Crisis on the Tigris

Last month, the global media plastered their front pages with the startling revelation that, while the world’s eye has focused on the struggle against ISIS in Iraq, a more unexpected crisis has developed that could, if the necessary actions are not taken, lead to the deadliest infrastructure failure in history. The Mosul Dam, a massive levee on the Tigris River, is close to failure, experts and engineers employed there have warned. If it is breached, the reservoir behind it will empty into the Mesopotamian region, sending surges tens of feet high into downriver areas. The cities of Baghdad, Tikrit, and Samarra would be hit by floodwaters, but in worst danger is Mosul itself: projected to be hit by 45 feet of water, the city is occupied by ISIS and its 750,000 inhabitants would be almost impossible to evacuate. The international community is currently scrambling to avert disaster; an international conference on the issue will be held in Rome in April, but the risk of collapse is reported to be growing every day.

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An aerial view of Mosul Dam

Mosul Dam was briefly occupied by the Islamic State for about two weeks in 2014 before being recaptured by Kurdish forces, with the aid of concentrated American air strikes. Pro-government soldiers now occupy the dam, but the workers performing necessary, continuous maintenance did not return. It is easy to point to ISIS as the cause of the current crisis, but in truth the dam’s problems began thirty years ago, when it was constructed under the rule of Saddam Hussein. Various political problems plagued the construction One was that western sanctions enacted during the construction rendered the construction of a smaller failsafe dam further downstream financially infeasible. It was abandoned almost half-completed. Another was that, out of fear that the dam would be sabotaged by insurgents, Hussein ordered its construction to be near his stronghold of Mosul, which, unlike other parts of the Tigris, has a geology dominated by gypsum rock.

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Mosul Dam

Gypsum is a very soft and soluble substance that develops large caverns and cracks when permeated by water. Water fills these fissures to capacity and, when it has no more room to expand, due to its incompressible nature it applies pressure in all directions, including upwards into the dam. Even though the structure is composed of thousands of cubic meters of solid stone, it and its foundation become buoyant, destabilizing the dam. The more water fills the gypsum, the more likely the dam is to disintegrate and unleash its liquid cargo. The constructors of the dam became aware of this problem almost immediately, but the dam’s location considered was more important than its structural integrity. After its completion, the dam was stabilized through the wasteful and cumbersome method of pumping grout into the base- 95000 tonnes of it over the dam’s lifetime.

 

Now, the dam is without workers and the grouting has stopped, so the edifice’s condition has quickly deteriorated. Of course, the need for a solution to the crisis is on every Iraqi’s mind. The government’s call for evacuation is likely to go unheeded by subsistence farmers on the riverbanks. Without urgent international action, repairs on the dam itself- still heavily compromised by the proximity of ISIS- may not go underway.

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Demolition of a dam in Olympic National Park

There are a few other options for the Iraqi government. One, put forth by various high-ranking officials, is to finish construction of the safety dam further downstream, which is in a more secure area. Another is to take steps to gradually let all of the water out of the Mosul reservoir, an action that could be completed by slowly and carefully demolishing the dam. This has been done before on a smaller scale; for example, in order to reclaim land in Washington State’s Olympic National Park, barge-mounted hammers were used to lower a dam several feet at a time and then enlarge the spillways until the river flowed freely. A final and risky option is  to look upstream for assistance. Turkey’s massive Southern Anatolia Project (GAP) has been ongoing for decades and has involved the construction of many dams, some on the Tigris. If Turkish authorities were willing, they could perhaps fill the dams to capacity, weakening the Tigris’s flow in the hopes that the coming dry Iraqi summer would lower the reservoir’s waters.

 

This final option, though an excellent opportunity for much-needed cooperation in the Middle East, relies a lot on chance. For now, residents near the Tigris will have to wait and hope that, despite the country’s resource-draining conflict, the powers that be will make the sacrifices necessary to prevent a complete disaster.

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The dam’s outflow

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