I take issue with the interpretation of the flow of the Chang Jiang River [``Environmentalists warn of damage from planned dam in China,'' Dec. 9]. Chongqing lies upstream from the proposed Three Gorges Dam site, not downstream. More serious is the inordinate haste displayed by the US Working Group advising the Chinese government to start construction on this -- the world's largest -- hydroelectric project as early as next year, before completion of the final design and without the benefit of an environmental-impact assessment.
Obviously there is no powerful environmental lobby in China, whereas the Western environmental movement promotes comprehensive and responsible planning and management.
China should allow at least five years of testing the impacts of the spectacular Gezhouba Dam project, a few miles downstream from the Three Gorges. This project is to be completed in 1986 and will afford China its largest power generating facility. Its success or failure should determine future efforts in taming the mighty Chang Jiang, which at one half billion tons a year ranks fourth amongst the world's rivers in sediment discharge.
In the meantime, the Chinese may ponder if further progress warrants the tremendous loss of the Three Gorges' scenic beauty. B. L. Oostdam Millersville University Professor of Oceanography Millersville, Pa.
Recent articles on earthquakes in New England and rising sea levels deserve comment. Contrary to the impression given, much is known about earthquakes due to a large and intensive eight-year study. Almost all earthquakes are around bays and river valleys in the region and appear related to local subsidence. The general location of earthquakes and their maximum size can be fairly well predicted, but not their timing. The recent earthquakes were no surprise.
These earth movements have a significant impact on the shape of our coastline and are probably responsible for most bays. For example, subsidence at Passamaquoddy Bay, on the northern Maine coast, is about one yard per century. The resulting change in sea level is several times the rate, due to icecap melting, and should be considered in some long-range planning. Patrick BaroshN. N.E. Seismotectonic Study Director Concord, Mass.
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