Long-Term Monitoring and Forecasting of Teesta Riverbank Dynamics Using Remote Sensing and GIS

Abstract The primary geomorphological processes that influence the riverine environments in Bangladesh are riverbank erosion and channel migration, which in most cases result in land loss and socioeconomic consequences. The Teesta River is a large transboundary river located in northern Bangladesh which is characterized by a very dynamic channel behavior based on the hydrological variability, sediment transport, and human activities. The purpose of this study is to examine long-term riverbank migration of the Teesta river and project potential future locations of the bankline using remote sensing and GIS-based tools. Google Earth Engine was used to retrieve a series of multi-temporal Landsat satellite images between 1989 and 2024 to extract the positions of historical banklines. Digital Shoreline Analysis System (DSAS) was used to measure shoreline changes in terms of statistical variables such as Net Shoreline Movement (NSM), End Point Rate (EPR) and Linear Regression Rate (LRR). Findings show that the left bank is largely erosional where erosion is present in about 69% of the transects examined and erosion rate is the highest at-74.32 m/year. Conversely, the right bank exhibits predominating accretion patterns, where deposition is present in almost 59% of the transects and the highest rate of accretion is 154.3 m/year. A trend-based forecasting method based on a Kalman filter was used to project potential riverbank locations in 2034 and 2044. These forecasts indicate that erosion may persist along the left bank and local accretion along the right bank if historical migration trends continue. The findings can be useful in river management, land-use planning, and disaster mitigation in Teesta River basin.