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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23172号 / 工博第4816号 / 新制||工||1753(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 Sameh Kantoush / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Soil aquifer treatment (SAT) of treated wastewater performance was evaluated across published full-scale and lab-scale studies developing insights on the aquifer and operational factors that affect SAT efficacy. The goal of this study was to develop a basis for predicting the contaminant removal capabilities of any given aquifer during managed recharge with treated wastewater. Over 40 published SAT studies were reviewed and systematically compared to determine the influence of five major factors on contaminant removal performance: geologic composition, geochemical conditions, hydrogeological conditions, operational methods, and source water quality. Removal mechanisms for standard contaminants (dissolved and total organic carbon, nitrogen, and pathogens) were considered for each factor. By supplementing the theoretical understanding of contaminant removal in SAT systems with full scale and lab scale results, recommendations were developed for practical and effective SAT feasibility standards. SAT of standard contaminants was found to be most effective in aquifers with a water table below 20-meters. SAT was also most favorable for source water with 10 to 20-mg/L of bulk organics and less than 10-mg/L of total nitrogen. Moreover, extended residence times in the saturated zone provide little additional bulk organic and nitrogen removal for aquifers with vadose zones that achieve more than 85% of total bulk organic removal. The results of this study should enhance feasibility studies for future soil aquifer treatment projects, thereby facilitating the use of sustainable indirect potable reuse.

Multiple saline tracers were used to explore the role of geologic structure on groundwater recharge at the Fractured Rock Research Site in Floyd County, Virginia. Tracer migration was monitored through soil, saprolite, and fractured crystalline bedrock for a period of 3 months with chemical, physical, and geophysical techniques. Potassium chloride (KCl) and potassium bromide (KBr) tracers were applied at specific locations on the ground surface to directly test flow pathways in a shallow saprolite and deep fractured rock aquifer. Previous work at the Fractured Rock Research Site have identified an ancient thrust fault complex that is present in the otherwise competent metamorphic bedrock; fracturing along this fault plane has resulted in a highly transmissive aquifer that receives recharge along the vertically oriented portion of the fault zone. A shallow aquifer has been located above the thrust fault aquifer in a heterogeneous saprolite layer that rapidly transmits precipitation to a downgradient spring. Tracer monitoring was accomplished with differential electrical resistivity, chemical sampling, and physical monitoring of water levels and spring discharge. Tracer concentrations were monitored quantitatively with ion chromatography and qualitatively with differential resistivity surveys. KCl, applied at a concentration of 10,000 mg/L, traveled 160 meters downgradient through the thrust fault aquifer to a spring outlet in 24 days. KBr, applied at a concentration of 5,000 mg/L, traveled 90m downgradient through the saprolite aquifer in 19 days. KCl and KBr were present at the sampled springheads for 30 days and 33 days, respectively. Tracer breakthrough curves indicate diffuse flow through the saprolite aquifer and fracture flow through the crystalline thrust fault aquifer. Heterogeneities in the saprolite aquifer had a large effect on tracer transport, with breakthrough peaks varying several days over vertical distances of several meters. Monitoring saline tracer migration through soil, saprolite, and fractured rock provided data on groundwater recharge that would not have been available using other traditional hydrologic methods. Travel times and flowpaths observed during this study support preferential groundwater recharge controlled by geologic structure. Geologic structure, which is not currently considered an important factor in current models of Blue Ridge hydrogeology, should be evaluated on a local or regional scale for any water resources investigation, wellhead protection plan, or groundwater remediation project. / Master of Science

Deep injection wells (DIW) in Florida are regulated by the U.S. Environmental Protection Agency (USEPA) and the state of Florida through the Underground Injection Control regulations contained within the Safe Drinking Water Act. Underground injection is defined as the injection of hazardous waste, nonhazardous waste, or municipal waste below the lowermost formation containing an underground source of drinking water within one-quarter mile of the wellbore. Municipalities in Florida have been using underground injection as an alternative to surface disposal of treated domestic wastewater for nearly 40 years. The research involved collecting data as of September, 2007 on all the Class I DIWs in the state of Florida and evaluating the differences between them. The analysis found regional differences in deep well practice and canonical correlation analyses concluded that depth below the USDW is the most significant factor to prevent upward migration of the injected fluid. / by Jie Gao. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The use of cross-correlation analysis on spring discharge and precipitation data in karst aquifer basins has been used for many years to develop a conceptual understanding of an aquifer and estimate aquifer properties. However, to this point, the application of these processes has relied on gaged precipitation at discrete locations. The use of spatially varying precipitation data and cross-correlation analysis provides a means of spatially characterizing recharge locations on a karst aquifer. NEXRAD provides a spatial estimate of precipitation based by combining reflectivity measurements from radar stations and traditional precipitation gages. This study combines NEXRAD precipitation data with spring discharge data to develop maps of contributing areas for two karst springs in Central Texas. By calculating the cross-correlation of each NEXRAD measurement to spring flow data for the same period of time a map showing the locations hydraulically connected to the spring can be developed. Both numerical experiments and field applications were conducted as part of the study. The numerical experiments conducted by Padilla and Pulido-Bosch are revisited using the numerical groundwater model MODFLOW. This allowed the introduction of spatially varying parameters into the model. The results show that spatially varying parameters can be inferred based on the results cross-correlation of spatially varying precipitation with respect to a single spring discharge location. Also, contributing area maps are prepared for both Barton Springs and Jacob’s Well. Barton Springs has a precise estimate of the recharge area. The current map of the recharge area and the NEXRAD derived map show good agreement with the cross-correlation results. Conversely, Jacob’s Well has not been sufficiently studied to delineate a contributing area map. This study provides an preliminary estimate of the area contributing to flow at Jacob’s Well. Finally, the development of these maps can also be applied to the construction of regional groundwater models. An application of this methodology with the groundwater availability model for the Barton Springs portion of the Edward’s aquifer is introduced. The application of spatial cross-correlation analysis to constrain recharge in the model showed a reduction in the objective function with respect to discharge at Barton Springs of 15%. / text

The Barton Springs Segment, part of the karstic Edwards aquifer in Central Texas, is a Sole Source aquifer, is habitat to rare karst species, and provides water to a well-loved municipal swimming pool, yet its hydrogeologic properties remain insufficiently understood. For this study, the hydrogeologic characteristics of the Barton Springs Segment were investigated using several approaches, including mapping of hydrostratigraphic units and faults, measurement of upland infiltration, groundwater traces, and aquifer tests. The depositional environment, diagenesis, fracturing, down-dropped and dipping faulted blocks, and subsequent dissolution were determined to play important roles in controlling groundwater flow-path development within the Barton Springs Segment. In particular, downdropped fault blocks create groundwater gradients to the southeast that influence flow in the Edwards outcrop area. Upland internal drainage basins were found to be extremely efficient at conveying recharge to the underlying aquifer. The maturity of natural internal drainage sinkholes can be measured by its bowl volume, which grows in proportion to the catchment area it captures. A 19-hectare internal drainage basin, HQ Flat sinkhole, was monitored for rainfall, evapotranspiration, soil moisture, and discrete runoff to the cave drain. During a 505-day period, 5.5% of measured rainfall entered the cave drain as discrete recharge, 26% of measured rainfall infiltrated through soils on the slopes, and the remaining 68% was lost through evapotranspiration. This amount of upland infiltration is consistent with infiltration measurements in other karst areas and is much larger than the 1% upland recharge of rainfall that was previously estimated. A chloride mass balance indicates that at the adjacent Tabor research site, about 50% of rainfall infiltrates to a 6-meter depth. Dye-tracing and pump tests demonstrated that primary and secondary groundwater flow paths are the major influence on transmissivity within the Barton Springs Segment. Groundwater tracing breakthroughs reveal very high advection and relatively low dispersion. Drawdown response to pump tests indicates a very high degree of anisotropy, controlled by location of groundwater flow paths. Overall the Barton Springs Segment is a mature karst aquifer with highly developed rapid, discrete network for both recharge and groundwater-flow. / text

Secondary effluent from the Roger Road Wastewater Treatment Plant undergoes tertiary treatment of dual media filtration and chlorination. The tertiary effluent is recharged and subsequently extracted for irrigation in Tucson, Arizona. The fate of chlorinated organics in this recharge system was investigated in this research. Nonpurgeable organic carbon was found to reach a constant level in the groundwater after being recharged. Not all of the organic carbon was removed from the water. Nonpurgeable organic halogens increased as they flowed away from the recharge basins. Reasons for this increase were not determined. Attempts were made to define the apparent molecular weight distribution of the NPOC and the NPOX. Measured values of the two parameters were consistently greater after the analytical processing than before, making the determination impossible.

L'aquifère du Trarza s'étend sur environ 40 000 km2 dans le sud-ouest mauritanien, entre le fleuve Sénégal au sud, l'Océan Atlantique à l'ouest et les formations métamorphiques de la chaîne des Mauritanides au nord et à l’est ; il est contenu dans les sédiments du Continental Terminal et du Quaternaire. L’objectif de cette thèse est d’étudier avec une double approche géochimique (ions majeurs, 18O, 2H, 14C, 13 C) et hydrodynamique les processus de recharge de la nappe en réponse aux changements environnementaux. Les campagnes de terrain menées entre 2010 et 2012 ont significativement complété les rares mesures anciennes. Le niveau de la nappe ne semble pas avoir connu d’évolution significative durant les cinquante dernières années malgré un pompage localement important. L’écoulement général des eaux souterraines de la nappe se produit du sud vers le nord, c'est-à-dire du fleuve Sénégal vers la dépression au nord de Boutilimit où la nappe est à plus de 30 m sous le niveau de la mer. Le croisement des approches hydrodynamique et géochimique a montré que, dans cette zone semi-aride, la dynamique de la nappe est influencée par les multiples changements actuels et anciens de l'environnement (depuis les transgressions quaternaires et les paléotracés du fleuve jusqu'aux différents barrages régulant le cours du fleuve Sénégal). La nappe est principalement alimentée par l’infiltration latérale des eaux de surface du fleuve Sénégal et dans une moindre proportion par les précipitations. La minéralisation des eaux souterraines reste largement influencée par les résidus des transgressions quaternaires. L'évaporation marque fortement les eaux de surface avant et durant leur infiltration. Des calculs encore très préliminaires faits par différentes méthodes indépendantes suggèrent une recharge annuelle inférieure ou égale à 5 % des précipitations, soit de 5 à 10 mm. / The Trarza aquifer covers about 40 000 km2 in the south-western Mauritania in a semi-arid environment, located between the Senegal River in the south, the Atlantic Ocean to the west and the metamorphic chain of Mauritanides in the north and east. The Trarza aquifer is made of Quaternary and Continental Terminal sediments. The objective of this work is to combine geochemical (majors ions, 18O, 2H, 14C, 13 C) and hydrodynamical approaches for identifying the groundwater recharge in response to current and past environmental changes. The field survey carried out from 2010 to 2012 significantly supplemented the limited older measurements. The water table levels appeared quite stable over the last fifty years despite important local pumping. The groundwater flows occurs from south to north, i.e. from the Senegal River to a depression north of the Boutilimit where the piezometric level is more than 30 m below the sea level. Combining geochemical and hydrodynamical approaches revealed that the dynamics of the aquifer is influenced by many changes in both current and former environment (from Quaternary transgressions and palaeobeds of the Senegal River to the dams now regulating the river flow). The main source of the aquifer recharge is lateral infiltration from the Senegal River, and precipitation to a lesser extent. Mineralization of groundwater is largely influenced by the residues of Quaternary transgressions. The important effect of evaporation on surface waters before and during their infiltration is strongly marked geochemical signature. Preliminary calculations performed with several independent methods suggest that the annual recharge rate from precipitation is up to 5 %, i.e. from 5 to 10 mm.

As maiores taxas de recarga subterrânea do Sistema Aquífero Guarani (SAG) ocorrem nas áreas de afloramento das Formações Botucatu e Pirambóia. O principal objetivo deste trabalho foi avaliar as taxas de recarga subterrânea e suas relações com as variações da precipitação e do uso do solo na bacia hidrográfica do Ribeirão da Onça, situada em área de afloramento do SAG. A variação do nível freático foi medida em 11 poços de monitoramento, distribuídos em diferentes culturas agrícolas na bacia, durante o período de estudo (Outubro de 2004 até Setembro de 2011). Técnicas de tratamento de imagens multiespectrais foram usadas para mapear o uso do solo na bacia. A recarga direta em cada poço foi estimada por um método de escala local (Water Table Fluctuation, WTF) um método de escala de regional (Recession Curve Displacement Method, RCDM). Outro método de escala local foi avaliado (Chloride Mass Balance, CMB) em poços com cultura de pastagem. Foi estimado o armazenamento subterrâneo, o escoamento direto, o escoamento de base e a percolação profunda do aquífero em direção à Formação Botucatu. A espacialização da recarga direta para a bacia, usando os resultados do método WTF, foi feita de acordo com as áreas das culturas agrícolas. A recarga direta para a bacia foi estimada entre 80 mm e 359 mm, correspondente a 7% e 20% da precipitação anual de aproximadamente 1175 mm e de 1808 mm, respectivamente. A recarga direta, usando o método RCDM, variou entre 16% (229 mm) e 34% (~618 mm) da precipitação do ano 2009-2010 e 2010-2011, respectivamente. Foram observadas menores taxas de recarga nas áreas com cultura de eucaliptos em citros em relação às áreas com pastagem e cana-de-açúcar. Caso haja diminuição das precipitações e aumento das áreas de eucaliptos na bacia do Ribeirão da Onça, a recarga poderá sofrer diminuição, ocasionando menores escoamentos de base em direção ao Ribeirão da Onça. A avaliação contínua da recarga nas áreas de afloramento é essencial para a futura utilização das águas do SAG nas atividades agrícolas, industriais e de abastecimento público. / The major groundwater recharge rates of the Guarani Aquifer System (GAS) occur in the outcrop areas of Botucatu and Pirambóia Formations. This work aimed at estimating recharge rates and its relation with precipitation and land use in Ribeirão da Onça watershed, located in outcrop area of the GAS, during a seven years term monitoring (October 2004 until September 2011). The water table fluctuations were measured at 11 piezometers, located in different crops areas. Processing techniques for multispectral images were used to map the land use. Recharge was estimated trough a local-scale method (Water Table fluctuation, WTF) and a basin-scale method (Recession Curve Displacement Method, RCDM). Another local-scale method was used (Chloride Mass Balance, CMB) to estimate recharge rate in grassland area. The upscaling of recharge estimates using the results of WTF method for the watershed was performed, according to crop areas. Groundwater storage, quickflow, baseflow and deep percolation toward from the shallow aquifer to Botucatu Formation were also estimated. The results demonstrated that recharge estimates for areas with eucalyptus and citrus was lower than areas with grassland, sugar cane and citrus. Annual recharge rates estimated by WTF ranged from 80 mm (7%) to 359 mm (20%) for annual rainfall of about 1175 mm and 1808 mm, respectively. Recharge rates by RCDM ranged between about 229 (2009-2010) mm to 618 mm (2010-2011) for the entire watershed. CMB method provides mean recharge rate about 590 mm (2010-2011). These results suggest that if eucalyptus areas continue rising in the watershed, the recharge rates and baseflow would considerably decrease. The continuing assessment of recharge in outcrop areas is essential for future use of the GAS.