The Mississippi Alluvial Plain (MAP) is a premier region for irrigated agriculture in the United States, producing approximately 9 billion dollars in annual revenues. The region receives around 138 cm of precipitation annually; however, irrigation is necessary to maximize crop yields as most of the precipitation does not occur during the growing season. There are 8 million irrigated acres within the Mississippi Alluvial Plain. The source of most of the irrigated water is the surficial aquifer in the Mississippi Embayment, the Mississippi River Valley Alluvial Aquifer (MRVAA), and due to the reliance on irrigation for maximum crop yields, recent potentiometric surface maps of the MRVAA show 1–1.5 ft/yr declines in groundwater levels. The US Geological Survey and US Department of Agriculture have produced models of the MRVAA to address groundwater sustainability issues. A large source of uncertainty within the Mississippi Embayment Regional Aquifer System (MERAS) and MAP project models is the contribution to groundwater from surface streams. Geophysical data estimating streambed sediment texture has been collected on numerous reaches within the MAP, but physical measurements are still desirable to constrain modeling efforts. Seepage meters are a potential tool for physical measurements of streambed seepage. Like all instruments, seepage meters must be calibrated to validate field measurements. Due to space limitations within the USDA National Sedimentation Laboratory, a tank with sufficient surface area to test a full-scale seepage meter was not feasible. Therefore, a scale-model seepage meter and seepage flux tank were constructed. Any consistent bias, if present, in measured seepage rates through the seepage flux tank could be accounted for by applying a correction coefficient. From the seepage flux tank data, a 95% confidence interval was calculated for the linear regression trendline through the data. The 1:1 line lies within the 95% confidence interval, indicating there is no need for a correction factor and any bias in measurements is due to installation of the instrument and not to system configuration. A field demonstration of the seepage meter was conducted within Goodwin Creek in Panola County, Mississippi yielding results consistent with estimates of seepage calculated using creek parameters and measured discharges.
|Advisor:||Holt, Robert M.|
|Commitee:||O'Reilly, Andrew, Rigby, James R.|
|School:||The University of Mississippi|
|School Location:||United States -- Mississippi|
|Source:||MAI 81/4(E), Masters Abstracts International|
|Subjects:||Hydrologic sciences, Geological engineering|
|Keywords:||MRVAA, Seepage, Seepage meter|
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