Rozprawy doktorskie na temat „Groundwater contribution”

This thesis investigates nutrient contribution to six hyper-eutrophic lakes located within close proximity of each other on the Swan Coastal Plain and 20 kilometres south of the Perth Central Business District, Western Australia. The lakes are located within a mixed land use setting and are under the management of a number of state and local government departments and organisations. These are a number of other lakes on the Swan Coastal Plain for which the majority are less than 3 metres in depth and considered as an expression of the groundwater as their base is below the regional groundwater table throughout most of the year. The limited amount of water quality data available for these six lakes and the surface water and groundwater flowing into them has restricted a thorough understanding of the processes influencing the water quality of the lakes. Various private and public companies and organisations have undertaken studies on some of the individual wetlands and there is a wide difference in scientific opinion as to the major source of the nutrients to those wetlands. These previous studies failed to consider regional surface water and groundwater effects on the nutrient fluxes and they predominantly only investigated single wetland systems. This study attempts for the first time to investigate the regional contribution of nutrients to this system of wetlands existing on the Swan Coastal plain. As such, it also includes new research on the nutrient contribution to some of the remaining wetlands. The research findings indicate that the lake sediments represent a considerable store of nutrients (nitrogen and phosphorus). These sediments in turn control the nutrient status of the lake's water column. Surface water is found to contribute on an event-basis load of nutrients to the lakes whilst the groundwater surprisingly appears to contribute a comparatively low input of nutrients but governs the water depth. Analysis of the regional groundwater shows efficient denitrifying abilities as a result of denitrifying bacteria and the transport is localised. Management recommendations for the remediation of the social and environmental value of the lakes include treatment of the lake’s sediments via chemical bonding or atmospheric oxidation; utilising the regional groundwater’s denitrifying abilities to ‘treat’ the surface water via infiltration basins; and investigating the merits of managed or artificial aquifer recharge (MAR).

Depuis plus d’un siècle, les changements globaux sont à l’origine de profondes modifications de nos sociétés, nos modes de vie et il en va bien sûr de même pour notre environnement. Cette trajectoire empruntée, bon gré mal gré, par l’ensemble de l’humanité n’est pas sans conséquences pour les systèmes naturels et semble déjà mener les générations futures au-devant de grands défis. Afin de ne pas compromettre notre capacité à relever ces épreuves futures et, devant l’urgence du besoin d’action, une partie de la communauté scientifique a choisi de concentrer ses efforts sur la couche superficielle de notre planète qui soutient la vie terrestre : la Zone Critique. L’émergence de ce concept souligne la nécessité de développer des approches scientifiques pluridisciplinaires intégrant une large variété d’échelles de temps et d’espace. En tant que lien entre les différents compartiments de la Zone Critique (Atmosphère, Biosphère, Hydrosphère, Lithosphère et Pédosphère), l’eau est une molécule essentielle aux échanges d’énergie et de matière dont la dynamique requiert une attention particulière. Compte tenu de la diversité et de la variabilité spatiotemporelle des transferts d’eau et de matière dissoute dans les milieux aquatiques, de nouvelles méthodes d'investigations sont nécessaires. L'objectif général de cette thèse est de décrire l’intérêt et le potentiel qui résident dans l’utilisation des gaz dissous, en particulier lorsqu’ils sont mesurés à haute fréquence sur le terrain, afin de caractériser la dynamique hydrobiogéochimique des eaux naturelles de la Zone Critique à différentes échelles spatiales et temporelles. Pour parfaire cette ambition, ce travail s’est tout d’abord attaché au développement d'une instrumentation innovante puis, à la mise en place de nouveaux traceurs intégrés dans des dispositifs expérimentaux originaux et enfin, à l'acquisition, au traitement et à l'analyse de différents jeux de données de gaz dissous en se focalisant sur les eaux souterraines
For more than a century, global change has led to a profound modification of our societies, our lifestyles and, of course, our environment. This trajectory followed willy-nilly by all mankind has consequences for natural systems and already seems to lead the future generations ahead of serious challenges. In order not to compromise our ability to meet these future ordeals, and because of the urgent need for action, part of the scientific community has chosen to concentrate on the near-surface environment that supports terrestrial life: the Critical Zone. The emergence of this concept underlines the need to develop multidisciplinary scientific approaches integrating a wide variety of temporal and spatial scales. As the link between the different compartments of the Critical Zone (Atmosphere, Biosphere, Hydrosphere, Lithosphere and Pedosphere), water is an essential molecule controlling the exchanges of energy and matter whose dynamics require special attention. In view of the diversity and spatiotemporal variability of water and matter transfers arising in aquatic environments, new methods of investigation are needed. The general objective of this thesis is to describe the interest and the potential lying in the use of dissolved gases, especially when they are measured at high frequency in the field, in order to characterise the hydrobiogeochemical dynamics of the natural waters of the Critical Zone at different spatial and temporal scales. To perfect this ambition, this work focused first on the development of an innovative instrumentation, then, on the implementation of novel tracers integrated into original experimental setups and finally, on the acquisition, processing and analysis of different dissolved gas datasets focusing on groundwater

2012/2013
The exploitation of geothermal heat by ground source heat pumps is presently growing throughout Europe and the world. In Italy, at the end of 2010, borehole heat exchangers covered most of the 30% of the total energy used for space conditioning, showing an increase of 50%compared to 2005. The forecasts for 2015 suggest a further increase in the direct uses of the geothermal heat exceeding 50% compared to 2010 and a corresponding increase in the geothermal energy consumption. The possibility to design plants with higher efficiency and lower costs of installation and operation is required, to support the growth of the ground source heat pump systems and the consequent diffusion of the exploitation of the geothermal resources. Research and better knowledge of the processes involved in the heat transfer between the borehole heat exchanger and the surrounding ground is crucial to predict the behavior of the plant-geothermal source interaction in any possible operational condition. The knowledge of the hydrogeological characteristics of the specific site where the plant has to be installed is also essential to prevent over- or under-sizing of the heat exchanger(s) due to a rough design. Over the years, several analytical solutions have been proposed to calculate the temperature distribution around a borehole heat exchanger during operation. The infinite line source analytical model considers an infinite linear heat source which exchanges heat with the surrounding ground by conduction only. Other models, based on the infinite linear heat source, have been later developed, considering also the contribution to the conductive heat transfer due to groundwater flow. The presence of flowing water around a borehole heat exchanger implies forced convection, resulting in an increased efficiency of the heat transfer between the ground and the borehole heat exchanger. Studying this process may suggest new ways to improve the efficiency and to reduce the cost of ground source heat pump systems. In this thesis, the contribution of groundwater flow in the heat transfer process between borehole heat exchangers and surrounding ground has been investigated, in order to increase the theoretical knowledge as well as to improve the existing design tools. Two-dimensional models have been considered, taking into account the actual cylindrical geometry of the borehole. The groundwater flow has been modeled as steady, horizontal and with variable flow rates, in order to encompass most of the real ground source heat pump applications. Gravitational effects, i.e. the effects of a possible natural convection, have been neglected. The results suggest that in the considered range of Darcy number, the calculation of the heat transfer efficiency is not affected if Darcynian model is used to describe the velocity field, although the viscous effects, and consequently the formation of the hydraulic boundary layer, are neglected. Calculations made using numerical simulations are compared with an analytical solution which takes into account forced convection due to groundwater flow and based on the linear heat source model. The regions of space and time where this analytical solution is affected by the effects of the line source assumption, in both cases of single- and multiple-borehole(s) systems, have been defined. The potential of the thermal response test analysis as a tool to predict the spacing between boreholes when groundwater flow occurs has been investigated, defining and studying the Influence Length as function of groundwater flow rate. The results suggest that even relatively low flow rates allow to reduce significantly the spacing between boreholes in the perpendicular direction with respect to groundwater flow. The distance from the borehole where the temperature disturbance becomes not-significant (Influence Length) is roughly predictable by thermal response test analysis. The study of the Influence Length may be a useful tool in the design of dissipative multiple-boreholes systems, as well as in areas with a high density of single-borehole plants, to reduce the spacing avoiding thermal interferences. Moreover, an expeditious, graphical method to estimate the hydraulic conductivity of the ground by thermal response test analysis has been proposed. An example of application of the methodology is presented, taking into account experimental data as well as plausible hydrological and petrological assumptions when the data are unavailable. The obtained result is in agreement with the hydraulic conductivity range reported in literature for the type of substrate considered in the example. In order to verify this method, further inv1estigations and developments are required. In fact, the graphs used in the procedure presented in this work are referred to specific borehole conditions (borehole filled by groundwater) and are based on two-dimensional models (i.e. end-effects and natural convection are neglected). Besides, the assumptions required to compensate the unavailable data imply that the method cannot be considered verified. Finally, further studies are suggested in order to improve and develop the proposed methods.
Negli ultimi anni, l’utilizzo del calore geotermico tramite pompe di calore accoppiate al terreno sta aumentando significativamente in tutta Europa e in generale nel mondo. In Italia, alla fine del 2010, le sonde geotermiche coprivano più del 30% dell’energia totale utilizzata per riscaldamento e raffrescamento degli edifici, mostrando un aumento del 50% rispetto al 2005. Le previsioni per il 2015 suggeriscono un ulteriore aumento degli utilizzi diretti del calore geotermico maggiore del 50% rispetto al 2010 e un analogo incremento del consumo di energia geotermica in generale. Con l’aumento della diffusione di questa tecnologia, e quindi un maggior sfruttamento di tale risorsa, aumenta anche la necessità di progettare impianti con la massima efficienza possibile e con bassi costi di installazione ed esercizio. La comprensione dei processi coinvolti nel trasferimento di calore tra sonda geotermica e terreno circostante è fondamentale per prevedere il comportamento degli impianti. Anche la conoscenza delle caratteristiche idrogeologiche del sito specifico nel quale l’impianto deve essere installato è essenziale al fine di evitare un’errata progettazione che può causare sovra- o sotto-dimensionamento della sonda. Nel corso degli anni, diverse soluzioni analitiche sono state proposte per calcolare la distribuzione di temperatura attorno alla sonda geotermica durante il suo utilizzo. Il modello analitico della sorgente di calore lineare e infinita considera lo scambio di calore che avviene per sola conduzione attorno ad una sorgente di raggio infinitesimo e di lunghezza infinita. Altri modelli successivi a questo e anch’essi basati sulla sorgente di calore lineare ed infinita, tengono conto anche del contributo convettivo dovuto al flusso dell’acqua di falda. La presenza di un flusso di acqua attorno ad una sonda geotermica, infatti, comporta convezione forzata e, di conseguenza, un aumento dello scambio di calore tra sonda e terreno. Per questo motivo, lo studio degli effetti di tale processo è un fattore chiave per riuscire a migliorare l’efficienza degli scambiatori di calore accoppiati al terreno. Questa tesi presenta lo studio del contributo del flusso delle acque di falda sul processodi scambio termico tra sonde geotermiche e terreno circostante, al fine di incrementare la conoscenza teorica e migliorare gli strumenti di progettazione già esistenti. Per raggiungere questo scopo ci si è serviti di modelli numerici bi-dimensionali che tengono conto della reale geometria cilindrica della sonda. Il fusso delle acque di falda è stato assunto come stazionale e orizzontale. Al fine di includere la maggior parte delle applicazioni geotermiche reali, un vasto range di portate è stato preso in considerazione. Gli effetti gravitativi, e quindi i possibili effetti di convezione naturale, sono stati invece trascurati. Sono stati confrontati i risultati del calcolo del trasferimento di calore ottenuti utilizzando rispettivamente l’equazione di Darcy e l’equazione di Darcy-Brinkman per descrivere il campo di velocità dell’acqua di falda attorno alla sonda. Le conclusioni raggiunte suggeriscono che utilizzando il modello di Darcy, il risultato risulta comunque sufficientemente accurato per i numeri di Darcy considerati, nonostante gli effetti viscosi, e quindi la formazione dello strato-limite fluidodinamico, vengano trascurati. I risultati delle simulazioni numeriche sono stati comparati con un modello analitico che prevede convezione forzata, dovuta al flusso di falda, attorno ad una sorgente di calore lineare ed infinita. Sono quindi state definite le regioni dello spazio e del tempo dove tale soluzione analitica è soggetta agli effetti della linearit`a della sorgente, sia nel caso di sonda singola, sia nel caso di campo-sonde. Sono inoltre state studiate le potenzialità dell’analisi del test di risposta termica come strumento per prevedere la spaziatura tra le sonde in funzione della portata del flusso dell’acqua di falda. I risultati suggeriscono che portate relativamente modeste, permettono una riduzione significativa della spazitura tra le sonde in direzione perpendicolare rispetto a quella di scorrimento dell’acqua di falda. Sfruttando l’analisi del test di risposta termica, è possibile stimare approssimativamente la distanza dalla sonda alla quale il disturbo di temperatura diventa trascurabile (distanza di influenza). Lo studio di questa distanza di influenza pu`o essere un utile strumento per la progettazione di sistemi dissipativi composti da sonde multiple, così come nelle aree con un’alta densità di impianti a sonda singola, al fine di ridurre la spaziatura tra le sonde, evitando allo stesso tempo l’insorgere di interferenze termiche tra sonde adiacenti. Inoltre è stato proposto un metodo grafico e speditivo per la stima della conducibilità idraulica del substrato tramite l’analisi del test di risposta termica. È stato presentato un esempio dell’applicazione di questa metodologia utilizzando sia dati sperimentali sia assunzioni plausibili di carattere idrologico e petrologico, quando non è stato possibile avvalersi di dati sperimentali. I risultati ottenuti sono in accordo con i valori di conducibilità idraulica proposti in letteratura per il tipo di substrato dell’esempio. Per poter verificare l’affidabilità di questo metodo, ulteriori studi e sviluppi sono sono necessari. Infatti, i grafici utilizzati nella procedura presentata in questa tesi, si riferiscono a specifiche condizioni della sonda (acqua di falda come materiale di riempimento) e sono inoltre basati su modelli bi-dimensionali (trascurando quindi gli effetti di fine-pozzo e il contributo della convezione naturale). Infine vengono forniti suggerimenti riguardo ulteriori studi che consentirebbero di migliorare e sviluppare ulteriormente le metodologie proposte.
XXVI Ciclo
1985

The objectives of this thesis were: (1) to quantify seasonal groundwater contribution to total stream discharge and (2) further our understanding of sub-arctic carbon sources and pathways within a sub-arctic discontinuous permafrost river catchment. Twenty-two samples were taken from the North Klondike River, 14 samples from 5 of its tributaries, and 46 rain and snowmelt samples from the Dawson City Airport, Yukon, Canada,. During the winter months, groundwater is responsible for greater than 95% of total river discharge. Spring freshet and summer flow bring snowmelt and precipitation, contributing anywhere from 30% to greater than 60% of total river discharge. Groundwater is characterised by high concentrations of geogenic solutes from weathering during recharge, dissolved inorganic carbon, and carbon-14 activities of 0.61 pMC. Tritium activities indicate a fast moving system, with groundwater ages measuring less than 10 years. The most significant discharge of organic carbon from the system is during spring freshet (434,192 kg carbon). Primary productivity within the system is estimated to be 10.2 grams of carbon per metre squared, with approximately 96% of carbon being sequestered or emitted as carbon dioxide.

Pour la climatisation de bâtiments ou d’installations industrielles, les nappes d’eaux superficielles représentent une source de frigories très convoitée. Leurs exploitations intensives depuis plusieurs dizaines d’années conjuguées au redéploiement de la filière géothermique ces dernières années, soulèvent des préoccupations quant à la préservation des ressources en eau. Dans ce contexte, la présente étude vise à évaluer l’impact de variations locales de température sur la qualité physico-chimique et microbiologique des eaux souterraines sur la base (i) de suivis in-situ au niveau de 3 installations réelles exploitant les nappes d’eaux superficielles et, (ii) d’expérimentations sur un pilote (BIOTHERMEX) permettant de reproduire, en conditions parfaitement maitrisées, l’effet de la propagation d’un panache thermique dans un modèle réduit d’aquifère. Dans la gamme de température relevée sur site, les principaux résultats obtenus montrent que les impacts thermiques sont circonscrits au voisinage immédiat de l’installation, pouvant altérer jusqu’à plus d’une dizaine de degrés la sténothermie des nappes. Le suivi des paramètres physico-chimiques n’ont pas fait apparaitre de perturbations significatives sur la période de surveillance, constat étayé par des modélisations hydrogéochimiques. En revanche, une influence significative a été relevée au niveau des principaux descripteurs microbiologiques (activité, diversité de la microflore totale). Enfin, les expériences menées à l’échelle du laboratoire ont permis d’appréhender finement le comportement réactionnel du système et de définir une température de réinjection critique, au-delà de laquelle des désordres potentiels sont attendus
The use of shallow groundwater as heat source for heat pump is very coveted for air-conditioning of building or industrial facilities. Their intensive use during many years combined with the redeployment of the geothermal industry these last years, raise concerns about the safeguarding of the water resources. In such a context, the present study aims to evaluate the impact of local variations of temperature on the physicochemical and microbiological quality of groundwater systems on the basis of (I) field investigation and, (II) experiments on a pilot (named BIOTHERMEX) making it possible to reproduce, in perfectly supervised conditions, the effect of the propagation of a thermal plume in a reduced aquifer model. Within the temperature recorded on site, principal outcomes showed that thermal impacts are confined in the immediate vicinity of the installation, and were able to deteriorate, up to about ten degrees, the stenothermy of the groundwater systems. The evolution of the physicochemical parameters did not reveal any significant disturbances over the monitoring period, this being also predicted by hydrogeochemical modeling. On the other hand, a significant influence was raised about some microbiological indicators-descriptors (namely activity, diversity of the total microflora). Lastly, the experiments undertaken on the laboratory scale made it possible to finely apprehend the reactional behavior of the system and to define a critical temperature of re-injection beyond which, potential disorders are expected

Potatoes (Solanum tuberosum) were grown in a fine sandy loam soil in southern Manitoba in a three-year field study comparing four water management treatments: No Drainage with No Irrigation (NDNI), No Drainage with Overhead Irrigation (NDIR), Free Drainage with Overhead Irrigation (FDIR), and Controlled Drainage with Subirrigation (CDSI). The objectives of the study were (i) to evaluate the effect of the four treatments on yield and quality of potatoes, (ii) to evaluate the effect of water management on the environment, (iii) to estimate the shallow groundwater contribution to potato water requirement, and (iv) to simulate the shallow groundwater hydrology using the DRAINMOD and HYDRUS 1-D model. Subsurface drains were installed at 0.9 m depth and at spacings of 15 m (FDIR) and 8 m (CDSI). Subirrigation was done by pumping water back into the tiles through the drainage control structures. Overhead irrigation was carried out using a travelling gun. Water table depth, soil water content, drainage outflow, nutrient concentration in drainage water, irrigation rate, weather variables, potato yield and quality parameters, and biomass were measured. Compared to the NDNI treatment, the potato yield increase in the other treatments ranged between 15-32% in 2011 and 2-14% in 2012. In 2011, potato yield from FDIR was higher than CDSI (p = 0.011) and NDNI (p = 0.001), and yield from NDIR was higher than NDNI (p = 0.034). In 2012, potato yield was higher in FDIR in comparison to NDNI (p = 0.021). In 2012, the NDIR gave higher dark ends (p = 0.008) compared to other treatments. Under dry conditions, up to 92% of the potato crop water demand could be met by shallow groundwater contribution. Compared to free drainage, controlled drainage was able to lower the nitrate export by 98% (p = 0.033) in 2010 and by 67% (p = 0.076) in 2011, and the phosphate export decreased by 94% (p = 0.0117) in 2010. A major part of the drainage flow and nutrient export took place between April and June in southern Manitoba. DRAINMOD was able to accurately predict the shallow groundwater hydrology for this particular research site.

Le stockage des déchets ménagers ou industriels fait l'objet d'inquiétudes vis à vis du devenir du sous-sol. En effet les déchets stockés génèrent des lixiviats pouvant s'infiltrer dans le sol et contaminer la nappe phréatique. Les sols fins compactés et de très faible perméabilité constituent des matériaux de choix pour réaliser des structures de rétention étanches interdisant la migration des liquides pollués vers des nappes phréatiques. Cependant les valeurs de perméabilité de ces sols mesurées in situ se sont souvent révélées différentes de celles mesurées au laboratoire. De nombreuses études ont été effectuées pour comprendre ces écarts mais la grande variété des procédures d'essais et des appareils utilisés s'est ajoutée à la complexité du problème. En plus ces différents sols sont le plus souvent non saturés. Comme la conductivité hydraulique est reliée au degré de saturation il est indispensable de connaitre la relation qui les relie. Cette étude nous a permis de mettre en évidence les problèmes lies à l'utilisation des appareils de mesure de perméabilité et à l'interprétation des essais. Les modifications apportées aux appareils ont permis de remédier à ces problèmes et d'améliorer les procédures d'essais. Des méthodes d'interprétation tenant compte de l'effet de succion ont été proposées et appliquées aux différents essais. Les résultats ont montré l'importance de ce paramètre pendant l'écoulement de l'eau.

Population increases and climate change are expected to increase water stress in the semi-arid Okanagan Valley in the Interior of British Columbia. Groundwater discharge from the largest unconsolidated aquifer system in the Okanagan Valley to Okanagan Lake was directly measured between September 2011 and August 2013. Seepage meter measurements (331) and gradient calculations (73) were used to measure flow from the Kelowna aquifers in an effort to constrain groundwater values in a basin-scale water-balance model constructed to inform water use and planning decisions within the Okanagan Valley. The complexity of the subsurface environment in the Kelowna area led to the construction of a 2-D MODFLOW transect to provide a sensitivity analysis of the percentage of total flow captured within the study area using a reasonable range of hydraulic conductivity values for the known confining and confined layers. Forty-two MODFLOW scenarios estimated 26% - 100% of the total flow from the Kelowna aquifers to Okanagan Lake was captured within the study area. Long-term station seepage meter measurements showed a large range of annual variabil^ity with flux measurements which ranged from 10-¹¹ to 10-⁹/10-⁸ m³/m²/s. A substantial reduction in flows observed within the study area between study year one (4.1 x 10⁵ m³) and study year two (2.9 x 10⁵ m³) was potentially due to anthropogenic water extractions. The annual groundwater discharge estimate of 3.7 x 10⁵ m³ found flow from the Kelowna aquifers to be less than one percent of some previous estimates and likely less than seven percent of the volume being extracted from upgradient aquifers. Long-term provincial potentiometric monitoring indicated groundwater pumping rates have likely exceeded recharge in some Kelowna aquifers for the past 34 years. Other studies using modelling and geochemistry have suggested groundwater pumping is inducing recharge from adjacent fluvial water bodies in some areas. The low discharge from the Kelowna aquifers to Okanagan Lake suggests cautious groundwater extraction rates need to be established in the Kelowna area to ensure the groundwater system can continue to support both human and environmental water needs.
Irving K. Barber School of Arts and Sciences (Okanagan)
Earth and Environmental Sciences, Department of (Okanagan)
Graduate

In subhumid to arid climates throughout the world, recharge to groundwater in urban areas is often found to be higher than pre-urbanization rates, despite an increased percentage of impermeable surfaces. Groundwater recharge in the city of Lethbridge is substantially higher than recharge rates prior to urbanization, resulting in the formation of perched water table conditions. High perched water table conditions, typically at depths between one and 2.5 metres, have created problems for the City and University of Lethbridge, including the increased occurrence of slope failures along nearby coulees. This study estimates of the volume of excess water available for groundwater recharge through the practices of urban turfgrass irrigation, and water storage. Between May and September, 1990-1996 irrigation was applied far above evapotranspiration demands, resulting in large volumes of water available for groundwater recharge in the Varsity Village subdivision of the City of Lethbridge. The relationship between the amount of water applied and the development of perched water table systems was strong enough that equations between inputs and water table depth could be derived, and used to predict water table elevation.
xiii, 190 leaves : ill., maps ; 28 cm.

Many abandoned mines in the United States are littered with waste metals that leach into watersheds and degrade habitats. Although metals-laden waters may appear pristine, fish bioaccumulate high concentrations of metals in their tissues, which create health risks if consumed by humans. This study examines the source and fate of metals in Bayhorse Creek near the abandoned Ramshorn mine outside of Challis, Idaho. In 2003, the U.S. Geological Survey found high levels of arsenic, cadmium, chromium, copper, lead, silver, and zinc in soils adjacent to the tailings pile. The Idaho Department of Environmental Quality authorized remediation to begin in summer 2011 without fully comprehending the source and fate of contaminants into the creek. Metals loads were determined along the reach of Bayhorse Creek adjacent to the mine by measuring the flow rates of streams and groundwater seeps, and collecting water samples for chemical analysis. The chemical controls on metals mobility and attenuation in the surface and groundwater at the site were determined by computer modeling, a diffuse double-layer surface complexation model and the geochemical program PHREEQC. Dissolved and suspended arsenic, copper, iron, manganese, lead, and zinc load the creek. The lowest site along the creek consistently measured as the highest load. Arsenic, copper, and lead loads were relatively insignificant compared to iron and manganese. The results indicate that 47% or more of the iron and manganese travel as metal-oxides, and arsenic and zinc tend to sorb to ferrous oxides. Large metals fluxes between SW-1 and SW-5 and at SW-8 suggest tailings and waste rock located between SW-1 and SW-5 and the slag pile adjacent to SW-8 are the main sources of metals contamination. Concentrations below the EPA drinking water standards and the absence of acidic pH indicate that the main metals loading consists of safe levels of iron, manganese, and zinc.

Thesis (Ph. D.)--Dept. of Geosciences and Dept. of Chemistry. University of Missouri--Kansas City, 2005.
"A dissertation in geosciences and chemistry." Advisor: James B. Murowchick. Typescript. Vita. Description based on contents viewed June 26, 2006; title from "catalog record" of the print edition. Includes bibliographical references (leaves 227-245). Online version of the print edition.

Groundwater is considered a reliable resource, relatively insensitive to seasonal or even multi-year climatic variation, however quantifying aquifer-scale estimates of stress in diverse hydrologic environments is particularly difficult due to data scarcity and the limited number of techniques in deriving stress parameters, such as use and availability, which can be applied over a large spatial area. The scope of this project is to derive aquifer-scale estimates of annual volumes for groundwater withdrawal, recharge, and groundwater’s contribution to environmental flows as a means to provide screening level estimates of aquifer-scale stress using the groundwater footprint. British Columbia (BC) has mapped and classified more than 1100 aquifers, but the level of development for each aquifer has always been subjectively based on well density or the anecdotal knowledge of groundwater use. Sectoral groundwater use is critical for local regions and aquifer-scale groundwater stress studies which are significantly impacted by changes in the groundwater use nominator. Results suggest that BC uses a total of ~562 million cubic meters of groundwater annually. The largest annual groundwater use by major sectors is agriculture (38%), finfish aquaculture (21%), industrial (16%), municipal water distribution systems (15%), and domestic private well users (11%). Estimating recharge uses multi-scale methods to examine the recharge mechanisms and provide a more reliable recharge estimate in complex mountainous terrain. Local-scale recharge was estimated using the water table fluctuation (WTF) method outlined by Cuthbert (2014). Aquifer-scale recharge was quantified using a quasi-2D water balance model and generalized aquifer parameters of soil and aquifer material, regional climate, and water table depth. Regional scale aquifer recharge was attributed the areal average recharge flux modelled by the global hydrologic model, PCR-GLOBWB. Results show that generally recharge predictably varies with precipitation and that the average recharge is 791 mm for the local-scale method, 462 mm (32% of precipitation) for the aquifer-scale and 393 mm (33%) for the global hydrologic model. This study estimates groundwater’s contribution to environmental flows across the province for this first time using two separate approaches. The first approach uses the groundwater presumptive standard, which is a general standard for managing groundwater pumping. The second method introduces a novel approach for estimating the contribution of groundwater to environmental flows using the existing environmental flow needs framework and an understanding of low flow zone hydrology. In general, both methods show larger contributions from groundwater to environmental flows in the Lower Mainland and southern Vancouver Island compared to the Interior. For each aquifer, the groundwater footprint (expressed as the unitless ratio of groundwater footprint to aquifer area) is calculated four times; using results from each of the two methods used to estimate recharge and each of the two methods used to estimate the groundwater contribution to environmental flows. Of the unconfined aquifers (n = 404) in the province, 43 aquifers (11%) are stressed with high certainty, 32 aquifers (8%) are stressed with low certainty, 296 aquifers (70%) are less stressed, and 29 aquifers (11%) were not included due to missing parameters or issues where modelled recharge was less than environmental flows.
Graduate
2019-10-25

How much groundwater flows to boreal streams depends on the relative contributions from each landscape unit (forested uplands, lakes, and peatlands) within a catchment along with its hydrogeologic setting. Although there is an understanding of the hydrologic processes that regulate groundwater outputs from individual landscape units to their underlying aquifers (both coarse- and fine-textured) in the boreal forest, less understood is how the topography, typology, and topology (i.e. hydrologic connectivity) of the landscape units regulates groundwater flow to streams. Improved understanding of groundwater-stream interactions in the Boreal Plain of Alberta and Saskatchewan is critical as this region is undergoing substantial environmental change from land cover disturbances for energy and forestry industries and climate change. This thesis determines groundwater-stream interactions during the autumn low-flow period in a 97 km2 glacial outwash sub-catchment of White Gull Creek Research Basin, Boreal Ecosystem Research and Modelling Site, Saskatchewan. The catchment (Pine Fen Creek) is comprised of a large (30 km2) valley-bottom peatland, two lakes, and jack pine (Pinus banksiana) uplands. The pine uplands are important areas of annual groundwater recharge for the catchment. Vertical hydraulic gradients (VHGs) show frequent flow reversals between the lakes and sand aquifer, and spatially diverse VHGs between the peatland and sand aquifer. Groundwater flow nets and lateral hydraulic gradients indicate the stream receives groundwater along its length. Isotopic samples of end members corroborate the hydrometric data. Catchment streamflow response during the 2011 low flow period was not simply the addition of net groundwater inputs from each landscape unit. Instead, the large size, valley-bottom position, and short water ‘memory’ of the peatland were the critical factors in regulation of catchment streamflow during low flow periods. Peatland hydrologic function alternated between a source and sink of runoff (surface and subsurface) to the stream, dependent on the position of the water table; a value of 0.15 m below peat surface was the critical functional tipping point. Given the high percentage of peatlands (21%) within the Boreal Plain, incorporating their runoff threshold is required in parameterizing runoff generation in hydrological models, and thus predicting impacts of peatland degradation and forest clearing on streamflow.

Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia
This study was made to provide a better knowledge of the hazard of groundwater resources to pesticides, in agricultural ecosystems, mainly in maize and potato irrigated areas inserted in North Vulnerable zone of Tejo. The studies were developed in areas of high vulnerability to groundwater contamination. Surface and groundwater resources are intimately connected, with changes in one affecting the other. Due to the importance of the integration of ground and surface water, sampling was performed in Almonda river and “Dique dos Vinte” marsh. The registered pesticides for the main crops in the region were selected and considered to environmental modeling (model of Mackay, Bacci & Gaggi, GUS and EPRIP indices). Of the 26 pesticides and metabolites tested, three were detected in the both natural resources: atrazine, alachlor, metolachlor, reaching a maximum concentration of 0.28, 1.73 and 0.21μg/L respectively. Ecotoxicological tests were performed with the Vibrio fischeri, Pseudokirchneriella subcapitata, Daphnia magna and Chironomus riparius aquatic organisms. Toxicity effects were observed in the both natural resources. P. subcapitata was the most sensitive organism followed D. magna. This study highlights the need for a more conscientious management of the factors which determine the contamination of water resources with pesticides.

Surface water and groundwater interactions are inherently complex because they occur across a range of spatial and temporal scales. This thesis envisages to improve our understanding of surface water and groundwater in the partially natural and human influenced environment of the Cauvery River Basin (CRB), which will contribute towards a better and efficient managing of water resources in a sustainable way. The primary objective of the thesis is to solve some open ended questions pertaining to the seasonality of stable isotope (δD, δ18O) variation within the Cauvery River Basin (CRB) with the aim to characterize the relative contribution of surface water and groundwater to the streamflow by using a two-component mixing model. Secondary objective is to evaluate the sources of dissolved inorganic carbon isotope (δ13CDIC) ratios of the Cauvery River and its tributaries within the CRB where the lithology is dominated by a silicate basement in the upper and middle reaches and a carbonate basement in the lower reaches. The study also investigates the major-ion chemistry of river water to quantify the silicate weathering rates (SWR) within the Cauvery River Basin (CRB) over spatial and temporal scales. Sampling was done from 2014 to 2016 which resulted in six seasonal datasets of river water along with measurement of groundwater (GW) composition, comprising of three seasonal datasets. The stable isotope (δD, δ18O) measurement recorded a negative seasonal shift in the river water isotopic composition of 8‰ for δD and 0.95‰ for δ18O between Pre-Monsoon (PM) and South-West Monsoon (SWM) seasons which can be ascribed due to different moisture iii sources during the SWM season and enhanced evaporation from the KRS reservoir during the PM season. The results from the two-component mixing model suggest that groundwater contribution to the stream flow during the PM season was ~57 ± 4% whereas surface runoff serves as the primary component with ~53 ± 7% contribution during the SWM season. The seasonal patterns were distinct with the PM season recorded lighter δ13CDIC value of −9.9 ± 2.8‰ and the SWM season with relatively heavier δ13CDIC value of −5.1 ± 2.0‰. This large seasonal variation (≈4.8‰) in the dissolved inorganic carbon isotope composition (δ13CDIC) of the Cauvery River is due to the release of CO2 with charnockite degassing in the headwater region. However, in the lower reaches of the Cauvery River dissolution of carbonate minerals still occurs due to high runoff during the SWM season. Published datasets were used for atmospheric and anthropogenic corrections were applied to the major ion datasets. Atmospheric deposition can either be in the form of wet (rainfall) or dry (dustfall) whereas anthropogenic correction was applied to negate the effect of anthropogenic induced pollution levels which are higher in the semi-arid zone of the Cauvery Basin including the excess contribution of Cl- and Na+ ions from salt affected saline soils. It was observed that sodium (Na+) was the dominant ion (in meq/l) during the PM season whereas bicarbonate (HCO3 -) was the dominant ion during SWM season followed by magnesium (Mg2+) and calcium (Ca2+). Silicate weathering rates (SWR) in the Cauvery River Basin and its flux to the ocean also varied seasonally as well as along the stream length. A iv gauging site at Kudige, located in the Western Ghats recorded high SWR of 11.48 ± 0.15 t/km2/y and 45.43 ± 1.57 t/km2/y during the PM and SWM season respectively whereas, terminal site at Musuri, located near the Cauvery delta recorded SWR of 2.83 ± 0.22 t/km2/y and 5.94 ± 0.09 t/km2/y during the PM and SWM respectively. These high silicate weathering rates especially during the SWM can be explained by the proximity of the gauging site to Western Ghat Mountains which record high rainfall and runoff, large diurnal temperature variability and lush vegetation, are the factors that contribute towards intense silicate weathering in the Western Ghats.
Ministry of Earth Sciences (MoES)

碩士
國立中興大學
土壤環境科學系所
100
Use hydrogen and oxygen isotopes as a natural tracer to find how the groundwater bonding to the Jing Mei Creek and identify the source of spring pit in Jing Mei Creek. This study chooses three seasons to analyze. It is August of 2009 (summer), January of 2010 (winter), and May of 2010 (spring).Kind of the samples includes: stream, hole water of stream and hole water of spring pit. According to hydrogen and oxygen composition isotopes between the hole water of spring pit and stream, can be divided into three kinds of spring pits. The typeⅠ, its hole water''s isotope composition lighter than stream, infer that it came from the catchment area of the high altitude about 700m. The typeⅡ,the isotopes composition of hole water of spring pits is similar to the stream, means there is no groundwater to gush out , or the hole waters are not be caused by groundwater, such as due to activity of the fish. The typeⅢ, its isotope composition in hole water is heavier than stream, infer its groundwater came from the rain of the surface of Jing Mei Creek. Analyzing each types of the relative frequency in all the hole, it find that the typeⅡ is the most. These data suggest that the spring pits of Jing Mei Creek to be part of typeⅡ roughly. To calculate the percentage contribution of groundwater to Jing Mei Creek, using three component of the point method to the result of the summer when the groundwatercontribution to stream on Jing Mei about 27% in the winter can not have reasonable results, the springgroundwater contribution of about 34 % Jingmei Creek are the foothills of the groundwater contribution to the range area, inferred from the east due to the infiltration of surface water from the mountains; in the spring than in summer the proportion of groundwater contribution to thehigher summer rainfall, although many may be, but mostly heavy rain, the soil is easy to reach saturation infiltrationrate slows down, resulting in runoff volume, less the proportion of groundwater contribution, winter can not estimate the contribution of groundwater, because there is no winter springs pits appear, and the endpoint can’t have accurate source.

Thesis (M.S.)--University of Wisconsin--Madison, 2002.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 72-73).

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%.
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Previous studies have shown that municipal water can provide a substantial surface water and groundwater recharge source for the Edwards aquifer in central Texas. Knowledge of how water sources to urban watersheds change with urbanization is essential for sustainable water resource management. The range for 87Sr/86Sr values for Austin municipal water (0.7086–0.7094) is distinct from that of naturally occurring phreatic groundwater (0.7076-0.7079) and stream discharge in many rural watersheds (0.7077– 0.7084). Many streams in urbanized Austin watersheds have elevated 87Sr/86Sr values (0.7085–0.7088) relative to these rural streams. These differences demonstrate the potential for Sr isotopes to serve as a tracer of municipal water inputs to urban streamflow. A few urban streams and springs, however, have 87Sr/86Sr values higher than those of municipal water. Soil is the likely source of these elevated values. Spatial variability in the distribution of high 87Sr/86Sr soil and temporal variability in soil-exchangeable Sr contributions to groundwater may result in naturally high streamflow 87Sr/86Sr values, making the identification and quantification of municipal water as a streamflow source using Sr isotopes unreliable in some instances. Temporal variability in climatic conditions and resulting changes in effective moisture can result in distinct natural groundwater 87Sr/86Sr and Mg/Ca ratio variations, due to differences in overall groundwater residence times and water-rock interaction. Unlike natural water sources, municipal water inputs to urban watersheds peak during the summer (and periods of drought) when natural recharge inputs (precipitation) are minimal or nonexistent. Thus, proportions of natural vs. municipal water sources in the streamflow of some highly urbanized streams vary seasonally, resulting in distinct 87Sr/86Sr and Mg/Ca temporal trends, based on the recharge source. In some urban watersheds, municipal water appears to be a significant streamflow component during dry periods. However, temporal variation in natural Sr inputs to vadose and phreatic groundwater may result in the overestimation of municipal water contributions to streamflow and groundwater recharge during relatively wet periods.
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Hillslope mechanisms and processes are a complex and dynamic set of interactions, but are nevertheless vital components of hydrology due to their critical interactions with surface and groundwater (Lorentz, 2001a). In order to observe and quantify these flow generating mechanisms, the Weatherley subcatchment was selected where the components of streamflow generation have been studied and can be quantified separately. Surface, shallow subsurface and the deeper groundwater interactions are particularly important when quantifying runoff generation from within hillslope, riparian and wetland zones as they are the dominant runoff generating zones within the Weatherley catchment. These components of flow are important to quantify for the further study of flow generation mechanisms, their dynamics and fluxes at the hillslope and small catchment scale, low flow contributions, climate change as well as the consequences of land use change (Lorentz, 2001b). Transfer functions were found to be the best adaptation of hydrograph separation for distributed hydrological modelling purposes when attempting to quantify the various streamflow hydrograph components. In this study, the runoff components were simulated along transects using the HYDRUS-2D model, where the simulated soil water dynamics are compared with the observed tensions and water contents at different depths within the soil profile in order to quantify the contributing hillslope fluxes to streamflow generation. The 2001 data set was used with the rainfall and potential evapotranspiration data being converted into rates according to the breakpoint rainfall data. The HYDRUS-2D modelling exercise is performed to calculate the variety of flux rates (timing and quantities) within the subcatchment, so that the overall stream hydrograph can be properly deduced when modelling this catchment with transfer functions in the future. An understanding of the driving forces as well as the behaviour of sources and flow paths was extracted from this thesis, along with gaining some knowledge about the mechanisms and behaviour of streamflow generating mechanisms at the hillslope and small catchment scale. Troch et al (2003) clearly encapsulates the essence of modern day catchment hydrology in stating that hillslope response to rainfall remains one of the most central problems of catchment hydrology in order to quantify catchment responses. The processes whereby rainfall becomes runoff continue to be difficult to quantify and conceptualise (Uhlenbrook et al., 2003) and this is because the characterisation of subsurface water flow components is one of the most complex and challenging tasks in the study of the hydrologic cycle (Achet et al., 2002). Since trying to understand the temporal and spatial variability of moisture content and the subsurface flow mechanisms is a complicated problem (Achet et al., 2002), an attempt is made in this thesis to gain insights into the temporal and spatial variability of soil tensions and soil moisture content at various depths on hillslope transects by combining modelling exercises with field observations. From this modelling, the hillslope water balance and contributing fluxes are derived in effort to augment, at a later stage, the hillslope response functions.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

Indiana University-Purdue University Indianapolis (IUPUI)
Non-rainfall waters such as fog and dew are considered as important source of water in drylands, and the knowledge of possible sources of its formation is very important to make future predictions. Prior studies have suggested the presence of radiation fog in drylands; however, its formation mechanism still remains unclear. There have been earlier studies on the effects of fog on soil moisture dynamics and groundwater recharge. On the contrary, no research has yet been conducted to understand the contribution of soil moisture and groundwater to fog formation. This study, therefore, for the first time intends to examine such possibility in a fog-dominated dryland ecosystem, the Namib Desert. The study was conducted at three sites representing two different land forms (sand dunes and gravel plains) in the Namib Desert. This thesis is divided into two parts: the first part examines evidences of fog formation through water vapor movement using field observations, and the second part simulates water vapor transport using HYDRUS-1D model. In the first part of the study, soil moisture, soil temperature and air temperature data were analyzed, and the relationships between these variables were taken as one of the key indicators for the linkage between soil water and fog formation. The analysis showed that increase in soil moisture generally corresponds to similar increase in air or soil temperature near the soil surface, which implied that variation in soil moisture might be the result of water vapor movement (evaporated soil moisture or groundwater) from lower depths to the soil surface. In the second part of the study, surface fluxes of water vapor were simulated using the HYDRUS-1D model to explore whether the available surface flux was sufficient to support fog formation. The actual surface flux and cumulative evaporation obtained from the model showed positive surface fluxes of water vapor. Based on the field observations and the HYDRUS-1D model results, it can be concluded that water vapor from soil layers and groundwater is transported through the vadose zone to the surface and this water vapor likely contributes to the formation of non-rainfall waters in fog-dominated drylands, like the Namib Desert.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
This study focused on the evaluation of how the traditional agricultural practices, namely pesticide application, are affecting the quality of ground and surface water, in vineyard ecosystems inserted in Alentejo, Portugal. The methodology adopted, following in an integrated approach, involved field and laboratory work, as well as an ecotoxicological characterisation, using environmental exposure models and environmental indicators. Every pesticide used in Portuguese vineyards was characterized, taking into account their physical-chemical properties, predicted environmental distribution, leaching potential, as well as the toxic effects to several organisms. This information aims to contribute to support decision making, in pesticide selection, considering vineyard ecosystems specific characteristics. To evaluate water exposure to pesticides, SPME and GC-MS techniques were adopted. Pesticides were detected in 10% of groundwater samples, and in 53% of surface water samples. The most frequently detected pesticide was terbuthylazine, with a maximum level of 0,24 μg/L in groundwater, and 4,50 μg/L in surface water. Microbiotests were used to evaluate toxic effects on Pseudokirchneriella subcapitata (algae) and Daphnia magna (crustacean). For both organisms selected, a maximum toxic effect of 100% was observed, in ground and surface water samples.