The objectives of this study were to test the degree to which anthropogenic factors impact surface water geochemistry by evaluating the connections between the built environment and selected chemical parameters in the storm water runoff system for Lafayette Parish, Louisiana. An approach that combines geospatial modeling and geochemical data collected on samples from natural and concrete lined coulee drainage channels in the parish was utilized to examine (1) the distribution and interactions of different water sources (e.g. surface runoff, alternating drainage flow pathways, groundwater, etc.); and (2) the effect of impervious and agriculture land cover on water chemistry in the engineered drainage network.
Chemical compositions were analyzed for trace and major cations using an Inductively Coupled Plasma – Optical Emission Spectrometer (ICP-OES). Anion concentrations were analyzed using an Ion Chromatograph (IC). Other variables, such as dissolved oxygen, temperature, conductivity, salinity, pH, and turbidity, were measured in situ using a YSITM sonde meter. Geographic Information Systems (GIS) software was used to model drainage boundaries at each site. Impervious cover and agricultural surface layers were created from the 2010 National Land Cover database and clipped to each microwatershed drainage area such that zonal statistics could be used to calculate total area and percentages of these land coverage types in each microwatershed.
Potential groundwater interactions were evidenced to occur near the Francois Coulee Lafayette. When urban and non-urban samples were analyzed together, impervious surface cover was significantly correlated to specific conductivity (µS/cm) and the dissolved ionic species: Ca and SO4 in the microwatershed drainage areas. The exact amount of remedial acreage needed to return runoff waters to a normal baseline was calculated for targeted microwatershed drainage areas using a statistically derived coefficient estimate that suggested a 5.9 (µS/cm) increase in specific conductivity concentrations for every 1% increase in impervious surface cover.
|Advisor:||Borrok, David B.|
|Commitee:||Broussard, Whitney P., Duex, Timothy W.|
|School:||University of Louisiana at Lafayette|
|School Location:||United States -- Louisiana|
|Source:||MAI 56/01M(E), Masters Abstracts International|
|Subjects:||Geographic information science, Geochemistry|
|Keywords:||Drainage, Louisiana, Pollutants, Watersheds|
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