Mosul Dam

http://www.dailykos.com/story/2016/1/11/1468380/-Worse-Than-Isis-Mosul-dam-foundation-dissolving-Half-a-million-Iraqis-could-die-State-Dept-Warns?detail=facebook
Only a madman would build a dam on a foundation of rock salt. That man would be Saddam Hussein. The dam would be Mosul Dam, Iraq’s largest. The rock salt would be gypsum, a salt of calcium and sulfate which is less soluble than sodium chloride (table salt) but dangerously soluble for the foundation of a dam. Mosul, a city of 2 million people below the dam could be hit by a 66 foot (20 meters) wall of water. The state department warns that half a million people could die and a million left homeless when the dam fails.

Mosul dam has required constant high maintenance since it was built, but occupation by ISIS disrupted the ongoing injection of grout to seal channels continuously forming in the dam’s foundation. Engineers have found extensive evidence of the connection of new channels formed by rock dissolution to ancient natural channels in limestone. The clay that was plugging those ancient channels may be washing away as the water flowing under high pressure erodes it and pushes open the channels. The Mosul dam may be beyond repair.

Engineers have recommended building a new dam below the failing dam to protect the people of Mosul, but time is running out. Dam failure could bring catastrophe beyond comprehension.

Mark and Wheeler and Washington Group Int. [3,13] proposed the following scenario for Mosul dam collapse: The City of Mosul is located about 60 km downstream of Mosul Dam. Analyses indicate that failure of Mosul Dam would produce a flood wave crest about 20 m deep in the City of Mosul. It is estimated that the leading edge of the failure flood wave would arrive in Mosul about 3 hours after failure of the dam, and the crest of the flood wave would arrive in Mosul about 9 hours after failure of the dam. The total population of the City of Mosul is about 3 million, and it is estimated that about 2 million people are in locations within the city that would be inundated by a 20 m deep flood wave. The City of Baghdad is located about 350 km downstream of Mosul Dam, and the dam failure flood wave will arrive after 72 hours to Baghdad and would be about 4 m deep.
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Mosul Dam from below http://mosul-photos.com/picture.php?/421
Plans to repair the dam have been delayed by Iraqi political infighting and the loss of skilled workers. Now, there may not be enough time to make repairs to prevent failure this year. The State department is warning Iraqis to make evacuation plans now because the dam could fail this spring when maximum river flow from snow melt adds pressure to the dam.

In the worst-case scenario, according to State Department officials, an estimated 500,000 people could be killed while more than a million could be rendered homeless if the dam, Iraq’s largest, were to collapse in the spring, when the Tigris is swollen by rain and melting snow. The casualty toll and damage would be much less if Iraqi citizens received adequate warning, if the dam collapsed only partially or if it were breached in the summer or fall, when the water level is lower.
Hundreds of workers working 3 shifts a day 6 days a week were needed to maintain the dam, but ISIS drove those workers away. Many of them never came back. Moreover, ISIS is still in control of the source region for grout to repair the foundation. Meanwhile the rock under the dam continues to dissolve and wash away.

The Islamic State controlled the dam for a little more than a week in August 2014, but its fighters did not damage the structure. After it was retaken later that month, however, many of the Iraqi workers never returned and the Iraqi government did not resume regular maintenance. The Iraqis also lost their usual source of grouting material, which was produced by a factory in Mosul, now under the control of the Islamic State.
Even if the people can be evacuated in time to save half a million lives, a city of 2 million people may be destroyed by a massive flood. Right now there is no alert system in place. The Iraqi government claims to have an evacuation plan, but ISIS controls much of the higher ground below the dam so the plan may be impossible to implement. And Baghdad and millions more people live further downriver. The American embassy could be under 13 feet of water.

The water would continue along the Tigris, which runs by Tikrit and Samarra down to Baghdad, potentially knocking out bridges along the way, according to the administration’s analysis. As the water traveled south, debris, pesticides and corpses would become part of the flow, threatening the country’s supply of clean water and its irrigation system.