IFSAR-DEM在岩溶洼地探测中的应用——以薄荷省旁劳市沉降灾害评估为例

岩溶研究中，通常会使用高分辨率卫星图像和地理空间数据识别、描绘岩溶发育及相关地质灾害发生的地貌特征。本文旨在利用ArcGIS10.0确定干涉合成孔径雷达数字高程模型（IFSAR-DEM）识别、量化和描述岩溶洼地。这种半自动岩溶洼地/天坑探测方法采用水流模拟法，并结合（1）流域划分；（2）下沉填充法提取洼地特征；（3）下沉深度测量及分类；（4）使用2013年至2014年谷歌高光谱卫星图像和数字地形模型对探测到的岩溶洼地进行验证。该方法已在薄荷省旁劳市进行的评估中进行了预测试。使用国家测绘资源信息局（菲律宾）1991年的1:50 000比例尺地形图进行的初步封闭洼地分析，发现旁劳岛有15个天坑。利用5米高分辨率IFSAR-DEM，共探测到820个天坑，其中424个根据详细的地面实况进行了描绘，以验证了岩溶洼地的存在。地表实况包含天坑大小、形状和深度等基本形态测量分析以消除误报数据。阈值设定为沉降深度大于1米，孔径大于10米，从而最大程度精确区分实际的天坑。这种基于GIS的工具有助于生成高分辨率岩溶塌陷易发区图，继而指导当地规划者、工程师及决策者进行开发规划和土地利用。 

Karst depression detection using IFSAR-DEM:A tool for subsidence hazard assessment in Panglao, Bohol

Karst studies employ high-resolution satellite images and geospatial data to identify and delineate geomorphic features that are critical to karst development and related hazard.This paper aims to determine the efficiency of Interferometric Synthetic Aperture Radar-derived Digital Elevation Model （IFSAR-DEM） to identify，quantify and characterize karst depressions using ArcGIS 10.0.The semi-automated karst depression/sinkhole detection method used water flow simulation approach that incorporated a）watershed delineation； b） sink-and-fill to extract depression features； c） sink-depth measurements and classification； and d）validation of detected karst depressions using Hyperspectral Google Satellite Image of 2013-2014 and Digital Terrain Model. The method was pre-tested in the assessment conducted in the Municipality of Panglao,Bohol.Initial closed-depression analysis using 1991 National Mapping and Resource Information Authority 1:50，000 scale topographic map counted 15 sinkholes in Panglao. Using 5 m high resolution IFSAR-DEM， there are 820 sinkholes detected， 424 of which were delineated through detailed ground truth to validate the presence of karst depressions. Ground truth included basic morphometric analysis，such as common sinkhole size，shape and depth，to eliminate false positives. Threshold values in sink depth of >1.0 m and aperture size of >10 m were designated to distinguish true sinkholes with maximum accuracy. This GIS-based tool is deemed helpful to generate high-resolution karst subsidence susceptibility map that will guide local planners and engineers,as well as policy-makers，in land use and development planning.