Urbanization in the twenty-first century has emerged as a defining trend, intensifying pressures on natural resources and the urban environment as population growth continues. While cities provide economic opportunities and cultural diversity, their rapid expansion has led to habitat degradation, biodiversity loss, and the exacerbation of environmental issues such as air and water pollution, urban heat islands, and the decline of per capita green space—all of which directly affect citizens’ quality of life. In this context, green infrastructure has been recognized as an efficient, nature-based approach that enhances water infiltration, reduces surface runoff, improves air quality, protects habitats, and regulates microclimates, thereby playing a critical role in strengthening urban resilience and environmental efficiency. Compared with conventional gray infrastructure, green infrastructure is more cost-effective, multifunctional, and environmentally compatible, and it has been widely promoted within the framework of the Sustainable Development Goals (SDGs). However, barriers such as limited financial resources, land scarcity, and inadequate public investment constrain its full potential. The concept of environmental efficiency, an advanced form of eco-efficiency, emphasizes minimizing ecological costs and impacts while maximizing benefits, particularly at large-scale urban planning levels. Tehran, as a megacity, faces challenges such as rapid population growth, unbalanced development, air pollution, urban heat islands, and unequal access to green spaces, which collectively reduce soil permeability, increase runoff, and diminish environmental efficiency. Accordingly, futures studies of green infrastructure and the enhancement of its key indicators in Tehran represent a strategic necessity that can mitigate environmental crises, promote spatial justice, and guide the city toward sustainable development. The present study, through a systematic and structural meta-analysis approach, seeks to provide an evidence-based framework for urban policy and planning aimed at improving environmental efficiency through the development of green infrastructure.

This research adopts a systematic review and path analysis approach. It is applied in purpose and descriptive-analytical in nature. First, a systematic literature search was conducted on June 30, 2024, using the Web of Science database and following the PRISMA framework. Keywords included terms such as green infrastructure, open green space, nature-based solutions, and environmental efficiency. Initially, 1326 articles were identified, covering the period 1992–2024. After preliminary screening, 1180 peer-reviewed articles remained, from which those unrelated to green infrastructure planning or implementation were excluded, reducing the number to 457. An additional 30 were removed for irrelevance to the research question, resulting in a final dataset of 427 articles: 304 addressing green infrastructure and environmental efficiency, 114 addressing the link with SDGs, and only 7 simultaneously covering all three dimensions. Bibliometric analysis of these studies was conducted using VOSviewer. In the second phase, the study focused on futures studies regarding the role of the Internet of Things (IoT) in urban water systems. A total of 36 related keywords were identified and refined through expert validation into 18 key indicators. The statistical population included university academics and researchers, urban managers and policymakers, and technical experts, from which a snowball sample of 60 participants was selected. A semi-structured questionnaire was distributed, and data were analyzed using MICMAC software. Finally, scenarios were developed using the Scenario Wizard tool.

Accelerating urbanization in the twenty-first century, combined with intensifying environmental pressures, has highlighted green infrastructure as a key approach to sustainable urban management. A systematic review of studies from 1992 to 2024 reveals a steady growth in the field, evolving from limited evaluations in earlier decades to broader, multidimensional research in recent years. During the 1990s and early 2000s, the focus was primarily on the economic valuation and role of urban green spaces; however, since 2016, coinciding with the UN’s SDG agenda, themes such as urban resilience, climate change, cost-benefit analysis, ecosystem services, air pollution, and water management have become central. Co-occurrence analysis identified four main clusters: environmental efficiency and air pollution, stormwater management and life cycle assessment, urban resilience and public health, and nature-based solutions related to water quality and biodiversity. The benefits of green infrastructure were classified into four categories—regulating, supporting, cultural, and provisioning services—spanning a wide range of functions from reducing urban heat islands and improving air quality to enhancing mental and physical health, ensuring food security, and protecting biodiversity. In the structural analysis of Tehran’s future, 18 key indicators were identified. Results showed that indicators such as increasing per capita green space and improving ventilation exert the highest influence, while soil permeability and reduced runoff were the most influenced. Based on these findings, three plausible scenarios emerged: an optimistic scenario of a sustainable green city, a moderate scenario of limited green development, and a pessimistic scenario of environmental crisis, each with distinct implications for the resilience and sustainability of Tehran.Green infrastructure has been widely recognized as a strategic pathway for improving environmental efficiency and reducing ecological pressures, although constraints such as land scarcity, financial limitations, and human resource shortages hinder its full implementation. A review of 427 articles indicated that only a small fraction directly addressed the relationship between green infrastructure and environmental efficiency, with most focusing on cost-effectiveness. Keyword co-occurrence analysis identified four major thematic clusters: urban heat and air pollution management, stormwater management and cost-efficiency, human well-being and environmental justice, and nature-based solutions for environmental quality. The benefits of green infrastructure, classified into regulating, supporting, cultural, and provisioning dimensions, encompass services ranging from reducing heat islands and improving air and water quality to safeguarding biodiversity and promoting urban health. The trajectory of research has shifted from economic evaluations toward multidimensional analyses incorporating resilience, climate change, and natural resource management. Futures analysis demonstrated that indicators such as air ventilation and per capita green space have the greatest influence, while soil permeability and protection of native species are most influenced. Accordingly, three scenarios were formulated: (1) an optimistic scenario characterized by large-scale investment and maximum environmental efficiency; (2) a moderate scenario marked by limited investment and partial achievement of goals; and (3) a pessimistic scenario, shaped by resource scarcity and poor governance, leading to environmental crises.