Thesis (M.S. - Hydrology and Water Resources) - University of Arizona. / Includes bibliographical references (leaves 93-102).

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on May 7, 2010). Includes bibliographical references (p. 116-118).

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2006. / Includes bibliographical references (leaves 70-71).

Low-tech rock structures called gabions are commonly used in dryland stream channels to reduce erosion, slow floodwaters, and increase infiltration. Gabions may also increase water availability for riparian vegetation, and increase the duration of surface flow in ephemeral stream channels. However, their effects on infiltration and recharge are not well-understood. This study tested low-cost methods for easily quantifying the total infiltration induced by gabion construction in an ephemeral stream channel, over the course of a single flow event. We used well-established methods to find point infiltration fluxes from subsurface temperature time-series. Unique to this study, we then upscaled these measurements to the gabion’s entire area of influence using time-lapse photo data, which recorded the onset of flow and the duration of ponding. For a flow lasting ~5 hours, we ran 225 model scenarios, estimating that a single gabion could have increased the total infiltrated volume in the channel reach between it and the next gabion by as much as 255% or as little as 0%, but the most likely scenario is a 10.8% increase. We found the photo data to be invaluable in obtaining these estimates, and in understanding the dynamics of a remote field site. Future work would benefit from more precise measurements of point infiltration fluxes and better records of ponded surface area over time. If these improvements are made and our estimates can be replicated reliably, they would suggest that gabions are a more powerful restoration and management tool than previously understood.

The Hampton Roads Sanitation District is heading a Managed Aquifer Recharge project designed to build water resiliency for the district as well as meet recent regulations concerning effluent released into the Chesapeake Bay. The Sustainable Water Initiative for Tomorrow (SWIFT) project will include five injection well fields across the Virginian Coast. The first of these fields to be implemented is the James River site, scheduled to begin in 2025. A model of the Virginia Coastal Plain region was created in 2009 and has been used to simulate the combined impact of the full-scale SWIFT project. This study estimated the change in hydraulic head in the Potomac Aquifer System caused by the proposed James River recharge well field at a regional and local level. That estimation required the use of a widely accepted model of the Virginia Coastal Plain developed in 2009 which was subjected to a limited validation using USGS monitoring well data for comparison. That model was then used to establish boundary conditions for a local scale model surrounding the James River site, after which each model was used to run four pumping scenarios with varying rates of recharge. The validation of the Virginia Coastal Plain model found it to be satisfactory for the scope of this work, and it was therefore used to interpolate boundary conditions for the developed local model. The regional and local model both showed an increase in the simulated head values of the Potomac Aquifer System. The regional model simulated a sharper initial increase than the local model, however, long term the local model simulated a greater impact to the groundwater levels from the proposed recharge. / Master of Science / The Potomac Aquifer System (PAS) is a main water source for most of eastern Virginia and high pumping rates have caused notable drawdown in several areas. The Hampton Roads Sanitation District (HRSD) has initiated the Sustainable Water Initiative for Tomorrow (SWIFT) project that is designed to alleviate the stress on the PAS by artificially recharging the PAS through injection well. A regional groundwater model, built in 2009, has been used to estimate the impact of the proposed recharge for the SWIFT project at full capacity. This work validated the use of the regional model within the region of the first proposed SWIFT well field at the James River Site. Once the validation was complete, the regional model provided a framework to develop a more detailed model on a smaller scale. That model was then used to simulate the proposed injection well field at varying rates to estimate the effect of the James River Site. This study has shown that the regional model provides an adequate framework to build local scale models. The simulations run in both the regional and local models found that the proposed recharge increases the water levels in the PAS immediately surrounding the well field and that the impact is felt to distances exceeding 50 miles after 10 years.

This dissertation presents the results of a detailed physical and hydrogeophysical study of two soil-filled sinkholes mantled by ancient New River fluvial terrace deposits. Research was performed at the Virginia Tech Kentland Experimental Farms in Whitethorne, Virginia, USA between fall 2003 and spring 2007, and focused on characterizing infiltration, deep drainage, and recharge through soil-filled sinkholes. Using hydrogeophysical methods, the spatial and temporal distribution of soil moisture was modeled and potential recharge was quantified in two soil-filled sinkholes. Access-tube time domain reflectometry (TDR) was used to derive one-dimensional (1-D) soil moisture profiles. During access-tube installation, 470 soil samples were obtained from depths between 0.3 and to 9.0 m and characterized both physically and chemically. Using these data, a TDR calibration method was developed. Physio-chemical, TDR moisture, and 1-D electrical resistivity tomography (ERT) data were used to derive a numerically optimized form of Archie's Law which was used to convert ERT measurements into volumetric soil moisture. These results led to development of 2-D ERT-derived distributions of soil moisture in three transects across the two sinkholes in two terraces. Potential recharge was quantified using time-series ERT data with comparison to modeled cumulative potential evapotranspiration (PET) and cumulative precipitation between May 17 and October 9, 2006. The patterns of ERT-derived potential recharge values compared well with those expected from PET and precipitation data. Over the monitoring period from late spring to early fall during this study, results showed that a period of intense rain followed by a 31-day period of consistent rain, in which the rate of precipitation was equal to or exceeded PET, were the only periods in which significant amounts of potential recharge occurred (from 19 to 31% of cumulative precipitation during the study). Spatial distributions of ERT-derived moisture clearly revealed that significant amounts of infiltration occurred on sinkhole flanks and bottoms. Runoff during periods of intense rain flowed to the topographically lowest point in the sinkholes where it infiltrated and resulted in localized zones of enhanced infiltration and potential recharge to the water table. / Ph. D.

A crescente importância da questão do uso sustentável da água e a conseqüente necessidade de se diminuir a poluição e o desperdício desse reservatório terrestre, impulsionaram esse estudo. O objetivo principal do trabalho é avaliar a aplicação de indicadores isotópicos ambientais, como Sr, Pb, O e D, para estudos da origem e qualidade da água de recarga de um aqüífero, bem como do impacto da impermeabilização da superfície da cidade sobre esses indicadores. Para isso foram escolhidas duas áreas na Bacia do Alto Tietê, na Cidade de São Paulo, uma na Zona Oeste (área 1 - USP) e outra na Zona Leste (área 2 - VE), onde foram coletadas amostras de água da SABESP, de água de chuva e de poços de monitoramento, por um ano, além de sedimentos. Foram realizadas análises químicas em 390 amostras de água e 62 de solos, além de 413 análises isotópicas de H e O e 122 de Sr e Pb em água, além de 34 de Sr e Pb em sedimento. A determinação de procedimentos químicoanalíticos, para análises isotópicas de Pb e Sr em águas com baixas concentrações destes elementos, foi o primeiro resultado deste trabalho e definiu que as amostras devem ser filtradas e acidificadas, antes da evaporação, e seus resíduos devem ser dissolvidos com HCl, HNO3 e HF, para depois a amostra ser purificadas por resina de troca iônica. Todas as amostras de água subterrânea apresentaram alguma contaminação antrópica. Os poços da VE apresentaram contaminação caracterizada por altas concentrações de cloreto, sulfato e nitrato e a USP de cloreto, sulfato, amônio, sódio e fluoreto, além de elevada alcalinidade. Os lixiviados de Pb em sedimentos mostraram que há pouca interação destes com a água subterrânea e esses não foram utilizados como membros finais da mistura. As análises isotópicas (H e O) das chuvas indicaram que as precipitações da Cidade de São Paulo sofrem influência tanto do efeito quantidade, quanto das diferentes origens de massas de ar em diferentes períodos do ano. A estimativa de recarga utilizando os isótopos mostrou que a VE, mais impermeável, apresentou uma contribuição antrópica 10% (H e O) a 20% (Pb) maior do que a USP. Na USP, a recarga natural calculada por isótopos de H e O possui uma média de 70%, enquanto na VE esse valor cai para 59%. Os isótopos de Pb forneceram médias de 53% e 35%, respectivamente para USP e VE, de recarga natural. Diante dos cálculos efetuados e análises (químicas e isotópicas) concluiu-se que os isótopos de Sr não são indicados para traçar a recarga de áreas contaminadas, já que mostram pouca interação entre a rocha e a água. Os isótopos estáveis não apresentaram muita diferença entre as assinaturas de água da SABESP e das amostras mais contaminadas por esgoto e não são bons diferenciadores dessas duas fontes. Já os isótopos de Pb são bons indicadores de recarga para áreas contaminadas, porque conseguem discriminar as águas oriundas de fugas da rede da SABESP e do esgoto. / The importance of a sustainable use of water and its resultant necessity of reducing groundwater pollution and waste is the driving force of this study. The main subject is to evaluate the application of environmental isotopes, as H, O, Sr and Pb, for studying the groundwater recharge sources and its quality, as well as the impact of the surface sealing on these indicators, due to urbanization. Two areas with different occupation in São Paulo City, within the Upper Tietê Watershed, one in west zone (area 1) and other in the east zone (area 2) were chosen to do this study. In both areas, water samples were collected for a year from: monitoring wells, supply agency and rain. Sediments were also sampled during drilling. Chemical analyses were carried out in 390 water samples and 62 sediments, whereas H and O isotopic analyses were performed on 413 water samples and Pb and Sr isotopic analyses on 122 water samples and 34 sediments. This work also determined that analytical procedures for Pb and Sr isotopic analyses of groundwater samples with low Sr and Pb concentration should filter and acidify water samples prior to evaporate it, their residue should be dissolved with HCl, HNO3 and HF, before purification by ionic exchange resin. All groundwater samples showed some anthropogenic contamination. Groundwater contamination in VE is characterized by high concentrations of Cl-, SO42- and NO3-, whereas in USP of Cl-, SO42-, NO3-, Na+ and F- besides high alkalinity. The Pb leaching isotopic technique applied on sediments showed that there is low water-rock interaction and they were not used as end members for the mixing calculation. The H and O isotopic analyses indicated that precipitation in São Paulo are dependent of the amount effect and the different sources of air masses in different climate periods. The isotopic estimate of recharge indicated that VE, which has a more impermeable surface, has approximately 10% (H e O) to 20% (Pb) more anthropogenic recharge than USP. At USP the natural recharge calculated by H and O isotopes has mean value of 70%, whereas in VE this value drops to 59%. The Pb isotopes indicated a natural recharge of 53% and 35% for USP and VE, respectively. The conclusions made with the isotopic and chemical results are that: Sr isotopes are not good recharge tracers for contaminated areas with low residence time; O and H isotopes do not present significant differences between isotopic signatures from water distributed by the public supply company and most contaminated samples by sewage; Pb isotopes are good indicators of recharge tracers for contaminated areas, as they can discriminate waters from sewer leakage and public supply company waters.

A crescente importância da questão do uso sustentável da água e a conseqüente necessidade de se diminuir a poluição e o desperdício desse reservatório terrestre, impulsionaram esse estudo. O objetivo principal do trabalho é avaliar a aplicação de indicadores isotópicos ambientais, como Sr, Pb, O e D, para estudos da origem e qualidade da água de recarga de um aqüífero, bem como do impacto da impermeabilização da superfície da cidade sobre esses indicadores. Para isso foram escolhidas duas áreas na Bacia do Alto Tietê, na Cidade de São Paulo, uma na Zona Oeste (área 1 - USP) e outra na Zona Leste (área 2 - VE), onde foram coletadas amostras de água da SABESP, de água de chuva e de poços de monitoramento, por um ano, além de sedimentos. Foram realizadas análises químicas em 390 amostras de água e 62 de solos, além de 413 análises isotópicas de H e O e 122 de Sr e Pb em água, além de 34 de Sr e Pb em sedimento. A determinação de procedimentos químicoanalíticos, para análises isotópicas de Pb e Sr em águas com baixas concentrações destes elementos, foi o primeiro resultado deste trabalho e definiu que as amostras devem ser filtradas e acidificadas, antes da evaporação, e seus resíduos devem ser dissolvidos com HCl, HNO3 e HF, para depois a amostra ser purificadas por resina de troca iônica. Todas as amostras de água subterrânea apresentaram alguma contaminação antrópica. Os poços da VE apresentaram contaminação caracterizada por altas concentrações de cloreto, sulfato e nitrato e a USP de cloreto, sulfato, amônio, sódio e fluoreto, além de elevada alcalinidade. Os lixiviados de Pb em sedimentos mostraram que há pouca interação destes com a água subterrânea e esses não foram utilizados como membros finais da mistura. As análises isotópicas (H e O) das chuvas indicaram que as precipitações da Cidade de São Paulo sofrem influência tanto do efeito quantidade, quanto das diferentes origens de massas de ar em diferentes períodos do ano. A estimativa de recarga utilizando os isótopos mostrou que a VE, mais impermeável, apresentou uma contribuição antrópica 10% (H e O) a 20% (Pb) maior do que a USP. Na USP, a recarga natural calculada por isótopos de H e O possui uma média de 70%, enquanto na VE esse valor cai para 59%. Os isótopos de Pb forneceram médias de 53% e 35%, respectivamente para USP e VE, de recarga natural. Diante dos cálculos efetuados e análises (químicas e isotópicas) concluiu-se que os isótopos de Sr não são indicados para traçar a recarga de áreas contaminadas, já que mostram pouca interação entre a rocha e a água. Os isótopos estáveis não apresentaram muita diferença entre as assinaturas de água da SABESP e das amostras mais contaminadas por esgoto e não são bons diferenciadores dessas duas fontes. Já os isótopos de Pb são bons indicadores de recarga para áreas contaminadas, porque conseguem discriminar as águas oriundas de fugas da rede da SABESP e do esgoto. / The importance of a sustainable use of water and its resultant necessity of reducing groundwater pollution and waste is the driving force of this study. The main subject is to evaluate the application of environmental isotopes, as H, O, Sr and Pb, for studying the groundwater recharge sources and its quality, as well as the impact of the surface sealing on these indicators, due to urbanization. Two areas with different occupation in São Paulo City, within the Upper Tietê Watershed, one in west zone (area 1) and other in the east zone (area 2) were chosen to do this study. In both areas, water samples were collected for a year from: monitoring wells, supply agency and rain. Sediments were also sampled during drilling. Chemical analyses were carried out in 390 water samples and 62 sediments, whereas H and O isotopic analyses were performed on 413 water samples and Pb and Sr isotopic analyses on 122 water samples and 34 sediments. This work also determined that analytical procedures for Pb and Sr isotopic analyses of groundwater samples with low Sr and Pb concentration should filter and acidify water samples prior to evaporate it, their residue should be dissolved with HCl, HNO3 and HF, before purification by ionic exchange resin. All groundwater samples showed some anthropogenic contamination. Groundwater contamination in VE is characterized by high concentrations of Cl-, SO42- and NO3-, whereas in USP of Cl-, SO42-, NO3-, Na+ and F- besides high alkalinity. The Pb leaching isotopic technique applied on sediments showed that there is low water-rock interaction and they were not used as end members for the mixing calculation. The H and O isotopic analyses indicated that precipitation in São Paulo are dependent of the amount effect and the different sources of air masses in different climate periods. The isotopic estimate of recharge indicated that VE, which has a more impermeable surface, has approximately 10% (H e O) to 20% (Pb) more anthropogenic recharge than USP. At USP the natural recharge calculated by H and O isotopes has mean value of 70%, whereas in VE this value drops to 59%. The Pb isotopes indicated a natural recharge of 53% and 35% for USP and VE, respectively. The conclusions made with the isotopic and chemical results are that: Sr isotopes are not good recharge tracers for contaminated areas with low residence time; O and H isotopes do not present significant differences between isotopic signatures from water distributed by the public supply company and most contaminated samples by sewage; Pb isotopes are good indicators of recharge tracers for contaminated areas, as they can discriminate waters from sewer leakage and public supply company waters.

Thesis (M.S.)--Baylor University, 2005. / Includes bibliographical references (p. 48-50).

Thesis (Ph.D.)--Murdoch University, 2006. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves 148-163)