Comparative Study on Riverbank Erosion and Accretion Using HEC-RAS and Landsat Imagery

In Bangladesh, riverbank erosion is a chronic and persistent problem. Due to erosion and deposition, the Padma river course changes from meandering to braided. Between Pangsha and Goalanda, a 48 km reach was selected for this study. This research aims to assess the riverbank erosion and accretion in the Rajbari area using HEC-RAS and satellite image processing. The historical dataset indicates that the Padma River is highly dynamic, with its position, planform, and morphological features often changing due to flow and sedimentation variations. About 75.59 and 20.83 km2 were degraded between 2014 and 2022, respectively, due to heavy discharge in the monsoon. Satellite images showed that during the last nine years (2014–2022), erosion on the right bank of the River Padma in Rajbari district had increased, i.e., 75.59 km2 and 20.83 km2, respectively. The simulation of sediment transport using a 1-D HEC-RAS model in the study area comprising d50 as 0.14 mm and Manning’s n = 0.025 showed reasonable responses. Thus, this assessment could be applied to the decision support system for these river stakeholders.