Evaluation of the Structure of Levee Transitions on Wave Runup and Overtopping by Physical Modeling
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Coastal regions are continually plagued by high water levels induced by river flooding or hurricane induced storm surges. As with any protective structure, it is essential to understand potential problematic regions which could result in a devastating loss for the regions nations value most. Coastal protective systems are primarily comprised of floodwalls and levees, each of which has practiced methodologies utilized for estimating their performance under design conditions. Methodologies concerning spatial variability are limited however, and transitions where earthen levees merge with floodwalls are considered vulnerable areas to erosion and possible breaching. Physical modeling of a specified levee transition is undergone in a three-dimensional wave basin to evaluate this hypothesis, and the detailed results of this assessment are presented within this thesis. From the physical model testing, analysis of the data reveals that the overtopping rates of the levee transition tend to be larger than traditional overtopping techniques have predicted. The runup values and floodwall wave heights tend to show potential problematic areas and mimic the variation of overtopping along the levee transition. Under the design conditions tested, extreme overtopping conditions and associated water level values propose that in order for the structure to sustain the hydraulic conditions, it must be well protected. It is shown that the variation of the still water level plays the largest role in the magnitude of the measured values, and increasing the peak wave period and wave heights also yields greater overtopping and water levels at the structure. Overall these extreme overtopping rates and water levels experienced at the structure irrefutably expose a greater risk of erosion and breaching of the protective structure than initially predicted. This study highlights the need to understand specific spatial variability along coastal protective systems, and provides a better understanding of the mechanisms affecting overtopping for the specific structure tested.
Oaks, Drake Benjamin (2010). Evaluation of the Structure of Levee Transitions on Wave Runup and Overtopping by Physical Modeling. Master's thesis, Texas A&M University. Available electronically from