GIS-based spatial analysis of sinkholes in Cebu City, Philippines: Insights on sinkhole genesis and development

In 2017, at least 770 sinkholes were reported to occur in Cebu City, a populated town in the Philippines dominantly underlain by karstic formations. In this study, the genesis and development of these sinkholes were related to various geomorphologic, geologic, and hydrologic factors in order to determine their influence on sinkhole distribution in the area using GIS-based spatial analyses. Results show that the sinkhole frequency varies with respect to the relative age of the underlying karstic formation, slope, and elevation. Most sinkholes occur on younger bedrock, low slope, and low elevation areas. However, sinkholes that occur on younger bedrock are significantly smaller in area than those in older bedrock; in terms of total area, the sum of the areas of sinkholes are greater on relatively older bedrock. Other factors found to influence sinkhole occurrence were lineaments and streams. GIS-based analyses of sinkholes such as those presented in this study are useful for sinkhole susceptibility prediction and disaster risk reduction management efforts of communities