan is located in a subtropical region and issusceptible to typhoons and torrential rains during the summer seasons. Taiwan is also located on actively shifting tectonic plates that can cause dramatic terrain changes. Taiwan’s river terrain frequently sustains substantial changes, especially after typhoons and torrential rains. Presently, digital terrain maps or models made by airborne LiDAR technology are reliable, have sufficient resolutions, are accurate, convenient, and can filter out buildings or tree cover to restore the original ground topography. This type of map or model can meet the requirements of geological and topographical analysis studies. In 2008, the Lanyang River region experienced four major typhoon events: Kalmaegi, Fung-Wong, Sinlaku, and Jangmi. These typhoons changed the riverbed terrain dramatically. Therefore, we used two occasions of digital terrain data measured using the airborne LiDAR system to conduct analytical comparisons of the riverbed terrain and river sediment transportation changes before and after typhoon events. The study is the first of its kind to demonstrate the excellent applications of the airborne LiDAR system for measuring river terrains in a large watershed area; digital terrain data were produced for periods before and after a typhoon season. We used the elevation difference topography measurement method to calculate river terrain changes before and after a typhoon season. This study’s results showed that the airborne LiDAR high resolution digital terrain model data produced excellent results when used to calculate river terrain and sediment volume changes or change amounts.