Nature-Based Solutions for Sustainable Cities using Urban Green Spaces Quality Assessment Index (UGSAI)

Urban Green Spaces (UGS) serve as crucial ecological and social assets in urban areas, significantly contributing to the sustainability and well-being of city life. This research delves into the assessment of UGS quality in Delhi, aligning with the 2030 Agenda for Sustainable Development, specifically Sustainable Development Goal (SDG) 11 - Sustainable Cities and Communities. This study emphasizes the importance of UGS as Nature-Based Solutions. Previous studies have explored diverse attributes to evaluate UGS quality, incorporating elements like percentage green, built-up density, and proximity to green spaces. However, these studies often focused on specific aspects associated with any of the three important elements: impervious areas, vegetation, and population. This approach leaves a gap in comprehensively assessing the overall status of UGS, even if one element is taken out of the picture. To address these limitations, this study adopts a holistic approach by considering nine key attributes, including Proportional Population, Impermeable Surface Area, Proportional Impermeable Surface Area, Per-capita Green Index, Buffer Area around UGS, Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index, Green Space Coverage, and Proportional Green, to offer a quantitative measure of UGS quality in Delhi. The Urban Green Spaces Assessment Index (UGSAI), derived from these attributes, provides a comprehensive understanding of UGS in the city, ranging from 0 to 100. The UGSAI categories, divided into five - Very Low (<20), Low (20-35), Moderate (35-50), High (50-65), and Very High (>65), were carefully determined for effective representation, revealing significant variations among wards. A higher UGSAI value indicates better green space conditions, signifying areas that are more accessible, sufficient to cater to the needs of the population of the particular ward, and have higher-quality green spaces. UGSAI values for the wards ranged from the lowest at 6.10 to the highest at 76.32. The study unveils that over 60% of wards fall into the Very Low to Low category, 33% in Moderate, and only 5% in the High to Very High category of UGSAI. Additionally, the correlation of the nine attributes used was tested with UGSAI, and the results indicated strong correlations between UGSAI and Green Coverage, SAVI, and NDVI (r=0.90), along with a strong negative correlation with Impermeable Surface Area (r = -0.87), revealing the attributes that are crucial for improving the UGSAI of a ward. This underscores the need for local-level improvements in management and an increase in UGS, especially in the identified critical areas. This research, grounded in Nature-Based Solutions, provides valuable insights for decision-makers, promoting informed choices that foster resilient and sustainable urban ecosystems. Moreover, the robust methodology and effectiveness of the Urban Green Spaces Assessment Index (UGSAI) presented in this study underscore its potential as a valuable tool applicable beyond Delhi, offering a comprehensive framework for assessing UGS in diverse urban contexts and guiding sustainable development initiatives.