Gorgan University of Agricultural Sciences and Natural Resources Environmental Resources Research 2783-4832 13 1 2025 07 01 Scenario-based modelling of ecological security: Integrating land use and climate change impacts in the Lavasanat Watershed 137 158 7380 10.22069/ijerr.2025.23274.1475 EN Yasser Moarrab Assistant Professor, Department of Safety, Health and Environment, Faculty of Passive Defense, Imam Hossein University, Tehran, Iran Vahid Novin Ph.D. in Environmental Planning, Faculty of Environment, University of Tehran, Tehran, Iran Journal Article 2025 02 01 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.<br />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.<br />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.<br />These findings highlight the critical role of sustainable land-use planning in mitigating environmental degradation and ensuring ecological security in rapidly urbanizing watersheds. https://ijerr.gau.ac.ir/article_7380_8a1e3347d22c882412565145bc64b005.pdf