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A new spatially telescoping approach was proposed to improve measurement flexibility and account for hydrologic scale in field studies of groundwater-surface water (GW-SW) interaction. We applied this spatially telescoping approach in a study GW-SW interactions along Lucile Creek, Alaska. Catchment-scale data were used to screen areas of potentially significant GW-SW exchange, indicating groundwater contribution from a deeper regional aquifer along the middle to lower reaches of the stream. This initial assessment was tested using reach-scale estimates of groundwater contribution during base flow conditions. The reach-scale measurements indicated a large increase in discharge along the middle reaches of the stream accompanied by a shift in chemical composition towards a regional groundwater end member. Point measurements of vertical water fluxes were used to evaluate spatial and temporal variability of GW-SW exchange within representative reaches. The spatially telescoping approach identified locations of GW-SW exchange and improved interpretation of reach-scale and point-scale measurements.

Master of Science / Department of Civil Engineering / David R. Steward / Kansas relies on groundwater for nearly 85 percent of the total water used each year, most of which is used for irrigation. Over the last 30 years, declining groundwater levels in some areas have put pressure on agricultural industries. Ongoing research on the usage of groundwater resources will be necessary to sustain agriculture. In this study, two groundwater models were developed to investigate groundwater availability and use in western Kansas. The first model, called the Saturated Thickness Model (STM), investigated how groundwater resources will change over the next century. The second model, called the Change in Water Level Model (CWLM), was used to forecast water use trends for three agricultural districts in western Kansas by relating the change in groundwater levels over time to the volume of water pumped for irrigation. To understand how these changes would affect the agricultural industry, the research investigated historical trends in reported groundwater use, corn production and cattle in feedyards. The results showed significant decreases in the modeled saturated thickness over the next 100 years in western Kansas. Modeled groundwater use matched reported groundwater use data relatively well. The model showed significant decreases in groundwater use over the next 100 years, with the largest decrease being in the southwest district. Overall, forecast water use trends were in agreement with current outlooks for each area. The results from the correlation analysis showed a negative relationship between groundwater use and irrigated corn production, indicating improved irrigation efficiency and crop species over the past 30 years. Further correlations showed the number of cattle on feed in a particular area increased with the amount of irrigated corn production in the same area. This implies the cattle feedyards tendency toward local source of grain. As groundwater resources decline, corn production will decrease, and changes in the agricultural landscape will require adaptation. Feedyards will need to find new sources of corn grain or change to a less water dependent feed. Further research is needed to determine where corn grain will be produced in the next 100 years, and how corn grain will be transported to feedyards in southwest Kansas.

This thesis describes the flow of ground water with a free water table, in an isotropic and homogeneous soil overlying a horizontal impermeable layer, from a surface-applied rainfall or irrigation supply to a system of horizontal tube drains. The idealized representation of this situation is in terms of a potential flow towards line sinks. The tube drains (sinks) may be at atmospheric pressure (free flow) or under back-pressure (submerged flow). After describing the flow to systems of drains at uniform depth and equal spacings, the thesis shows the effect of horizontal, vertical and combined misalignments of a single line sink on the free surface, the flow pattern and the rates of flow to each sink. The study was carried out by viscous-flow and electrical analogues, by a numerical method (Relaxation), and by the exact solution of equations based on physical approximations. In theory the extent of the effect of any misalignment is infinite. Experimentally it was found that the vertical misalignment had a significant effect on the free surface, discharge and flow net over the whole range of the experiment, while the horizontal one had a noticeable effect only extending over one spacing on either side of the misaligned drain. An approximate mathematical solution for the horizontal displacement has been obtained. Experiments on the viscous-flow model revealed the importance of the effect on the free surface etc. of the back pressure. The distribution of the effect along the free surface and the correlation between the free surface height and the back pressure are also presented. A new approach was used to elucidate the effect of negative pressure (capillary rise) on the free surface and obtain the surface of atmospheric pressure. An equation, independent of the geometrical scale ratio was derived to relate the various parameters for the unsteady flow to the scaling laws. The introduction of a reference potential at a fixed point in the field provides a method for the correction of the change with time in the position of equipotentials and represents a new technique. The variations of free surface heights with discharge, as observed on the viscous-flow model, were compared with the results of s some recent theories and showed discrepancies between the experiment and theories.

Die Schriftenreihe gibt in 11 Fachbeiträgen die Ergebnisse aktueller Projekte und Forschungsvorhaben des LfULG wieder. Die Themen sind breit gefächert und beinhalten beim Grundwasser die Nitratbelastung an der Wasserfassung Diehsa, das Vorhaben eines digitalen Hydroisohypsenplanes in Sachsen, Sensor- und Thermo-Flowmetermessungen für den Ersatz von Grundwasseraufschlüssen sowie Informationen zum Projekt KLIWES mit Abschätzung der Auswirkungen der Klimaveränderungen auf den Wasserhaushalt in Sachsen. Die Themen des Altlastenbereiches umfassen neben dem Sächsischen Altlastenkataster die Schwerpunkte Sickerwasserprognose, Resorptionsverfügbarkeit von Schadstoffen aus Böden der Erzgebirgsregion, die Flutung der Grube Königstein und Informationen zum Projekt SUMATECS zur Anwendung sanfter Sanierungsverfahren. Die Vernetzung der einzelnen Fachdisziplinen wie z. B. bei Klimaänderungen oder der EU-Wasserrahmenrichtlinie (WRRL) spielt dabei eine immer größer werdende Rolle. »Grundwasser - Altlasten aktuell« erscheint mit dieser Ausgabe erstmals als Heft der Schriftenreihe.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 2001. / Includes bibliographical references (leaves 122-124).

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona, 1991. / Includes bibliographical references (leaves 263-274).

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