This study investigates the hydrological consequences of Land Use and Land Cover (LULC) transformations within the Sam Ngao Watershed (SNgW) from 2000 to 2020. Utilizing the Soil and Water Assessment Tool (SWAT), the research simulates watershed hydrological responses to observed LULC dynamics. To forecast future hydrological conditions, LULC scenarios for 2040 and 2060 were generated using a hybrid Cellular Automata-Markov Chain (CA-Markov) modeling approach. A hybrid classification methodology enhanced the accuracy of LULC mapping from Landsat imagery, integrating multiple classification techniques. Results reveal that LULC alterations between 2000 and 2020 significantly influenced the watershed’s hydrological regime, including declines in dry season flow (7.36%), groundwater discharge (25.43%), and evapotranspiration rates (7.63%), and increases in average annual streamflow (9.85%), wet season streamflow (12.85%), and surface runoff (33.21%). These shifts are primarily attributed to agricultural expansion and deforestation. Projected LULC changes for 2040–2060 indicate a potential reversal in trends, with increases in dry season flow, groundwater recharge, and evapotranspiration, accompanied by decreases in annual and wet season streamflow as well as surface runoff. Hydrological impacts were notably heterogeneous across sub-watersheds, reflecting the spatially uneven distribution of LULC changes. These findings offer valuable insights for decision-makers, water resource managers, and local stakeholders toward creating adaptive strategies for sustainable water resource management in the SNgW and analogous catchments. The study supports international efforts aligned with Sustainable Development Goal 6 (SDG 6) to secure universal access to clean water and sanitation through sustainable management, and with SDG 11 to create sustainable cities and communities through resilient infrastructure, inclusive urban planning, and climate-adaptive water management systems. The outcomes also provide a robust scientific foundation for researchers and policy developers engaged in hydrology, watershed management, and national land use planning frameworks.
Faksomboon et al. (Tue,) studied this question.