Date of Award

8-7-2008

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Engineering and Applied Science

Department

Earth and Environmental Sciences

Major Professor

Stoessell, Ronald

Second Advisor

Kulp, Mark

Third Advisor

O'Connell, Martin

Fourth Advisor

Georgiou, Ioannis

Fifth Advisor

McCorquodale, J. Alex

Abstract

The Tangipahoa River and Natalbany River watersheds (Tangipahoa Parish/County) in the Lake Pontchartrain Basin (southeastern Louisiana) are experiencing rapid urbanization, particularly in the wake of the 2005 hurricane season. To document the impact of land use on water quality, thirty sites were monitored for surface water physiochemical, geochemical, and bacteriological parameters. Water quality data was compared to land use within four sub-watersheds of the Tangipahoa Watershed and three sub-watersheds of the Natalbany Watershed. Urbanization had the most profound impact on water quality of all land uses. In watersheds with little urban land cover (< 7% with the sub-watershed) waterbodies had low dissolved salt, nutrient, and fecal coliform concentrations and high dissolved oxygen levels. Waterbodies within the urban region (> 28% urban land cover within the sub-watershed) of the parish had significantly greater dissolved salt, nutrient, and fecal coliform concentrations and decreased dissolved oxygen concentrations. Specifically, nutrient and fecal coliform concentrations increased as streams flowed through urban areas. The specific conductance, fecal coliform counts, concentrations of sulfate, HCO3-C, sodium, and nutrients (NO3-N, NO2-N, NH4-N, and PO4-P), and the ratios of Na:Cl, Cl:Br, and SO4:Cl were shown to be the parameters most indicative of urban impacts. Many of the geochemical parameters correlated significantly with each other, particularly within the urban streams (the streams with the greatest concentrations). While fecal coliform counts were high within the urban streams, programs to address malfunctioning wastewater treatment plants (WWTP) appear to be working, with fecal coliform counts declining and dissolved oxygen levels rising during the course of the data collection. In contrast, sites undergoing rapid development showed an increase in turbidity levels and a decrease on dissolved oxygen levels (both going from healthy to unhealthy levels) during the 18-month course of the data collection. By understanding the impacts of urbanization on streams of the Gulf Coast, local and regional municipalities may be able to reduce the impacts in already urbanized areas or mitigate the impacts at the outset of development.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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