Groundwater Professionals Research Articles

Using Expert Participation to Evaluate the Accuracy of Hand-Drawn Water-Table Maps.

Water-table maps are fundamental to hydrogeological studies and a manual, hand-drawn method is still commonly used to produce them. Despite this, the accuracy and variability of such maps have received little attention in international literature. In a unique experiment, 63 groundwater professionals drew water-table equipotential contours based on the same dataset of point measurements and were asked to infer flow directions and predict groundwater elevations at predefined locations. The root mean squared error (RMSE) for the average map calibration data was 10.5 m, which is accuracy comparable to numerical groundwater models. This study confirmed that to produce hand-drawn water-table maps, practitioners seek to not only fit the spatial data, but also to conform to their own cognitive model of hydrogeological concepts and processes. The calibration accuracy increased with experience; from a RMSE of 13.3 m for practitioners with 0-3 years of experience to a RMSE of 9.2 m for those with four or more years. Despite considerable variability in the style of the hand-drawn water-table maps, the maps were consistent in their representation of the dominant regional groundwater flow directions. There was less consensus, however, in predicting the direction of surface water-groundwater interaction for a stream reach. Hand-drawn water-table mapping remains useful and valid, especially as a starting point for hydrogeological conceptualization, yet further work is required to resolve issues around transparency, repeatability, and reproducibility.

Modeling Dissolution of Soluble Compounds from Multi-Component NAPL Using a Desorption Approximation.

Groundwater professionals require methods to estimate the potential time required to achieve remedial goals, including locations within and downgradient of zones containing non-aqueous phase liquids (NAPLs). NAPLs have long been recognized as persistent contaminant sources to groundwater. Dissolution of multi-component NAPLs is particularly complex, and numerical models that explicitly simulate it are not widely available. This study introduces an equilibrium partitioning approximation to simulate the dissolution of the most soluble chemical components from multi-component NAPL containing a significant fraction of relatively insoluble mass. The effective distribution coefficient that describes depletion of a specific compound from NAPL is estimated based on the properties of the NAPL and the porous medium. This study also presents numerical modeling results that support the utility of the method, with verification using published empirical data collected during dissolution of residual coal tar in a controlled laboratory sand tank experiment. The numerical modeling method uses equilibrium partitioning as an approximation and matched the concentrations of the two most soluble NAPL components in and downgradient of the NAPL zone with reasonable accuracy. The results suggest that the method should be useful for screening level assessments and can be adapted to compare relative groundwater restoration timeframes of select NAPL components for various remedial alternatives.

Modeling PFAS Fate and Transport in Groundwater, with and Without Precursor Transformation.

Groundwater professionals require tools to evaluate a variety of technical issues related to per- and polyfluoroalkyl substances (PFAS). These include the potential impact of PFAS precursors on groundwater plumes of perfluoroalkyl acids (PFAAs). Numerical modeling results show that, by adjusting the mass loading rate, source zones with or without a precursor can produce similar PFAA plumes. However, if a precursor is present, it can impact PFAA plume concentrations and extend PFAA plume durations by decades. Additional research regarding in situ precursor transformation rates-and improvements in source area characterization-will further advance the predictive value of modeling.

On Per- and Polyfluoroalkyl Substances: Suggested Resources and Considerations forGroundwater Professionals.

Per- and polyfluoroalkyl substances, a synthetic class of chemicals comprising thousands of compounds, are receiving increased attention over their presence in the environment, their potential effects on human health, and evolving regulation. This article summarizes suggested resources and key considerations for groundwater professionals wishing to familiarize themselves with this class of compounds. Background information, current groundwater-related regulations, risk considerations, comparison to other groundwater contaminants, and mitigation options are discussed, and a broad selection of references is supplied as a resource.

Cumulative deviation from moving mean precipitation as a proxy for groundwater level variation in Wisconsin

Groundwater management questions often require understanding how water levels respond to precipitation. However, direct observations of precipitation alone rarely explain variation in water levels. This study introduces a modified method for comparing cumulative precipitation anomalies to groundwater level variation. This method transformed gridded monthly precipitation data from 1895 to 2018 into monthly deviations from different moving mean lengths at 90 USGS groundwater monitoring locations in Wisconsin. The precipitation data was then compared to water level variation at each site and correlations were calculated. The average optimal a priori moving mean window length for all sites was identified as 60 months. Fifty-four percent of the monitoring wells were moderately to highly correlated the cumulative deviation from 60-month precipitation and fewer than 30% were uncorrelated. Well depth, aquifer classification and location were tested as potential factors influencing the strength of correlation with groundwater levels and optimal mean length. Aquifer classification had no effect on correlation or optimal moving mean length indicating aquifer response rates are similar in both bedrock and unconsolidated aquifers. Correlation strength was also independent of well location. Well depth and casing in Cambrian/Ordovician formations were the only variables with a weak but statistically significant effect on correlation between the precipitation deviation and water level. This work illustrates how this method can help diagnose factors affecting monitoring well response, identify inconsistencies in a monitoring record and generate hypotheses regarding aquifer response to precipitation. This method leverages easily accessible datasets to serve as a starting point that engineers, groundwater professionals and resources managers can use to generate and test hypotheses about sites without prior knowledge of the geology or aquifer properties, extraction rates, and land cover.

Groundwater modelling using an analytic element method and finite difference method: An insight into Lower Ganga river basin

Groundwater flow modelling provides the water flow dynamics for the estimation and prediction of groundwater movement and its condition in the aquifer. The modelling helps for the management of the groundwater resources under various hydrological and anthropogenic stresses. In this paper, a modelling exercise was performed using the analytic element method (AEM) and finite difference method (FDM) for the part of Ganga river basin which includes the Varanasi district. Further compression was performed to understand the limitations and benefits of both AEM and FDM based on ease of model development, data requirement and their performances. The groundwater model was developed for the transient state condition based on data for the year 2004–2017. The results show that for most of the observed wells, the difference between the observed head and the simulated head is found in the 90% confidence level. It is found that the AEM does not require a fixed boundary condition which makes the development of the conceptual model less complicated. In the FDM, pumping wells are approximately located and averaged over the cell which becomes a cause of the inaccurate location of the wells. It is found that model development in the AEM is less complicated compared to the FDM. It can be concluded that in some cases AEM-based modelling is more accurate as compared to FDM-based flow modelling. This study can be very helpful for groundwater professionals in deciding the best suitable method for their study area and to avoid the complexity of the model.

Water data and the legitimacy deficit: a regulatory review and nationwide survey of challenges considering cumulative environmental effects of coal and coal seam gas developments

ABSTRACTEnvironmental water management in relation to groundwater occurs mainly by controlling groundwater withdrawals under water and environmental assessments and approvals, rather than by actively managing groundwater rights for environmental purposes. Despite apparently close regulation of coal mining and coal seam gas developments, significant public concerns remain regarding the assessment and approval processes that seek to control their cumulative effects on groundwater-dependent ecosystems. This paper analyses a key element of concern: regulatory aspects of water data relevant to assessments and approvals. It outlines a three-part framework for considering requirements for water information in the regulatory context. It then analyses Australian federal legal requirements in relation to water information and data from a new nationwide, exploratory survey of groundwater professionals. Both suggest improved legal measures are required to govern the nature of groundwater data that is produced by governments and proponents, and how and when it is produced.

On Methods for In‐Well Nitrate Monitoring Using Optical Sensors

AbstractOptical sensors are promising for collecting high resolution in‐well groundwater nitrate monitoring data. Traditional well purging methods are labor intensive, can disturb ambient conditions and yield an unknown blend of groundwater in the samples collected, and obtain samples at a limited temporal resolution (i.e., monthly or seasonally). This study evaluated the Submersible Ultraviolet Nitrate Analyzer (SUNA) for in‐well nitrate monitoring through new applications in shallow overburden and fractured bedrock environments. Results indicated that SUNA nitrate‐N concentration measurements during flow cell testing were strongly correlated (R 2 = 0.99) to purged sample concentrations. Vertical profiling of the water column identified distinct zones having different nitrate‐N concentrations in conventional long‐screened overburden wells and open bedrock boreholes. Real‐time remote monitoring revealed dynamic responses in nitrate‐N concentrations following recharge events. The monitoring platform significantly reduced labor requirements for the large amount of data produced. Practitioners should consider using optical sensors for real‐time monitoring if nitrate concentrations are expected to change rapidly, or if a site's physical constraints make traditional sampling programs challenging. This study demonstrates the feasibility of applying the SUNA in shallow overburden and fractured bedrock environments to obtain reliable data, identifies operational challenges encountered, and discusses the range of insights available to groundwater professionals so they will seek to gather high resolution in‐well monitoring data wherever possible.

A B-Spline Framework for Smooth Derivative Computation in Well Test Analysis Using Diagnostic Plots.

In the oil and gas industry, well test analysis using derivative plots, has been the core technique in examining reservoir and well behavior over the last three decades. Recently, diagnostics plots have gained recognition in the field of hydrogeology; however, this tool is still underused by groundwater professionals. The foremost drawback is that the derivative function must be computed from noisy field measurements, usually based on finite-difference schemes, which complicates the analysis. We propose a B-spline framework for smooth derivative computation, referred to as Constrained Quartic B-Splines with Free Knots. The approach presents the following novelties in relation to methodological precedents: (1) the use of automatic equality derivative constraints, (2) a knot removal strategy and (3) the introduction of a Boolean shape parameter that defines the number of initial knots to choose. These can lead to evaluate both simple (manually recorded drawdown measurements) and complex (transducer measured records) datasets. Furthermore, we propose an additional shape preserving smoothing preprocess procedure, as a simple, fast and robust method to deal with extremely noisy signals. Our framework was tested in four pumping tests by comparing the spline derivative with regards to the Bourdet algorithm, and we found that the latter is rather noisy (even for large differentiation intervals) and the second derivative response is basically unreadable. In contrast, the spline first and second derivative led to smoother responses, which are more suitable for interpretation. We concluded that the proposed framework is a welcome contribution to evaluate reliable aquifer tests using derivative-diagnostic plots.

The Yin and Yang of Groundwater

As an early-career geologist in the late 1980s, I went into hydrogeology because there were no jobs in oil or mining, which was where I expected to work. But I did find a job as a field geologist working at drilling sites for water supply, geotechnical characterization, and environmental remediation. The first week on the job a mentor lent me a textbook, Groundwater, and a journal, Ground Water. Practically, the first thing I read was the editorial by R. Allan Freeze titled “Groundwater is Probably One Word (Or Maybe Two), More or Less: An Allegory.” I found the one-word two-word debate mildly interesting, but more importantly at the time, I was astounded that such a detail as the proper spelling of “groundwater” had not been fully worked out in the groundwater community by the time I entered the profession. I figured there might be a little room for me to contribute and decided to pursue groundwater as a career. Even by then, I had felt a bit of a Yin-Yang ring to groundwater. I quickly realized a deeper dualism in groundwater, which is that all groundwater problems require knowledge of both hydrology and geology, which are very different disciplines each with their own unique theories and methods of discovering new knowledge, the Yin and Yang of groundwater. The water and rocks through which it flows impart different but complementary forces that interact and form a dynamic system in which the whole, for example, an aquifer, is greater than the sum of the parts. To better understand the water part of groundwater, I went back to school to study hydrology and became a hydrogeologist. I embarked on a lifelong mission to learn everything there is to know about groundwater. That, obviously, was a very naïve mission. The more I learn the less I know. But there is an even deeper duality in groundwater in that it is almost the perfect combination of theory and practice. As Dr. Molz recently noted (vol. 55, no. 1), “In natural subsurface systems … reality lies outside of the computer and cell phone screens, and we have to stay in touch with that reality. Thus, field experience is more vital than ever.” Amen. A computer model cannot solve problems or discover new knowledge without data, and the results of a hydrogeologic field test such as a well test or tracer study cannot be useful without a sound theoretical foundation. The field data must be combined with theory, and vice versa, to gain insight and solve problems. Thus, the study of groundwater requires equal measures of both theoretical knowledge and real-world data. Hydrogeology is at once cerebral and physical, imaginative and practical, and abstract and hands on. To go from field work one day to computer modeling the next can be inspiring and satisfying, which I suspect is a common attraction for most groundwater professionals. It is this combination of right-brain left-brain thinking, I believe, that is the true essence of groundwater—its Yin and Yang. This leads me to the Technology Spotlight column for which I am the Editor. My vision for this column is to capture, highlight, and amplify this theoretical-practical duality in groundwater. To that end, we will continue to publish reviews of new software and hardware technologies. In addition, to give Groundwater readers the direct access to relevant, interesting nonproprietary technical reports, we will now publish Executive Summaries of such reports in the column. This opens the door for “publication” to groundwater consultants and engineers who have completed an interesting and publicly available technical report that contains an important contribution in the field of hydrogeology, but who do not have the time and resources to develop a full blown peer-reviewed case study paper. The executive summary receives editorial review, but not peer review and the underlying report will be made available as online Supporting Information.

Semi-automated filtering of data outliers to improve spatial analysis of piezometric data

The identification and removal of data outliers remains a major challenge for spatial analysis of piezometric data. In this context, a simple semi-automated procedure for filtering outliers of depth to static water level was developed and used as a part of a regional groundwater-mapping project in the Quebec Metropolitan Community, Quebec, Canada. Following a few basic steps of data control, potential outliers were detected using two simple automated steps: (1) identifying water levels that are deeper than the 99th percentile of a high-reliability dataset compiled by groundwater professionals and assumed to adequately represent depths to static water level, and (2) using moving averages within a search radius of 250 m calculated around each well. All detected potential outliers were visually examined in a geographic information system and compared to neighbouring data before being kept or discarded. To evaluate the efficiency of the procedure, exploratory statistics, histograms and semi-variograms of the initial, intermediate and filtered datasets were compared to the high-reliability dataset. Objective interpolation was then performed using ordinary kriging. A cross-validation analysis showed a less biased and more accurate interpolation after applying the proposed outlier filtering procedure. Qualitative knowledge of the hydrogeological settings is an important component of this procedure which combines advantages of both manual and automated processing, making the procedure adaptive and easy to use. The final outcome of the proposed procedure is an improved interpolation map of depth to static water level along with minimised and low squared estimation errors.

Kresic N, Mikszewski A | Hydrogeological conceptual site models: data analysis and visualization

This book, Hydrogeological Conceptual Site Models: Data Analysis and Visualization, provides the explanation and information related to key concepts in professional hydrogeology for students, practicing groundwater professionals, regulators, communities affected by contaminated sites and/or water supply projects, industrial clients and the public that may be faced with real world hydrogeological issues. These concepts include quantitative spatial data analysis, data visualization and mapping. This book is unique in that it combines new computer techniques and classical exploration methods. Focusing on the main concepts of practical data analysis and visualization strategies, this book by Neven Kresic and Alex Mikszewski fills the gap in hydrogeological literature by identifying and explaining essential techniques. Real life examples are given in each chapter. Following the introductory chapter, there are eight chapters in the book—each containing self-explanatory figures. This visually powerful text covers a significant amount of material and contains hundreds of colored figures and illustrations. The chapters cover various applications in professional hydrogeology as follows: Conceptual Site Model (Chap. 2), Data Management, GIS and GIS Modules and Geographic Information Systems (Chap. 3), Contouring (Chap. 4), Groundwater Modeling (Chap. 5), Three-Dimensional Visualization (Chap. 6), Site Investigation (Chap. 7), Groundwater Remediation (Chap. 8) and Groundwater Supply (Chap. 9). A conceptual site model (CSM) described in this book helps professional hydrogeologists to develop defensible characterization strategies and conclusions. Concepts related to CSM and investigations are presented in Chapters 2 and 7. Data management and contouring being key elements of investigations are discussed well in Chapters 3 and 4, respectively. Chapters 5 and 6 cover at length, the concepts and visualization related to groundwater models and three-dimensional visualization. The integrated water resources (surface water and groundwater) are described in Chapter 9. Both the visualization examples presented throughout the book and the companion DVD help in developing graphs, maps, illustrations and animated examples of modeling results. This serves to provide a clear understanding of the problem through technically viable solutions and conclusions, and in this way to better communicate results and recommendations to both technical and nontechnical professionals. It also assists clients in making informed decisions.

Slug Test in Confined Aquifers, the Over‐Damped Case: Quasi‐Steady Flow Analysis

In the great majority of slug tests performed in wells fully penetrating confined geologic formations, and for over-damped conditions, the response data are evaluated with the transient-flow model of Cooper et al. (1967) when the radial hydraulic conductivity K(r) and the coefficient of specific storage S(s) are to be estimated. That particular analytical solution, however, is computationally involved and awkward to use. Thus, groundwater professionals often use a few pre-prepared type-curves to fit the data by a rough matching procedure, visually or computationally. On the other hand, the method of Hvorslev (1951), which assumes the flow to be quasi-steady, is much simpler but yields only K(r) estimates. In this work, we develop a complete quasi-steady flow model that includes a storage balance inside the aquifer and allows estimating K(r) and S(s) simultaneously, through matching of the well response data to a type-curve. The new model approximates the model of Cooper et al. closely and has the practical advantage that its solution type-curves are generated easily using an electronic spreadsheet, so that the optimal fit of data by a type-curve can be readily automated.

Book review: Estimating Groundwater Recharge, by Richard W Healy (Cambridge University Press, 2010)

Estimating Groundwater Recharge by Richard W. Healy (Healy 2010, with contributions from Bridget R. Scanlon) is an excellent addition to the growing knowledge base of groundwater science and technology. Understanding groundwater recharge is a prerequisite for the meaningful simulation of groundwater flow and transport, and, hence, successful management of renewable water resources. By placing an emphasis on method, this book provides clear concepts of the recharge process and associated methods that stem from more than 800 peer-reviewed references. Estimating Groundwater Recharge is organized into nine relatively concise chapters. It begins with descriptions of the conceptual framework of groundwater recharge and ends with an example of the USA to illustrate how the conceptual models are applied in reality. Chapters 2 through 8 deal with various methods. Theoretical models are combined with cases studies, drawn largely from the research projects undertaken in developed countries. Chapter 2 discusses water-budget methods, a foundation of following methods. Chapter 3 is about the modelling approach, while chapter 4 introduces the methods related to surface-water data. The physical, chemical and heat-tracer methods form chapters 5 through 8, which acknowledge the differences between applications for both the unsaturated and saturated zones. For instance, chapter 5 is dedicated to the physical methods as applied in the unsaturated zone, whereas chapter 6 discusses the same methods but in the saturated context. The organization of chapters in the book does, in some respects, resemble Groundwater Recharge in a Desert Environment: The Southwestern United States edited by Hogan et al. (2004). Perhaps due to the common authorship, some similarities exist. However, Healy’s book offers a comprehensive yet focused treatment in both theoretical and practical aspects through a wealth of cited references. The approach helps to reinforce theoretical concepts and therefore gives it a more modern feel. Introduction of recharge terminology in section 1.2 of the book is helpful, not only for its use as an academic text but also for practical clarity for those who are not necessarily groundwater practitioners. ‘Recharge’ is defined in the book as the downward flow of water reaching the water table, adding to groundwater storage. In fact, adding storage should be seen as an innate part of water arrival at the water table. Depending on the rate of groundwater discharge, the build up of the groundwater storage due to recharge may not necessarily be observed as this storage is conditioned by other factors apart from recharge. Healy rightly points out that the definition excludes water flow to an aquifer from an adjoining groundwater system, which is referred to as interaquifer flow or groundwater underflow. Another interesting term that is expanded upon is ‘base flow’, which is sometimes understood differently between groundwater and surface-water professionals. The groundwater camp would insist that base flow is water that has been discharged from the saturated zone. This is the stated definition in many groundwater books, including this one. In the opposing camp, base flowmay be regarded as all streamflow that is not derived directly from surface runoff. Without proper clarification of the terminology used, confusion may arise as has been experienced during the assessment of the role of base flow in the instream flow requirements required by the national Water Act in South Africa. The conceptual clarification of base flow made in section 4.1.2 of this book is practically valuable for multi-disciplinary research. Like many other hydrogeological phenomena, recharge varies both spatially and temporally, dependent upon the combination of influencing factors such as climate, soils, geology, geomorphology, hydrology, vegetation and land use. Based on the source of data, its availability and the nature of the parameters considered, etc., the book comprehensively documents some 40 methods that can be applied for estimating groundwater recharge in a range of hydrogeological scenarios. A distinction is made between point and integrated values of recharge estimation. Diffuse and focused recharges are also highlighted throughout the text for the readers’ consideration. The concepts used are consistent with those given by popular Received: 24 May 2011 /Accepted: 4 July 2011 Published online: 21 July 2011

An Aquifer Classification System and Geographical Information System‐Based Analysis Tool for Watershed Managers in the Western U.S.1

Payne, Scott M. and William W. Woessner, 2010. An Aquifer Classification System and Geographical Information System‐Based Analysis Tool for Watershed Managers in the Western U.S. Journal of the American Water Resources Association (JAWRA) 46(5):1003‐1023. DOI: 10.1111/j.1752‐1688.2010.00472.xAbstract: Aquifers and groundwater systems can be classified using a variety of independent methods to characterize geologic and hydraulic properties, the degree of connection with surface water, and geochemical conditions. In light of a growing global demand for water, an approach for classifying groundwater systems at the watershed scale is needed. A comprehensive classification system is proposed that combines recognized methods and new approaches. The purpose of classification is to provide groundwater professionals, policy makers, and watershed managers with a widely applicable and repeatable system that reduces sometimes cumbersome complex databases and analyzes to straightforward terminology and graphical representations. The proposed classification system uses basin geology, aquifer productivity, water quality, and the degree of groundwater/surface water connection as classification criteria. The approach is based on literature values, reference databases, and fundamental hydrologic and hydrogeologic principles. The proposed classification system treats dataset completeness as a variable and includes a tiered assessment protocol that depends on the quality and quantity of data. In addition, it assembles and catalogs groundwater information using a consistent set of nomenclature. It is designed to analyze and display results using Geographical Information System mapping tools.

A Watershed in Our Profession

As ground water professionals, we have reached a watershed in our profession. Over the past 50 years, ground water hydrology has developed and matured into a quantitative and sophisticated discipline. The scientific maturity of ground water hydrology is such that researchers are now extending old subject boundaries into interdisciplinary areas such as ground water dependent ecosystems, contaminant biogeochemistry, and societal drivers for ground water use. Are we about to see a gradual deemphasis of ground water skills and decreasing interest as new fields rise to prominence? No, on the contrary; I believe we are just embarking on a path that will reinforce and reinvigorate ground water hydrology as a discipline. In fact, it is likely that our discipline will soon be regarded as fundamental to our very survival. Our world is changing. United Nations statistics show that humans are congregating in urban centers at an astonishing rate. In 1950, the percentage of humanity living in urban centers was 29%; now it is 49% and is expected to reach approximately 60% in the next two decades. Over the same period, global population will climb from 2.5 billion to approximately 8.2 billion, and almost 5 billion people will live in urban centers by 2030. Yet the total amount of accessible fresh water on the earth, held in lakes, rivers, and aquifers, is constant. The United Nations estimates that, currently the global population appropriates 54% of the accessible fresh water, and this fraction will exceed 70% by 2025. With almost 70% of this fresh water demand currently expended on agriculture, it is clear that the amount of accessible fresh water available for domestic use is disturbingly close to a limit. If we assume that the projections are correct, then the need for change in the way we regard our water resource is clear—both quantity and quality are paramount. Even developed nations are now experiencing water shortages, and an estimated 6000 people die each day from drinking contaminated water. Urbanization is not a guarantee of population health. The incredible growth of Asian, African, and South American megacities has generated intractable problems of ground water supply, management, and regulation. As one example, the population of Karachi in Pakistan has grown almost fiftyfold to at least 16 million in the past five decades and the water infrastructure is collapsing. Arsenic and fluoride are found in ground water beneath large areas of densely populated Africa, Asia, and elsewhere, threatening the health of hundreds of millions. In some urban locations, there is rapid transmission of effluents to ground water and potential for hazardous chemical species to persist through the water treatment and disposal trains, thereby increasing in concentration in successive passages through the urban water cycle. Of particular concern here are pharmaceuticals and endocrine disruptors, which may affect a range of life forms at trace concentrations. As fresh water in easily accessible surface water systems is exploited, ground water will become the priority drinking water resource for the future. This simple and expedient choice of water resource will have profound impacts on our relation to water. To use water sustainably in our heavily urbanized future, ground water resources must be protected and managed now through every step of the urban water cycle. Failure to do so may render valuable supplies unusable just when we need them the most. The global call for ground water professionals will only increase. Better identification and characterization of ground water assets will become a growth industry as urban centers proliferate across the world. Application of geospatial characterization techniques from other disciplines may boost productivity and reduce costs associated with this major ground water exploration effort. At the same time, ground water professionals will be required to develop new levels of expertise in assessing ground water quality to secure and manage resources of potable drinking water in heavily urbanized areas where sources of contamination are many and varied. The focus of ground water research will shift from exploitation of supply to sustainability and protection of human and environmental health. Communities around the world will demand high-quality scientific and engineering advice as they deal with the demographic and environmental consequences of expanding urbanization in the face of water limitation. Ground water professionals must be ready to embrace the expanding challenges ahead. This represents a great opportunity for our profession, but the global consequences of failure are unthinkable. It is not a time to be disinterested.

Editors’ Message: the Hydrogeologist Time Capsule — archival video recordings of influential hydrogeologists

If we look back through history, we can all recall scientists and engineers who have made a material difference to the society in which we live. Hydrogeology is no exception. From Henry Darcy to Charles Vernon Theis, from William Smith to Thomas Chrowder Chamberlin, from Jacob Bear to Jozsef Toth, the many achievements of our hydrogeologic ancestors form the very basis for the work we do today as groundwater scientists, engineers, and professionals. But how well do we really know these people and their achievements? It is probably true that we usually know the technical details of the work of these individuals. However, rarely have we gained insights into them as people—to better understand their personal motivations, aspirations, and living philosophies. It is interesting to ponder, even momentarily, upon questions like: What were they like as people? What motivated them? What lead them to make their discoveries? What thoughts did they have about the state of science in their time? What visions did they have for the future of hydrogeology? Science is after all more than just a collection of theories, equations, experiments and journal papers, it is also vitally about people—the scientist who makes a discovery, the hydrogeologist who has a vision or an idea, the inspirational leader who makes a tangible difference to a community, the student who works with a professor in a vibrant research team where science and discovery are infectious. How do we get answers to these often non-technical and perhaps seemingly personal questions? Sometimes, if we are lucky enough, we might find an occasional answer in an original monograph or paper. However, this is usually very unlikely because journal papers and archival records are most often technical documents that do not reveal answers to these fundamental questions. In some cases, we may be able to find either biographical, or even better, autobiographical information—but there are few of these that are widely available. One compelling example can be used to illustrate why searching for our historical roots and getting to know the scientists behind hydrogeologic science is important. Every hydrogeologist, geoscientist and engineer knows Darcy’s Law. For many of us, Darcy’s Law brings to mind his frequently used equation, a column filled with sand, a bundle of manometer tubes, and some flow-rate calculations in aquifers. Discovered in 1856, Darcy’s Law is now hydrogeologic mantra. However, until very recently, we did not know very much about Darcy’s life and the process of his discovery. One often wondered: Did he stumble onto his law? Did he know he had discovered something deeply profound about nature? Did he die not knowing? We did not even know what he looked like, or why his name was spelt Henry Darcy and not Henri d’Arcy. Recently, we have begun to exhibit curiosity about Darcy’s life and science (Freeze 1994; Sharp and Simmons 2005; Simmons 2007). These and other accounts reveal that Darcy was a selfless citizen who was deeply inspired to make a change in this world by building the impressive water distribution system for his native town of Dijon in France. His work transformed a city rid with filth and squalor to one whose water supply was second best only to Rome in Europe by 1840. He waived all fees, which would have amounted to near US $1.5M in today’s currency. Darcy’s life and science has been brought to life through the discovery of old portraits, letters and archival records. Critically, we also learn of the important details of the process of his scientific discovery. We now know with certainty that Darcy suspected his law before he did his now famous column experiments in the unnamed hospital courtyard in Dijon in 1856 (Simmons 2007). He knew his discovery was significant, but he was not surprised by it. Imagine if we could have asked Darcy about his life as an engineer, why research was important to him, and how it was that he came to make a number of major scientific and engineering contributions (outlined in Simmons 2007). Imagine if we could have asked Darcy about the day he plotted his experimental data from his column experiments to find that his experimental data fell Received: 19 November 2007 /Accepted: 22 November 2007 Published online: 19 January 2008

Groundwater Hydrology: Conceptual and computational models by Rushton . Wiley 2003, £60 hardback: 416 pp. ISBN 0-470-85004-3

‘There are many similarities between detective stories and groundwater investigations,’ writes Ken Rushton in the introduction to this book. Continuing with the analogy, he stresses that groundwater studies depend on teamwork, in contrast to many detective stories where the vital breakthrough is usually made by a famous individual. However, this book presents an individual view, based on a lifetime's work on groundwater hydraulics and acknowledging the contribution of numerous co-workers. Groundwater Hydrology summarizes the concepts of groundwater flow and conceptual models, using an approach and examples which are familiar to the many groundwater professionals who are former students or colleagues of the …

An unusual coexistence of sulphate-reducing bacteria and algae in a confined groundwater production system

Abstract An unusual occurrence of the coexistence of algae, oxygen and hydrogen sulphide from sulphate-reducing bacteria (SRB) in an overseas groundwater production system is described that had an interesting origin and some important implications both for groundwater professionals and for the water industry in general. A deep, confined anaerobic groundwater source containing SRBs was being pumped to a new municipal water treatment works by underground pipeline from a wellfield some 3 km distant. Pumping continued at a steady rate of around 70 000 m 3 /d for a period of three months from start-up without significant problems. However, in the fourth month of operation, progressively serious fouling problems appeared in the sand filters that nearly caused a plant shutdown, with the consequent near loss of supply of a major drinking water source for a nearby city. This paper describes the cause of those problems and highlights both the complex chain of events and the biochemical interactions involved, with particular emphasis on the unusual coexistence of SRBs and algae in a groundwater system. This apparent paradox is explained in terms of an unfolding sequence of seemingly unconnected events with a rather surprising origin.

Uncertainty Recognition for Ground Water Professionals

Uncertainty Recognition for Ground Water Professionals