Three Gorges Dam and Reservoir, Yangtze River, China, June 2009
Standing on the Nevada shore (being careful not to cross over into Arizona where one might be arrested as an enemy alien) and admiring the sleek arch and art deco works of the great Boulder Dam (aka Hoover Dam) across the Colorado it is difficult not to be awed at the power of humanity. Many years ago a famous architect working on one of the megalomaniac urban design projects for which his field is notorious said something to the effect "make no little plans for they have no power to stir men's blood." The design project thankfully came to naught, but his statement still has power. Nowhere is that more true than in the construction of huge dams. The icons of the New Deal in the United States are large dams, from the impressive structures on the Tennessee River and its tributaries as a part of the TVA to the grandest two of all, Boulder Dam on the Colorado and Grand Coulée on the Columbia. Subsequently dictators, autocrats, and even a few leaders in nominally democratic states have ordered construction of immense dams including ones on most of Russia's great rivers, on the Nile, on the Paraná, and on China's Yangtze. The dams have been variously designed to prevent flooding, to improve navigation, to store water for irrigation, and to produce electricity, with most of them intended to do at least two of that magic four.
Immense dams have come with a set of problems, however. Blocking the normal flow of the river, they serve also to block the flow of silt, and it collects behind the dams. The Aswan Dams on the Nile have blocked the flow of silt onto Egypt's riverine fields. While they generate a huge amount of electricity, much of that is used to produce fertilizer to take the place of the silt that once made the Nile Valley a breadbasket. Meanwhile the Nile delta is rapidly receding (and Egypt is getting smaller) as it is not receiving silt from upstream. The huge dams on the Colorado in the United States are also rapidly silting, though the low flows of the past decade mean that silting has been slowed. Eventually silting will render the dams useless for water storage and degrade or eliminate their benefits of flood control, navigation, irrigation water storage, and hydroelectric production. All dams are subject to silting, but the problem is especially great on rivers like the Colorado and the Nile whose headwaters include areas of easily eroded materials like sandstone.
A motto of the early Soviet experiment was "socialism plus electricity equals communism," and the construction of immense hydroelectric dams was a key goal throughout the ill-fated Leninist-Stalinist pseudo socialist experiment. A year ago Sayano–Shushenskaya Dam, one of the huge dams in Russia built by the Soviets to produce electricity, experienced a large explosion in its powerhouse, flooding the powerhouse and among other things sending a plume of lubricant oil down the Yenisei toward the Arctic, destroying several turbines, and killing at least 74 people. For a time Russia's electricity supply was reduced by a sizable percentage, and several key export industries, including aluminum production, were harmed. The flooded powerhouse had ot be closed and repaired, a process still ongoing, though the dam is again producing electricity.
Yesterday evening BBC News America had a story on flooding in China, high water on the Yangtze below the world's largest dam. One of the functions of the dam was to prevent downstream flooding, but it would seem it is having almost the opposite result. At least according to Chinese authorities the dam itself, also intended to is secure Earlier it was discovered that large dams in China were creating earthquakes and might have been directly responsible for several large and deadly temblors.
One must hope the Three Gorges Dam is the final immense dam built on earth to improve navigation on the Yangtze, to store water for downstream irrigation, and to produce hydroelectricity. Given the predilictions of totalitarian governments that may be a vain hope, but accumulated evidence makes it clear that huge dams create problems far greater than those they are intended to resolve.
One must hope the Three Gorges Dam is the final immense dam built on earth to improve navigation on the Yangtze, to store water for downstream irrigation, and to produce hydroelectricity. Given the predilictions of totalitarian governments that may be a vain hope, but accumulated evidence makes it clear that huge dams create problems far greater than those they are intended to resolve.
