Spatial and temporal dynamics of urban sprawl: land use and land cover analysis of the Mangaluru-Udupi coastal region, Karnataka, using geospatial tools

Social development, integrated with urban development, has a primary influence on land use change and contributes to urban climate change. The current trends highlighted in the literature reveal the need for an eco-friendly urban plan based on up-to-date information on urban growth and land use changes. This study aims to analyze the spatiotemporal variation of the land surface in the two rapidly growing cities of Karnataka, India—Mangaluru and Udupi—which have been facing the burden of higher temperatures in recent years. The study targets medium-sized cities, an urban category largely overlooked in sprawl research relative to large metropolitan areas. Landsat images of the research site were used to generate classification maps for the years 1994, 2004, 2014, and 2024 using the Random Forest technique on the Google Earth Engine platform. Land cover transitions were quantified using post-classification change detection. Shannon’s Entropy approach was used to assess the urban growth and sprawl patterns in the study region. The study shows that, during the study period, the urban area in these cities expanded by 183.81%, while the open land experienced a 22.73% expansion. A significant decrease in vegetation area was observed, with a reduction of 49.53%, and there were also declines in agricultural land and water bodies by 3.27% and 19.73%, respectively. The urban pattern was found to be compact in this region, as evidenced by Shannon’s entropy analysis. The increase in Shannon’s entropy values during the observed period, especially from 2014 to 2024, points to an emerging rather than fully realized sprawl condition in the study area. The study also applies Jensen-Shannon Divergence alongside a corridor-based analysis of the Mangaluru–Udupi highway to evaluate land-use similarity between the two cities and examine growth driven by transportation infrastructure.