Assessing the potential of Tehran's green space master plan to enhance urban ecological performance, cooling capacity, and spatial equity

Tehran, a rapidly urbanizing semi-arid metropolis, faces severe Urban Heat Island (UHI) effects, exacerbating thermal discomfort, health risks, and energy consumption. ​ This study evaluates the potential effectiveness of Tehran's Green Space Master Plan (GSMP) in enhancing ecological performance and mitigating urban heat stress. ​ Using Biotope Area Factor and Urban Cooling Capacity indices, the analysis reveals that the GSMP significantly improves ecological functionality (Biotope Area Factor increase from 0.11 to 0.20) and cooling capacity (Urban Cooling Capacity increase from 0.146 to 0.211). ​ However, the benefits are unevenly distributed, favoring affluent northern districts over densely populated, socioeconomically disadvantaged central and southern districts. ​ A quantitative spatial equity analysis using the Gini coefficient confirms this disparity (Gini BAF: 0.287 to 0.200; Gini UCC: 0.181 to 0.154), with statistically significant improvements in both indices (Wilcoxon signed-rank test, p < 0.001). To address spatial disparities, a modified GSMP scenario incorporating green roofs in high-density neighborhoods was proposed, resulting in substantial improvements in Biotope Area Factor (from 0.06 to 0.35) and Urban Cooling Capacity (from 0.18 to 0.35). ​ The findings underscore the importance of tailored interventions, such as vertical greening and blue infrastructure, to enhance cooling effects, promote environmental justice, and improve urban resilience. ​This study highlights the critical role of integrative urban planning in mitigating UHI effects and advancing equity, offering valuable insights for climate-responsive strategies in arid and semi-arid megacities.