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dc.contributor.advisorStotler, Randy L
dc.contributor.authorLong, Molly
dc.date.accessioned2015-06-17T04:06:04Z
dc.date.available2015-06-17T04:06:04Z
dc.date.issued2014-12-31
dc.date.submitted2014
dc.identifier.otherhttp://dissertations.umi.com/ku:13647
dc.identifier.urihttp://hdl.handle.net/1808/18095
dc.description.abstractShallow aquifers located near streams can be affected by groundwater contamination as a result of recharge from surface water; however, stream stage variation, subsurface geology, and seasonal changes can alter the magnitude of groundwater-surface water interactions. Knowledge of the influence these factors have on surface water connections with groundwater will help determine possible recharge and contaminant flow paths affecting future water supply wells installed in similar alluvial environments. This research capitalized on previously collected physical data, including geology, water-level measurements, and hydraulic conductivity, as well as new physical, geochemical, and isotopic data to assess the effects of hydrogeological and seasonal conditions on groundwater-surface water interactions at two geologically distinct field sites. Groundwater level measurements and surface and groundwater samples were collected at both field sites during the growing and non-growing seasons to assess changes in groundwater-surface water interactions. Water samples were collected from wells in sands and gravels of the alluvial aquifer and the deeper High Plains aquifer that are separated by a clay aquitard in a river valley at the Larned Research Site (LRS) in central Kansas. Water was sampled from a small stream and wells at different depths in alluvium overlying a shallow limestone bedrock aquifer at the Rock Creek Site (RCS) in southeastern Kansas. Dissolved inorganic concentrations and deuterium and oxygen-18 isotope compositions were determined for all samples to indicate the influence of changing stream stage and geology on groundwater-surface water interactions. Water from the aquitard wells at the LRS had considerably lower dissolved solid concentrations compared to the shallow and deep aquifer wells. The isotopic compositions became lighter with depth from the shallow to deep aquifer samples, but were lightest in the aquitard samples. The isotopic compositions of the precipitation and groundwater indicate that surface water recharge to the aquifers is likely to occur primarily in the spring and summer. The disparity between the aquifers and aquitard samples implied older, fresher water contained in a leaky aquitard system. The low hydraulic conductivity of the aquitard acts as a geologic barrier, although heterogeneities of the leaky aquitard apparently connect the two aquifers. The good hydrologic connection between the alluvial aquifers and the river bed acts as a contamination pathway for groundwater under the direct influence of surface water, whereas the aquitard protects the High Plains aquifer from rapid contamination by surface water. At the RCS, selected dissolved constituent concentrations in groundwater near the water table varied seasonally in two water table wells with evidence of lateral flow to and from the stream. In contrast, groundwater in the alluvium base wells, located at the base of the silty-clay alluvium and top of the weathered limestone, and in a bedrock well generally exhibited similar geochemical and isotopic values. The geochemical and isotopic differences between the stream and two water-table well samples and the remaining water-table, alluvium base, and bedrock well samples suggest different groundwater storage times at the RCS. The geochemical and isotopic values for groundwater from the two water-table wells best connected to the stream varied with changing stream stage and season, indicating short-term storage compared to the consistency of the deeper groundwater, which represented longer-term storage. Surface water recharge pathways at the RCS, which could function as recharge or contamination pathways, vary substantially as a result of the heterogeneous subsurface geology, but only appear to substantially affect selected portions of groundwater near the water table. The shallow bedrock aquifer is protected from contamination by the silty-clay alluvium.
dc.format.extent83 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectGeology
dc.subjectHydrologic sciences
dc.subjectGeochemistry
dc.subjectGroundwater-Surface Water Interactions
dc.subjectStable Isotopes
dc.titleCharacterizing the Groundwater-Surface Water Interactions in Different Subsurface Geologic Environments Using Geochemical and Isotopic Analyses
dc.typeThesis
dc.contributor.cmtememberRoberts, Jennifer A
dc.contributor.cmtememberStearns, Leigh A
dc.contributor.cmtememberWhittemore, Donald O
dc.thesis.degreeDisciplineGeology
dc.thesis.degreeLevelM.S.
dc.rights.accessrightsopenAccess


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