Dissertation Defense Schedule
Academic Excellence
Sharing original dissertation research is a principle to which the University of Delaware is deeply committed. It is the single most important assignment our graduate students undertake and upon completion is met with great pride.
We invite you to celebrate this milestone by attending their dissertation defense. Please review the upcoming dissertation defense schedule below and join us!
PROGRAM | Ocean Engineering
Modeling Hydrodynamics and Sediment Transport in an Inlet-Beach System
By: Mohammad Keshtpoor Chair: Jack Puleo
ABSTRACT
Indian River Inlet (IRI), DE, USA, is located at roughly the midpoint of ~ 40 km Atlantic coast of Delaware and is the major waterway that connects the Atlantic Ocean to two Delaware inland bays. Twin jetties constructed in late 1930s to keep the inlet from filling also interrupt the alongshore sediment transport. The direct impact of jetty construction has been updrift beach accretion and downdrift beach erosion. In 1990, the U.S. Army Corps of Engineers (USACE) constructed a sand bypassing system to mitigate the downdrift beach erosion by transferring sand slurry from the updrift to downdrift side of the inlet. In an effort to investigate the impact of the bypassing system on downdrift beach, statistical analyses techniques are applied on beach profile data collected from 1985 until 2008 to address two questions. First, did the bypassing system fulfill the beach nourishment goals? If so, how much material is enough to be bypassed to protect the downdrift beach? Empirical Orthogonal Eigenfunction analysis was applied to investigate the temporal and spatial dependency of the downdrift beach on bypassing volumes. The downdrift beach has eroded severely since 2009, even though the bypassed volumes have exceeded the design values. A two dimensional (2D) depth averaged numerical model was used to shed light on nearshore hydrodynamic and morphodynamic patterns near the inlet. The major goal is to estimate the sediment transport rate variability under the effect of dominant directional waves to determine the important processes for downdrift beach erosion. In addition to downdrift beach erosion, the jetty construction has constrained the flow field through the inlet and increased the flow velocity, bed shear stress and sediment entrainment from the bed. With the background water depth of 5-6 m, the continuous bed erosion led to the evolution of two scour holes with the maximum water depth exceeding 30 m. Three dimensional (3D) turbulence and sediment transport models were developed in a 3D hydrodynamic model to study the potential causes of deep scour hole evolution within the IRI. Both field measurements and modeling results indicate that bed shear stress exceeds the critical bed shear stress of cohesive consolidated mud inside the channel under the impact of tidal current. The channel bed interacts with the flow field and increases the turbulence intensity within the scour hole that also incorporates sediment entrainment within the developed scour holes. Thus, inlet stabilization not only causes downdrift beach erosion but also may lead to local bed erosion and scour development.
The Process
Step-by-Step
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Dissertation Manual
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Defense Submission Form
This form must be completed two weeks in advance of a dissertation defense to meet the University of Delaware Graduate and Professional Education’s requirements.
