Identifier

etd-10282016-123551

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Coastal Louisiana exhibits some of the highest rates of land conversion to open water in the world. This is most apparent in Terrebonne Bay, Barataria Bay, and Breton Sound (Couvillion et. al, 2011). The hypothesis is made that locally generated wind waves are responsible for the observed land loss. Recent research has attempted to relate the marsh edge erosion rate to wave energy flux density. Under the appropriate assumptions, this relationship is modeled reasonably well by a linear relationship between erosion rate and wave energy flux. Such a model is a valuable tool for coastal resource management. A deficiency of some of the proposed models is the exclusion of the marsh's resistivity to erosion or, generally speaking, its strength. Marsh edge strength is a complex function of abiotic, biotic, and geochemical factors. A plausible assumption however is that geotechnical soil properties form a governing set of parameters with respect to erosion. The inclusion of spatially varying, site-specific soil properties in addition to the hydrodynamic driving force is then a logical step towards improving any model of marsh edge erosion. A parametric wave generation model is validated with an existing, observed wave record and a state-of-the-art numerical model. The parametric model is used to calculate wave energy flux at the marsh edge study sites in Terrebonne Bay, LA over 9 years. A key subset of soil parameters is identified from an extensive geotechnical and geological data set. The geotechnical data set was derived from a related field campaign in the Mississippi river delta's coastal region which has a simimlar age and sediment source. The distribution of a proposed influential soil property in marsh edge strength (undrained shear strength) is used to demonstrate the site-specific differences in the relationship between observed marsh edge erosion and modeled wave energy flux density. Recommendations for the future success of modeling marsh edge erosion in the Mississippi river delta region are provided based on the applicability and suitability of the soil property framework and the method of modeling wave energy flux in Terrebonne Bay.

Date

2016

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Chen, Qin Jim

DOI

10.31390/gradschool_theses.4610

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