Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
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.
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Johnson, Cody Lee, "The Influence of Soil Properties on Marsh Edge Erosion" (2016). LSU Master's Theses. 4610.
Chen, Qin Jim