A novel mode of shallow aquifer management could increase the volumetric potential and distribution of underground, freshwater storage: Shallow aquifer storage and recovery (SASR). In this mode, water is efficiently stored in basin fill aquifers with strong hydraulic connection to surface water. Regional numerical modeling can provide a linkage between storage efficiency and local hydrogeologic parameters, which in turn may contribute to useful rules guiding how and where water can be stored. This study: (1) uses a calibrated model of the central Willamette Basin (CWB), Oregon to correlate SASR storage efficiency to basic hydrogeologic parameters using the stream depletion factor (SDF); (2) uses SDF to identify regions of high storage efficiency, and (3) estimates potential volumetric storage and injection rates for storage-efficient regions. Potential storage for the CWB is estimated to be 2.40 million m��. Given areal average hydrogeologic parameters, 8 wells--roughly 35 m deep and 0.3 m diameter--would be capable of managing this storage on an annual basis. Given otherwise similar conditions, greater depth to groundwater would yield greater volumetric potential, greater injection rates, and either unchanged or increased efficiency. / Graduation date: 2013

Title from PDF of title page. / Document formatted into pages; contains 322 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Ground water resources are heavily used for drinking water supply and often as a receptacle for waste water. One concern is the possible contamination of wetland areas by ground water receiving septic system infiltration. To investigate this, two tracer studies were performed using the bacteriophage PRD-1 by seeding septic systems adjacent to wetlands with the phage and monitoring migration towards wetland areas. Transport velocities were evaluated based on appearance of tracer in sampling wells at various distances from the injection point. Velocities were estimated to be 0.25 m/d and 0.4 m/d at the two sites. Some retardation with respect to the conservative tracer SF6 was observed, with a factor of about 1.5. Due to dry conditions, the water table was well below surface, so transport of the virus into surface water was not observed. Survival of public-health-related microorganisms in ground water is also a concern. / ABSTRACT: The effects of temperature and total dissolved solids (TDS) on survival of 5 groups of indicator organisms were evaluated in controlled experiments. TDS did not have significant effects on inactivation of these microbes up to 1000 mg/l, but there was indication of reduced inactivation of enterococci at TDS concentrations of 3000 mg/l. Increased temperature consistently resulted in more rapid inactivation. Survival in aquifer and reservoir water samples was also evaluated, and significant effects due to water type, temperature, and pasteurization treatment were observed. Inactivation was more rapid in surface water sources, and pasteurization enhanced survival. For enterococci and DNA coliphage, pasteurization effects were more pronounced in surface water. DNA coliphage and perhaps fecal coliform appeared to be the more-conservative indicator organisms for aquifer injection monitoring. / ABSTRACT: Lastly, it was observed that inactivation rates were considerably slower in pore water of saturated limestone than in the bulk water column of similar water sources and conditions, particularly for enterococci and fecal coliform. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

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The Biscayne Aquifer is a primary source of water supply in Southeast Florida. As a coastal aquifer, it is threatened by saltwater intrusion (SWI) when the natural groundwater flow is altered by over-pumping of groundwater. SWI is detrimental to the quality of fresh groundwater sources, making the water unfit for drinking due to mixing and reactions with aquifer minerals. Increasing water demand and complex environmental issues thus force water utilities in South Florida to sustainably manage saltwater intrusion and develop alternative water supplies (e.g., aquifer storage and recovery, ASR). The objectives of this study were to develop and use calibrated geochemical models to estimate water quality changes during saline intrusion and during ASR in south Florida. A batch-reaction model of saltwater intrusion was developed and important geochemical reactions were inferred. Additionally, a reactive transport model was developed to assess fate and transport of major ions and trace metals (Fe, As) at the Kissimmee River ASR. Finally, a cost-effective management of saltwater intrusion that involves using abstraction and recharge wells was implemented and optimized for the case of the Biscayne Aquifer. Major processes in the SWI areas were found to be mixing and dissolution-precipitation reactions with calcite and dolomite. Most of the major ions (Cl, Na, K, Mg, SO4) behaved conservatively during ASR while Ca and alkalinity were affected by carbonate reactions and cation exchange. A complex set of reactions involving thermodynamic equilibrium, kinetics and surface complexation reactions was required in the ASR model to simulate observed concentrations of Fe and As. The saltwater management model aimed at finding optimal locations and flow rates for abstraction and recharge wells. Optimal solutions (i.e., minimum total salt and total cost Pareto front) were produced for the Biscayne Aquifer for scenarios of surface recharge induced by climate change-affected precipitation. In general, abstraction at the maximum rate near the coast and artificial recharge at locations much further inland were found to be optimal. Knowledge developed herein directly supports the understanding of SWI caused by anthropogenic stressors, such as over-pumping and sea level rise, on coastal aquifers.