The Impact of Urbanization on Wetland Ecology in Delhi Using AWEI and GIS

Abstract

This study examines the spatial and temporal patterns of wetland degradation in Delhi from 1991 to 2021 using remote sensing and GIS techniques. The Automated Water Extraction Index (AWEI) was applied to pre-monsoon Landsat imagery to delineate surface water bodies over the past 30 years accurately. Supervised classification was employed to generate land use maps, while census data was utilized to analyze urbanization trends across the region. Classification accuracy was assessed using Google Earth reference data through a confusion matrix, ensuring the reliability of the land cover analysis. Results reveal a significant decline in wetland extent, especially in densely populated and rapidly urbanizing districts such as North West, South, and East Delhi. During this time, the urban population increased from 52.7% to 97.4%, accompanied by a 70.2% expansion of built-up areas, while wetlands contracted from 32.9 km² to 30.2 km². South Delhi experienced the most severe wetland loss, with water body coverage dropping from 0.800% to 0.025%, whereas North East and Central Delhi maintained higher wetland coverage due to the influence of the Yamuna River and targeted conservation efforts. The study highlights the strong linkage between urban growth and wetland decline, which threatens biodiversity, groundwater recharge, and ecological stability. These findings emphasize the urgent need for integrated urban planning and conservation policies to safeguard wetlands, thereby promoting sustainability and water security in the National Capital Region.