GIS-Based Assessment of Karstification Potential in Siargao Island, Philippines

Karstic terrains are formed by the dissolution of carbonate rocks and are essential zones for groundwater reservoirs but are susceptible to geological and climatic conditions. Thus, delineation and characterization of potential karst development sites are necessary, especially in areas with limited data on karst development, which hinders accurate groundwater assessment, hazard mitigation, and sustainable land-use planning, especially in remote areas such as Siargao Island, Philippines. By applying a data-driven geospatial framework that combines statistical analysis with Geographic Information System (GIS) techniques, it is possible to evaluate the island’s karstification potential as support for future water resource management strategies.

Principal Component Analysis (PCA) was applied to eight initially selected variables, which were then reduced to four key components: geology, slope, precipitation, and vegetation. These components were used for GIS-based multi-criteria evaluation to generate a karst potential map of Siargao Island. Results show strong spatial variability in karst development wherein high to very high potential zones are in the southern and southeastern regions, characterized by mature cockpit karsts, caves, and sinkholes. The eastern and western parts of the island, where transitional stages of karst development are present, exhibit moderate karstification potential. Non-carbonate areas with minimal karst expression in the central and northern regions showed low to very low potential zones. Field observations, existing geomorphological maps, and sinkhole inventory data were utilized for model validation, resulting in an overall accuracy of 80.6% and a Kappa coefficient of 0.44, indicating moderate agreement between the predicted and observed karst features.

Through this approach, a cost-effective monitoring strategy for assessing groundwater resources and geohazards in data-scarce, remote areas with karstic terrains, such as Siargao Island, can be developed. The generated karst potential map provides a baseline for sustainable water resource management, groundwater protection, and land-use planning. Furthermore, this study demonstrates the use of geospatial and decision-support methods to strengthen hydrological management in remote environments.