A Look at Dams

I’m writing about dams lately and have been researching the unintended consequences of conventional hydroelectric power. Here is an excerpt.

Egypt’s Aswan Dam is a telling example of the march of technology in the name of improving people’s lives and solving environmental problems.1 The dam project had three goals: bring stability to Egypt’s agricultural production, generate power for a growing industrial sector, and reduce the effects of too-large floods, but its benefits appear to be outweighed by their costs if each goal is examined in turn.

Although Egypt was able to feed itself before the construction of the dam, it now imports 70 percent of of its food. Instead of trapping the annual flood in large basins to allow the nutrients and silt to precipitate out onto field surfaces and leach out soil salinity in the process, fields are now irrigated by canals, which has led to the water-logging of 90 percent of Egypt’s fields, 35 percent of which are now salinized. Instead of the robust system that fed Egypt for more than four thousand years, they have adopted the practices of the Mesopotamians that led to societal collapse. The Nile Delta, which contains most of Egypt’s agricultural land, is disappearing at a rate of 30 m per year because the now-silt-free Nile does not redeposit what the Mediterranean erodes away. Artificial fertilizers are now heavily applied. Fertilizers (and pesticides) are produced using power from the dam but also wreak ecological havoc by running off into the waterway.

Power generation exacerbates the negative effects of the dam: it requires a full reservoir, a constant flow, and a lower, smaller downstream channel. Aswan is also quite far from the population center of Egypt, requiring long power lines and the loss of electricity in its transmission.

Uncontrolled flooding can ruin homes and infrastructure, but the permanent flooding upstream of the dam has displaced over 100,000 people. The flood used to give water-borne diseases an annual boom-and-bust cycle; malaria and intestinal schistosomiasis now have perennially wet habitats for continual reproduction.

Additional effects of the dam include the reduction of Egypt’s catch in the Mediterranean, as the fisheries depended on the nutrients discharged by the annual flood, and suffer from increased salinization and loss of water from evaporation in the dam’s reservoir.

The greatest crime of the Aswan Dhumans cannot control every aspect of itam was not that it was built with the lack of knowledge about the problems it would create, but instead it was constructed with willful ignorance of these facts. Since the mid-1800s, major water-control projects had been undertaken in Egypt, including the previous Aswan Dams, first completed in 1902. Even with an ecologically minded design that allowed the silt-and-nutrient-laden first surge of the annual flood to pass through the dam,2 field salinity, disease, and human displacement were already occurring. Furthermore, discussions of problems related to downstream flow, silt removal, channel erosion, water evaporation, sedimentation, degradation of the delta, seepage, and seismic activity were suppressed once the decision to build the new Aswan Dam was made.

Hughes’s (2001:167, emphasis added) most prescient comment is that “The antidote for a non-integrated approach is consideration of the many facets of the ecosystem, including the fact that humans cannot control every aspect of it, since massive actions always have massive unintended effects, nor can humans exceed the limits of the ecosystem without catastrophic results for themselves.”


1The data here largely come from Hughes’s (2001) An Environmental History of the World: Humankind’s changing role in the community of life, unless otherwise cited.

2Sir William Willcocks, designer of the original Aswan Dam, stated that “It will be an evil day for Egypt if she forgets that . . . the lessons which basin irrigation has taught for 7,000 years cannot be unlearned with impunity. The rich muddy water of the Nile flood has been the mainstay of Egypt . . . and it can no more be dispensed with today than it could in the past” (quoted in Hughes 2001:166).

2 thoughts on “A Look at Dams

  1. This is fascinating! Globally, there seem to be efforts to remove smaller dams because of similar consequences. Do you have any sense of how feasible that is for such a large dam? Is there now too much infrastructure downstream assuming the absence of flooding?


    1. Hi Eric,
      It all depends on how committed the downstream communities are to taking it down. For generations they haven’t kept up or used the flood-retention dikes and reservoirs, so they’d have to be rebuilt–a huge undertaking. Any infrastructure built in the last 50 years anywhere near the Nile would have to be evaluated and potentially moved, retrofitted, or demolished. The economy would have to be reorganized around the seasonal flood instead of the constant stream. Plus they’d lose energy generation that would have to be made up or conserved. The Aswan Dam is a great example of a technological trap: once it’s depended upon, it’s hard to remove it, much like industrial agriculture.


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