A geomorphological model of intertidal cove marshes with application to wetlands management

Abstract

Detailed topographic and hydrologic surveys were conducted in five intertidal cove marshes in an outer coastal plain landscape to test the hypothesis that the equilibrium geologic state of intertidal habitats residing in similar landscape situations conforms to a consistent geometric form. The equation V=1571.84 A 1.70 ( R 2=96.2%) describes the relationship between hectares of marsh ( A) and cubic meter volume at mean high tide ( V). An empirical relationship between tide height and volume was found to obey the power series V p= L 2.38 ( R 2=99.6%), where V p is volume as a percent of full pool and L is water height as a percent of mean high tide. A dimensionless index describing the relationship between area and volume is consistent for each marsh and approaches 0.10. A channel form parameter describing width to channel depth ratios is of consistent value for four of the five marshes. These provide evidence of deterministic rather than stochastic geologic development. The benefits of applying natural basin shape patterns in the design and engineering of created/restored intertidal marshes are highlighted and a generic basin is modeled (based on the geometrical section of a paraboloid retained by simple integration) as an example of the potential applicability of the study.