Which one of the following major ports of India is located on a riverine estuary rather than directly on the open sea?

Introduction / Context:
This question tests your understanding of Indian port geography and coastal landforms. Some ports are built directly on the open sea, while others are located on estuaries, creeks, or river mouths. An estuary is a widened tidal mouth of a river where fresh water mixes with sea water. Recognising which important Indian port complex lies on an estuary is a common requirement in geography examinations.

Given Data / Assumptions:

• The options are Kandla, Marmagao, Kolkata Haldia, Tuticorin, and Cochin.
• The question asks for the port that is located on a riverine estuary.
• We assume the conventional descriptions in school geography, which classify the Kolkata port and its Haldia dock system as an estuarine port on the Hooghly river.
• Other ports are to be evaluated in terms of their coastal setting.

Concept / Approach:
An estuarine port is situated on the tidal mouth of a river where the river widens and allows large ships to enter, often requiring regular dredging to maintain depth. The Kolkata port complex, including Haldia, is located along the Hooghly river, which is a distributary of the Ganga and forms an estuary as it approaches the Bay of Bengal. Textbooks frequently refer to Kolkata as an inland riverine port on an estuary. In contrast, ports such as Marmagao, Tuticorin, Kandla, and Cochin are associated more with harbour or creek settings directly on or very close to the sea coast.

Step-by-Step Solution:
Step 1: Recall that Kolkata port lies about one hundred kilometres inland on the Hooghly river. Step 2: Understand that the Hooghly river forms a tidal estuary as it nears the Bay of Bengal, with strong tidal effects and siltation. Step 3: Recognise that Haldia dock complex is part of the same port system located further downstream on the estuary. Step 4: Compare this with Kandla, Marmagao, Tuticorin, and Cochin, which are positioned closer to open sea coasts or in natural harbours, not on a large river estuary of the Ganga system. Step 5: Select Kolkata Haldia as the port complex located on an estuary.

Verification / Alternative check:
A physical map and port description in school textbooks clearly label Kolkata port as an inland riverine port on the Hooghly estuary. The need for continuous dredging due to silt deposition from the river and tides is often highlighted as a challenge. In comparison, port descriptions for Marmagao, Tuticorin, Cochin, and Kandla focus on natural harbours, lagoons, or creek based locations but do not class them in textbooks as classic estuarine ports of a large river system like the Hooghly.

Why Other Options Are Wrong:
Kandla lies on the Kandla creek near the Gulf of Kachchh and is better known as a tidal port rather than a classic river estuary based port. Marmagao in Goa is a natural harbour on the Arabian Sea coastline, not on a major river estuary. Tuticorin, also called Thoothukudi, is a port on the Gulf of Mannar on the southeastern coast of India. Cochin is a natural harbour on the Arabian Sea formed partly by backwaters and lagoons, but standard exam keys usually highlight Kolkata as the estuarine port on the Hooghly river.

Common Pitfalls:
Students sometimes choose Kandla or Cochin because they remember words like creek or backwaters and associate them with estuaries. Another pitfall is to focus only on whether a port is inland or coastal without thinking about its relationship with a major river mouth. To avoid confusion, remember the specific phrase used in many textbooks that Kolkata is an inland riverine port on the Hooghly estuary, which directly answers this kind of question.

Final Answer:
Kolkata Haldia