This study focuses on modeling the effects of forest management practices on eco-hydrological processes in the Antalya River Watershed, Turkey. With increasing global pressures from urbanization, deforestation, and climate change affecting water resources and ecosystems, understanding the impact of forest management on vital water sources is essential for sustainable water resource management and ecosystem protection. The Soil and Water Assessment Tool (SWAT) model assessed the hydrological impacts of afforestation and urban forest scenarios in the Antalya River Watershed—the model's parameterization, sensitivity analysis, and calibration phases accurately simulated base watershed processes. The validation process confirmed the accuracy of results, particularly in yearly time steps, providing a comprehensive understanding of the watershed's water management strategies. The results indicate that the afforestation scenario reduced surface runoff and increased lateral flow, decreasing erosion risk and improving groundwater recharge. Although soil evaporation and plant transpiration decreased, the increase in “revap” values highlighted higher water vapor emission from the soil, contributing to atmospheric water cycle processes. Similarly, the urban forest scenario resulted in decreased surface discharge and increased groundwater flow, indicating improved water retention and recharge capabilities. The increased evapotranspiration demonstrated the positive influence of trees and vegetation on the water cycle and atmospheric processes, emphasizing the significance of urban forest applications as valuable nature-based solutions for sustainable water resource management and conservation. In conclusion, implementing afforestation and urban forest initiatives can contribute to ecologically sound utilization of water supplies, enhance ecosystem functioning, and foster resilience in the face of environmental obstacles. The study emphasizes the potential benefits of afforestation and expanding green spaces in promoting sustainable water resources and mitigating erosion and flooding risks. The results of this study provide a scientific basis for policymakers and stakeholders to consider afforestation practices as a vital component of water resource management and watershed conservation strategies.