Have you seen Longest dam in India? In movies or TV shows, or maybe in real life? Have you marvelled at these architectural feats? I know I have. I feel dams are a testament to mankind’s engineering skills. To stop an entire river or change its course is nothing short of a miracle if you think about it closely.
That is why in this blog post I discuss this amazing feat that is present in most countries around the world. India too has many dams built around strong rivers and has the distinction of having the longest dam in the world. These dams have many uses and are big enough to kick-start and power the economy in any country. Now you might be wondering about the basic question of what exactly a dam is.
What is a dam?
A dam is a structure that acts as a barrier and stops or restricts the flow of water or underground streams. Dams also create reservoirs that provide water for activities like irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is generating electricity through water and can be harnessed when a dam is constructed.
Now that the basic understanding of a dam is elaborated let’s see why they are constructed and what purpose they serve.
Why is a dam constructed?
Dams are constructed for the dual purpose of suppressing floods and creating reservoirs of water that is later used for many purposes like irrigation, human consumption, industrial use, aquaculture, and navigability. They are also used to control the water levels. They are seen as providing a secure and permanent water supply that can be used throughout the year, especially in droughts.
Surprisingly enough dams were not discovered recently and people have been constructing them well before the Common Era. Due to the usefulness of this structure people of ancient civilizations have been constructing dams on rivers and have been using it for many purposes. The history of dams is as old as civilization itself and please keep reading as I shed more light on its long history.
The History of dams
The first dams were discovered in Ancient Mesopotamia and the Middle East. The Mesopotamians constructed their dams on the rivers Tigris and Euphrates and were used to control the water levels as these rivers were easily affected by the weather. Ancient Egyptians too built dams on their rivers and the work was commissioned by the Pharaohs.
In India, an intricate water management system was built in Dholavira which had 16 reservoirs, dams and various channels for collecting and storing water.
The Romans too constructed dams on a large scale and were instrumental in introducing new designs to dam construction like the arch gravity dams, arch dams, buttress dams and the multiple arch buttress dams. These dams were constructed all over the Roman Empire around the 2nd century CE and can be found even in modern-day Iran.
In the middle ages, low lying countries like the Netherlands built dams to regulate the water levels of rivers and prevent the sea from entering the marshlands. The present capital of the Netherlands Amsterdam began with a dam on the river Amstel in the late 12th century. These dams often mark the beginning of a city or town because it is easy to cross the river at such a place.
During the Industrial Revolution, many pioneering techniques for dam construction were invented. The British Empire built around 3 arch dams in the early 19th century. The Mir Alam dam was constructed to supply water to the city of Hyderabad and is still in use to this day.
In the modern era, the Hoover Dam is a massive concrete arch gravity dam constructed in the Black Canyon on the Colorado River. The purpose of this dam was to control floods, provide water for irrigation and produce hydroelectricity. This dam was constructed by a consortium of 6 companies who built it 2 years ahead of schedule and handed it over to the US government on 1st March 1936.
After looking at the history of dams and the improvement in technology with each passing era it brings me back to an interesting question – What about the dams in India? Which is the longest and the highest dam in India?
List of Longest dam in India
When I first thought of this question I confess Bakhra Nangal dam came into my mind. But a thorough research proved me wrong. It is the Hirakud dam present in Odisha which is the longest concrete dam in India and is 55 kilometres long. Constructed on the Mahanadi River this dam was the first multipurpose river project of a newly independent India.
The dam forms the biggest artificial lake in India with a reservoir holding 743 square km at full capacity. It has 2 observation towers the Gandhi Minar and the Jawahar Minar that offer extensive views of the lake. It also has 3 canals namely Bargarh Main Canal, Sason Canal and Sambalpur Canal.
The dam contains 2 powerhouses which in turn contain very powerful turbines that generate electricity. The capacity of the powerhouses are 347.5 MW and these powerhouses were built in stages.
The purpose of constructing this dam was to control the water flow of the river Mahanadi. This river has a unique situation where the upper basin of this river located on the plains of Chhattisgarh suffers from periodic droughts and the lower basin of this river suffers from periodic floods.
Hence to counter this problem the dam was constructed. The dam successfully controls the floods in the lower basin of the Mahanadi delta and irrigates 75000 square km of land. It drains an area of land that is twice the area of Sri Lanka and amounts to 133,090 square kms.
This dam also provides an ideal atmosphere for wildlife. The famous Debigarh wildlife is located here and boasts of having special species of migratory birds here. The commonly seen species of birds are common pochard, red-crested pochard, and great crested grebe among several others
So, after learning about this amazing dam built in post Independent India you would be even more amazed by the tallest or highest dam in India. It is the Tehri dam situated in Uttarakhand.
The highest dam in India
The Tehri dam is built on the river Bhagirathi in Uttarakhand and is the highest dam in India. It was finished in 2006 and has a reservoir for irrigation, municipal water supply and the generation of 1,000 megawatts of hydroelectricity. This dam is 260.5m high and is an earth filled embankment.
The power generated by this dam is supplied to Uttar Pradesh, Uttarakhand, Punjab, Delhi, Haryana, Jammu and Kashmir, Chandigarh, Rajasthan and Himachal Pradesh. A supply of 270 million gallons of drinking water per day is generated which is distributed to the industrialised areas of Delhi, Uttar Pradesh and Uttarakhand.
This dam will also be able to afford irrigation to an area of 270,000 hectares and the total expenditure of this project was 1 billion USD. In November 2019 NTPC Limited has taken over the operation of the dam after getting approval from the Government of India. The Tehri dam’s pumped storage scheme is currently under construction and will be completed in 2025. This will further produce 1000 MW of hydropower.
The dams Tehri and Hirakud were built to cater to India’s prosperity and have since generated a lot of economic opportunities including employment. Water stored in these dams is also used for many purposes including industrial use. These dams are constructed keeping longevity in mind and will last for many years to come.
Dams are an architectural marvel that has a long history. They were built on small scales at first and as technology improved large scale dams were built paving way for new and pioneering techniques to come into the picture. Dams have many purposes and are often constructed keeping their multiple functions in mind.
Dams also impact the environment negatively as you would have read several news articles extolling their bad influence on nature. At the end of the day, it’s a balancing act between generating economic opportunities and protecting the environment. With this post, I hope you learnt about dams and confidently say that the Hirakud dam is the longest in India as opposed to Bhakra Nangal as I had thought previously.
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