ABSTRACT WAJE, JOBELLE L, Department of Resource Engineering and Agricultural Mechanization, College of Engineering and Computer Studies, Pampanga State Agricultural University, PAC, Magalang, Pampanga. June 2023. "GIS-based Suitability Analysis for Potential Shallow Tube Well Irrigation Development in Magalang, Pampanga" Adviser: Co-Adviser: Engr. Russell A. Rivera Engr. Melissa P. Olalia This study features a geographic information system (GIS)-based decision support system in order to identify potential locations for the development of shallow tube well irrigation in Magalang, Pampanga. It developed a suitability criterion that is based on evaluation factors such as slope, soil type or texture, land use or land cover and groundwater table depth which were utilized as input parameters in the assessment of suitable sites for STW irigation development. With thís criteria, it was determined 94.776% of the total area of the municipality, covering an area of 781,876.6 hectares, was classified as marginally suitable to highly suitable for STW irrigation development based on slope suitability analysis; however, only 26.07% of that area, or 2,585 hectares was classified as marginally suitable to highly suitable for STW irrigation development based on soil texture suitability analysis; and only 58.89%, or 5,73 1.34 hectares, is highly suitable for STW irigation development based on land cover suitability analysis. Additionally, it was discovered through ground validation and field sampling that San Pedro I has the shallowest groundwater table depth at 0.82m, while Ayala has the deepest groundwater table at 5.71m. All other areas of the municipality have shallow groundwater tables that fall within the acceptable depth range of less than 6.5m. In order to plan and identify potential sites for STW irigation development for various purposes in agricultural production in Magalang, Pampanga, and other areas, the results of this study and the necessary factors taken into account in combination with the GIS tool may assist in the decision-making processes.