Tarbela Dam

A giant wall holds back the Indus River.

This wall is in Pakistan. It is the biggest wall of its kind in the world. It makes a very large lake.

The water in the lake helps in many ways. It can help farms grow food. It can also make power for homes.

Moving water turns big machines to make this power.

The dam was finished in 1976. It is a very important place for the land.

The Tarbela Dam is a giant wall in Pakistan.

It is built on the Indus River. It is the largest earth-filled dam in the world. This means it is made of earth and rock. The dam holds back water to make a big lake. This lake is called Tarbela Lake.

The dam helps people in many ways. It stores water for farms to use. It also helps control floods. Most importantly, it makes electricity. This is called hydroelectric power. Moving water flows through tunnels to turn machines called turbines. These machines make power for homes and cities.

The dam was finished in 1976. It uses five large tunnels to move water. Four tunnels make power. The fifth tunnel helps with farming. New projects will make the dam even better. These plans will help make more electricity. The dam is a very important part of life in Pakistan. It helps provide water and power for many people.

The Tarbela Dam is a massive structure in Pakistan.

It sits on the Indus River in the Khyber Pakhtunkhwa province. This dam is the largest earth-filled dam on Earth. It is built using earth and rock fill. The dam is very high above the riverbed. Behind the wall, a huge lake called Tarbela Lake forms. This lake has a surface area of about 350 square kilometers. The dam is located where the river leaves the Himalayan foothills. It is near the town of Topi.

The dam works in several important ways. It captures water from monsoon flows. It then releases that water during the dry winter months. This helps with irrigation for farms. It also helps with flood control. Most importantly, it makes hydroelectric power. This is electricity made from moving water. Water flows through large tunnels to reach turbines. These turbines turn to create power. Currently, four tunnels are used for electricity. The fifth tunnel is used for irrigation.

Building the dam was a huge job. It was part of the Indus Basin Project. This project followed the 1960 Indus Waters Treaty. This treaty was signed between India and Pakistan. The dam was built to replace water lost from other rivers. An Italian firm called Salini Impregilo did the work. Construction happened in three main stages. The first stage took about two and a half years. The second stage took three years. The final stage was finished in 1976.

There are many important numbers to know about Tarbela. The dam has a storage capacity of 11.9 billion cubic meters. The power stations can make 4,888 MW of electricity. This will grow to 6,418 MW after a fifth extension. The reservoir receives water from snow and glacier melt. It also gets water from the Shyok and Siran rivers. During construction, a mishap happened in 1974. Damage to the tunnels caused delays. This cost the country a lot of money. Many people had to move because of the lake. About 96,000 people were displaced from 135 villages.

Even though the dam is old, it is still growing. New projects like the Tarbela-IV Extension are finished. This project used Tunnel 4 to add more power. A fifth extension is also planned for Tunnel 5. This will add about 1,800 GWh of power each year. The work on this part began in August 2021. It should be done by December 2026. The dam might last until the year 2060. This is because the sediment buildup is slower than expected.

The Tarbela Dam is a massive earth-filled dam located on the Indus River. It sits in Pakistan's Khyber Pakhtunkhwa province, specifically near the town of Topi. This structure is the largest earth-filled dam in the entire world. It serves as a vital tool for managing the river's resources. The dam helps provide water for irrigation and helps with flood control. Most importantly, it is used for hydroelectric power generation.

The dam functions by capturing water from monsoon flows. It stores this water in a large reservoir called Tarbela Lake. The reservoir has a surface area of approximately 350 square kilometers. During the low-flow winter period, the dam releases this stored water. This ensures a steady supply for farms and power plants. The average annual flow available to the dam is 101 billion cubic meters. This equates to a flow of 3,221 cubic meters per second. The reservoir has a total storage capacity of 11.9 billion cubic meters.

To generate electricity, the dam uses a system of large tunnels. Five large tunnels were constructed as part of the outlet works. Currently, hydroelectricity is generated from turbines located in tunnels 1 through 4. Tunnel 5 is used for irrigation purposes. However, plans exist to convert tunnel 5 to hydropower use as well. The main dam wall is built of earth and rock fill. A pair of concrete auxiliary dams spans the river from an island to the river left. The dam also features two spillways to manage excess water.

Power generation happens within the MA hydroelectric power plant on the right side of the main dam. This plant houses 17 generators that are fed by tunnels 1, 2, and 3. The capacity varies depending on which tunnel is used. Tunnel 1 has four 175 MW generators. Tunnel 2 has six 175 MW generators. Tunnel 3 uses four 432 MW generators. Tunnel 4 uses three 470 MW generators. These combined units provide a total current capacity of 4,888 MW.

The construction of the dam was a major historical undertaking. It was part of the Indus Basin Project following the 1960 Indus Waters Treaty. This treaty was signed between India and Pakistan. The dam was built to compensate for the loss of water from the eastern rivers. These rivers include the Ravi, Sutlej, and Beas. An Italian firm named Salini Impregilo carried out the construction. The work was completed in 1976 after three distinct stages.

Construction moved through three carefully planned stages to manage the river. In Stage 1, the Indus River flowed in its natural channel. Workers excavated a wide diversion channel and built a high buttress dam. This stage lasted about two and a half years. In Stage 2, the main embankment dam and upstream blanket were built. This stage took 3 years to complete. In Stage 3, the diversion channel was closed. The river was then directed through the diversion tunnels. The final works were concluded in 1976.

Building the dam caused significant changes to the local area. The reservoir submerged 135 villages. This resulted in the displacement of about 96,000 people. Many people were relocated to townships near the reservoir or in higher valleys. The project also faced a serious mishap in 1974–75. Damage to the tunnels during the initial filling prevented the planned impoundment of water. This caused economic costs and delayed power generation. It also led to a lower agricultural output for the country.

Despite these challenges, the dam continues to expand through new projects. The Tarbela-IV Extension Project was completed in February 2018. This project used Tunnel 4 to add 1,410 MW of capacity. A fifth extension project is also underway. This project involves Tunnel 5 and aims to generate 1,800 GWh of power annually. Construction on this phase began in August 2021. It is expected to be finished by December 2026. Once finished, the total capacity will reach 6,418 MW. This will make it the 12th largest hydroelectric dam in the world for electricity production.