Mosul Dam (), formerly known as Saddam Dam (), is the largest

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...

. It is located on the

Tigris The Tigris ( ; see #Etymology, below) is the eastern of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Armenian Highlands through the Syrian Desert, Syrian and Arabia ...

river in the western governorate of

Nineveh Nineveh ( ; , ''URUNI.NU.A, Ninua''; , ''Nīnəwē''; , ''Nīnawā''; , ''Nīnwē''), was an ancient Assyrian city of Upper Mesopotamia, located in the modern-day city of Mosul (itself built out of the Assyrian town of Mepsila) in northern ...

, upstream of the city of

Mosul Mosul ( ; , , ; ; ; ) is a major city in northern Iraq, serving as the capital of Nineveh Governorate. It is the second largest city in Iraq overall after the capital Baghdad. Situated on the banks of Tigris, the city encloses the ruins of the ...

. The dam serves to generate hydroelectricity and provide water for downstream irrigation. At full capacity, the structure holds about of water and provides electricity to the 1.7 million residents of Mosul. The dam's main power station contains four

Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The pro ...

–generators. A

pumped-storage hydroelectricity Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing (electrical power), load balancing. A PSH system stores energy i ...

power plant with a capacity of and a

run-of-the-river Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amou ...

dam downstream with a capacity also belong to the Mosul Dam scheme. It is the fourth largest dam in the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

, as measured by reserve capacity, capturing snowmelt from

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

, some north. Built in the 1980s on a

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

foundation, concerns over the dam's instability have led to major remediation and rehabilitation efforts since the 2003 U.S. invasion of Iraq.

Characteristics

The Mosul Dam is a tall and long earth-fill embankment type with a clay core. The width of the crest is . At an elevation of above sea level, the reservoir, named Lake Dahuk, withholds of water. Of that capacity is active (or useful for power and downstream releases) and is inactive (dead) storage. On the east side of the dam is the service

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

which is controlled by five radial gates and has a maximum discharge capacity of . Further to the east is a fuse-plug-controlled emergency spillway with a capacity. At the toe of the dam on its west side is the main hydroelectric power station (Mosul 1). It contains four

generators for an installed capacity of 750 MW. Behind the power station are four surge tanks. Downstream of the dam is the Mosul regulation dam, which serves to regulate the tail-waters of the main dam and to generate electricity as well. The hydroelectric plant (Mosul 2) has an installed capacity of 62 MW with four 15.5 MW Kaplan turbine generators. Immediately upstream of the dam is the 240 MW

pumped storage Pumping may refer to: * The operation of a pump, for moving a liquid from one location to another **The use of a breast pump A breast pump is a mechanical device that Lactation, lactating women use to milking, extract milk from their breasts. They ...

power station (Mosul 3). It serves as a peaking power station by pumping water to small reservoir above Lake Dahuk, storing it, then releasing the water back down to two 120 MW reversible Francis turbines during peak energy usage. The entire Mosul multi-purpose project has an installed capacity of 1,052 MW.

History

Before the dam

To ensure as many of the archeological sites were inspected before being submerged under the lake that would form behind the dam, the Iraqi government invited several foreign delegations to participate. This rescue operation included the British Archaeological Expedition to Iraq as a prominent participant. In 1985, one of their sites, Tell Deir Situn garnered an Assyrian fibula, some Hellenic oil lamps, and a

Seleucid The Seleucid Empire ( ) was a Greek state in West Asia during the Hellenistic period. It was founded in 312 BC by the Macedonian general Seleucus I Nicator, following the division of the Macedonian Empire founded by Alexander the Great, a ...

coin of

Alexander Balas Alexander I Theopator Euergetes, surnamed Balas (), was the ruler of the Seleucid Empire from 150 BC to August 145 BC. Picked from obscurity and supported by the neighboring Roman-allied Kingdom of Pergamon, Alexander landed in Phoenicia in 1 ...

. In 2010, following a massive drought, the ruins of an ancient palace were discovered in the reservoir. The palace, which is approximately 3,400 years old, is believed to have belonged to the

Mitanni Mitanni (–1260 BC), earlier called Ḫabigalbat in old Babylonian texts, ; Hanigalbat or Hani-Rabbat in Assyrian records, or in Ancient Egypt, Egyptian texts, was a Hurrian language, Hurrian-speaking state in northern Syria (region), Syria an ...

. The first excavation occurred in 2019 by a joint Kurdish-German team. The ruins include a terrace of mud bricks, walls two meters high and two meters thick, wall paintings, and ten clay tablets covered in

cuneiform Cuneiform is a Logogram, logo-Syllabary, syllabic writing system that was used to write several languages of the Ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. Cuneiform script ...

Planning

Development of Iraq's rivers progressed rapidly in the mid-20th century as Saddam Hussain sought to control water resources for agriculture and to prevent flooding in

Baghdad Baghdad ( or ; , ) is the capital and List of largest cities of Iraq, largest city of Iraq, located along the Tigris in the central part of the country. With a population exceeding 7 million, it ranks among the List of largest cities in the A ...

. Planning for the Mosul Dam began in the 1950s with the help of Sir Alexander Gibb & Partners, a British firm who identified a location in 1953. In 1956, the Iraq Development Council contracted Koljian American to carry out studies for an irrigation dam at the location. The studies were completed the next year when Iraq asked the Harza Company to carry out a similar investigation who recommended a different location in 1960, based on

foundations for two other recommended locations. In 1962, Iraq sought a third opinion from the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

Technoprom Export company who recommended a separate site. A fourth company, a Finland firm, Imatran Voima carried out a study in 1965 and a fifth company, Geotehnika of Yugoslavia, carried out studies in 1972. Based on the findings of all five companies which cited complex foundations, Iraq had a French firm, Soletanch, to carry out in-depth geological studies which occurred between 1974 and 1978. In 1978, the Swiss Consultants Consortium became the official consultants for the dam.

Construction

During

Saddam Hussein Saddam Hussein (28 April 1937 – 30 December 2006) was an Iraqi politician and revolutionary who served as the fifth president of Iraq from 1979 until Saddam Hussein statue destruction, his overthrow in 2003 during the 2003 invasion of Ira ...

's rule, the construction of the Mosul Dam began in 1981 by a GermanItalian consortium that was led by

Hochtief Hochtief AG is a global provider of infrastructure technology and construction services, with locations in North America, Australia, and Europe. The Essen based company is primarily active in the fields of high tech, energy transition, and sustai ...

Aktiengesellschaft. Because the dam was constructed on a foundation of soluble

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

, the engineers recommended thorough grouting within the foundation before the superstructure was built. Instead, to speed construction of the dam, engineers blanket-grouted deep around the foundation and a curtain directly below the dam. A grouting gallery that would allow continuous grouting of the dam's foundation in order to promote stability was also installed. Construction was complete in 1984 and in the spring of 1985, the Mosul Dam began to inundate the

Tigris River The Tigris ( ; see below) is the eastern of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of the Armenian Highlands through the Syrian and Arabian Deserts, before merging ...

, filling the reservoir which submerged many archaeological sites in the region. The power station began generating power on 7 July 1986. Because of significant structural stability issues associated with the Mosul Dam, ongoing grouting and additional construction and repairs are necessary. In 1988, Iraq began construction on the Badush Dam downstream which would serve the primary purpose of absorbing and releasing a Mosul Dam flood wave in the event of a breach. Works were halted in 1991 though due chiefly to UN sanctions.

Demolition concerns during the 2003 invasion

In early April 2003, following the

invasion of Iraq An invasion is a military offensive of combatants of one geopolitical entity, usually in large numbers, entering territory controlled by another similar entity, often involving acts of aggression. Generally, invasions have objectives ...

by a US-led coalition, military intelligence had developed several scenarios, including one in which Iraqi forces would have wired the dam for detonation. This would release the wall of water, to reach Mosul in about two hours. Subsequent investigation found nearly 500 dam workers to still be at work nearly a month after pay had stopped being distributed.

2014 takeover of dam by the Islamic State

For several weeks in July and August 2014,

Islamic State of Iraq and the Levant The Islamic State (IS), also known as the Islamic State of Iraq and the Levant (ISIL), the Islamic State of Iraq and Syria (ISIS) and Daesh, is a transnational Salafi jihadist organization and unrecognized quasi-state. IS occupied signi ...

(ISIS or ISIL) held Mosul Dam. On August 7, 2014, the organization captured the dam complex from the

Peshmerga The Peshmerga () are the internal security forces of Kurdistan Region. According to the Constitution of Iraq, regional governments are responsible for "the establishment and organization of the internal security forces for the region such as p ...

. ISIS's control of the dam created fears that its power supply could be restricted or that its water flows to downstream areas would be greatly inhibited. In a less likely scenario, there were worries the dam could be breached, causing widespread flooding and destruction downstream. On August 17, 2014, the Peshmerga and the Iraqi Army launched a successful operation to retake control of the dam from ISIS militants.

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

airstrikes assisted the Kurdish and Iraqi military, damaging or destroying 19 vehicles belonging to ISIS, as well as striking an ISIS checkpoint near the dam.

Instability and remediation

The earthen

embankment dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface ...

is located on top of

, a soft mineral that dissolves in contact with water. Continuous maintenance is required to plug, or "

grout Grout is a dense substance that flows like a liquid yet hardens upon application, often used to fill gaps or to function as reinforcement in existing structures. Grout is generally a mixture of water, cement, and sand, and is frequently employe ...

", new leaks with a liquefied slurry of cement and other additives. More than of material have been injected into the dam since leaks began forming shortly after the reservoir was filled in 1986, and 24 machines currently continuously pump grout into the dam base. Between 1992 and 1998 four sinkholes formed downstream of the dam and a fifth sinkhole developed east of the dam in February 2003 that was filled several times. In August 2005 another sinkhole developed to the east. Mosul Dam sinkhole

A September 2006 report by the

United States Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wo ...

noted, "In terms of internal erosion potential of the foundation, Mosul Dam is the most dangerous dam in the world." The report further outlined a worst-case scenario, in which a sudden collapse of the dam would flood Mosul under of water and

, a city of 7 million, to , with an estimated death toll of 500,000."Iraqi Dam Seen In Danger of Deadly Collapse"
by Amit R. Paley, ''

The Washington Post ''The Washington Post'', locally known as ''The'' ''Post'' and, informally, ''WaPo'' or ''WP'', is an American daily newspaper published in Washington, D.C., the national capital. It is the most widely circulated newspaper in the Washington m ...

'', October 30, 2007 A report on 30 October 2007 by the US Special Inspector General for Iraq Reconstruction (SIGIR) said that the dam's foundations could give way at any moment."Iraq dismisses Mosul Dam warnings"
BBC news, October 31, 2007 According to ''

The Economist ''The Economist'' is a British newspaper published weekly in printed magazine format and daily on Electronic publishing, digital platforms. It publishes stories on topics that include economics, business, geopolitics, technology and culture. M ...

'', "One study says that if the dam collapses, Mosul would be submerged within hours. Another warns that half a million Iraqis could be killed by floodwaters, and more than a million forced from their homes. Disease and looting as the floodwaters raced through

Baiji The baiji (''Lipotes vexillifer'') is a probably extinct species of freshwater dolphin native to the Yangtze river system in China. It is thought to be the first dolphin species driven to extinction due to the impact of humans. This dolphin is ...

Tikrit Tikrit ( ) is a city in Iraq, located northwest of Baghdad and southeast of Mosul on the Tigris River. It is the administrative center of the Saladin Governorate. In 2012, it had a population of approximately 160,000. Originally created as a f ...

Samarra Samarra (, ') is a city in Iraq. It stands on the east bank of the Tigris in the Saladin Governorate, north of Baghdad. The modern city of Samarra was founded in 836 by the Abbasid caliph al-Mu'tasim as a new administrative capital and mi ...

, and even parts of

would complete that dreadful scenario." Nadhir al-Ansari, an engineer involved in the building of the dam who is currently Professor of Engineering at the

Luleå University of Technology Luleå University of Technology is a Public university, public research university in Norrbotten County, Sweden. The university has four campuses located in the Arctic, Arctic Region in the cities of Luleå, Kiruna, Skellefteå, and Piteå. With ...

, Sweden, said that the floodwaters would take four hours to reach Mosul and 45 hours to reach Baghdad, and that more than a million people would be killed if a "good evacuation plan" were not in place. In 2004, dam manager Abdulkhalik Thanoon Ayoub ordered the dam's water level, which can reach above sea level, to have a maximum of , thus reducing the pressure on the structure. Nevertheless, Iraqi officials maintain that the U.S. government is overstating the risk. The Army Corps of Engineers has proposed that the Badush Dam downstream be completed to serve its purpose of obstructing the large wave that would result if the Mosul Dam collapsed. This has been resisted by Iraqi officials, who note that the current plan for the Badush Dam is US$300 million to provide hydroelectric power and help irrigation while the proposed expansion would cost $10 billion. In 2007, the

U.S. Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wor ...

developed and executed a US$27 million plan to help continue maintenance and repairs on the dam in the short-term. The Iraq Government was also recommended a long-term solution that includes the construction of walls around the dam foundation. The project would cost $4 billion and take approximately four to five years to complete.

Renewed stability concerns

Maintenance had been deferred during the Battle for Mosul Dam due to security concerns, and many workers did not work both because of the risk of attacks by ISIS and lack of pay. Half of the workers who worked at the dam have quit because they had not been paid for more than five months, and budget shortfalls and political infighting between the Kurdish regional government and the central government of Iraq have made it difficult to hire new workers. Together these factors have made Mosul Dam the "most dangerous dam in the world", because there are "almost certainly an unprecedented level of untreated voids in the dam's foundation." Growing instability concerns due to the previous control of the dam by ISIL, and poor security led the Iraq government to award a €273 million contract to the Italian company Trevi S.p.A. in 2016 to grout and stabilize the dam’s foundation and to rehabilitate other key infrastructure on the dam. In July 2018, a contract extension was negotiated for an additional €89 million for a total contract amount of €363 million ($408M). The contract covers repairs to the dam and the Italian government plans to send 450 additional troops to provide security at the dam site. In January 2016, U.S. General Sean MacFarland warned that the dam might undergo a "catastrophic" collapse. He added, "What we do know is this—if this dam were in the United States, we would have drained the lake behind it." Maintenance had suffered as ISIL had removed equipment and chased technicians away in August 2014, and the grouting schedule had not been maintained. He indicated that contingency plans are in the works to protect people downstream in case of a collapse. Some Iraqi officials continued to dismiss claims of a potential failure. In February 2016, the Minister of Water Resources, Muhsin al-Shammari, stated "The looming danger to Mosul dam is one in a thousand. This risk level is present in all the world's dams." In February 2016, the United States Embassy in Iraq warned of a "serious and unprecedented" danger of the dam collapsing and suggested that plans for evacuation should be made, as the cities

, and

could be at risk in the event of collapse, and that up to 1.5 million people could be killed in the ensuing flash floods. The

Prime Minister of Iraq The prime minister of the Republic of Iraq is the head of government of Iraq and the commander-in-chief of the Iraqi Armed Forces. On 27 October 2022, Mohammed Shia' Al Sudani became the incumbent prime minister. History The prime minist ...

, Haider al-Abadi, repeated these concerns, and called for citizens in Mosul to evacuate and move at least 3.5 miles away from the river, a proposal that was criticized by Professor al-Ansari: "What are all these people, millions of people, supposed to do when they get 6 km away? There is no support for them there. Nothing to help them live." On February 29, a Trevi spokesman said that the contract had still not been signed. There were concerns that the dam could collapse before the repair works begin. On March 2, 2016, the Iraqi government announced that the contract with Trevi was finalized and signed. A team of Italian specialists from Trevi arrived on April 14 to set up camp for the group of engineers who are expected to arrive within a few weeks. Italian Defence Minister Roberta Pinotti met Iraqi Prime Minister Haider al-Abadi on May 9 to discuss logistics for deploying 450 troops near the frontline with ISIL to protect the workers carrying out repairs on the dam. Trevi started working on the dam in September 2016. The repairs were started in October 2016. In May 2017, Iraqi Minister of Water Resources Hassan Janabi stated that no danger to the dam remained and it was going back to normal operation. Carlo Crippa, the project manager, said the dam structure now showed no significant signs of distress. However, constant maintenance will be necessary, as "the rocks of the foundations are prone to dissolution due to the circulation of water." Five waterways that controlled the flow of water into the dam became operational after 12 years, with Janabi saying the water level was at the highest level since 2005. The repairs were completed by 2019. In 2022 the scheme was awarded the Outstanding Project Award by the Deep Foundations Institute.

Notes and references

External links

*
Database of archaeological sites flooded by the dam's construction
{{Authority control Dams in Iraq Dams on the Tigris River Buildings and structures in Mosul Earth-filled dams Geography of Iraq Hydroelectric power stations in Iraq Pumped-storage hydroelectric power stations Reservoirs in Iraq Dams completed in 1986 Energy infrastructure completed in 1985 Energy infrastructure completed in 1986 Energy infrastructure completed in 1989 1986 establishments in Iraq 1980s in Iraq 20th century in Mosul