Geomorphologists suggest that the dramatic historical shifts and changes in the course of the Kosi River ultimately resulted in:
- Athe Ganga river flowing primarily through the Padma channel in Bangladesh.
- Bthe Teesta river changing its path to flow through North Bengal.
- Cthe continuous decline and heavy siltation of the Kolkata Port.
- Dsevere tectonic earthquakes in the Gangtok and Darjeeling regions.
Solution & Step-by-step Explanation
The shifting courses and avulsions of major northern tributaries like the Kosi and Teesta over the centuries altered the hydrographic equilibrium of the Ganga system. This shift caused the bulk of the Ganga's water to flow through the eastern Padma channel into Bangladesh, reducing the freshwater inflow into the Hooghly-Bhagirathi distributary, which led to heavy siltation and the subsequent structural decline of Kolkata Port.