Hydrogeological Practice Research Articles

Solution of filtration problems of construction geotechnology in thin water layers

Filtration problems of construction geotechnics during water movement in thin permeable layers of soils and artificial materials are considered. Under such conditions, traditional approaches borrowed from classical hydrogeology give errors. This is due to the fact that under normal conditions of underground aquifers of a sufficiently large depth, in hydrogeological practice, the hydraulic theory of filtration is used, in which the velocities of filtration currents are averaged along the vertical coordinate. The original nonlinear differential equations of filtration flows are subjected to forced linearization by one or another known method. In this case, the method of linearization by introducing the average power (depth) of the filtration flow is widely used. This method was originally developed for aquifers of great depth. In the presented work, an attempt was made to abandon such a linearization and solve some of the problems of unsteady filtration flows in thin aquifers, which are characteristic of building geotechnics, with obtaining analytical solutions of the final form without introducing artificial simplifications. A methodology is proposed for combining analytical and numerical methods in the process of finding solutions to filtration problems of construction geotechnics with obtaining self-similar dependencies. This approach will make it possible to avoid linearization errors and carry out filtration calculations in thin permeable layers of soils and artificial materials more accurately. A review of domestic and foreign scientific publications on the topic of research has shown some stagnation in this direction. The comparison revealed that in thin permeable layers of soils and artificial materials, preference can be given to filtration calculations using the presented method, since it more accurately describes the non-stationary movement of water in construction geotechnics.

Geological and tectonic preconditions for hydraulic heterogeneity of the rocks in the area of the Gotse Delchev valley

Hydrogeological conditions largely depend on the permeability of the geological environment. In areas with complex geological and tectonic conditions, the detection of hydraulic heterogeneity of the rocks and determination of groundwater-rich zones is a challenge for hydrogeological practice. The aim of the study is to analyze the geological and tectonic prerequisites for hydraulic heterogeneity of the sediments for the Gotse Delchev valley (Southwestern Bulgaria), which predetermine the degree of their water productivity. In order to obtain more precise data for specific sites, a geophysical survey was conducted. The Self-Potential method was chosen, which is one of the most commonly used techniques for applications for hydrogeological purposes. The results of the geophysical survey carried out in selected sites allowed to locate groundwater-rich zones, to establish the depth of occurrence of hard low permeable rocks, as well as to confirm the presence of faults.

Numerically enhanced conceptual modelling (NECoM) applied to the Malta Mean Sea Level Aquifer

Conventional hydrogeological practice is to formulate a conceptual model, which is often the basis of a numerical model. The numerical model is then used to test groundwater management strategies. A workflow is proposed, employing the numerically enhanced conceptual model (NECoM) of the Mean Sea Level Aquifer (MSLA) on the island of Malta. The Malta MSLA is overexploited and under threat of salinization. Data (heads, chloride concentrations, electrical conductivity logs, tidal tests and qualitative analyses) were assimilated into a fast-running numerical model. Simultaneously, strategies for optimal acquisition of further data were examined through the modelling process. The model was delivered through the Energy and Water Agency, with suggestions for flexible model deployment. These workflows will, hopefully, spawn model improvements through further revision of the base concepts. The model allows the agency to make predictions, which have uncertainties that are quantified and reduced through data assimilation as new data become available. Contemplated management plans can therefore be properly assessed before implementation. The proposed NECoM approach can be generalized since it bases model usage on the premise that modelling should make maximum use of existing data by assimilating its information content, thereby highlighting the uncertainties of decision-critical predictions that remain because of data insufficiency. Thus, the presently disjointed process of modelling on the one hand, and data acquisition on the other, can be better aligned. Conceptual and numerical model development become parallel, rather than sequential, activities. Together, they enable predictions of future system behaviour for which bias is reduced and uncertainties quantified.

Filtration of the underground water to the workings of a large diameter

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Collected Rain Water as Cost-Efficient Source for Aquifer Tracer Testing.

Locally collected precipitation water can be actively used as a groundwater tracer solution based on four inherent tracer signals: electrical conductivity, stable isotopic signatures of deuterium [δ2 H], oxygen-18 [δ18 O], and heat, which all may strongly differ from the corresponding background values in the tested groundwater. In hydrogeological practice, a tracer test is one of the most important methods for determining subsurface connections or field parameters, such as porosity, dispersivity, diffusion coefficient, groundwater flow velocity, or flow direction. A common problem is the choice of tracer and the corresponding permission by the appropriate authorities. This problem intensifies where tracer tests are conducted in vulnerable conservation or water protection areas (e.g., around drinking water wells). The use of (if required treated) precipitation as an elemental groundwater tracer is a practical solution for this problem, as it does not introduce foreign matters into the aquifer system, which may contribute positively to the permission delivery. Before tracer application, the natural variations of the participating end members' tracer signals have to be evaluated locally. To obtain a sufficient volume of tracer solution, precipitation can be collected as rain using a detached, large-scale rain collector, which will be independent from possibly existing surfaces like roofs or drained areas. The collected precipitation is then stored prior to a tracer experiment.

INFILTRATION, EFFECTIVE POROSITY, TRANSMISSIBILITY AND CRITICAL YIELD OF WATER WELLS IN THE CARBONATE FISSURED AQUIFERS OF ATTICA – A CONTRIBUTION TO THE REGIONAL AND MANAGERIAL HYDROGEOLOGY

In the hydrogeological practice and the groundwater resources management the accurate knowledge on the infiltration, effective porosity, transmissibility, and on the sustainable yield of water wells is of fundamental value. It is so, because these parameters are the information primarily required in prediction and decisions relevant to the ground water abstractions and the hydrogeological evaluation of specific sites. In this paper, we present these quantities from the carbonate fissured formations of Attica, non metamorphic (limestones, dolomitic limestones, dolomites ) and metamorphic (marbles), which all are of great areal extent and thus of great interest for groundwater exploitation. In addition, they show good geomorphological, structural and lithologic resemblance with analogous formations elsewhere in this country, so that figures calculated can be reliably transferred for use. In our work we used methods of increased reliability, and having known precipitation (P) we estimated — The Infiltration Index (Ic) from the yield of springs of well defined hydrogeological catchments (natural lysimeters) and results found fall in the range of values 0.38P < Ic < 0.42P — The Effective Porosity (pe), obviously secondary because of the nature of the carbonate aquifers ( fissure flow aquifers ). We calculated it from groundwater level hydrograph and values found are in between 1.31%< pe < 6.91% with the most common in between 1.58%< pe < 4.8% — The Transmissibility (T), we calculated from pumping tests, with Jacob method, using semilogarithmic plots of drawdowns (s) versus time (t) from start of pumping. Values found are mostly (70%)in the range 10m3 /h.m < T < 75m3 /h.m — The Critical Yield (Qc) of water wells we calculated from the “characteristic well curve” Q vs. s (with Q and s standing for yield and drawdown respectively). Values are mostly in between 15m3 /h < Qc <75 m3 /h. Cretaceous limestones showed the best of the parameters, followed by the marbles free of schist in- Δελτίο της Ελληνικής Γεωλογικής Εταιρίας, 2010 Bulletin of the Geological Society of Greece, 2010 Πρακτικά 12ου Διεθνούς Συνεδρίου Proceedings of the 12th International Congress Πάτρα, Μάιος 2010 Patras, May, 2010 tercalations and distant from schist boundary . Karstic processes on the fracture network, structures vulnerable to tectonic extension, like anticlines and tension faulting zones are the underlying reasons for better hydrogeologic performance and thus for higher values of the parameters studied. Dolomites outside the previous zones show very low values .

Meeting sustainability and water resources: a dialogue about groundwater science and hydrogeology practice

An impressive dialogue with the Portuguese Hydrogeologist Jose Martins Carvalho, Emeritus Professor of Polytechnic of Porto (IPP), retired Professor of Hydrogeology, professional EuroGeologist (EurGeol.) and European Federation of Geologists (EFG) panel of experts on Hydrogeology, was highlighted in the scope of the thematic issue—Sustainability and Water Resources—in Environmental Earth Sciences journal honouring his long career over the last 50 years. This approach encompassed insights from his life-long outlook acting as a professional hydrogeologist and professor of groundwater science that contributed to the graduation of several generations of geologists and engineers. Moreover, Emeritus Professor J. Martins Carvalho served as mentor to numerous geo-professionals in environmental hydrogeology practice and research.

Book review: 200 Years of British Hydrogeology, by J. D. Mather (ed.) (Geological Society, London, 2004) Geol Soc London Spec Publ 225, 393pp. ISBN 978-1-86239-155-0

The subject book (Mather 2004) is a very well written compendium of papers by various authors on key people and topics, which describe the evolution of the practice of hydrogeology in Great Britain. Summaries of contributions of distinguished hydrogeologists have been published previously, especially contributions from other European countries and America, but none, to the author’s knowledge, are as thorough and detailed as presented in this book about the British hydrogeologists. The book has an overview which nicely summarizes the 24 papers. It appears that the evolution of British hydrogeology essentially had two primary periods. The first was characterized by prominent individuals who made significant contributions, starting with William Smith (1769–1839) who, among other things, showed the relationship of springs to stratigraphy in 1799. Robert Stephenson (1803–1859), an engineer, wrote a hydrogeologic report on the London water supply and accurately described the shape of the cone of depression around a pumped well. The Reverend James Clutterbuck (1801–1885) noted how groundwater pumping affected surface water and saline intrusion beneath London; he is considered the father of English hydrogeology. Joseph Prestwich (1812–1896) apparently was the first to show hydrogeological information on a British geological map; and, John Snow (1813–1858) discovered that cholera was spread by contaminated drinking water. The second primary period in the evolution of British hydrogeology was one in which the majority of the contributions were made primarily through employees of various government organizations, beginning in about 1870 with scientists in the Geological Survey of Great Britain. William Whitaker (1836–1925) was a meticulous compiler of well logs and other groundwater information during his work with the Geological Survey. Whitaker was also involved later in his career as a consultant on proving a source of well pollution using a lithium chloride tracer. Joseph Lucas (1846–1926) is claimed to be the first person to have used the term “hydrogeology” in its modern context, was the first to refer to himself as a hydrogeologist, and drew the first British maps showing groundwater level contours. Lastly, Charles de Rance (1847–1906) produced a book surveying the water supplied to each town and sanitation authority in England and Wales which included a hydrogeological map showing the permeability of the strata. Hydrogeologic research was rather limited in the latter part of the nineteenth century but covered diverse segments, mostly conceptual or empirical in nature, such as intergranular and fracture flow, recharge, water balances, specific yield, and unsaturated flow. Especially intriguing are the solute transport experiments of Issac Roberts in 1879. It was also surprising to learn that the famous British scientist, John Dalton, constructed what was perhaps the first soil lysimeter to quantify infiltration as a percentage of precipitation in 1799, and the results of this work were applied about 90 years later in quantitative assessments of water resource availability. It was not until 1937 that there was a formal water unit within the Geological Survey. In response to major legislation, 1945 began an era of resource assessment. Research, however, within the Geological Survey seems to have begun in earnest after 1963 on aquifer properties, modeling, and hydrogeochemistry including applications to groundwater contamination. Prior to this time, much of the hydrogeological work was more descriptive in nature. Perhaps the most notable British contribution to the entire field of quantitative hydrogeology was from Norman Boulton (1899–1984), a civil engineering professor, who pioneered work in aquifer mechanics. He is best known for his “delayed yield” equations on the behavior of pumped unconfined aquifers. Mather’s book points out Received: 27 March 2009 /Accepted: 12 May 2009 Published online: 23 June 2009

A proposed framework for hydrogeological conceptual modelling

The process whereby hydrogeologists interpret the available information to produce a justifiable set of simplifying assumptions to describe a groundwater system is called conceptual modelling. Although this process is inherent in all hydrogeological assessments and can therefore be regarded as synonymous with hydrogeological practice there are no standard specifications for it. A framework for conceptual modelling has been designed to both assist in the planning and process of the work and to provide an audit trail to facilitate independent scrutiny. The application of this framework is illustrated by two case histories, one of a small-scale investigation for a proposed cemetery and the other of an investigation of the migration of a large-scale sulphate plume in a public supply aquifer. This framework is applicable across the full range of scales of hydrogeological systems, and indeed is readily extendable to other analogous areas of endeavour in the management of natural resources.

Using Synthetic Data and Artificial Wells to Teach the Construction and Use of Water Level Contour Maps

Contour maps that depict groundwater levels (e.g., water table maps and potentiometric surface maps) are essential to the practice of hydrogeology. However, there are significant barriers to effectively teaching students how to create and interpret such maps. Barriers to instruction include the logistics of accessing real wells, assuring that students are provided with a challenging problem, and the lack of a unique solution. We present a new approach that overcomes these barriers through the use of artificial wells and synthetic data. Our approach provides students with a challenging problem that takes them through the whole process, from data collection to interpretation of the resulting maps. In the end, students are able to see how their efforts compare to a known solution, rather than another estimate. Students are also able to choose locations for additional wells that they believe will enhance their ability to create an accurate map. These qualities lead to a substantial improvement in student comprehension over instructional approaches that are based on existing data or limited field measurements.

Hydrogeology – Principles and Practice by Kevin Hiscock , Blackwell Publishing 2005, £34.95, softback. ISBN 0-632-05763-7

Kevin Hiscock has written this text book with the aim of providing an introduction to the principles and practice of hydrogeology and thus explaining the role of groundwater in the aquatic environment. His target audience is undergraduate and graduate students in earth and environmental sciences. The book is clearly written and very well illustrated: the …

Groundwater in Nigeria – a millennium experience – distribution, practice, problems and solutions

Lack of appropriate hydrogeological base maps, poor knowledge of the geology of the Nigerian terrain, lack of infrastructural facilities and absence of a working legislature beset the practice of hydrogeology causing problems in exploration, exploitation, operation, control and management of the abundant groundwater resources of Nigeria.

Principles of Hydrogeology, Second Edition

Hydrogeology is a broadbased field of study, bringing together geology, physics, hydraulics, chemistry, geography, biology, and many branches of engineering. As a result, practicing hydrogeologists come from diverse back‐grounds and must work closely with professionals with skills and experiences different from their own. Thorough understanding of the underlying physical, geological, and chemical principles of hydrogeology is a requisite basis for technical communication among hydrogeologists. A convenient source of working definitions and commonly used parameters is a useful tool for hydrogeologic practice.Principles of Hydrogeology falls somewhere between a complete introduction to the underlying concepts of hydrogeology and a detailed description of hydrogeologic methods. The simplified, schematic figures used throughout the text are clear and readable, well‐suited for use in classroom instruction. Many sample calculations are provided together with tables of useful parameter values. A wide range of topics relevant to the practice of hydrogeology are introduced. Its clarity and brevity will make this book a useful primer for professionals working in fields related to hydrogeology for students at the beginning of their careers, and for hydrogeologic technicians who need an accessible source of definitions of hydrogeologic concepts.

Discussion on ‘Drift deposit influences on the Triassic Sandstone aquifer of NW Lancashire as inferred by hydrochemistry’ by

The authors are to be congratulated on this interesting paper, the implications of which extend beyond purely local considerations. The evident agreement between the hydrochemical data and the earlier geophysical interpretation of the glacial sands (Worthington 1972) supports the integrated use of these diverse techniques in hydrogeological evaluation. Although surface geophysical methods are well proven, they are not universally regarded as established within the framework of hydrogeological practice. If this paper encourages a more general acceptance of hydrogeophysics, it will have served an additional useful purpose. One or two specific points do call for comment. The statement ‘Worthington (1977) records that the aquifer has a predominant intergranular permeability’ is not strictly correct and it therefore seems somewhat inappropriate to label the alleged proposition as ‘contentious’. The basic assertion of the paper cited is immediately evident from the abstract: ‘... the intergranular component of groundwater flow (within the Triassic Sandstone) can vary markedly from place to place and is apparently the predominant mechanism within a sizable area. Elsewhere intergranular flow is supplemented by fissure drainage, and is sometimes relatively insignificant. It is concluded that intergranular permeability exerts a basic control upon abstraction well productivity, with maximum benefits being derived where a comparatively strong intergranular flow is augmented by a well-developed, localized fissure network’. The major point to emerge here is that it is intergranular permeability which appears to exert a fundamental control upon the hydraulic conductivity of the Triassic Sandstone. It is therefore especiallv encouraging to note the agreement between,