Given the history of large cost overruns associated with megadam construction, why do you believe they are so popular, especially in the developing world? In recent years there has been a surge in the construction of large dams in both developing and developed countries including Brazil, Ethiopia, Pakistan, and China. There are several reasons for this increased interest in dam building. Demand for electricity is expected to double worldwide between 2010 and 2035. Thus, hydroelectric power is seen as a cheap, available option for countries with river systems that allow for dams, particularly as it is a preferred option to dirtier coalburning plants. Other arguments in favor of building these dams include their use for flood control, crop irrigation, inland transportation, urban water supplies, and as a job creators. These are all powerful and tempting arguments in favor of building large dams. However, there is one important counter-argument to the push toward these hydropower megaprojects: they fail to offer the advantages they are assumed to provide.

There are several criticisms of large dam projects.

First, megadams take on average nearly nine years to complete. Thus, arguments that they will ease the burden of energy demands must be taken on faith; given their long lead times, they certainly are not an option for energy crisis situations. They also assume that all current circumstances (energy demand, population growth patterns, water availability, and energy prices)

are likely to remain steady, or at least predictable, over the period in which the dam is developed, which can lead to dangerous assumptions of future benefits. Nigeria’s Kainji Dam, for example, has fallen short of generating its expected hydroelectricity levels by as much as 70%. Also, cost and schedule projections to complete these dams are almost always grossly underestimated.

In fact, research suggests that cost overruns for large dam projects average 96% higher than estimated costs;

that is, actual project costs were nearly double the original estimates. Schedules for these dams averaged overruns of 44%, or 2.3 years.