Biophysical Suitability Mapping for Solar Salt Production in the Philippines Using Geospatial Analysis and Analytic Hierarchy Process (AHP)

Salt production through solar evaporation is inherently sensitive to land-use competition and climatic variability. These constraints make spatially guided site selection essential for reducing production risks and supporting sustainable industry development. Despite its extensive coastline and archipelagic geography, the Philippines continues to import nearly 83% of its annual salt requirements, indicating substantial untapped potential for domestic production. This study presents the first comprehensive national-scale assessment of natural favorability for solar salt production in the Philippines using an integrated geospatial analysis and Analytic Hierarchy Process (AHP) framework. Key biophysical determinants, including climatic variables and land characteristics, were evaluated across thirteen priority provinces identified under the Philippine Salt Industry Development Act. The results indicate that climatic variables exert the greatest influence on site suitability because of their inherent variability and limited controllability relative to land constraints. Approximately 22.38% of the assessed areas were classified as highly suitable, with pronounced regional variation. Provinces such as Pangasinan, Ilocos Norte, and Occidental Mindoro contain extensive highly suitable areas that closely align with existing salt production centers, thereby supporting the robustness of the assessment. The findings further emphasize the value of integrating additional considerations, including hazard exposure, updated land cover, and local land-use plans, to refine site selection and manage investment risks. The resulting spatial decision-support tool provides policymakers, industry stakeholders, and investors with a science-based foundation for strategic planning and sustainable expansion of the Philippine salt industry, thus