Catchment-Wetland Associations Based on Multiscale Landscape Structure and Hydro-Ecological Indicators at Bakhira...

Wetland condition in floodplain landscapes is influenced by seasonal hydrology, catchment land-use change, and landscape fragmentation. This study assessed long-term catchment-wetland associations and hydro-ecological condition at Bakhira Ramsar Site, India, from 1990 to 2023 using Landsat-derived indices, FRAGSTATS-based landscape metrics, LULC transformation analysis, Pearson correlation, Redundancy Analysis, and a Pressure-State-Response-based Wetland Health Index. The Modified Normalized Difference Water Index, Water-Adjusted Vegetation Index, Enhanced Aquatic Vegetation Index, and Floating Algae Index were used to evaluate open-water extent, aquatic vegetation, macrophyte condition, and floating algae. Results showed a persistent decline in wetland water extent, with decreasing trends of -46.62 ha yr⁻¹ during pre-monsoon and -37.30 ha yr⁻¹ during post-monsoon. Increasing EAVI and FAI values indicated expansion of aquatic vegetation and floating algae. Catchment cropland increased from 61.62 km² in 2000 to 116.17 km² in 2022, while fallow land decreased from 138.15 to 70.10 km² and marshy wetland declined from 54.77 to 28.80 km², indicating loss of buffering areas. Correlation analysis showed strong seasonal linkages, including positive relationships between catchment waterbody LPI and wetland water LPI (r = 0.90) and PROX (r = 0.98) during pre-monsoon, and between catchment waterbody COHESION and wetland water COHESION (r = 0.77) during post-monsoon. RDA provided multivariate support for interpreting these linkages, explaining 30.70% and 49.26% of wetland-response variation in the pre- and post-monsoon seasons, respectively, and the results were interpreted as indicating associations rather than causation. The WHI classified Bakhira Wetland as Moderate in both seasons, with mean values increasing from 0.52 in pre-monsoon to 0.58 in post-monsoon. These findings provide a practical framework for Ramsar monitoring, restoration prioritization, and catchment-based wetland management.