Determining Tidal Elevations in Dry Elements within a Coastal Salt Marsh Model

Authors

Martin Coleman, University of Central FloridaFollow

Mentor

Dr. Stephen Medeiros

Abstract

An integrated hydrodynamic/marsh biomass model is a useful tool for analyzing multiple hydrologic activities on a shoreline. A key component of this type of model is the location of local tidal elevations. During astronomic tide simulations, nodes in the finite element mesh are either wet or dry. At nodes that are continuously wet during the simulation, tidal elevations are computed from ADCIRC-2DDI (ADvanced CIRCulation) output. In areas that are intermittently wetted, tidal constituents cannot be determined using ADCIRC because the drying of nodes leaves a gap in the water-level time series. The Inverse Distance Weighting (IDW) interpolation method can be used to interpolate unknown groundwater elevations over dried areas that are then used to calculate tidal elevations. The Dupuit equation is examined as a method to simplify and/or replace the interpolation method. Dry nodes in the ADCIRC output are post-processed using the Dupuit equation to calculate groundwater elevation. The author completed a field study on Apalachicola Bay to compare the interpolation method to the Dupuit method. A transect between two known water surface elevations was selected as a test site. The mean high water (MHW) and mean low water (MLW) tidal elevations were calculated by averaging the local high tide and low tide water surface elevations, respectively, throughout the time-series output. Nodes that were dry at some point in the simulation were treated using the IDW and Dupuit to fill in water surface elevations during those dry periods. After finding the unknown water surface elevations using the Dupuit and interpolation method, the Dupuit estimation was on average 3.4% higher for MHW and 52% lower for MLW. This indicates that this process is sensitive to both the method and parameters used.

About the Author

Martin is a fourth year UCF student studying Environmental Engineering, planning to graduate in the summer and pursue a Master of Environmental Engineering degree in the fall. Through the EXCEL Program, he worked as an undergraduate researcher in the Center for Hydroscience Analysis, Modeling and Predictive Simulations (CHAMPS Lab) for almost 2 years. Martin currently works as an undergraduate research assistant in the Drinking Water Research Lab. When he is not in classes or helping with research, he loves being outdoors, going to local dog parks, going to the movies, and traveling.

Recommended Citation

Coleman, Martin (2015) "Determining Tidal Elevations in Dry Elements within a Coastal Salt Marsh Model," The Pegasus Review: UCF Undergraduate Research Journal: Vol. 8: Iss. 1, Article 5.
Available at: https://stars.library.ucf.edu/urj/vol8/iss1/5