Spatiotemporal dynamics of urban green and blue spaces using geospatial techniques in Chandannagar city, India

Green and blue spaces are important landscape elements in a city and there is strong literary evidence available regarding the ecological, social, cultural and recreational benefits of these spaces to people and urban sustainability. Comprehensive quantitative assessment of these spaces is gaining scientific recognition for their utility in sustainable urban planning and drafting greening policies. This study analyzed the spatiotemporal change in urban green and blue spaces in Chandannagar city, India through quantitative assessment for the years 1991, 2001, 2011, and 2020 using Landsat data of 30 m spatial resolution. Normalized Difference Vegetation Index and Normalised Difference Water Index was applied to extract information on urban green and blue spaces. The classified maps were validated through field observations and Google earth images. Spatio-temporal analysis was carried out at ward level to analyze the distribution of urban green spaces (UGS) at the micro level. The result indicated that there was a reduction in green and blue spaces in the central and eastern parts of the city while there was a good amount of UGS in the western part of the city. The findings of this study shed light on important policy implications for the UGS planning in the city.