Semester of Graduation

Fall 2020

Degree

Master of Science (MS)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

The Amite River Basin is a 2,220 square-mile basin spanning from southwest Mississippi through southeast Louisiana, encompassing Baton Rouge and its suburbs. In response to historic flooding in August 2016 and other major flood events in the past several decades, the basin has been the subject of a number of studies to quantify the impacts of changes in land-use and reduction in river length and sinuosity. However, there have yet to be relationships defined between the changes in the historical river planform and the resulting flow, stages, and subsequent flood depths. River lengths and sinuosity were measured from the 1930s to present, confirming there has been an overall 6 and 13% decrease in length and sinuosity of the Comite and Amtie Rivers upstream of their confluence, respectively, from the 1930s to present. Planform geometries from four time period scenarios from the 1930’s to present were input into a combined 1D/2D unsteady flow HEC-RAS model, which is run using four spatially-variable rainfall events ranging from 1- to greater than 500-year return period flows to examine the significance on flood characteristics. The results show an overall increase in flow and stage peak magnitude over time, corresponding to an overall decrease in river length and sinuosity. The impacts were largest for for the 3- to 6-year return period flow event due to the magnitude and rainfall distribution of the historic event used. Results from this study will be compared to and combined with complementary projects, focused on spatial and temporal changes in land use and precipitation events, to better understand the driving variables impacting the stages, discharges, and subsequent flood risk within the basin. Further, this knowledge can be applied to better inform mitigation and construction projects within the basin in the future.

Committee Chair

Willson, Clinton

DOI

10.31390/gradschool_theses.5211

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