The mighty Susquehanna-extreme floods in Eastern North America during the past two millennia
|Author(s)||Toomey Michael1, Cantwell Meagan2, Colman Steven3, Cronin Thomas1, Donnelly Jeffrey3, Giosan Liviu3, Heil Clifford4, Korty Robert5, Marot Marci6, Willard Debra1|
|Affiliation(s)||1 : Florence Bascom Geoscience Center, U.S. Geological Survey; Reston VA, USA
2 : Department of Geology; College of William & Mary; Williamsburg VA, USA
3 : Department of Geology & Geophysics; Woods Hole Oceanographic Institution; Woods Hole MA, USA
4 : Graduate School of Oceanography, University of Rhode Island; Narragansett RI, USA
5 : Department of Atmospheric Sciences; Texas A&M University TAMU3150; College Station TX, USA
6 : St. Petersburg Coastal and Marine Science Center, United States Geological Survey; St. Petersburg FL, USA
|Source||Geophysical Research Letters (0094-8276) (American Geophysical Union (AGU)), 2019-03 , Vol. 46 , N. 6 , P. 3398-3407|
|WOS© Times Cited||4|
|Keyword(s)||hurricane, flood, Holocene, east coast, river, Chesapeake|
The hazards posed by infrequent major floods to communities along the Susquehanna River and the ecological health of Chesapeake Bay remain largely unconstrained due to the short length of streamgage records. Here we develop a history of high‐flow events on the Susquehanna River during the late Holocene from flood deposits contained in MD99‐2209, a sediment core recovered in 26 m of water from Chesapeake Bay near Annapolis, Maryland, USA. We identify coarse‐grained deposits left by Hurricane Agnes (1972) and the Great Flood of 1936, as well as during three intervals that predate instrumental flood records (~1800‐1500, 1300‐1100 and 400‐0 CE). Comparison to sedimentary proxy data (pollen and ostracode Mg/Ca ratios) from the same core site indicate that prehistoric flooding on the Susquehanna often accompanied cooler‐than‐usual winter/spring temperatures near Chesapeake Bay—typical of negative phases of the North Atlantic Oscillation and conditions thought to foster hurricane landfalls along the East Coast.
Plain Language Summary
Despite the vulnerability of many mid‐Atlantic cities to flooding, including Washington D.C., few long‐term records exist to assess the risks posed by extreme, infrequent, storm events. Here we document recent and prehistoric floods on the Susquehanna River, which has the largest watershed on the U.S. Eastern Seaboard, using sediment cores collected from Chesapeake Bay. Our analysis finds that much of the Susquehanna's observed centennial‐millennial scale flood variability may be driven by the frequency of hurricane landfalls along the U.S. East Coast.