Year of Publication

2015

Season of Publication

Spring

Paper Type

Master's Thesis

College

College of Education and Human Services

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Engineering

NACO controlled Corporate Body

University of North Florida. School of Engineering

First Advisor

Dr. Peter Bacopoulos

Second Advisor

Dr. William R. Dally

Third Advisor

Dr. Nick W. Hudyma

Department Chair

Dr. Murat M. Tiryakioglu

College Dean

Dr. Mark A. Tumeo

Abstract

A preexisting version of the 2D finite-element hydrodynamic model (code) ADCIRC was modified to enable assimilation of velocity data for calculation of longwave hydrodynamics of the lower St. Johns River. The data assimilation also enables model calibration and parameter estimation of directionally variant Manning’s n value using an anisotropic formulation of bottom roughness. This modified version of the ADCIRC code differs from the original ADCIRC model, as it introduces a module to provide evaluation of directional Manning’s roughness coefficient using observed velocity data for ebb and flood flow durations. The vector-based directional Manning’s n value is found by comparing the observed velocity data with the ADCIRC output from the original model dataset, depicting how the friction factor depends on flow direction. The modified ADCIRC model was calibrated for the velocity dataset and then validated with a different dataset of water surface elevation and streamflow. It is shown that the influence of the directional variability in bottom roughness is a significant factor in calibration of the model, especially given the to-and-fro nature of the tidal motions, which is contrary to present practices that ignore the temporal variability and any anisotropy in bottom roughness. This thesis makes a measured impact on how 2D hydrodynamic models (herein demonstrated with ADCIRC) are able to represent the directionality of bottom roughness in hydrodynamic simulation.

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