Marsh Equilibrium Theory
James T. Morris, Donald R. Cahoon, John C. Callaway, Christopher Craft, Scott C. Neubauer, Nathaniel B. Weston
Abstract
The analysis presented here was motivated by an objective of describing the interactions between the physical and biological processes governing the responses of tidal wetlands to rising sea level and the ensuing equilibrium elevation. We define equilibrium here as meaning that the elevation of the vegetated surface relative to mean sea level (MSL) remains within the vertical range of tolerance of the vegetation on decadal time scales or longer. The equilibrium is dynamic, and constantly responding to short-term changes in hydrodynamics, sediment supply, and primary productivity. For equilibrium to occur, the magnitude of vertical accretion must be great enough to compensate for change in the rate of sea-level rise (SLR). SLR is defined here as meaning the local rate relative to a benchmark, typically a gauge. Equilibrium is not a given, and SLR can exceed the capacity of a wetland to accrete vertically.