Date of Graduation

12-2023

Document Type

Thesis

Degree Name

Master of Science in Geology (MS)

Degree Level

Graduate

Department

Geosciences

Advisor/Mentor

David W. Stahle

Committee Member

Feng, Song

Second Committee Member

De Avila Fernandes, Katia

Keywords

Discharge, Ouachita River, Streamflow Reconstruction, Tree-Ring Chronology

Abstract

The Ouachita River drains the Ouachita Mountains and Upper Coastal Plain in Arkansas and Louisiana. The Ouachita River is used for navigation, power generation, recreation, water supply, and wastewater treatment. The river has been prone to low flows during drought and extreme flooding, which were principal justifications for the construction of three large multipurpose dams on the stream. It is likely that the use of the Ouachita River will be stressed by future population growth, economic expansion, and climate change. For this study, tree-ring chronologies from various locations in and near the Ouachita River drainage basin were used to reconstruct instrumental measurements of water year (October-September) and summer discharge (June-August) for the past 253- to 352-years, respectively. These reconstructions provide an extended long-term perspective on drought, periods of surplus water, and the potential modifications of Ouachita River streamflow due to reservoir management. The construction of the Blakely Mountain Dam and the impoundment of Lake Ouachita may constitute the largest anthropogenic impact to the river. Dam construction began in 1947 and Lake Ouachita was completely filled by 1952. The reconstructions of June-August discharge, when compared with the instrumental measurements of summer low flows, suggests that the regulation of the Blakely Mountain Dam has not strongly impacted the summer high and low flow extremes recorded at the Camden streamflow gauge. Additionally, no major changes in water year extremes were detected that might be related to reservoir management. Water year and summer discharge have both increased in the late 20th and early 21st century, which may be part of a trend toward increased precipitation over the eastern United States recorded in instrumental observations and proxy precipitation reconstructions.

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