A continuity-based sedimentological model for temperate-zone tidal salt marshes

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Abstract
An exploratory model for the hydraulic and sedimentary regimes of tidal salt marshes predicts a velocity pulse as the tide enters the dry channel network, generally low channel velocities otherwise for undermarsh tides, pulses of high velocity as overmarsh tides at first flood onto and finally ebb off the marsh platform, generally sluggish flows otherwise over the marsh platform, and the retardation of the flow over the platform with increasing distance from channels and the marsh front. The model points qualitatively to a long-term depositional regime on marsh platforms, characterized by a decline away from channels and the marsh front in the accretion rate and grain size of sediment advected by overmarsh tides. The sedimentary regime in the channel network is more complex but, over periods of years, a state of quasi-equilibrium is plausible. Under these circumstances, the model hints that the external factors of tidal range and the texture and mineralogy of available sediment may determine the character of the branching channel network.