Evaluating Water Resource Response to Projected Climate Variability in a Coastal Tropical Environment: The Case Study of Mati City, Philippines
Received: 26 July 2025 | Revised: 7 September 2025, 17 September 2025, and 28 September 2025 | Accepted: 9 October 2025 | Online: 26 October 2025
Corresponding author: John Christopher S. Algallar
Abstract
Factors such as climate variability, rapid urbanization, and limited adaptive capacity affect the water resources of tropical coastal cities. This study evaluates the response of water resources to projected climate variability in Mati City, Davao Oriental, Philippines, using the Soil and Water Assessment Tool (SWAT). Surface runoff, Evapotranspiration (ET), and water yield were simulated by integrating historical climate records (2000–2024) and the downscaled Coupled Model Intercomparison Project Phase 6 (CMIP6)-based projections (2025–2050) from the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (DOST-PAGASA) across seven sub-catchments. During simulations, three climate scenarios were considered: dry, median, and wet. The temperature trend analysis indicates a statistically significant positive trend (+0.004 °C/year) in contrast to non-statistically significant precipitation trends. Across all future scenarios, water yield is projected to decline due to increased ET and reduced recharge—despite a higher runoff under wetter conditions. The dry scenario results in the steepest reductions in water availability. The wet scenario fails to compensate for the present losses. Under the dry scenario, water availability per capita is expected to have decreased below the Falkenmark water stress threshold by the 2040s and to have reached scarcity by 2050, when considering the projected population growth. These findings underscore the necessity of climate-informed water governance, integrated planning, and resilient infrastructure investments to ensure future water security. The study supports Sustainable Development Goals 6 (Clean Water and Sanitation) and 13 (Climate Action) by providing a localized, evidence-based framework for water resource planning under climate change.
Keywords:
water resource management, water availability, climate variability, sustainable water managementDownloads
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