<p>Wetlands are diverse ecosystems that provide significant socioeconomic and ecological benefits to society. This study aims to analyze the changes in the water spread area, bathymetry profile, volume, and water balance of the Ashtamudi brackish wetland, a Ramsar Site of international importance, over a 43-year period from 1980 to 2023. The objectives of the study were to assess the spatiotemporal changes in water spread area, estimate volume loss, examine bathymetric profiles, and evaluate the water balance of the wetland. Remote sensing techniques, specifically the Normalized Difference Water Index (NDWI), and Geographic Information System (GIS) were employed to assess and map these changes. The results revealed a 27% reduction in the wetland’s area (from 62.73 km² in 1980 to 46.01 km² in 2023) and a 46.30% decrease in its volume (from 54,340 to 39,180 Mm³) during the study period. The greatest reductions were observed in the Kanjirottu, Kallada, and Kandachira regions. The water balance analysis showed a 12.67% reduction in water storage. These changes were attributed to factors such as encroachment for urbanization and aquaculture farming, unsustainable tourism, violations of Coastal Regulation Zone (CRZ) norms, erratic rainfall patterns, alterations in hydrological patterns, and the dumping of waste materials from nearby industries. The bathymetry profile of the wetland in 2024 revealed a gradient, with an average depth of 6&#xa0;m near the inlet and 3&#xa0;m near the outlet, contributing to saline influx with salinity levels ranging from 22.59 to 47.86 ppt. The findings highlight the urgent need for an integrated management action plan to support the conservation of Ashtamudi wetland in alignment with the Ramsar Convention’s wise use approach.</p>