River Bank Erosion and Vulnerability Assessment for the Alluvial section of Barak River in North-East India by In-situ Approach

In the floodplains of alluvial rivers, riverbank erosion is one of the most significant geomorphological problems. The Barak River is one of the critical river basins of North-East India. During the monsoon, the river is subject to regular catastrophic floods and erosion, which significantly impact the state's overall development. Embankment breaches induced by riverbank erosion have become a frequent occurrence. This study aims to determine the annual riverbank erosion and identify the locations most vulnerable to erosion of the Barak River by in-situ submerged Jet Erosion apparatus. 40 in-situ submerged jet experiments were conducted to determine the erodibility parameters of the bank soil. The results show that the spatial variation in erosion parameters of river banks varies significantly, with a magnitude of T (critical shear stress) range from 0.1 to 55 Pa, and the values of K (erodibility coefficient) range from 0.1 to 10 cm/N.s. Annual River bank erosion at the study sites was estimated using measured erosion parameters, and the results fell within the ranges previously reported. The JET test result indicated that a highly erodible to resistant vulnerability condition exists within the selected location. The most erodible sites are Sonai, Tarapur Nathpara, and Panchgram. The actual bank erosion of the chosen reach was checked by comparing the estimated bank erosion to the observed satellite images. The findings of this study demonstrate that the soil erosion parameters of the river bank are location specific; and therefore, it needs to be tested locally for precise estimation of stream bank erosion.