Mendenhall Research Seminar
Tidal Rivers: Sediment Dynamics and Ecosystem Functions at the Front Lines of Sea Level Rise
Scott Ensign, USGS, Reston, VA
Wednesday, October 24, 2012 – at 12 Noon
USGS National Center, Reston, VA – Room 4C315
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The geography and geochemical processes in tidal rivers and their adjoining wetlands are changing as sea level rises. Low rates of sediment accretion in tidal freshwater forested wetlands relative to non-tidal wetlands and oligohaline wetlands in four rivers on the mid-Atlantic coast indicate that forested tidal wetlands are the habitat most susceptible to change as sea level rises. Measurements of river hydrology and sediment transport reveal that tidal hydraulics enhance sediment delivery to wetlands near the head-of-tide and oligohaline zone but restrict sediment delivery to the tidal forested wetlands in between. Consequently, accumulation of sediment, carbon and nitrogen are highest near the head-of-tide and near the oligohaline estuary, leaving tidal forested wetlands vulnerable to sea level rise. Knowledge of these patterns in sediment accretion and ecosystem functions will contribute to research on tidal river salinity regimes, carbon and nutrient flux from watersheds to estuaries, and ecosystem changes in response to sea level rise.