Flood Assessment 120 Years Later

The Johnstown Flood of 1889 killed 2,209 people when a dam failed. In one of the worst disasters in American history, a torrent of water from the lake behind the dam rushed through the Little Conemaugh River then slammed into Johnstown, Pa.

In an article on the New York Times website, Henry Fountain says the beginnings of the flood have never been rigorously assessed until now. Dr. Davis Todd, a hydrologist and assistant professor of geology, was curious about the flood of 1889 and visited the dam site with three colleagues. Todd presented his findings last week at a meeting of the Geological Society of America in Portland, Ore.

He and his colleagues found that the lake behind the dam “held about 23.5 million cubic yards of water, which at one point passed through the breach at nearly 11,800 cubic yards per second,” Fountain writes. But the peak flow occurred about four miles downstream, and the researchers have come up with an explanation of why water and debris comparable to “the average flow of the Mississippi River” caused such destruction in Johnstown.

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