Proposal for urban green infrastructure: A case study of Çankaya neighborhood

Cities are facing significant threats due to global environmental pressures such as population growth, rapid urbanization, and climate change. These threats manifest as deforestation, biodiversity loss, disruptions in ecosystem services, the shrinking of species' habitats, and the deterioration of ecological balance. In recent years, sustainability concerns have driven both developed and developing countries to seek new approaches to address the impacts of the climate crisis. Within this framework, urban green infrastructure (UGI) systems have emerged as an important planning tool for transforming cities into climate-resilient, self-sufficient, and sustainable environments that preserve ecosystem services and support long-term development. Green infrastructure, by integrating natural and artificial ecosystems, is considered capable of making cities more resilient, healthier, and livable. In this context, considering the social, physical, and economic impacts of climate change, the increasing pressure of population growth, and the unsustainable use of natural resources, the need for an integrated planning approach that produces nature-based solutions and enables the joint management of ecological and economic values has become evident. Green infrastructure is defined as systems that encompass ecological, functional, and sustainable values, including natural and cultural areas, and can be implemented at both urban and rural scales. These systems consist of diverse components such as green corridors, parks, gardens, vertical gardens, rain gardens, permeable surfaces, recreational areas, and street-scale green solutions. In this respect, green infrastructure is considered a comprehensive network that provides the necessary ecological basis for addressing climatic challenges in urban and natural environments. In this study, Çankaya Neighborhood, located in the Çankaya District of Ankara Province, was selected as the case study area, and the impacts of climate change and urban heat island (UHI) formation were evaluated within the framework of the green infrastructure approach. The study aimed to analyze the changes in vegetation cover, land surface temperature (LST), and land use characteristics between 1985 and 2024, to identify suitable green infrastructure strategies, and to develop proposals for sustainable urban planning. In the first stage, an extensive literature review was conducted to establish the conceptual framework for green infrastructure and urban heat islands, and applicable methods at national and international scales were assessed. During the analysis, Landsat satellite imagery, data from the Turkish State Meteorological Service, and base maps obtained from Çankaya Municipality were integrated and processed using ArcGIS 10.8. Using Landsat 4-5 TM and Landsat 8 OLI images, analyses of land surface temperature (LST), normalized difference vegetation index (NDVI), and normalized difference built-up index (NDBI) were conducted for July periods between 1985 and 2024, and long-term spatial and temporal changes were revealed. The analysis results indicated that the land cover of Çankaya Neighborhood, derived by overlaying zoning maps with satellite imagery, consists of institutional areas, built-up zones, and fragmented green spaces. According to data from the Turkish State Meteorological Service Station No. 17130, the average July temperature was between 19.3°C and 20.5°C in 1985, increasing to 24.4°C to 25.6°C by 2024, revealing a rise of approximately 5°C over the last 40 years. The LST analysis showed that in July 1985, the minimum land surface temperature was 29.9°C, the maximum was 38°C, and the average was approximately 30°C. In July 2024, the minimum LST ranged between 28.2°C and 30°C, while the maximum reached 39.8°C. Particularly in highly urbanized and impervious areas, temperature differences of approximately 8–9°C compared to greener areas were identified. NDVI analysis revealed that in July 1985, the highest NDVI value for healthy vegetation was 0.74, while the lowest value in densely built-up areas was -0.19. For July 2024, the highest NDVI value increased to 0.88, and the lowest value was 0.01. The NDVI difference analysis demonstrated a positive increase between 0.1 and 0.3 in vegetation cover across the neighborhood between 1985 and 2024. When LST and NDVI difference analyses were evaluated together, it was observed that surface temperatures in densely urbanized areas increased by 4°C to 9.4°C, whereas areas with more vegetation maintained significantly lower temperatures. The functional land cover analysis identified the main green infrastructure components as institutional gardens, residential gardens, recreational areas, schoolyards, commercial facility gardens, and inter-street green spaces. Within the neighborhood, three critical zones with the highest temperatures were determined, and considering building height-to-street width ratios, solar exposure, and existing green potential, six streets and one avenue were selected as priority implementation areas. For these locations, green infrastructure applications suitable for local structural characteristics and climatic conditions were proposed, and the strategies were visualized through AI-supported modeling techniques. In conclusion, the findings of this study demonstrate that climate change has significantly intensified the urban heat island effect within Çankaya Neighborhood, while vegetation and green areas play a crucial role in mitigating this impact. Based on these results, it is recommended to reduce impervious surfaces and improve the local microclimate through nature-based solutions such as permeable pavements, rain gardens, green parking areas, vertical gardens, street tree planting, and landscaping with native plant species. The green infrastructure strategies developed in this study are expected to contribute to the creation of climate-resilient, sustainable, and livable urban environments, particularly for the Çankaya District of Ankara.