Geo-Spatial Assessment of Urban Expansion Dynamics and Its Implications on Foy Sagar Lake, Ajmer, Rajasthan

Foy Sagar, now renamed as Varun Sagar, is a historically significant artificial lake in Ajmer, Rajasthan. It was constructed in 1892 as a famine relief project, it has undergone substantial land use and land cover (LULC) transformations due to rapid urbanization and environmental changes over the past three decades. This study utilizes remote sensing and GIS techniques, including Landsat 4–5 TM and Landsat 8–9 OLI/TIRS satellite imagery, to analyze LULC changes within a 2.5 km buffer zone around the lake from 1991 to 2023. The analysis detects shifts in five major classes: water bodies, built-up areas, agriculture, vegetation, and bare land using supervised classification for precise mapping. Areal changes in the Foy Sagar Lake catchment from 1991 to 2023 were assessed using satellite imagery processed in Google Earth Engine and ERDAS IMAGINE 2015. Preprocessing involved cloud masking, radiometric correction, and atmospheric correction. Lake boundary delineation was performed using spectral indices and manual digitization in ArcGIS at 1:5000 scale for accurate spatial comparison. Additionally, primary data was gathered from 353 local respondents through structured questionnaires to enhance the research findings. The results indicate that water extent fluctuated from 0.76 sq km in 1991 to 0.47 sq km in 2001, representing a 38% decline due to drought and sedimentation. Partial recovery occurred by 2011 with water area reaching 0.50 sq km. Substantial expansion followed, with water extent increasing to 1.13 sq km in 2021 and 1.08 sq km by 2023, representing a 42% overall increase from baseline. Concurrently, built-up areas expanded dramatically from 0.10 sq km in 1991 to 3.08 sq km in 2023, representing a 2980% increase reflecting rapid urban sprawl, infrastructure development, and population growth. Agriculture declined significantly from 9.29 sq km to 3.83 sq km, a 59% reduction. Vegetation increased from 4.92 sq km to 7.20 sq km, showing 46% growth. Bare land remained relatively stable, declining marginally from 12.82 sq km to 12.68 sq km. This study highlights the critical need for sustainable urban planning, integrated water resource management, and stricter land-use regulations to mitigate further ecological degradation. Without comprehensive management strategies addressing urban pressures, climate variability, and environmental governance, the long-term sustainability of Foy Sagar and its surrounding ecosystem remains threatened.