30 October 2007

Iraq's Water Crisis, Part 2: Mosul Dam

Primary Sources:
5 May 2003: Engineering News-Record
Iraqi Dam Has Experts On Edge Until Inspection Eases Fears
9 September 2005: US Army Corps of Engineers, Gulf Region Division
Mosul Dam Repairs Benefit Tigris Basins
11 September 2005: PortAl Iraq
Mosul Dam repairs progress with safety, electricity, irrigation for Tigris Basins
September 2007: US Army Corps of Engineers, Engineer Research and Development Center
Geologic Conceptual Model of Mosul Dam (pdf)
September 2007: US Army Corps of Engineers, Engineer Research and Development Center
Geologic Setting of Mosul Dam and its Engineering Implications (pdf)
30 October 2007: US Special Inspector General for Iraq Reconstruction
October 2007 Report to Congress
30 October 2007: Bloomberg.com
Project to Reinforce Iraq's Largest Dam Mismanaged, Audit Says
30 October 2007: New York Times
Lack of Security Limits Iraq's Recovery
30 October 2007: Washington Post
Iraqi Dam Seen In Danger of Deadly Collapse
You may need Acrobat Reader for some of the links above. Additional sources include Wikipedia and specific links provided below.

The largest dam in Iraq was completed in 1983, under Saddam Hussein's regime and thus named the "Saddam Dam" until 2003, about 50 km upstream of Mosul on the Tigris River. The dam is primarily an earth embankment, with concrete reinforcement, 131 m tall and approximately 3.5 km wide at the base. Now named the Mosul Dam, the structure impounds approximately 12B cubic meters of water, provides irrigation and drinking water to the surrounding region and downstream through Baghdad, and generates more than 300MW in electricity for the region.

But it seems the dam is in danger of catastrophic failure. More than 500,000 residents downstream, in Mosul and Baghdad and numerous smaller cities and villages, are in danger of a drowning flood wave. Of course, after the flood wave passes, the survivors in the service area (more than 1.7M in Mosul, and innumerably more downstream through Baghdad) will be without electricity and clean water for some time. It is both an infrastructure and humanitarian emergency in the making.

It turns out that we've known this for at least a couple of years. The Mosul Dam was built on top of a gypsum formation. According to MinDat.org, gypsum is a "marine evaporite" sedimentary mineral, flexible but inelastic and brittle. What do these mean? It collapses under stress, and it dissolves in water. Apparently, the dam started showing signs of leakage as soon as it was built, and engineers have been injecting grout (a mixture of concrete and gravel, with cement to hold it all together) into the foundation of the dam ever since. New sinkholes appear frequently, and at one point the dam engineers had 24 pumps working 24 hours a day to inject that grout. In the meantime, larger stabilization efforts at the site are either suspect or incomplete. A recent audit of post-war reconstruction expenditures in Iraq says that the $27M US-led effort to reinforce the dam has been "mismanaged" and, in the process, exposed the extent of the danger to the dam's structural integrity.

Needless to say, the original engineering reports on site selection are unavailable. An examination of the geologic formations underlying the dam, and some of its safety implications, was originally published in 1991 and reprinted in the text of Water Resources Engineering in Karst by P.T. Milanović in 2004 (available on Google Books). Extensive mineral dissolution and water leakage, also known as "karstification," beneath the dam was observed during the initial filling period (1983-1986), and the recommendation in that text was that "grouting maintenance should be systematically and continuously applied" throughout the life of the dam. A recent report by the US Army Corps of Engineers (USACE) indicated that "grouting at one location causes the flow path (seepage) of subsurface water to move to another location, but does not stop the seepage." The report also indicated that "the rate of subsurface dissolution increases markedly" at a reservoir depth that is 12 meters below the overall dam height, leading to a recommendation that the reservoir remain limited to this depth and, effectively, eliminating some of the design capacity and margin of safety, especially in flood control operations, for the site.

When coalition forces first invaded Iraq in early 2003, there was a great deal of concern over the safety of dams on the Tigris and Euphrates Rivers. It was believed that Saddam Dam, on the Tigris River, and Haditha Dam on the Euphrates River had been fitted with explosives to be detonated by retreating Iraqi forces. The Haditha Dam was captured US Army Rangers and came under coalition control early in the invasion. Mosul Dam, as it was renamed by the locals, was not captured in the initial invasion, but rather inspected later by the USACE. In April of 2003, during the conflict, the site was found to be free of explosive devices. Moreover, it was found that the dam was already under protective control: more than 500 laborers and engineers were still hard at work at the site, a month after the government had stopped paying them, under guard by Kurdish militia. It makes me wonder if that protective move was in the invasion plans for our cooperation with the Kurds all along, or whether it was a unilateral decision on their part as a matter of Kurdish, and larger Iraqi, security.

So instead of malicious intent, the Mosul Dam and many Iraqis remain in danger due to poor engineering and management, both in the Saddam era and now, as the safety and viability of the dam is addressed by the USACE. One of their proposals has been to build another dam downstream, to catch the flood wave if and when the Mosul fails. Though such a plan should be feasible as an intentional and eventual replacement for the Mosul Dam, planning for an incidental replacement is dubious: it is a risky proposition to "catch" a 110-meter flood wave crest, as the engineering reports suggest could occur. It is also not at all a short-term solution: in order to avoid the same mistakes made in the original site selection, extensive geological testing and exploratory engineering for a new site will take a long time, and only then would the actual construction of a new dam begin. On the positive side, there is a partially-completed dam at Badush, on the Tigris River between Mosul Dam and the city of Mosul, that has been recommended by the USACE to the Iraqis for completion. However, much uncertainty surrounds both the "stabilization" of Mosul Dam and the construction of new facilities, either at Badush or another location, for lack of planning and funding. That uncertainty comes primarily from finger-pointing between the US and the Iraqi parliament.

Should the politics of the US-led occupation of, and eventual withdrawal from, Iraq take precedence over the safety and security of the country's infrastructure and natural resources? Of course not. One would think that an increase, even a doubling, from the $27M already allocated to the Mosul site stabilization would be but a drop in the bucket (no pun intended) of large-scale post-conflict reconstruction efforts in Iraq. But many Iraqis, especially outside of Kurdistan, remain without consistent supplies of water, food and electricity, and it's not necessarily because of the new Iraqi government's planning efforts.

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