Identifier

etd-04032015-121942

Degree

Master of Science (MS)

Department

Renewable Natural Resources

Document Type

Thesis

Abstract

Floodplain lakes in floodplains of large rivers undergoing intensive alterations are subject to hydrologic alteration. One example is in the Lower Mississippi Alluvial Valley (LMAV) and pivotal habitat for wildlife. Catahoula Lake has experienced hydrologic regime alterations over the past ~150 years that may be contribute to changes in the habitat with expansion of woody plants. A Diversion Channel was constructed in 1972 to provide the natural, annual de-watering of the lake to maintain its ecological integrity, but ecologic changes are still occurring. Our general goal is to understand the hydrologic regime of the lake, particularly the historical hydrologic regime of Catahoula Lake and to identify the contribution of the adjacent rivers – Little, Atchafalaya, Red, Black, Ouachita, Tensas, and Mississippi rivers – to the variability of Catahoula Lake prior to and after extensive hydrologic modifications in the LMAV. Historical lake level and neighboring rivers stage time series were used to estimate the hydrologic links between the lake and its surrounding rivers. Our analyses were done for three time periods: (1) immediately prior to the Diversion Channel construction, (2) post-Diversion Channel period, and (3) estimated condition in the late 1800s prior to incision of the Atchafalaya River. Results indicate that water levels on the lake are complexly related to the influxes of the Little River or the stage of the Black River stage at Jonesville, and the most consistent relationship is with the Atchafalaya River, which controls the lake level via a backwater effect at stage 7.3 m or higher. This backwater effect has been reduced from 207 to 120 days per year between 1880 and 2010. Compared to its condition prior to hydrologic alterations, results indicate modifications in the LMAV and the construction of the Diversion Channel have altered the lake regime. Our best estimates is that current lake levels are lower in the high-water spring, less variable in the dry period, and lack the extreme high water events of 100+ years ago.

Date

2015

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Keim, Richard

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