scenario-based modelling of ecological security: integrating land use and climate change impacts in the lavasanat watershed

Understanding the impact of land-use and climate change on ecosystem services is crucial for ecological security assessments. this study examines spatiotemporal land-use/land-cover (lulc) changes in the lavasanat watershed, tehran, iran (2000–2040) and evaluates their effects on water yield under different management and climate scenarios.four lulc scenarios were defined: s1 (business-as-usual), s2 (pessimistic), s3 (realistic), and s4 (optimistic). additionally, three climate scenarios (b1, n, and m) were incorporated into the analysis. the invest model was used to simulate water yield variations, while ca-markov and lars-wg5 projected future lulc and climate conditions.findings indicate a 1.92-fold increase in water yield in residential areas from 2000 to 2020. the highest water yield was recorded under s2n (37.64 million m³ watershed-wide, 35.09 million m³ in residential areas), while the lowest was observed under s4m (8.33 million m³ watershed-wide, 7.35 million m³ in residential areas). all scenarios suggest that urban expansion will continue to drive water yield increases while reducing ecologically valuable lands by 2040.these findings highlight the critical role of sustainable land-use planning in mitigating environmental degradation and ensuring ecological security in rapidly urbanizing watersheds.