Quantified Impact of Projected Climate Change on Groundwater Recharge and River Discharge Leveraging the Use of Open Access Geospatial Data

In previous years, water is abundant in the Padsan River Watershed, even in tropical climates. However, with increasing variability due to global warming, the watershed faces disruption of water resources. This requires thorough study, yet with fragmented data management, it becomes challenging. With technological advantages, integrated water resources management (IWRM) becomes possible using open-access data to understand the potential impact of climate variability. The corrected Climate Hazards Group InfraRed Precipitation (CHIRPS) and ten Coupled Model Intercomparison Project Phase 6 (CMIP6) becomes the notable open-access data including request-based institutional data were used as inputs for the Soil and Water Assessment Tools (SWAT) to quantify the impact of climate change on river discharge and groundwater recharge. Results showed that all Shared Socioeconomic Pathways (SSPs) will disrupt river discharge and groundwater recharge, with a prominent increase in river discharge. Furthermore, SSP 585 in the 2090s has a more notable impact on river discharge than others. In contrast, the SSP 126 has a lesser impact but displays higher variability across the rest of the century. This important simulated observation highly supports the Philippine Development Plan (PDP) aims, which is that climate change's impact could disrupt existing infrastructure and recharge conservation while establishing recharge areas to combat water scarcity during the dry period in the watershed. In contrast to the PDP regarding groundwater use, the study also supports the increasing conjunctive use of surface and subsurface resources, given that comprehensive management of the subsurface extraction must be established based on the study’s results.