Abstract: Deepor Beel is a wetland of great biodiversity, situated in the southwest part of the Guwahati city of Assam. The Rani and Garbhanga Reserved Forests are adjacent to the wetland, which altogether stands as a complete ecosystem providing environmental solutions, food security and different types of biodiversity to the city. With the rapid advancement of urban development in the city of Guwahati, the wetland is under constant threat of diminishing area of the wetland, extinction of biodiversity, as well as transformation of land use pattern of the entire area and its surroundings. The study aims to assess the changes in the lake water area from the surface area using the Modified Normalized Difference Water Index(MNDWI) and the changes in the vegetation and human habitation area using the Land Use Land Cover(LULC) classification with the help of the Arc GIS software. Time- series Landsat 8 images of the years of 2014, 2016, 2018, 2020 and 2021 were used to extract the MNDWI in GIS domain.

The analysis showed a declining nature of the area of the wetland with the years and an increase in the built-up area near the wetland. The decline in the lake water area is a serious concern in the age of rapid urbanization of big cities like Guwahati. The study reveals the potential of Landsat data and GIS study in mapping the change in the wetland ecosystem. It is hoped that the study will have its utility in the preparation of proper management plan for the conservation of the ecosystem of the Deepor Beel wetland.

Keywords: Surface area, Modified Normalized Difference Water Index, Land Use Land Cover, Landsat.

| DOI: 10.17148/IARJSET.2025.12323