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AI-generated city illustration of KolkataKolkata · AI city illustration

Kolkata · South Asia

A port that outlived its river

Why Calcutta was built where it was, and why the water stopped cooperating.

What you should be able to do after this: Explain how a shifting delta channel created Kolkata and then undermined it, and how partition reshaped the city.

0 of 4 · about 9 min

Start with geography

A delta channel is not a fixed address

In a big delta, the river does not have one course. It has many distributaries, and over decades and centuries the main flow shifts between them as channels silt up and new ones open. The Hooghly is a western distributary of the Ganges system, and it was navigable far enough inland for ocean-going ships when the East India Company set up there in the 1690s.

A port needs deep water reaching inland. The Hooghly provided it. What nobody could guarantee is that it would keep providing it, because delta channels are not promises.

On the map

The Bengal DeltaKolkata
Check your understanding

Which delta is Kolkata's river part of?

Answer the check to continue.

Sources for this chapter

Every source in this quest

Written by Globe Quest editorial and last reviewed 2026-09-07. Every claim above is traceable to one of these sources; where accounts genuinely differ, the chapter says so rather than choosing for you.