Theses and Dissertations

ORCID

0009-0006-7332-4155

Issuing Body

Mississippi State University

Advisor

Howard, Isaac

Committee Member

Vahedifard, Farshid

Committee Member

Freyne, Seamus

Committee Member

Taylor, Oliver

Date of Degree

8-12-2026

Original embargo terms

Immediate Worldwide Access

Document Type

Graduate Thesis - Open Access

Major

Civil Engineering

Degree Name

Master of Science (M.S.)

College

James Worth Bagley College of Engineering

Department

Richard A. Rula School of Civil and Environmental Engineering

Abstract

Levee breaches from overtopping erosion present a significant flood risk across the US. Biopolymers have been proposed as a soil-stabilization method for embankments to improve slope stability and mitigate erosion. This study evaluates the technical and economic efficacy of two biopolymers, Rhizobium tropici (RT) and Xanthan gum (XG). Silt treated with 1% biopolymer was subjected to five wetting-drying cycles to assess erosion performance and durability. Laboratory testing revealed significant, temporary improvements to mechanical properties. Compared to untreated soil, RT and XG treatments increased critical shear stress by nearly one order of magnitude and more than an order of magnitude, respectively, while reducing erodibility by over 90%. Despite degradation confirmed by microstructural analysis, residual improvements were observed at the final cycle. Laboratory results were then integrated into numerical simulations, yielding a 2-4-hour increase in breach delay for low overtopping heights. A cost analysis was also performed, in which biopolymers accounted for 80% (RT) and 92% (XG) of the unit cost for lime.

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