Urban growth and environmental impact assessment in Malda: A comprehensive study using Shannon's entropy and remote sensing

Abstract

Urbanization poses enormous environmental and ecological challenges, making it crucial to strike a balance between urban growth and ecological preservation for the benefit of future generations. This study assesses the spatiotemporal changes and Environmental Impacts of Urbanization (EIU) in the Malda Urban Agglomeration (MUA) areas between 1990 and 2020 using geospatial techniques. Satellite-derived indices, Normalized Difference Built-up Index (NDBI), Normalized Difference Vegetation Index (NDVI), and Land Surface Temperature (LST)—were combined with field-based data to evaluate urbanization trends and their ecological consequences. Shannon's entropy model was employed to assess aerial urban growth during the study period. The relative entropy values were 0.751 in 1990 and 0.814, 0.882, and 0.947 in 2000, 2010, and 2020, respectively, indicating rapid urbanization in the MUA region, where the growth rate of urban expansion was found to be more than four times from the base year, 1990. This study took a different perspective to assess the impacts of urban expansion on environmental effects. The linear regression (LR) model demonstrated a substantial association between population growth and an increase in built-up areas in English Bazar, Old Malda, and MUA, with R² values of 0.927, 0.989, and 0.982, respectively. The LR model also revealed that rapid urbanization has significantly impacted environmental conditions (NDBI, LST, and vegetation cover) in the study. Thus, this study demonstrates the impacts of urbanization using Geospatial techniques, which can help policymakers plan for sustainable development (SDGs) and effectively mitigate urban planning and management challenges for a sustainable city environment.