Dams are one of the greatest engineering feats of humankind. They supply power, water for irrigation, potable water and flood control to millions of people. But others are so large, so distant or with such an interesting past that they evoke fear as well as reverence. These huge structures, standing hundreds of meters high over river valleys, containing billions of cubic meters of water, are impressive both for their human achievement and the power of nature.

Some have been the scene of disastrous events in their history, and others may be located in areas where earthquakes are a possibility, or in locations that must be continually monitored for safety. These are the top 10 scariest dams in the world, in some cases due to their size, in other cases due to their history and in some due to their stunning locations.

Three Gorges Dam, China

The Three Gorges Dam is the world’s biggest hydroelectric power station by installed capacity, and is among the largest engineering structures ever built. It spans over 2.3 kilometers (1.4 miles) of the Yangtze River and is about 185 meters (607 feet) tall, and supports a massive reservoir.

It’s big, so it’s interesting and frightening. The dam holds billions of cubic meters of water and a major structural failure would have dire consequences downstream. While it is highly improbable in this day and age due to advances in engineering and continuous monitoring, its massive size makes it a spot on the list of the world’s scariest dams.

The dam is not only of engineering importance but has also been a subject of controversy due to ecological alterations, landslides, and the displacement of more than one million people during its construction.

Vajont Dam, Italy

The Vajont Dam has one of the most heart-wrenching of any dams in the world. It was finished in 1960 and was once thought to be an engineering masterpiece, standing 262 meters (860 feet) above a narrow gorge.

A big landslide fell into the reservoir in October 1963. This wave surged the dam causing almost 2,000 deaths in villages downstream.

The dam itself, amazingly, was not damaged. The disaster showed that although well designed buildings can stand up, they can be destroyed by geological events. The concrete wall is now silent, silently witnessing one of the most devastating events in dam history today.

Hoover Dam, United States

The Hoover Dam was constructed during the time of the Great Depression and is still one of the most famous engineering achievements in the United States.

It is 221 meters (721 feet) above the Colorado River, creating Lake Mead, one of the largest reservoirs in the United States. From the top of the dam, one might find him or herself feeling the weight of being high above Black Canyon.

Hoover Dam is one of the most imposing dams in the world with its huge curved concrete wall, steep cliffs and massive spillways.

Oroville Dam, United States

The tallest dam in the United States is the Oroville Dam in California, which stands about 235 meters (770 feet) tall.

The awful reputation of its damage to the spillway due to heavy rainfall in 2017 has been increasing its reputation. Authorities said they would have to evacuate almost 190,000 people if the emergency spillway failed and released floodwaters.

Even though the disaster was averted by emergency repairs, the incident highlighted how infrastructure failures can escalate to a public safety emergency in no time.

Mosul Dam, Iraq

This dam is one of the most closely-watched dams in the world due to an unusual foundation.

The foundation is built on soluble gypsum rock and continuous grouting and maintenance work must be done to bring up new cavities in the foundation. For decades, engineers have been endeavoring to stabilize the structure and to greatly minimize risk.

It sits on a geologically difficult site, and despite many improvements, it has gotten a bad reputation for being one of the most problematic engineering projects in the world.

Kariba Dam, Zambia and Zimbabwe

The Kariba Dam is a large dam built across the Zambezi River in Africa to form one of the world’s largest man-made lakes.

It is 128m (420ft) tall and provides power to Zambia and Zimbabwe. The riverbed below the spillway has been eroded over the years, however, and extensive river rehabilitation projects are underway.

It’s huge reservoir and continued construction of its structure makes it one of the most fearsome dams in Africa.

Xiaowan Dam, China

The Xiaowan Dam is one of the tallest dams in the world, standing almost 292 meters (958 feet) above the Mekong River.

The dam is located between the steep mountains in Yunnan Province and its height is truly stunning. Whether one gazes upward from the river below or downward from the crest, the magnitude of forces that are required to retain this immense mass of water is appreciated.

The dramatic landscape only enhances its imposing appearance.

Glen Canyon Dam, United States

The Glen Canyon Dam is located in the Colorado River in Arizona, 216 m (710 ft) high.

It was constructed in the midst of a huge red rock canyon, forming the spectacular Lake Powell reservoir.

The dam is very safe, but the sheer size and steep side of the canyon and the size of the spillways make it look almost like a movie set. The sound of the water through the spillway, during periods of heavy water release, is a truly memorable and somewhat scary experience.

Daniel-Johnson Dam, Canada

The Daniel-Johnson Dam is not on this list of dams, but it is located in Quebec.

It is not a single wall, but a multiple-arch buttress wall more than 1.3 kilometers (0.8 miles) long. It is a unique architecture, like a fortress of the future emerging out from the wilderness.

The length of the structure, and its unusual appearance, make it one of the most impressive and intimidating dams ever built.

Mica Dam, Canada

Mica Dam is a world’s largest earthfill dam located in the rugged mountains of British Columbia.

It is located in a remote area, with the dense forests and high mountains, giving it a sense of isolation that is uncommon to large engineering structures.

The dam, which is supported by a massive earthen wall, holds back a vast amount of water, which can be seen extending into the surrounding valleys. The reservoir behind the dam is massive, stretching for miles into the surrounding valleys, and is supported by a thick earthen wall.

Why Are Some Dams So Frightening

These engineering giants have a bad rap for a number of reasons.

• Massive Height: The world’s tallest dams are often over 200m tall and rise above valleys, like man-made cliffs.
• Enormous Water Pressure: The force behind each large dam is enormous, and the pressure of water in the back of each dam is huge every second.
• Dramatic Landscapes: Many of the dams sit in narrow gorges in mountain terrain or deep canyons, which accentuates the impressive nature of the structures.
• Historical Disasters: Natural disasters and engineering problems can create significant problems, such as the tragedy of Vajont or the Oroville spillway issue.
• Engineering Complexity: These modern dams must be monitored continuously with sensors, inspections, and maintenance to assure long-term safety.

Conclusion

Today’s most fearsome dams are not necessarily bad dams, but dams built to be revered for their massive size, astounding engineering and the power they harness from nature. The Hoover Dam, Vajont Dam, the Three Gorges Dam and the Xiaowan Dam are examples of human-made dams that have changed the landscape; and the lessons learned from Vajont Dam clearly show the importance of geology and nature in addition to engineering.

Though highly frightening to the eye and having dramatic stories, these dams play important roles in the production of renewable energy, flood control and access to water for millions of people. They are a testament to human ingenuity, a source of awe and admiration, and a reason for respect to human achievement.