Comparative Study of LANDSAT-8 and SENTINEL-2A Images for Water Spread Area Analysis using NDWI Approach Wetland of Rajasthan: The Largest Saline Sambhar Lake

The present study investigates the use of satellite remote sensing techniques to analyze the distribution and extent of surface water in Sambhar Lake, a prominent inland saline lake located nearly 80 kilometers southwest of Jaipur, Rajasthan. Given the ecological and hydrological significance of this lake, monitoring its water spread is crucial, especially in the context of fluctuating climatic conditions and increasing anthropogenic pressures. To carry out this assessment, satellite imagery from two reliable sources—LANDSAT 8 and SENTINEL-2A—was employed, focusing on their spectral capabilities in identifying surface water features. For LANDSAT 8, Band 3 (Green) and Band 5 (Near Infrared) were utilized, while for SENTINEL-2A, Band 3 (Green) and Band 8 (Near Infrared) were selected. These spectral bands were processed using the Normalized Difference Water Index (NDWI), which effectively highlights water bodies by enhancing the contrast between water and other land features. The NDWI maps generated from these datasets helped visualize and compare the surface water extent captured by each satellite. The analysis revealed that SENTINEL-2A, owing to its higher spatial resolution of 10 meters, offered more detailed and accurate results compared to the 30-meter resolution of LANDSAT 8. It allowed for the identification of finer water channels, fragmented patches, and more defined lake boundaries, making it more suitable for precise surface water studies. In contrast, LANDSAT 8 still proved useful for broader-scale assessments but lacked the level of detail seen in SENTINEL-2A imagery. This study demonstrates the value of remote sensing tools in environmental monitoring, particularly in arid and semi-arid regions like Rajasthan, where water resource management is vital. The findings support the use of high-resolution satellite data for continuous observation of dynamic water bodies and contribute to improved decision-making in hydrological planning and ecological conservation. Overall, the research highlights the importance of selecting appropriate satellite data based on the objective and scale of analysis in surface water mapping.