The Department of Geological Sciences Colloquium Series presents Dr. Carrie Davis Todd on “A Re-examination of the 1889 Johnstown Flood Using Historical Accounts, Field Measurements, and Hydrologic Modeling” on Nov. 14 at 4:05 p.m. in Clippinger 205.
Dr. Carrie Davis Todd
Davis Todd is a professor of geology at of Baldwin Wallace University.
Abstract: The Johnstown Flood of 1889 caused over 2200 deaths and was the deadliest natural disaster in U.S. history at the time. Although widespread rainfall and low-level flooding occurred in the city of Johnstown, the devastation was ultimately the result of the catastrophic collapse of the South Fork Dam located 14 miles up the Little Conemaugh River from the outskirts of Johnstown. The resultant flood wave caused damages in Johnstown and in communities throughout the Little Conemaugh valley. The floodwaters were temporarily impounded on their path downstream by two railroad bridges, which caused the lake to reform and subsequently burst through the temporary dams with renewed force. Despite the infamy of the Johnstown Flood, much of the information surrounding the contributing factors to the flood and the flood itself contain inaccuracies. New scientific and historical research into the events shaping the flood has resulted in new insight into the cause of the dam’s failure, the time of the failure, and the travel time of the flood wave to Johnstown. This research was possible due to the preservation of the South Fork Dam remnants by the National Park Service. We compared detailed post-flood topographic profiles to our own modern topographic surveys and digital elevation models (DEMs). The DEMs were also used to determine the volume of water held by the dam at the time of failure. Combining this information with a model for the mechanism of dam failure and historical information, we conclude that the dam failed approximately 20 minutes earlier than previously thought and modifications to the original dam design made failure inevitable.
Upcoming Colloquia
Jesse Hastings, Adriane Lam and Joshua Work, Geological Sciences graduate students, present their research on Nov. 21 at 12:30 p.m. in Clippinger 205. (Note special starting time.)
One Comment