Mosul Dam, the largest such structure in Iraq, urgently requires maintenance to prevent its collapse, a disaster that could drown as many as five hundred thousand people downstream and leave a million homeless. Four days earlier, the energy minister of Zambia declared that Kariba Dam, which straddles the border between his country and Zimbabwe, holding back the world’s largest reservoir, was in “dire” condition.
.. In 2014, researchers at Oxford University reviewed the financial performance of two hundred and forty-five dams and concluded that the “construction costs of large dams are too high to yield a positive return.” Other forms of energy generation—wind, solar, and miniature hydropower units that can be installed inside irrigation canals—are becoming competitive, and they cause far less social and environmental damage. And dams are particularly ill-suited to climate change, which simultaneously requires that they be larger (to accommodate the anticipated floods) and smaller (to be cost-effective during the anticipated droughts).
.. But the main issue is that, like many such dams, the project shouldn’t exist in the first place. Opened in 1986, it was built on unstable gypsum bedrock, requiring grout to be constantly injected into the foundation to prevent the dam’s collapse. That work has ceased. In 2006, long before ISIS began making headlines, the U.S. Army Corps of Engineers called Mosul Dam “the most dangerous dam in the world.”
.. At least three million people live in the flood’s path; most would die or lose their crops or possessions. About forty per cent of the electricity-generating capacity of twelve southern African nations would be eliminated.
.. But maintaining a dam is expensive—and much less popular than building one.