The frequency distribution of intertidal marsh elevations as a diagnostic of vulnerability to sea-level rise.
Morris, James*,1, Porter, Dwayne1, Jensen, John1, Noble, Peter, 1 University of South Carolina, Columbia, SC, USA
ABSTRACT- Vertical elevation relative to mean sea level is a critical variable for the productivity and stability of saltmarshes. This research classified a high spatial resolution ADAR image of a saltmarsh landscape at North Inlet, South Carolina, USA using an artificial neural network and integrated the classified image with LIDAR data in order to compute the frequency distribution of marsh elevation relative to tidal elevations. The distribution of elevations of Spartina habitat within its vertical range was statistically normal, and 80% of the saltmarsh was situated between a narrow range of 0.22 and 0.481 m (NAVD 88). The relative elevation of the Spartina marsh at North Inlet is consistent with recent work that predicts a decrease in equilibrium elevation with an increasing rate of sea level rise and suggests that the marshes here have not kept up with an increase in the rate of sea-level rise during the last two decades. The frequency distribution of marsh elevations should be diagnostic of the vulnerability of intertidal marshes to sea-level rise. Most vulnerable are marshes with a skewed frequency distribution focused near the lower limit of the vegetation's potential range within the intertidal zone.
Key words: saltmarsh, geomorphology, sea level, indicator
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