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Oceanography and Atmospheric Sciences and Meteorology
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
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Full-Text Articles in Physical Sciences and Mathematics
Numerical Modeling Of The Effects Of Land Use Change And Irrigation On Streamflow Depletion Of Frenchman Creek, Nebraska, Moussa Guira
Numerical Modeling Of The Effects Of Land Use Change And Irrigation On Streamflow Depletion Of Frenchman Creek, Nebraska, Moussa Guira
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
A three-dimensional Control Volume Finite Difference-based numerical groundwater flow model was constructed to assess the effects of agricultural irrigation and land use change on streamflow depletion. The study area is Frenchman Creek basin located in southwestern corner of the State of Nebraska, USA. This area was subject to an increased proliferation of groundwater abstraction for agricultural purposes since industrial revolution. It has also been subject to land use change from native rangeland to dry and irrigated cropland. The groundwater flow model was spatially discretized using Voronoi cells in unstructured grid built with the USGS MODFLOW-6. Temporal discretization defined 151 time …
Isotopic And Geochemical Analysis Of Nitrate Contaminated Groundwater In Edgar, Nebraska, Nathan Roddy
Isotopic And Geochemical Analysis Of Nitrate Contaminated Groundwater In Edgar, Nebraska, Nathan Roddy
Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research
High nitrate concentrations in the groundwater beneath Edgar, Nebraska have been measured for well over a decade, exceeding the EPA’s MCL of 10 mg-N/L. Investigating the isotopic signature of nitrate and groundwater have determined the likely source(s) of contamination. Apparent seasonal changes exists in nitrate concentration, isotope ratios, and geochemistry, suggesting that sources and flow paths change as a result of irrigation. Samples collected in December and May had very similar nitrate concentrations (average value of 13.7 mg-N/L) and isotopic ratios (δ15N 4.46‰ and δ18O-NO3 20.21‰), suggesting synthetic nitrate fertilizers are the major source of …