The tallest dams in Iran are the Karun-3 Dam at 205 meters, the Masjed Soleyman Dam at 177 meters, and the Karun-1 (Shahid Abbaspour) Dam at 200 meters – though the exact ranking can shift as new projects are completed. This article lists the five highest dams in the country, explains how their heights are measured, and gives context on why Iran builds such massive structures.
Why Iran Builds Very Tall Dams
Iran is a mountainous, semi-arid country with uneven rainfall. Most rivers flow from the Zagros and Alborz mountain ranges, and the terrain allows for high dams that store large volumes of water for irrigation, drinking water, and hydroelectric power. The steep valleys also make it economical to build tall concrete dams rather than wide earth-fill structures. The Ministry of Energy and regional water authorities plan dams to manage seasonal floods and to supply water to cities and farms in drier lowlands.
The Five Tallest Dams in Iran
Heights are measured from the foundation (lowest point of the dam base) to the crest (top of the dam), not from the riverbed. The following list is based on the most recent official data available, but some projects are under construction or have been recently completed, so the order may change.
- Karun-3 Dam (205 m) – Located on the Karun River in Khuzestan province, this double-curvature concrete arch dam was completed in 2005. It has an installed hydroelectric capacity of about 2,000 MW and is the tallest dam in Iran.
- Karun-1 Dam (Shahid Abbaspour) (200 m) – Also on the Karun River, this concrete arch dam was completed in 1976. It is 200 meters high and was the tallest in Iran for many years.
- Masjed Soleyman Dam (177 m) – Built on the Karun River as well, this rockfill dam with a concrete face was completed in 2002. It is 177 meters high and supports a 2,000 MW power station.
- Khersan-3 Dam (175 m) – A concrete double-curvature arch dam on the Khersan River (a tributary of the Karun) in Chaharmahal and Bakhtiari province. It was completed in 2023 and stands 175 meters tall.
- Dez Dam (203 m) – Wait – the Dez Dam is actually 203 meters high, making it taller than Karun-1, but it is often listed as 203 m. The official height is 203 m, so it should be second. Let me correct the list: the tallest is Karun-3 (205 m), then Dez (203 m), then Karun-1 (200 m), then Masjed Soleyman (177 m), then Khersan-3 (175 m). The Dez Dam, completed in 1963, is a concrete arch dam on the Dez River in Khuzestan. It is a major source of hydroelectric power and irrigation.
How Dam Height Is Measured
Dam height can be defined in several ways: from the lowest foundation level to the crest, from the riverbed to the crest, or from the crest to the maximum water level. The most common standard is the height from the foundation, which gives the tallest numbers. For example, the Dez Dam’s foundation is deep in the bedrock, so its height is 203 m even though the visible dam above the riverbed is about 180 m. When comparing dams, always check which measurement is used.
Concrete Arch vs. Rockfill Dams
Iran has built both concrete arch dams and rockfill dams. Concrete arch dams, like Karun-3 and Dez, are thin and strong because they transfer the water pressure to the canyon walls. They are suitable for narrow, rocky gorges. Rockfill dams, like Masjed Soleyman, are made of compacted earth and rock with a waterproof face. They are cheaper to build with local materials but are usually lower because they need a wider base. The choice depends on the valley shape, geology, and available materials.
Hydroelectric Power and Water Storage
Most of Iran’s tallest dams are multi-purpose. They generate hydroelectricity, store water for irrigation, and control floods. For example, the Karun-3 Dam’s power station produces about 2,000 MW, which helps meet peak electricity demand. The Dez Dam provides water for the sugarcane fields of Khuzestan and also generates power. The reservoirs also support fishing and recreation, though these are secondary uses.
Challenges and Environmental Concerns
Building very tall dams in Iran has faced challenges. The Karun River basin is seismically active, so engineers must design dams to withstand earthquakes. Sedimentation is a major issue: rivers carry large amounts of silt, which gradually fills the reservoir and reduces storage capacity. This is a problem for older dams like Dez, which has lost a significant portion of its capacity. Environmental groups have also raised concerns about the impact on river ecosystems and downstream water quality. In some cases, dam construction has required relocating villages and has affected archaeological sites.
Frequently Asked Questions
What is the tallest dam in Iran?
The tallest dam in Iran is the Karun-3 Dam, with a height of 205 meters from its foundation to the crest. It is located on the Karun River in Khuzestan province.
Is the Dez Dam taller than the Karun-3 Dam?
No, the Dez Dam is 203 meters tall, which is slightly shorter than Karun-3 at 205 meters. However, some older sources list Dez as 203 m, and it is the second tallest.
Why does Iran build such tall dams?
Iran needs to store water for agriculture and drinking, generate hydroelectric power, and control floods. The mountainous terrain allows for high dams that can hold large volumes of water in narrow valleys.
Are there any dams in Iran taller than 200 meters?
Yes, two dams are over 200 meters: Karun-3 (205 m) and Dez (203 m). Karun-1 is exactly 200 meters. Khersan-3 is 175 meters, and Masjed Soleyman is 177 meters.
What is the difference between a concrete arch dam and a rockfill dam?
A concrete arch dam is a curved structure that transfers water pressure to the canyon walls, making it thin and strong. A rockfill dam is made of compacted rock and earth with a waterproof membrane, and it is usually wider and lower. Iran uses both types depending on the site.
How long does it take to build a dam like Karun-3?
Construction of Karun-3 began in 1993 and was completed in 2005, taking about 12 years. Large dams often take a decade or more because of the extensive planning, excavation, and concrete pouring involved.
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