Monitoring multi-decadal riverbank dynamics of the Padma river in Bangladesh using geospatial analysis and DSAS model

Abstract One of South Asia’s vital transboundary rivers, the Padma River, exhibits intense erosion and accretion patterns and frequently alters the bank line position across Bangladesh due to its dynamic and destructive behaviour. We conducted a complete analysis of Padma Riverbank dynamics (1972–2023) across Bangladesh using the Google Earth Engine (GEE) and digital shoreline analysis system (DSAS) model. Shoreline positional uncertainty was minimized considering single-scene dry-season imagery and semi-automatic digitization. The DSAS model calculates shoreline dynamics through shoreline change envelope (SCE), end point rate (EPR), linear regression rate (LRR), and net shoreline movement (NSM). The research showed that the North bank is mostly eroded (mean rate: − 4.44 m/yr, max: − 97 m/yr), while the South bank is mostly accreted (mean rate: 14.59 m/yr, max: 298.72 m/yr). The shoreline erosion rates based on EPR and LRR demonstrate a mean of − 4.44 m/yr and − 4.06 m/yr on the Northern bank, respectively, indicating 64.98% of transected areas. The South bank shoreline reveals average accretion rates amounting to 14.59 m/yr (EPR) and 12.88 m/yr (LRR), with 51.97% of the transects. These dynamics are driven by different anthropogenic and natural factors such as sediment transport, hydrological variability, dredging activities, sand mining, embankment construction, and localized human interventions. The findings emphasize adaptive management strategies to combat the environmental and social concerns arising from the dynamic nature of the Padma River aligning with national policies.