HOOVER DAM: DAM THAT TAMED COLORADO RIVER

The Hoover dam was developed towards the end of the Great Depression in the US to tame the Colorado River and transform the south-western part of the country. More than 80 years after its construction, it still attracts a million tourists every year, who are astonished at the engineering feat

Words: N B Rao

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This morning I came, I saw, and I was conquered, as everyone would be who sees for the first time this great feat of mankind. . . .Ten years ago the place where we gathered was an unpeopled, forbidding desert.

In the bottom of the gloomy canyon whose precipitous walls rose to height of more than a thousand feet, flowed a turbulent, dangerous river. . . . The site of Boulder City was a cactus-covered waste. And the transformation wrought here in these years is a 20th century marvel.”

WHEN American President Franklin D. Roosevelt spoke at the inauguration of the Hoover dam (then known as the Boulder dam), on September 30, 1935,

the US was just emerging from the Great Depression that began in 1929 and continued for another four years.Considered an engineering wonder more than 80 years ago when it was built, the dam was then the most expensive project on a river and the highest dam that was developed.

Besides being an engineering wonder, the dam is today also seen as a work of art.

Julian Rhinehart, a writer, a regional public affairs officer in Boulder City, had written about the ‘engineering superlatives’ of the dam.

“Few structures in America display the diversity of design and craftsmanship that you see at Hoover Dam,” he wrote on the 60th anniversary of the dam.

“It is a showcase of seldom-seen skills of artists and artisans – beautifully presented terrazzo tiles, sculpture, metalwork, and even military emplacements.

”According to James C. Maxon, another writer on the dam, who retired from government service after a career with the National Park Service and the Bureau of Reclamation, the impossible became reality with the completion of Hoover dam in 1935.

“This dam became the symbol of man’s ability to harness nature, even an element as ancient and powerful…as the Colorado River,” he wrote in his book, ‘Lake Mead & Hoover Dam – The story behind the scenery.’

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According to James C. Maxon, another writer on the dam, who retired from government service after a career with the National Park Service and the Bureau of Reclamation, the impossible became reality with the completion of Hoover dam in 1935.

“This dam became the symbol of man’s ability to harness nature, even an element as ancient and powerful…as the Colorado River,” he wrote in his book, ‘Lake Mead & Hoover Dam – The story behind the scenery.’

James notes that one of the most incredible statistics of all was the time it took to complete the massive project – less than five years to accomplish an engineering feat that would astound the world.

The first generator began operations in October 1936 and the 17th one went into operations in 1961.

Hoover is 660 ft at its base and rises 726 ft above the bedrock. It stretches nearly 1,250 ft across the Black Canyon.

The dam is built on the Colorado River, which ensures irrigation facility to a million acres of land in the US and half a million acres in Mexico. The water needs of nearly 15 million people are met by the river.

Hoover meets the energy needs of half a million homes annually in Nevada, Arizona and California.

TYPES OF DAMS

THEY are classified under various categories including those built based on their purpose, structural behaviour, hydraulic design and construction material.

There are five types of dams that are built based on purpose: storage or impounding dam, detention dam, diversion dam, coffer dam and debris dam. The storage dam is built to create a reservoir to store water when there is a huge flow and to be used later when there is a shortfall.

The detention variety is built to temporarily detain flood waters in a river. The diversion dam sends water from a river into a conduit or a channel. Coffers are temporary dams built to exclude water from a specific area, and the debris dam is built to prevent debris from entering a river.

Those built on structural behaviour include gravity, arch, buttress, embankment and gravity dams. While gravity dams are classified as solid or hollow, they are generally made of concrete or masonry. Stability in arch dams is through a combination of arch and gravity.

Hoover dam is the largest concrete arch-gravity dam in the western hemisphere, weighing about 6.5 million tons.

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INDIA’S LARGE DAMS

A LARGE dam is one that is more than 15 m high (taller than a four-storeyed building) from its deepest foundation to the crest. Giant (or major dams) are those that are at least 150 m high.

There are nearly 60,000 large dams worldwide and more than 300 major dams. China has over 23,000 large dams, the US about 9,200 and India around 5,200 large dams.

Maharashtra tops the list with about 1,850 large dams, followed by Madhya Pradesh (900), Gujarat (630), Chhattisgarh (260), Karnataka (230), Rajasthan (210) and Odisha (200).

The country’s tallest dam is the Tehri, which is 260.5 m high. It is the world’s 10th tallest dam. China has the tallest dam – Jinping-I, which is 305 m high – and also accounts for four of the 10 tallest dams in the world.

Bhakra Nangal in Himachal Pradesh, with a height of 225 m, is the largest dam in India and the second-largest in Asia. Hirakud in Odisha, which is 26 km long, is one of the longest dams in the world.

Nagarjuna Sagar dam in Andhra Pradesh is the world’s largest masonry dam and also hosts the largest manmade lake in the world. Other large dams in India include Lakhwar (204 m) in Uttarakhand (204 m), Idukki (169 m) in Kerala, Pakal Dul (167 m) in Jammu & Kashmir and Sardar Sarovar (163 m) in Gujarat.