In this study, we used the model established by Pham et al. (2025b) to evaluate the effects of global climate change and sea-level rise on groundwater supplies. The configuration of hydrogeological units, boundary conditions, drainage systems, and rivers remained consistent. Furthermore, we calibrated the model parameters, including inflow flux boundary, river and drainage conductance, and hydraulic conductivity values, utilizing observation wells and water level measurements from two field campaigns conducted during both the rainy and dry seasons. The results (Figure 2) indicate that in the next 50 years, saline water will persist in the aquifers of the research area, aligning with the conclusions of Pham et al. (2022, 2025b). Seawater may encroach up to 1 km inland from the coastline if groundwater is extracted at the current rate, resulting in increased salt in the shallow aquifer. The dune systems possess significant potential for groundwater extraction in the region and will serve as a crucial resource, as they mitigate the issue of saltwater intrusion on the alluvial plain. Water should be preferentially sourced from these reservoirs, as they reduce the risk for further salinization. However, this requires the development of a regional groundwater management plan. The presence of saltwater in the bedrock remains an unknown. Groundwater extraction should therefore be preferentially integrated with managed aquifer recharge to prevent overexploitation of the resource. Comprehensive research should be conducted to evaluate the dune system's capacity to supply irrigation water to the town. The findings of this study will aid government officials in evaluating groundwater resource capacities and implementing appropriate policies to ensure the long-term sustainability of groundwater in the research area.