This study focused on determining the groundwater flow paths in the crystalline subsurface rocks of the Bulawayo metropolitan, Zimbabwe, through analysing the discontinuities of the electrical properties of the ground, as well as in the magnetic field of the underlying rocks. Further, borehole water quality was analysed by measuring and mapping several chemical parameters, specifically TDS, salinity and the electrical conductivity. The electrical and magnetic anomalies were measured at two field sites within the Bulawayo province, the Harry Allen Golf Course and the Barbour Fields dumpsite, while 120 boreholes were sampled for water quality in a large part the province. Two magnetometers were used to measure the magnetic field and the time and location of the measurements, which resulted, after processing in SURFER, into the magnetic field map of these areas. This was used, in conjunction with the geologic map of the Bulawayo province, in order to determine useful locations for the electrical resistivity surveys. These included electrical resistivity tomography and vertical electrical sounding and were performed with an earth resistivity/induced polarization (IP) meter in order to measure the electrical resistivity of the ground. Inverse modelling was used in the RES2DINV software program to produce the topographic image of resistivity. The results for the borehole sampling showed that the maps for the three chemical parameters were very similar, with the western and northern parts of the mapped area displaying higher concentration values. The results of the electrical resistivity surveying showed probable areas of groundwater flow with its relationship to electric conductivity.

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. 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. 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.

Groundwater overexploitation can cause the collapse of coastal aquifers. The goal of this study was to apply a template, the computer code SEAWAT to evaluate the behavior of the salt wedge Coastal Aquifer System, which has studied the case of complex Barreira/Marituba in Part Coast Metropolitan Region of Maceió-AL. In addition they were analyzed physicochemical indexes to characterize the study area and verify the source of salt contamination. The model calibration was performed in two parts. The underground flow calibration obtained a correlation coefficient between calculated hydraulic loads and observed of 0.764 and the calibration concentration of Total Dissolved Solids, which has very close to the salt concentration value, obtained a 0.682 correlation coefficient for the year 2015 . Since then analyzed two different scenarios, which allowed us to verify the effect of groundwater exploitation in the salt wedge for the year 2025. The first considered the existing exploitation by 2015 without pumping increments. As a result, it was found advancing saline wedge area into two areas, an area that suffers decrease, besides the formation of cones with vertical rise of the seawater. In the second scenario were added licenses of water works as well and plus the assumption of 32 new pumping wells installation, according to the city's growth. However, in this case, it was not possible to see variations in the mix zone for the first scenario for the year 2025. The analysis of hydrogeological indices pointed to higher chloride concentrations in the region close to the line of the Atlantic Ocean, with little influence of nitrate and, in general, showed the existence of seawater intrusion. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A exploração indiscriminada de água subterrânea pode causar o colapso dos aquíferos costeiros. O objetivo deste trabalho foi aplicar um modelo, o código computacional SEAWAT, para avaliar o comportamento da cunha salina em Sistema Aquífero Costeiro, onde foi estudado o caso do Complexo Barreira/Marituba na costa de Parte da Região Metropolitana de Maceió-AL. Ademais foram analisados índices físico-químicos para caracterizar a região de estudo e verificar a fonte de contaminação salina. A calibração do modelo foi realizada em duas vertentes. A calibração de fluxo subterrâneo obteve um coeficiente de correlação entre cargas hidráulicas calculadas e observadas de 0,764 e a calibração de concentração de Sólidos Totais Dissolvidos, que possui valor muito próximo à concentração de sal, obteve um coeficiente de correlação de 0,682 para o ano de 2015. A partir de então foram analisados dois cenários distintos, que permitiram verificar o efeito da explotação de água subterrânea na cunha salina para o ano de 2025. O primeiro considerou a explotação existente até 2015, sem acréscimos de bombeamentos. Como resultado, verificou-se o avanço da cunha salina em duas áreas do domínio, uma área que sofre recuo, além da formação de cones com ascensão vertical da água do mar. No segundo cenário foram adicionadas as licenças de obras hídricas como poços e mais a hipótese de instalação de 32 novos poços de bombeamento, de acordo com o crescimento da cidade. Porém, neste caso, não foi possível visualizar variações na zona de mescla em relação ao primeiro cenário para o ano de 2025. A análise dos índices hidrogeológicos apontou para maiores concentrações de cloretos na região próxima à linha do Oceano Atlântico, com pouca influência do nitrato e, no geral, indicaram a existência de intrusão de água do mar.

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.

In recent years, the excessive specific conductance (SC) of Appalachian coal mining runoff waters has become a parameter of concern with the EPA due to its negative effect on aquatic life and water quality. In order to comply with the EPA guidance suggesting an effluent SC of 500 µS/cm, the Appalachian Research Initiative for Environmental Science (ARIES) Center at Virginia Tech requested that testing be done to determine the most effective technologies for reduction of SC. Runoff water was collected from two sites in southwestern Virginia and characterized to determine the source of SC in the water. The main contributing ions were determined to be Na⁺, Mg²⁻, Ca²⁺, and SO₄²⁻. Testing was performed to assess the possibility of using the speciation software, MINEQL+, with a set of empirical equations which predict SC using ionic composition for natural waters with a low to medium SC. The physicochemical treatment methods tested were ion exchange, excess lime-soda softening, and the Cost Effective Sulfate Removal (CESR) process. Both cation (H⁺ exchanger) and anion (Cl⁻ exchanger) exchange media were tested separately in batch reactors, which resulted in a higher effluent SC than initial SC. The softening method investigated, excess lime-soda softening, also resulted in increased SC levels because non-carbonate hardness levels were high and carbonate concentrations were low. The CESR process successfully lowered SC from 1,500-2,500 µS/cm to below the proposed EPA limit of 500 µS/cm. The success of this process was due to its ability to remove more than 85% of the calcium, magnesium, and sulfate from the water, which together accounted for more than 90% of ions in the source water. / Master of Science

MPH / Department of Public Health / See the attached abstract below