Thayer Watkins

The San-men (Three Gate) Gorge Dam
on the Yellow River

The Yellow River (Huang He) arises in the Chinghai Uplands of northwestern China and flows easterly until it detours around the Great Bend and then continues eastward to the Yellow Sea. Its course passes through the thirty meter thick and easily eroded loess soils. Its name comes from its muddy appearance; it carries the highest sediment load of any major river, approximately 60 pounds per cubic yard. This high sediment load leads to rapid silting up of the river bed and now after many generations of levee building the river bed is yards higher than the crop fields in the flood plain.

The Yellow River floods frequently and has changed its course 26 times in recorded history. Sometimes, as in the twelfth century, these course shifts have taken the Yellow River into entirely different basins. Thus, although the Yellow River has only five percent of the flow of the Yangtse River, it is known as China's Sorrow.

Flooding is but one of the problems concerning water and agriculture, the others being drought and the water-logging of fields. Flooding may be partially countered by planting forests and building catchment basins to delay the runoff. But at best these measures are only partially effective and large reservoirs are needed to contain the flood waters and prevent rupture of the levees downstream. The stored water may later be used for irrigation and maintaining the river flow in the dry season.

The Japanese occupation forces in China in the 1930s first proposed a dam where the Yellow River passes through the rock-walled gorge at San-men ("three gates"). San-men is near where the Yellow River leaves the Great Bend and flows eastward to the sea. This plan gave the highest priority to electrical power generation. American engineers who reviewed it after World War II praised it but offered an alternate site because a dam at San-men would inundate too much level farm land and would silt up very quickly. They recommended that any dam in this area be built with large outlets near the base for sluicing out silt to the sea. Another American engineer opposed the sluicing out of silt as a waste of good soil and recommended that a dam at San-men be built only after other reservoirs had been created upstream which catch the silt. According to this plan crops would be grown in these, upstream reservoirs once they silted up. Later, the Communist Government considered the controlling of the Yellow River. The site at San-men Gorge had five major advantages:

The disadvantages were:

The Communist Government chose to build the dam at San-men Gorge. But, as with other elements of the Chinese First Five Year Plan (1953-57), the program to control the Yellow River was a Soviet operation. Soviet experts proposed 46 dams to "staircase" the main stem of the Yellow River. In the region upstream from the Great Bend the dams emphasized power generation; in the Great Bend region and in the flood plain the dams were primarily for irrigation. These were large-scale, capital intensive pro jects. The dam at to be San-men Gorge was/large (but not the largest in the system), being nearly 400 feet high, two thirds of a mile wide, and having a storage capacity of close to five million acre-feet. It would have a generating capacity of 1100 megawatts. No sluice gates were included in the design.

Construction had begun on all these sites by 1958, but in 1960, because of ideological differences, the ~oviets withdrew~taking with them the plans and equipment. For fifteen years there was no information about the progress on the projects on the Yellow River but in 1974 and 1975 the Government in Beijing (Peking) announced their completion, including the one at San-men Gorge.

The original plan called for the control of silting by reducing erosion through aforestation, but this proved ineffective. Because of silt accumulation the dam was reconstructed to create silt- discharge tubes. These stabilized the silt level but reduced the effectiveness of the dam and reservoir to approximately the level of the least expensive alternative among those which were originally considered. Thus, a portion of the construction cost was wasted.

The dam at San-men Gorge is a notable achievement, but the Communist Party leadership made costly design errors in not providing an effective remedy for the predictable(and predicted) problem of silting. The cost to the Chinese people of mistakes such as these have been substantial and represent the price that has to be paid for leadership chosen on the basis of ideology rather than technical competency.

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