Bank Erosion Problems in River Barak—A Case Study

The river Barak is the second largest river in the state of Assam. It originates from the hills of Manipur and flows through three states namely, Manipur, Mizoram, and Assam. It bifurcates into two parts Surma and Kushiara before entering into Bangladesh and finally discharges its water to the river Meghna. The river Barak is highly meandering and changes its course frequently, thereby destroying the river side villages every year. Three years ago, the abutments of a bridge were constructed on both the banks of the river. During peak monsoon time, the river changed its course, destroyed one village completely, and started flowing along a new route whereby both the abutments were shifted on one side. The present study includes detailed survey of the river at some other eroding location. The total station survey and bathymetric survey were carried out to obtain the cross sections of the river, geotechnical survey included borelog survey for characterizing the soil layers and geophysical survey was intended to obtain the continuous profile of the substrata. Finally, PLAXIS 3D software was used to obtain the probable deformations and factor of safety of the river banks under steady state, slow draw down, and rapid draw down conditions. Important conclusions were drawn at the end of the study.