Assessment of Groundwater Potential in North-Central Palawan using Remote Sensing and Geophysical Analysis of Fractured Basement Aquifers

Abstract. Aquifers are geologic units capable of storing and transmitting water from surface runoff or precipitation. Porosity and permeability are key factors in determining whether rocks can function as aquifers. While aquifers typically occur in sedimentary deposits, sufficiently fractured crystalline units can also serve as groundwater reservoirs. This is especially true in regions underlain by igneous and metamorphic rocks. Such is the case in Palawan, an island province within a microcontinental block in the Philippine archipelago. The municipality of Puerto Princesa in Palawan is a major eco-tourism hub with a growing population. However, water scarcity during the dry season significantly disrupts local livelihoods. This study aims to evaluate the groundwater potential of North-Central Palawan using remote sensing and geophysical analysis. SRTM and Landsat-9 images were used in the delineation of surface lineament features, while subsurface lineaments were identified from edge detection enhancements of gravity anomaly data. By integrating lineament density data with elevation, lithology, and rainfall data, a groundwater potential map was generated using normalized weight factors derived from an Analytic Hierarchy Process. Results indicate that areas with low elevation and a broad sedimentary cover have very high groundwater potential. In contrast, igneous and metamorphic rocks generally exhibit low potential, except where dense fracturing is present. Statistical analysis using the chi-square test reveals a significant association between well depth and groundwater potential, which validates the model generated in this study. The results underscore the practical advantages of non-invasive geophysical and remote sensing means in characterizing key groundwater sites for future drilling.