Dams and Multipurpose River Projects of India
India's rivers are both a blessing and a danger: they water the fields and carry the trade, but they also flood and shift their channels. To control them, India built a series of multipurpose river projects in which one dam serves several purposes at once, such as flood control, irrigation, electricity, water supply and navigation. After independence, these projects were proudly called the temples of modern India, and they changed agriculture by bringing canal water to dry lands and industry by generating hydroelectric power. The records attached to the dams, the rivers on which they stand and the projects of Assam and the North-East are all standard exam material, and this chapter arranges them so that they can be revised quickly.
What is a multipurpose river project
A multipurpose river project is a scheme in which a river is used for several purposes together. The main purposes are flood control, irrigation, power generation and navigation, and many projects also supply drinking water and support fisheries. The dam stores the monsoon water and releases it slowly, so that the deadly floods of the rainy season are reduced and the farms get water in the dry season. The same stored water turns turbines to produce hydroelectricity, which is a clean and renewable source of power. Because the benefits are shared, these projects are usually planned for a whole river basin rather than for a single city, and the Damodar Valley Project was created on the model of the Tennessee Valley Authority of the United States.
The first projects: Damodar Valley and Bhakra Nangal
The first multipurpose river project of India is the Damodar Valley Project, built on the Damodar river, and the Damodar Valley Corporation that runs it was established in 1948. The Damodar was once called the "sorrow of Bengal" because of its destructive floods, and controlling it was the project's first aim. In the north-west, the Bhakra Nangal Dam stands on the Sutlej river, and the Bhakra dam is famous as the highest gravity dam in the world, rising about 226 metres. These early projects showed what large dams could do, and they became the model for the many projects that followed.
The great dams and their records
The records of the dams are easy one-mark questions, so they must be learnt clearly. The highest dam of India is the Tehri Dam in Uttarakhand, about 260 metres high, built on the Bhagirathi river; it is also the largest dam of India by water capacity. The longest dam of India is the Hirakud Dam in Odisha, on the Mahanadi river, with a length of about 4,801 metres. The Nagarjuna Sagar Dam on the Krishna river is the largest masonry dam in the world and the largest in India by storage capacity. The Sardar Sarovar Dam stands on the Narmada river, the Rihand Dam on the Rihand, a tributary of the Son, and the Gandhisagar Dam on the Chambal. The Mettur Dam is the dam of the Kaveri, and the Banasura Sagar Dam in Kerala is the largest earthen dam of India.
Dams of the Deccan and the south
In peninsular India the rivers are rain-fed and seasonal, so storage is even more important than in the Himalayan rivers. The Nagarjuna Sagar project on the Krishna is the largest multipurpose river project of South India and also one of the largest in the whole country. The Koyna Dam on the Koyna river in Maharashtra supports an important hydroelectric station, and the Idukki Dam on the Periyar river in Kerala is the highest arch dam of India. On the Godavari stands the Sriramsagar (Pochampad) Dam, on the Tungabhadra the Tungabhadra Dam, on the Tapi the Kakrapar Dam in Gujarat and on the Gandak the Gandak project in Bihar. The Farakka Barrage on the Ganga in West Bengal is a special case: its main purpose is to divert Ganga water into the Hooghly river so that the Kolkata port remains navigable and does not silt up.
Dams and projects of Assam and the North-East
The North-East has steep rivers and heavy rainfall, so it has great potential for hydropower. The first multipurpose project of the North-East is the Umiam project of Meghalaya, built on the Umiam (Barapani) river. The largest multipurpose project of Assam is the Karbi Langpi project, and the Kopili hydroelectric project is built on the Kopili river. The Subansiri Lower Project, which is among the biggest hydroelectric schemes in the region, is built on the Subansiri river on the Assam-Arunachal border. These projects can supply clean power to a power-hungry region, but they must be planned carefully because the hill slopes are young, the rainfall is heavy and the rivers carry a very large load of silt.
Benefits and problems of large dams
Large dams have clear benefits: they reduce floods, extend irrigation into the dry season, produce renewable electricity, supply drinking water and help river navigation. They also have serious costs. They displace people from the land that is submerged, they trap silt that would otherwise enrich the delta and the floodplain downstream, they change the flow of the river and the life of its fish, and in earthquake-prone mountain regions they raise questions of safety. The debate about large dams is therefore really a debate about how to balance the needs of farmers, towns, industry and the environment, and about whether the same benefits could be obtained from many smaller, less damaging schemes.
Quick revision
For quick revision, fix the "firsts": the Damodar Valley Project is the first multipurpose river project of India, the Damodar Valley Corporation began in 1948, and the Umiam project of Meghalaya is the first in the North-East. Then fix the records: Tehri is the highest dam and the largest by capacity, Hirakud is the longest at about 4,801 metres, Nagarjuna Sagar is the largest masonry dam in the world and the largest project of South India, Bhakra is the highest gravity dam in the world and Banasura Sagar is the largest earthen dam of India. Keep the rivers joined to their dams: Tehri with the Bhagirathi, Hirakud with the Mahanadi, Bhakra Nangal with the Sutlej, Nagarjuna Sagar with the Krishna, Sardar Sarovar with the Narmada, Idukki with the Periyar and Mettur with the Kaveri. In the North-East remember Karbi Langpi in Assam, Kopili on the Kopili and the Subansiri Lower project on the Subansiri. Finally, the Farakka Barrage exists to keep the Kolkata port navigable.
How to prepare this topic
- Split the chapter into two lists, one for the "firsts" such as Damodar Valley and Umiam, and one for the "largest, longest and highest" such as Tehri, Hirakud, Nagarjuna Sagar and Banasura Sagar.
- Learn every dam together with its river, because examiners often ask the river instead of the dam or the dam instead of the river.
- Keep the special-purpose projects separate: Farakka for navigation, the Damodar Valley for flood control and the Karbi Langpi and Subansiri Lower for the North-East.
- Prepare the North-East list on its own, with Karbi Langpi, Kopili and Subansiri, since Assam exams set questions on them frequently.
- Revise the benefits and problems of large dams as a balanced answer, so that a long-answer question can be written without missing either side.
Common exam traps
- Tehri is the highest dam and the largest by capacity, but Hirakud is the longest; do not merge these two records.
- Bhakra is the highest gravity dam in the world, while Nagarjuna Sagar is the largest masonry dam in the world.
- The first multipurpose project of India is the Damodar Valley Project, while the first in the North-East is the Umiam project of Meghalaya.
- The Farakka Barrage is not mainly a power project; it exists to divert Ganga water to the Hooghly to keep the Kolkata port navigable.
- Idukki is the highest arch dam of India and stands on the Periyar, not on the Kaveri or the Krishna.
Frequently Asked Questions
What is a multipurpose river project and which was the first in India?
A multipurpose river project uses a river for several purposes together, such as flood control, irrigation, power generation and navigation, and often also for drinking water and fisheries. The first multipurpose river project of India is the Damodar Valley Project, built on the Damodar river, and the Damodar Valley Corporation was established in 1948. The first multipurpose project of the North-East is the Umiam project of Meghalaya, on the Umiam or Barapani river.
Which are the highest, longest and largest dams of India?
The highest dam of India is the Tehri Dam in Uttarakhand, about 260 metres high, on the Bhagirathi river, and it is also the largest by water capacity. The longest dam is the Hirakud Dam in Odisha, on the Mahanadi river, with a length of about 4,801 metres. The Nagarjuna Sagar Dam on the Krishna river is the largest masonry dam in the world and the largest in India by storage capacity, while the Banasura Sagar Dam in Kerala is the largest earthen dam in India.
Which rivers are the important dams of India built on?
The important pairs are Tehri with the Bhagirathi, Hirakud with the Mahanadi, Bhakra Nangal with the Sutlej, Nagarjuna Sagar with the Krishna, Sardar Sarovar with the Narmada, Rihand with the Rihand, Mettur with the Kaveri, Idukki with the Periyar, Koyna with the Koyna, Kakrapar with the Tapi, Gandhisagar with the Chambal and the Sriramsagar or Pochampad Dam with the Godavari. The Bhakra dam is the highest gravity dam in the world at about 226 metres.
What are the important river projects of Assam and the North-East?
The largest multipurpose project of Assam is the Karbi Langpi project. The Umiam project of Meghalaya on the Umiam or Barapani river is the first multipurpose project of the North-East. The Kopili hydroelectric project is on the Kopili river, and the Subansiri Lower Project is on the Subansiri river on the Assam-Arunachal border. These projects use the steep rivers and heavy rainfall of the region, but must be planned carefully because of the young hill slopes and heavy silt load.
What is the purpose of the Farakka Barrage and what are the problems of large dams?
The main purpose of the Farakka Barrage on the Ganga in West Bengal is to divert Ganga water into the Hooghly river so that the Kolkata port remains navigable and does not silt up. Large dams have great benefits, including flood control, irrigation, hydroelectricity, water supply and navigation, but they also displace people, trap silt, change the flow of the river and its fish life and raise safety concerns in earthquake-prone regions.