A regional synthesis of fluvial activity in major river basins of the eastern U.S. during the Holocene

Authors: Rachel Lombardi*, University of Alabama - Tuscaloosa, AL, Lisa Davis, University of Alabama, Gary Stinchcomb, Murray State University, Lance Stewart, Murray State University, Matt Therrell, University of Alabama, Samuel Munoz, Northeastern University
Topics: Physical Geography, Paleoenvironmental Change, Geomorphology
Keywords: Regional synthesis, paleorecords, fluvial activity, paleoclimate
Session Type: Poster
Day: 4/5/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: No File Uploaded

In the eastern United States, existing fluvial reconstructions consist primarily of site-specific investigations. We gain further insight into the spatial and temporal variation in regional river activity by synthesizing these site-specific reconstructions. Here we present the first regional syntheses of fluvial reconstructions from across the six major river basins of the eastern U.S., including the Lower Mississippi, Tennessee, South Atlantic-Gulf Coast, Ohio, Mid-Atlantic, and New England basins. Fluvial activity (i.e., alluvial deposition) and stability (i.e., soil development) chronologies derive from synthesized data addressed following questions: 1) does fluvial activity vary between basins and through the Holocene, and 2) how is regional fluvial activity related to climate change? The fluvial chronologies suggest the most active period of fluvial deposition for a majority of the study basins was the early Holocene, decreased fluvial sedimentation during the middle Holocene, and increased fluvial sedimentation again during the late Holocene. During the Medieval Climate Anomaly (650-1050 cal yrs BP) and the Little Ice Age (100-500 cal yrs BP), the depositional activity and stability showed a lack of synchronicity in stability or activity occurring between the study basins. The Little Ice Age was a more fluvially active climate period with five out six regions indicating increased fluvial activity. These findings suggest that rivers in the eastern U.S. have heterogenous responses to global climate change. Future directions for the regional syntheses include expanding the syntheses as new data become available and comparing the fluvial activity to other potential mechanisms of flooding such as paleohurricane reconstructions.

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