Landscape transformation and ecological risk assessment in Chalan Beel wetland of Bangladesh using multispectral satellite data

Chalan Beel, Bangladesh’s largest inland wetland, is experiencing rapid ecological degradation under rising anthropogenic pressure. This study examines spatiotemporal land use/land cover (LULC) change and associated landscape ecological risk from 2000 to 2023 using multispectral satellite imagery for 2000, 2010, and 2023. After preprocessing, images were classified in ENVI 5.3 into five classes: deep water, shallow water, agricultural land, settlement–vegetation mix, and vegetation. LULC transitions were quantified for 2000–2010, 2010–2023, and 2000–2023 using Change Detection Statistics and the Thematic Change Workflow. Landscape ecological risk was then evaluated in Fragstats 4.2 using an ecological risk index and categorized from lowest to highest. Results show substantial LULC change over the study period: around 40% of vegetation cover was converted to settlement–vegetation mixed areas (indicative of rural settlement expansion), 22.88% of deep water shifted to shallow water, and 31.83% of shallow water converted to agricultural land; agricultural land also showed a 28.76% conversion to rural settlements. During 2000–2010, major transitions included vegetation to rural settlements (41.63%), agricultural land to rural settlements (28.78%), and deep water to shallow water (23.76%). From 2010–2023, key changes were deep water to shallow water (31.67%) and shallow water to agricultural land (28.29%). Ecological risk varied over time, and by 2023 more than half of the area fell into the middle-to-high risk classes. High-risk zones are concentrated in the southeast and northwest, whereas low-risk zones are mainly in the central and northern parts, indicating an overall increase in ecological risk.