Spatial-Temporal Assessment of Urban Wetlands in Metropolitan Area, India: A Framework for Sustainable Restoration and Management

Urban wetlands play a pivotal role in maintaining ecological balance, regulating hydrology, supporting biodiversity, and offering socio-economic benefits. This study presents a comprehensive, multi-tiered framework for assessing wetland distribution, condition, and transformation in Borough-XIII of the Kolkata Municipal Corporation, India. Employing an integrative methodology that combines high-resolution satellite imagery, GIS-based spatial analysis and systematic ground-truthing, the research identifies both historical trends and current site-specific conditions of wetlands across different Wards. The spatial-temporal analysis (2004–2022) reveals contrasting trajectories marked expansion in Wards 115 and 122, and significant shrinkage in Wards 116, 117 and 119 attributable to factors such as urban encroachment and partial restoration. The decadal LULC analysis revealed an 80% decline in waterbodies alongside a 26% increase in built-up areas, highlighting rapid urban encroachment. MNDWI results further confirmed fragmentation and shrinkage of surface water features, underscoring urgent conservation needs. Field condition assessments highlight spatial heterogeneity in water quality, eutrophication, and vegetation cover, with macrophyte dominance signalling nutrient loading and altered ecological states. Site status data point to alarming wetland loss in Wards 119 and 120, while emerging waterbodies in Ward 115 suggest improved detection and potential restoration. Temporal satellite comparisons further confirm ongoing degradation, with wetland disappearance driven primarily by infrastructure development. Scientifically, these findings underscore the fragmented and vulnerable state of urban wetlands and highlight the need for integrated watershed management, policy enforcement and community participation. This study introduces the critical role of spatial monitoring and ground validation in guiding sustainable urban planning and ecological resilience in megacities.