Which major dam project in India is constructed across the Bhagirathi River?

Introduction / Context:
Large dams in India are often associated with specific rivers, and questions in geography and general knowledge frequently test these pairings. Knowing which dam is built on which river helps in understanding regional development, hydropower generation, irrigation projects, and environmental issues. This question focuses on the Bhagirathi River, one of the head streams of the Ganga in Uttarakhand, and asks which major dam project is constructed on it.

Given Data / Assumptions:

• The river of interest is the Bhagirathi, a key source stream of the Ganga.
• The options are Sardar Sarovar Dam, Tehri Dam, Koyna Dam, and Srisailam Dam.
• Only one of these dams is actually located on the Bhagirathi River.
• We assume standard mappings of major Indian dams to their rivers.

Concept / Approach:
To answer, we recall well known dam river pairs. Tehri Dam is a large rock and earth fill dam in Uttarakhand built on the Bhagirathi River. It is one of India's tallest dams and part of the Tehri Hydro Development Project. In contrast, Sardar Sarovar Dam is on the Narmada, Koyna Dam is on the Koyna River in Maharashtra, and Srisailam Dam is on the Krishna River. Matching each dam with its correct river allows us to eliminate the distractors and select the right answer.

Step-by-Step Solution:
Step 1: Recall that Tehri Dam is located in Uttarakhand and is associated with the Bhagirathi River. Step 2: Remember that Sardar Sarovar Dam is constructed on the Narmada River in Gujarat and Madhya Pradesh region. Step 3: Note that Koyna Dam is built on the Koyna River, a tributary of the Krishna in Maharashtra. Step 4: Recognise that Srisailam Dam is on the Krishna River in Andhra Pradesh and Telangana region. Step 5: Therefore, the only dam actually built on the Bhagirathi River is Tehri Dam.

Verification / Alternative Check:
An alternative verification method is to recall controversies and news associated with Tehri Dam, such as debates about displacement, seismic safety, and submergence of Tehri town in Uttarakhand. These discussions consistently mention the Bhagirathi River and its role in forming the Ganga. No such association appears with the other dams regarding Bhagirathi. Textbook tables of dams and rivers also list Tehri Dam with Bhagirathi, confirming the correctness of this pairing.

Why Other Options Are Wrong:
Sardar Sarovar Dam is wrong because it is explicitly built across the Narmada River, not Bhagirathi. Koyna Dam is wrong because it harnesses the Koyna River in the Western Ghats of Maharashtra and has no connection with Uttarakhand or the Ganga headwaters. Srisailam Dam is wrong because it is situated on the Krishna River in the south of India, far away from the Himalayan Bhagirathi. Each wrong option is associated with a different river system.

Common Pitfalls:
A common pitfall is mixing up dams because their names are familiar, but their rivers are not memorised accurately. Students sometimes think of Sardar Sarovar or Srisailam simply because they remember them as large projects without recalling the exact river. Another mistake is confusing Bhagirathi with other Himalayan rivers and guessing at random. To avoid such errors, it is useful to study dam river pairs using charts or flashcards and revise them regularly.

Final Answer:
The major dam project constructed across the Bhagirathi River is the Tehri Dam.