Saptarshi Dey , Abhirup Basu, Sudeep Narayan Banerjee, Vikrant Jain

Riverbank erosion coupled with recurrent flooding has been a persistent problem in large parts of the Eastern India. Published data on bank erosion of the Ganga River in West Bengal suggests an annual average of 8 sq. km. land-loss during 1969-1999 and that potentially affected lives of nearly a million people and destroyed various human establishments. In this study, we aim to constrain the spatiotemporal change in the path of the Ganga River and its impact of on sediment reworking in the plains area. For this, we used LANDSAT imagery from the year 1987 to 2019. Our analysis is based on a MATLAB-based toolbox called RivMAP. We show that the mean reach-averaged migration rates of the Ganga River vary from 200-600m/yr. Over the last three decades, the Malda district suffered a land-loss of ~140 km2, yielding an average annual loss of 4.5 km2. First order mass estimate suggests ~30 Mt/yr sediment yield from the Ganga riverbank in Malda, which is ~815% of the total annual sediment load of the large Ganga River expected in Farakka Barrage. In the end, this study highlights the role of climate on river migration and bank erosion.