Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 101 - 150 of 795 results

Title	Presenter Name	Presenter Surname	Area Sort descending	Conference year	Keywords
Hydraulic tests of strong artesian boreholes; wellhead construction and test design	Kornelius	Riemann		2015
Abstract Artesian boreholes are a common feature worldwide in confined aquifers, but the hydraulic testing of these boreholes, and estimation of aquifer properties from such tests, still poses a challenge for hydrogeologists. Common hydraulic tests, such as step-drawdown or constant-discharge rate tests require a static water level at the start of the test, and the measurement of drawdown (increasing over time) and abstraction rate (fixed for a period of time). Usually, when undertaking a pumping test in an artesian borehole, the drawdown is measured from ground level, and the drop in hydraulic head between static pressure and ground level is often ignored. This procedure also implies that the starting time of the test is not at the static water level. A constant-head test, set at ground level, is the other option. However, the decrease in flow rate is not only dependent on the hydraulic properties of the aquifer, but also masked by pipe hydraulic effects within the well. This kind of test would also limit the available drawdown to be utilized for the test. Hence, it was required to develop a method for undertaking hydraulic tests in strong artesian boreholes, allowing for the drawdown to fluctuate between levels both above and below ground and avoiding the pitfalls described above. The solution is a specially designed and constructed wellhead for the installation of the pump and monitoring equipment prior to the hydraulic test. The standard tests are slightly modified and are only undertaken after sealing the wellhead and reaching static hydraulic pressure. The recommended wellhead construction and subsequent hydraulic tests were implemented at a strong artesian borehole in the Blossoms Wellfield, south of Oudtshoorn in the Western Cape province of South Africa.
Hydraulic Fracturing Of Coal Bed Methane In The Springbok Flats	Gerrit	van Tonder		2015
Abstract It is estimated that the three coal layers in the Springbok Flats contain about 5 TCF of coal bed methane (CBM). Two sedimentary basins, namely the southern Tuinplaas basin and the northern Roedtan basin, exist with coal layers with a total thickness of 7m which occurs mainly in three mayor seams. The coal layers are located between 20 m to more than 600m. Farmers in the Flats are concerned about the environmental impact of fracking the coal beds. They are mostly worried about the risk of groundwater pollution; the drawdown of the water table and the producing of a bad quality water during the mining process. They set up an EPA for the Springbok Flats in 2010 and until now, they have stopped more than 6 companies to conducted exploration (stopped strictly on account of the different laws in SA that were not adhered too). On average, 1000 liters of water is produced for every 2000 cubic feet coal bed methane mined in the USA. The quality of the produced water is not good (with typical Na values of more than 5 000 mg/l) and cannot be used for irrigation purposes. It is thus expected that about 500 million m3 of bad quality water will be produced for every 1 TCF mined in the Flats. This groundwater will be removed from the system and it is expected that a drawdown of up to 30m will be evident at places in the Springbok Flats. There are also a large number of dykes and faults in the Flats which imply that the upward movement of methane and water will be very probable after abandonment of each coal methane well.
Groundwater In Sustainable Development Goal 6: The South African Case Study	Sivashni	Naicker		2019	Domesticate, South Africa, United Nations
Abstract South Africa has committed to achieving the United Nations Sustainable Development Goals (SDG's) by 2030. But what does this mean and how does groundwater fit in to this? SDG 6 in particular focuses on ensuring universal access to safe and affordable drinking water for all by 2030. SDG 6 requires that the country protects and restores water-related ecosystems such as forests, mountains, wetlands, aquifers and rivers which are essential if we are to mitigate water scarcity. To accomplish this, South Africa has proceeded to align various plans, strategies, and policies to encompass the targets of the SDG's. This paper will focus on SDG sub-goal 6.3 which incorporates improvement of water quality and sub-goal 6.6 which involves protection and restoration of ecosystems. The methodology given by the UN for the groundwater in indicator 6.3.2 stipulates that countries are required to report on "proportion of water with good ambient water quality", in South Africa however we had to domesticate the indicator i.e. render it suitable for South African conditions so we changed the methodology to "proportion of water the conforms to the Water Quality Objectives (WQO's)" but there are virtually no WQO's developed for groundwater. Four core groundwater quality parameters (Electrical Conductivity, pH, Nitrate and Sulphate) are available through ZQM stations categorized through 65 hydrogeological (Vegter) regions. Groundwater water quality baseline is calculated as a reference period/range per hydrogeological region. For SDG 6.6, the indicator required for groundwater is "Quantity of groundwater within aquifers" The methodology received by the UN for "Quantity of groundwater within aquifers" required a baseline (average reference period of five years) in meters per hydrogeological region. This indicator is again domesticated for South Africa and based on the 40-60 percentiles of groundwater levels per hydrogeological region. There are a number of future indicators that can be included for aquifers under SDG 6.6, but the groundwater sector needs to come together and decide what is important to report on. These SDG targets reporting has given the Water and Sanitation sector a new look at data. It has forced us to critically think of concepts such as baseline and performance monitoring. We now know where our data gaps and targets are, and we have to provide an action plan to address these.
Groundwater Assessment using Borehole Magnetic Resonance	Benjamin	Birt		2019	magnetic resonance
Abstract Hydraulic behaviour of an aquifer is defined in terms of the volumes of water present, both producible and not (specific yield and specific retention), and the productivity of the water (hydraulic conductivity). These parameters are typically evaluated using pumping tests, which provide zonal average properties, or more rarely on core samples, which provide discrete point measurements. Both methods can be costly and time-consuming, potentially limiting the amount of characterisation that can be conducted on a given project, and a significant measurement scale difference exists between the two. Borehole magnetic resonance has been applied in the oil and gas industry for the evaluation of bound and free fluid volumes, analogous to specific retention and specific yield, and permeability, analogous to hydraulic conductivity, for over twenty years. These quantities are evaluated continuously, allowing for cost-effective characterisation, and at a measurement scale that is intermediate between that of core and pumping tests, providing a convenient framework for the integration of all measurements. The role of borehole magnetic resonance measurements in hydrogeological characterisation is illustrated as part of a larger hydrogeological study of aquifer modeling. Borehole magnetic resonance has been used for aquifer and aquitard identification, and to provide continuous estimates of hydraulic properties. These results have been compared and reconciled with pumping test and core data, considering the scale differences between measurements. Finally, an integrated hydrogeological description of the target rock units has been developed.
Characterising surface water-groundwater interactions in the Vo?lvlei (Agulhas Plain), using a multi-disciplinary approach	Nabuweya	Noordien		2015
Abstract Coastal wetlands are complex hydrogeological systems in which groundwater have a significant influence on both its water balance and hydrochemistry. Differences in groundwater flow and groundwater chemistry associated with complex hydrogeologic settings have been shown to affect the diversity and composition of plant communities in wetland systems. A number of wetlands can be found across the flat terrain of the Agulhas Plain, of which the most notable is the Soetendalsvlei and the Vo?lvlei. Despite the ecological and social importance of the Vo?lvlei, the extent to which local, intermediate and regional groundwater flow systems influences the Vo?lvlei is poorly understood. The aim of this work is to characterize the spatial and temporal variations in surface water and groundwater interactions in order to demonstrate the influence of groundwater flow systems on the hydrology of the Vo?lvlei. The specific objectives of the study are; 1) to establish a geological framework of the lake sub-surface, 2) to determine the physical hydrological characteristics of the Vo?lvlei and 3) to determine the physical-chemical and isotopic characteristics of groundwater and surface water. Data collection will be done over the period of a year. Methods to be used will include the use of geophysical (electrical resistivity) to determine high water bearing areas surrounding the wetland, a drilling investigation (the installation of piezometers at 5-10m depths and boreholes at 30m depth, sediment analysis (grain size analysis, colour and texture), hydraulic (slug testing to determine hydraulic properties; hydraulic conductivity and transmissivity), hydrological (to estimate groundwater discharge; Darcy flux and hydraulic head difference between groundwater level and lake level), physical-chemical (electrical conductivity, temperature and pH) and stable environmental isotopic (oxygen and hydrogen) analysis of surface water and groundwater, to determine flow paths and identify processes. Thus far, results obtained for the geophysical survey has revealed that the sub-surface of this wetland system is highly variable. Three traverses were done on the South-Western, South-Eastern and Northern side of the wetland (See Figure 1). In VOEL1 (South west), the upper couple of meters show areas of very low resistivity, which is associated with clays, poor water quality and water which has high dissolved salts. The changing of medium to high resistivity values on the North-eastern side is usually indicative of weathered sandstone (Table Mountain Group). VOEL2 (South eastern), indicates that the subsurface is of low resistivity. These low values are the result of noticeable salt grains in the sand. VOEL3 (Northern), indicated upper layers of low resistivity, while the lower depth indicate areas of high resistivity. It is expected that the results of this study will provide a conceptual understanding of surface water-groundwater interactions and the processes which control these interactions, in order to facilitate the effective management and conservation of this unique lacustrine wetland.
Estimating groundwater availability at catchment scale using streamflow recession and instream flow requirements of rivers	Girma Yimer	Ebrahim		2015	streamflow, RDM
Abstract Groundwater is an important resource for multiple uses in South Africa. Hence, setting limits to its sustainable abstraction while assuring basic human needs is required. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater availability, the present article presents a novel method for determining allocatable groundwater in quaternary catchments through information on streamflow. Using established methodologies for assessing baseflow, recession flow, and instream ecological flow requirement, the methodology develops a combined stepwise methodology to determine annual groundwater storage volume using linear reservoir theory, essentially linking low flows proportionally to upstream groundwater storages. The approach was trialled for twenty-one perennial and relatively undisturbed quaternary catchments with longterm and reliable streamflow records. Using the Desktop Reserve Model, maintenance low instream flow requirements necessary to meet present ecological state of the streams were determined, and baseflows in excess of these flows were converted into allocatable groundwater storages on an annual basis. Results show that groundwater development potential exists in nineteen of the catchments, with upper limits to allocatable groundwater volumes (including present uses) ranging from 0.02 to 2.60 Mm3/a over the catchments. With a secured availability of these volumes 75% of the years, variability between years is assumed to be manageable. A significant (R2 = 0.86) correlation between baseflow index and the drainage time scale for the catchments underscores the physical basis of the methodology and also enables the reduction of the procedure by one step, omitting recession flow analysis. The method serves as an important complementary tool for the assessment of the groundwater part of the Reserve and the Groundwater Resource Directed Measures in South Africa.
The Utilisation Of Hydro-Geophysical Methods For Soil Moisture Measurements To Optimise Irrigation Management	Christian	Steyn		2019	soil moisture, Irrigation, flow
Abstract Precision agriculture continuously seeks improved methods to enhance productivity whether it is for greater crop yields or economic viability regarding labour inputs and satisfying the demand in a shorter time span. Soil moisture is one important factor that drives the agricultural industry and is therefore of utmost importance to manage it correctly. A shortage of water may result in reductions in yield, while excess irrigation water is a waste of water resources and can also have a negative impact on plant growth. Knowledge of the spatial distribution of soil moisture is important for determining soil moisture storage and soil hydraulic transport properties. Capturing field heterogeneity without exhaustive sampling and costly sample analysis is difficult. Electromagnetic induction, Frequency Domain Reflectometry, Neutron Scattering and conventional soil sampling have been utilised to determine the spatial variability of soil moisture within a field. Emphasis has been placed on practicality and accuracy of all the methods. Electromagnetics have proven itself to be the primary method to determine soil moisture within the field by comparing the results of the volumetric soil water content present in the field together with a combination of various soil properties such as clay and silt content, sand fraction, concretions, density and soil depth that contribute towards the accumulation of soil water. Electromagnetic induction has the highest resolution of data collected for a specific time period of all considered methods making it economically the best option for soil moisture management within a variable rate irrigation system. Electromagnetic induction has proven to be successful in delineating a field into management zones consisting of different classes based on observed conductivity values. Higher conductive zones are considered with small water demand. Lower conductive zones are considered with a greater water demand through a variable rate irrigation system. These water management zone maps could be informative for modelling, experimental design, sensor placement and targeted zone management strategies in soil science, hydrogeology, hydrology, and agricultural applications.
Dewatering Impacts of a South African Underground Coal Mine	Paul JH	Lourens		2017	coal mine, hydrocensus, dolerite contact zones, Monitoring, over-abstraction
Abstract The University of the Free State investigated the possible dewatering of boreholes situated on the farm properties in the vicinity of an underground coal mine. The investigation consisted of three phases. Phase one was a hydrocensus on the farm properties. Phase two consisted of borehole yield determination by conducting pumping tests on the boreholes (where possible) identified in the hydrocensus phase. Phase three included a visit to the underground mine workings, where water samples were collected at different groundwater inflow locations (especially water flowing in at the ventilation shaft). The monthly groundwater monitoring data of the underground coal mine was also incorporated for interpretation purposes. It appears that the water levels of the boreholes outside the mining boundaries are not affected. The water levels of the monthly monitored boreholes stabilized or even started recovering over the last few years. It also seems as though the larger streams in the area drains the groundwater as most of the deeper water level areas coincides with the presence of the streams. Most of the boreholes have typical borehole yields that is to be expected from Karoo formations i.e. between 0.5 and 1.5 L/s. An interesting observation is that a number of the boreholes with deep water levels are situated along dolerite contact zones at the western side of the mine. This may also be a geological structure resulting from the impact of a meteorite? From the available data it appears that the boreholes along this structure have the same chemical character as the water flowing down the ventilation shaft, strengthening the belief that the water from the shaft originates from this structure (or structures). To determine the origin of the water flowing down the ventilation shaft, a detailed study of the structure to the west of the shaft is recommended. The farmers in the area should carefully monitor their water use in the boreholes, as over-abstraction can result in total failure of some of the boreholes.
The use Vegetable Oil Substrate's in the treatment of contaminated groundwater	Michelle	Pienaar		2015
Abstract Edible vegetable oil (EVO) substrates have been successfully used to stimulate the in situ anaerobic biodegradation of groundwater contaminated chlorinated solvents as well as numerous other anaerobically biodegradable contaminants like nitrates and perchlorates at a many commercial, industrial and military sites throughout the United States of America and Europe. EVO substrates are classified as a slow release fluid substrate, and comprise of food grade vegetable oil such as canola or soya bean oil. The EVO substrate serves as an easily biodegradable source of carbon (energy) used to create a geochemically favorable environment for the anaerobic microbial communities to degrade specific contaminants of concern. EVO substrate's can either be introduced into the subsurface environment as pure oil, in the form of light non aqueous phase or as an oil/water emulsion. The emulsified vegetable oil substrates holds several benefits over non-emulsified vegetable oil as the fine oil droplet size of the commercially manufactured emulsified oils can more easily penetrate the heterogeneous pore and fracture spaces of the aquifer matrix. The use of this technology to stimulate in situ biodegradation of groundwater contaminants is still relatively unknown in South Africa. This paper will give an overview of the EVO technology and its application, specifically looking at the advantages of using this relatively inexpensive, innocuous substrate based technology to remediate contaminated groundwater within fractured rock environments commonly encountered in South Africa. {List only- not presented}
Performance Monitoring Of The Monitored Natural Attenuation Of Petroleum Hydrocarbons In Groundwater Using Geochemical Parameters	AR	Gemmell		2017	MNA, geochemical indicators, geochemical parameters, monitoring network
Abstract Monitored Natural Attenuation (MNA) refers to the monitoring of naturally occurring physical, chemical and biological processes. Three lines of evidence are commonly used to evaluate if MNA is occurring, and this paper focusses on the second line of evidence: The geochemical indicators of naturally occurring degradation processes and the site-specific estimation of attenuation rates. The MNA geochemical indicators include the microbial electron acceptors (e.g. dissolved oxygen, nitrate and sulphate) and the metabolic by-products (manganese (II), iron (II) and methane). In addition, redox and alkalinity are important groundwater indicators. So as to properly assess the geochemical trends a groundwater monitoring well network tailored to assessing and defining the contaminant plume is required. The expressed assimilative capacity (EAC) is used to estimate the capacity of the aquifer to degrade benzene, toluene, ethylbenzene and xylene (BTEX compounds) using the concentrations of geochemical indicators. Using the EAC, the groundwater flow through a perpendicular cross-section of the source area, and the source mass, the life of the contaminant source can be made. A practical example of the performance monitoring of MNA using geochemical parameters is described for a retail service station in KwaZulu-Natal, which has groundwater impacted by a petroleum hydrocarbon plume. This includes a description of the monitoring well network, the geochemical measurements, the calculation of the EAC, and the estimated life of the contaminant source.
The Value Of Monitoring: Case Study Of An Artesian Borehole	Neville	Paxton		2019	Monitoring
Abstract Groundwater monitoring, especially from the end users' point of view, is often considered an add-on, or even unnecessary overhead cost to developing a borehole. Simply measuring groundwater level over time can however tell a story on seasonal rainfall fluctuations as well as the response of an aquifer to the removal of an abstracted volume of water. In this case an artesian borehole of high yield and exceptional quality was drilled in an area of minimal groundwater use because of known poor quality and low yields. The borehole was drilled in two stages with the deeper drilling resulting in significantly higher yields and the artesian flow. Sediment free water, deep artesian water strikes and a lack of flow around the casing led to the conclusion that capping at surface would control the visible artesian flow of 4 L/s. A slight drop in pressure indicated that subsurface leakage may however be occurring. Neighbouring boreholes with automated water level monitoring provided data showing a correlation of drop in water level to the second deeper drilling event. The artesian borehole was yield tested and this too was visible in the water level monitoring data. Hereafter it became apparent that each activity performed at the artesian borehole had an impact on the monitoring boreholes, and that a subsurface leak was causing local depressurization of a semi-confined to confined aquifer. An initial attempt to save the artesian borehole was unsuccessful, resulting in the necessary blocking and abandonment of a high yielding, superior quality borehole. If monitoring data was not available the local drop in water level would never have been noticed with disastrous effect and no evidence for the cause. Simple water level monitoring has averted this and kept neighbourly relations and ground water levels intact
An Approach To Determining The Most Suitable Combination Of Groundwater Impact Mitigation Measures With The Use Of A Gold Tailings Case Study	Pieter F	Labuschagne		2019	impact mitigation measures
Abstract The mitigation of groundwater impacts related to gold mining tailings disposal within the Orkney-Klerksdorp region was assessed and presented as a case study. The most pressing concern for the facility owners is the potential for pollution of water resources in the vicinity of the mines, especially after mine closure. The key focus of this paper is to describe how methods were applied to characterise the aquifer and keeping the source-pathway-receptor principles in mind. Characterisation also involves lessons learn by comparing pre-tailings deposition and post-tailings deposition aquifer bahviour. Ultimately the process followed in this paper has led to the development of a logical approach to estimate groundwater liability costs in a typical tailings environment. The link between hydrogeology, geotechnical engineering and civil engineering was identified as a critical foundation for the development of a successful groundwater management strategy
Selling the invisible: Communicating the Groundwater Message	Elanda P	Botes		2015	stakeholder communication, strategy, policy implementation
Abstract As we look at the legislation set out in the driving policies and its guiding frameworks, the need for able institutions to implement strategies that promise and deliver social growth and development, are highlighted. It is only possible to define an 'able institution' through its ability to fulfil its function and enable stakeholders to be part of the decision-making process. (Goldin, 2013) It is this relationship with the collection of stakeholders, in particular strategic water resource stakeholders, their linkages as well as the identification of specific stakeholder issues, that are critically reviewed. The recent Groundwater Strategy (2010) identified key strategic issues/themes. Each chapter listed a number of well thought out recommended actions that address specific challenges in each theme. It is the need for strategic direction (to put these strategies in place "plans into action") and to articulate the specific vision in the right context to the different stakeholders, (internal as well as external) that requires thinking. It is also the uptake of this information by publics (social action and intervention) and the impact of new learning that will need to be measured. This paper will present on a study where the groundwater sector and all its stakeholders are strategically examined to understand the process of communal thinking in the current environmental conditions. It would draw from current communication practices, style, strengths, sector experiences and trends and also reference specific and unique experiences as with the recent WRC Hydrogeological Heritage Overview: Pretoria project. {List only- not presented}
Validating Hydrological Models In A Data Scarce Country- Getting The Right Results For The Right Reasons.	Jane L	Tanner		2015
Abstract This study explores some of the principle issues associated with quantifying surface and groundwater interactions and the practical application of models in a data scarce region such as South Africa. The linkages between the various interdependent components of the water cycle are not well understood, especially in those regions that suffer problems of data scarcity and there remain urgent requirements for regional water resource assessments. Hydrology (both surface and groundwater hydrology) is a difficult science; it aims to represent highly variable and non-stationary processes which occur in catchment systems, many of which are unable to be measured at the scales of interest (Beven, 2012). The conceptual representations of these processes are translated into mathematical form in a model. Different process interpretations together with different mathematical representations results in the development of diverse model structures. These structural uncertainties are difficult to resolve due to the lack of relevant data. Further uncertainty is introduced when parameterising a model, as the more complex the model, the greater the possibility that many different parameter sets within the model structure might give equally acceptable results when compared with observations. Incomplete and often flawed input data are then used to drive the models and generate quantitative information. Approximate implementations (model structures and parameter sets), driven by approximate input data will necessarily produce approximate results. Most model developers aim to represent reality as far as possible, and as our understanding of hydrological processes has improved, models have tended to become more complex. Beven (2002) highlighted the need for a better philosophy toward modelling than just a more explicit representation of reality and argues that the true level of uncertainty in model predictions is not widely appreciated. Model testing has limited power as it is difficult to differentiate between the uncertainties within different model structures, different sets of alternative parameter values and in the input data used to run a model. A number of South African case studies are used to examine the types of data typically available and explore the extent to which a model is able to be validated considering the difficulty in differentiating between the various sources of uncertainty. While it is difficult to separate input data, parameter and structural uncertainty, the study found that it should be possible to at least partly identify the uncertainty by a careful examination of the evidence for specific processes compared with the conceptual structure of a specific model. While the lack of appropriate data means there will always be considerable uncertainty surrounding model validation, it can be argued that improved process understanding in an environment can be used to validate model outcomes to a degree, by assessing whether a model is getting the right results for the right reasons.
Development of United Nations Framework Classification for Resources (UNFC) for Groundwater Resources Management	Peter	van der Keur		2023	SDGs, UNFC, common pool resources, subsurface geo-resources, sustainable groundwater resources management
Abstract There is an urgent need to support the sustainable development of groundwater resources, which are under increasing pressure from competing uses of subsurface geo-resources, compounded by land use and climate change impacts. Management of groundwater resources is crucial for enabling the green transition and attaining the Sustainable Development Goals. The United Nations Framework Classification for Resources (UNFC) is a project-based classification system for defining the environmental-socio-economic viability and technical feasibility of projects to develop resources and recently extended for groundwater. UNFC provides a consistent framework to describe the level of confidence in groundwater resources by the project and is designed to meet the needs of applications pertaining to (i) Policy formulation based on geo-resource studies, (ii) Geo-resource management functions, (iii) Business processes; and (iv) Financial capital allocation. To extend use in groundwater resources management, supplemental specifications have been developed for the UNFC that provide technical guidance to the community of groundwater professionals to enhance sustainable resource management based on improved decision-making. This includes addressing barriers to sustainably exploiting groundwater resources, avoiding lack of access to water and also related to ‘common pool resources’ in which multiple allocations are competing with domestic water supply (e.g. geo-energy, minerals, agriculture and ecosystems, and transboundary allocation of natural resources). UNFC for groundwater resources is designed to enhance governance to protect the environment and traditional users while ensuring socio-economic benefits to society. Consequently, it is a valid and promising tool for assessing both the sustainability and feasibility of groundwater management at local, national and international levels.
The National Integrated Water Information System (NIWIS) for geohydrology in South Africa	N	Nungu			Data, Decision Making, Groundwater, Information, Information System, Integration, South Africa
Abstract For the Department of Water and Sanitation (DWS) to better leverage the wealth of information being collected by various “silo” operational source water information systems, a high-priority initiative was launched to establish a National Integrated Water Information System (NIWIS), which currently consists of over 40 web-accessible dashboards including groundwater related dashboards mostly accessible to the public. Dispersed and disintegrated data and information stored in different sources and formats would hinder decision support in the water sector and deter improvement in service delivery by the DWS. The DWS undertook an extensive and rigorous business requirements analysis exercise within the DWS to ensure that the proposed system does not become a white elephant and facilitate the prioritization of system deliverables. A prototype (waterfall) approach was adopted to develop the NIWIS to ensure the development was still within the suggested business requirements. NIWIS has enabled mostly DWS managers to establish one trusted source of decision-making information for timeous, effective and efficient responses to service delivery. The number of NIWIS dashboards continues to grow as improved data-related business processes are adopted. The unavailability of reliable data from DWS data sources and the exclusion of business requirements from organizations external to DWS were identified as the main challenges to NIWIS disseminating comprehensive, credible information. Therefore, this paper aims to provide some details of the geohydrological information that NIWIS provides and seek feedback from this International Hydrogeologists community for further development of NIWIS.
Physico-Chemical Assessment of Groundwater in the Orange Water Management Area	Olma Tsakani	Makonto		2015
Abstract The groundwater quality of the Orange Water Management Area (OWMA) was assessed to determine the current groundwater status. Groundwater is of major importance in the Orange Basin and constitutes the only source of water over large areas. Groundwater in the OWMA is mainly used for domestic supply, stock watering, irrigation, and mining activities. Increase in mining and agricultural activities place a demand for the assessment of groundwater quality. The groundwater quality was assessed by collecting groundwater samples from farm boreholes, household boreholes, and mine boreholes. Physical parameters such as pH, temperature and Electrical Conductivity (EC) were measured in-situ using an Aquameter instrument. The groundwater chemistry of samples were analysed using Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, and Spectrophotometer for cations, anions and alkalinity respectively. The analyses were done at Council for Geoscience laboratory. The results obtained indicated high concentration of Nitrate (NO3), EC, sulphate (SO4), Iron (Fe), and dissolved metals (Chromium, Nickel, Copper, Zinc, and Lead). The concentrations were higher than the South African National Standards (SANS) 241 (2006) drinking water required guideline. The OWMA is characterised by the rocks of the Karoo Supergroup, Ventersdorp Supergroup, Transvaal Supergroup, Namaqua and Natal Metamorphic Province, Gariep Supergroup, and Kalahari Group. Groundwater is found in the sandstones of the Beaufort Group. Salt Mining occurs in the Namaqua Group, hence the high concentration of EC observed. High EC was also found in the Dwyka Group. The salt obtained from the pans underlain by the Dwyka Group rocks has relatively high sodium sulphate content, this probably results from oxidation of iron sulphate to sulphate. Therefore, high concentration of SO4 is due to the geology of the area. High concentration of NO3 is due to agricultural activities, whereas high concentration of EC, Fe, SO4 and dissolved metals is due to mining activities.
Building a Groundwater Educational Pipeline from Elementary to Continuing Education	Todd	Halihan		2023	K-12, PSM, Drilling, online education, professional master’s programs
Abstract Water resources worldwide are stressed, and the number of groundwater professionals required to manage those resources is not being generated in sufficient numbers. Groundwater educational resources must be placed in schools to generate excitement and raise awareness. Additionally, people entering the workforce need training throughout their professional careers. Oklahoma State University partnered with the U.S. National Ground Water Association to develop a framework for providing education and training programs in groundwater that allow for interactive online education at all levels. The Awesome Aquifer 360 program targets grades 5-8, allowing students to conceptually explore aquifers and the people who manage them. The Drilling Basics Online program provides a 40-hour basic safety and drilling training to recruit professionals into the groundwater industry and reinforce safe operations. These programs and future plans for the technique will be discussed.
Groundwater for people and the environment: A globally threatened resource	H	Loaiciga		2023	Groundwater, groundwater sustainability, overdraft, population growth, recharge, safe yield
Abstract Groundwater is an essential source of water worldwide. The increased reliance on groundwater has caused the mining of many aquifers, a situation compounded by climate change, rising surface-air temperature, declining precipitation, and reduced groundwater recharge in many regions. The global annual intensity of groundwater use rose from 128 to 155 m3 per capita between 1950 (when the world population was 2.5 billion people) and 2021 (when the population was 7.9 billion people) and is herein projected to rise to 178 m3 per capita by 2050 as the world’s population is projected to increase (to 9.7 billion people by 2050) throughout the rest of the 21st century and beyond. This study projects a global annual groundwater depletion of 1,008 km3 by 2050, representing a 256% rise from the estimated 2010 depletion. This projection is most likely a lower bound of the actual groundwater depletion that would be realized considering environmental flows, historical trends of global economic growth, and climate-change impacts, thus being a harbinger of rising environmental degradation (e.g., land subsidence, seawater intrusion, streamflow reduction, aridification). Measures to achieve groundwater sustainability are herein identified.
Advances In The Realm Of Hydrogeophysics: The Emerging Role Of Quantum Geoelectrophysics (Qgep) In Deeper Aquifer Exploration	R	Hatala		2017	Deep aquifers, Geophysics, QDMI, QGEP, Electromagnetics, ERT
Abstract Water is integral to our economy, the health of our environment, and our survival as a species. Much of this water is accessed from surface sources, mostly rivers, which are now under increased threat due to over use and the resulting hydro-political forces. Yet, groundwater exists as a viable option in many countries facing these mounting challenges. Knowledge of our deeper groundwater systems, although increasing, is still quite limited due to our propensity to focus efforts in the lower cost, lower risk, near- surface environment. However, accessibility to shallower groundwater is tightening due to increasing use, changing regulatory requirements, and climate change. The use of classical geophysics to explore for groundwater resources, such as seismic, gravity, magnetics, and resistivity, has been the industry standard for many decades. These technologies have proven quite effective both in the shallow and medium depth environments. However, newer remote sensing and ground-based technologies are now emerging with the ability to significantly reduce costs and time, and increase success for groundwater exploration and development programs. Quantum Direct Matter Indicator (QDMI) technologies, or applied methods of Quantum Geoelectrophysics (QGEP), are poised to enhance the hydrogeophysical industry, much like electro-magnetic (EM) and electrical resistivity tomography (ERT) did years ago. QDMI utilizes resonant frequency remote and direct sensing technologies that detect perturbations in the earth’s natural electric, magnetic and electromagnetic fields. Controlled source electromagnetic pulse methods with electromagnetic spectrum spectroscopy are used to identify aquifers, including thickness, water quality (fresh or saline) and temperature, to depths of 1000 m or more accurately. With multiple successes around the world, the deployment of this inventive and effective approach to groundwater exploration is poised to advance exploration geophysics globally.
Variability In Borehole Responses During Yield Testing: Case Studies Deviating From Ideal Drawdown Curves.	Reuben	Lazarus		2019	yield-testing, theory vs practice, realistic aquifers
Abstract The expectation that during yield tests, a borehole will react within the expected framework of the existing numerical models, is often not met within real-world scenarios. This is mainly due to the observation that the Theis solution for confined aquifers, Neuman solution for unconfined aquifer and Barker Generalised Radial Flow Model for hydraulic tests in fractured rocks all include idealised assumptions regarding the physical aspects of a hypothetical. In order to interpret the data from a yield test these methods, along with the Flow Characteristic method for sustainable yield estimates, are commonly used. However, as these assumptions are not always met, the analysis is usually focused on time periods within the test that approximate these solutions. In some cases, the extent to which these assumptions are not met can produce drawdown data that is not well described by the usual analytical models used to analyse this data. This study addresses some of the shortcomings experienced during testing in non-ideal aquifers, as well as briefly describing some tests where small budgets, short deadlines, a lack of information and/or unforeseen circumstances resulted in similar challenges to analyses. This study does not present new solutions to drawdown data analyses, but rather discusses how the mentioned solutions were used during testing to accommodate for the shortcomings experienced.
Groundwater and Surface Water Interaction Study for the Ingula Wetland	Christie	Terrell		2015
Abstract The Bedford Dam is the upper storage dam for the Ingula Pumped Storage Scheme and is situated in the Ingula/Bedford Wetland. This wetland has a high structural diversity which supports a unique assemblage of plants and invertebrates. The flow regulation and water purification value is of particular importance as the wetland falls within the Greater Vaal River catchment. Concern was raised with respect to the potential negative impact of the newly constructed dam on the dynamic water balance within the wetland. An assessment of the extent to which groundwater drives / sustains the wetland systems and the water requirements needed to sustain the wetland processes was determined. This includes establishing the impact of the Bedford Dam on the groundwater and wetland systems as well as providing recommendations on management and monitoring requirements. The hydropedological interpretations of the soils within the study area indicate that baseflow to the wetland is maintained through perennial groundwater, mainly recharged from infiltration on the plateau, and was confirmed through isotope sampling and hydrometric measurements. It is apparent that the surface flows in the main wetland are fed by recent sources, while the subsurface layers in the wetland are sustained by the slower moving near-surface and bedrock groundwater. The movement of groundwater towards the wetland is hindered by the numerous dykes creating a barrier to flow. Nevertheless, there seems to be a good connection between the groundwater sources in the upland and the surface drainage features that conduct this water to the contributing hillslopes adjacent to the main wetland. The surface flows of the main wetland are sustained by contributions from tributary fingers. The discharge out of the wetland is highly seasonal
A case study review of a high tech approach towards wellfield and aquifer management.	Paul	Lee		2015
Abstract Faced with a burgeoning population and property growth, and in preparation for a future drier climate regime; the coastal town of Hermanus in the Western Cape has set up two wellfields to abstract groundwater from the underlying aquifer in order to augment the constrained surface water supply from the De Bos Dam. Water Use Licences (WUL) were issued to the Overstrand Municipality in June 2011 and December 2013. The licences authorise a maximum annual abstraction of 1 600 Ml of water from the Gateway wellfield and 800 Ml of water from the Volmoed and Camphill wellfield via several boreholes. The water abstracted from the Gateway wellfield is pumped via a booster pump station to the Preekstoel Treatment Plant. The Volmoed and Camphill wellfield are situated at a higher altitude allowing for a gravity feed pipeline. Earth Science Company, Umvoto Africa, has the responsibility to ensure Resource Quality Objectives are met which include balancing the need to protect the resource on the one hand; and the to develop sustainable utilisation of the Hermanus groundwater resources and compliance with the WUL on the other. The consultancy provides hydrogeological support, wellfield management and technical advice in operating the boreholes, pumps, boosters and related infrastructures. Running the operations of the wellfield relies on a high-tech, semi-automated system, incorporating a remotely controlled, telemetry based structure. Vital parameters are monitored by electronic sensors, feeding data to processors which alters pump performance to maintain specified boundary levels. Data is simultaneously communicated via telemetry to a central control which uses data acquisition software to portray information to the operators. Warning alarms both alert operators via SMS and in certain instances auto-shut down the system. To ensure ecological sustainability of the ground water resource, the wellfield also requires hydrogeological monitoring at far field locations within the recharge areas. Some of these locations are in remote areas making data download costly. The high-tech telemetry approach is used with positive results. Any automated telemetry system is prone to malfunction and environmental hazards. The challenge lies in managing this and providing sufficient back up and duplication of systems. The paper gives an overview of the components and flow of data based on the experiences gained during the evolution and development over 12 years of operation. Automation produces vast data bases which are often not sufficiently analysed, the premise that "once collected, the task is done". However data is only as good as the people who drive the systems and this paper provides a critical analysis of human intervention in an automated system and the decisive role of quality-checks. Finally the paper seeks to provide a pragmatic guideline for water users to comply with the WUL and institutional regulations.
A numerical simulation of solute transport in dry coal ash dumps with a case study in South Africa	Innocent	Muchingami		2015
Abstract An understanding of the movement of moisture fluxes in the unsaturated zone of waste disposal sites play a critical role in terms of potential groundwater contamination. Increasing attention is being given to the unsaturated or vadose zone where much of the subsurface contamination originates, passes through, or can be eliminated before it contaminates surface and subsurface water resources. As the transport of contaminants is closely linked with the water ?ux in through the unsaturated zone, any quantitative analysis of contaminant transport must ?rst evaluate water ?uxes into and through the this region. Mathematical models have often been used as critical tools for the optimal quantification of site-speci?c subsurface water ?ow and solute transport processes so as to enable the implementation of management practices that minimize both surface and groundwater pollution. For instance, numerical models have been used in the simulation of water and solute movement in the subsurface for a variety of applications, including the characterization of unsaturated zone solute transport in waste disposal sites and landfills. In this study, HYDRUS 2D numerical simulation was used to simulate water and salt movement in the unsaturated zone at a dry coal ash disposal site in Mpumalanga, South Africa. The main objective of this work was to determine the flux dynamics within the unsaturated zone of the coal ash medium, so as to develop a conceptual model that explains solute transport through the unsaturated zone of the coal ash medium for a period of approximately 10 year intervals. Field experiments were carried out to determine the model input parameters and the initial conditions, through the determination of average moisture content, average bulk density and the saturated hydraulic conductivity of the medium. A two dimensional finite-element mesh of 100m x 45m model was used to represent cross section of the ash dump. Two dimensional time lapse models showing the migration of moisture fluxes and salt plumes were produced for the coal ash medium. An explanation on the variation of moisture content and cumulative fluxes in the ash dump was done with reference to preexisting ash dump data as well as the soil physical characteristics of the ash medium. {List only- not presented}
Feasibility Of Coal Ash Backfilling In Opencast Mines Using The Darcy Column Experiment.	Bongiwe	Seleka		2019	Poster, coal ash
Abstract The generation of acid mine drainage (AMD), as a result of mining activities, has led to the degradation of groundwater quality in many parts of the world. Coal mining, in particular, contributes to the production of AMD to a large extent in South Africa. Although a vast number of remediation methods exist to reduce the impacts of AMD on groundwater quality, the use of a coal fly ash monolith to act as a reactive and hydraulic barrier has not been extensively explored. This study, therefore, aims to investigate how different ways of packing ash affect the hydraulic conductivity of ash and influence leachate quality when acid-mine drainage filters through the ash. Coal ash is highly alkaline due to the existence of free lime on the surface of the ash particles. Previous studies that investigated alternative uses of coal ash, particularly in AMD treatment, suggest that coal ash has the potential to neutralise pH in acid water and remediate acidic soils. To test the effects of different packing methods of coal ash on the hydraulic conductivity and quality of acid mine leachate flowing through it, several Darcy column tests will be conducted. During the course of these experiments, the following parameters will be measured, electrical conductivity, pH discharge, lime (CaCO3) and selected elements of environmental concern.
Geochemical Simulation of Drain Water Quality in Gold Tailings	Terry R	Harck		2017	geochemistry, modelling
Abstract This paper presents data obtained from sampling and geochemical analysis of gold tailings and associated pool and drain water. Inverse geochemical modelling using PHREEQC indicated geochemical processes operating in the tailings between the pool and drains. These included pyrite oxidation and dissolution of various minerals identified in the tailings. The processes were incorporated into an ensemble geochemical model to calculate post-closure sulphate concentration in tailings seepage. The ensemble model included a spreadsheet model to calculate oxygen flux at various depths in the tailings column, and a one-dimensional transport model in PHREEQC. The calculated oxygen flux was applied to each cell in the tailings column to determine the amount of sulphide oxidation and the release of acidity into the tailings pore water. The rate of vertical transport of pore water in the column was determined from physical characterisation of the tailings particle size and saturated hydraulic conductivity. The model results indicate elevated sulphate concentrations and acidity moving as a front from the top of the column downwards. The modelled sulphate concentration of 1 500 to 1 900 mg/L 8-16 years after closure compared well with measurements of drain water quality at a tailings dam decommissioned approximately 16 years ago. This provided some credibility to the modelled result of 2 300 mg/L sulphate up to 50 years post-closure. However, the tailings moisture content, infiltration rate, and pyrite oxidation rate in the model were based on literature values, rather than site-specific measurements.
Transport and attenuation of microplastics in saturated sands	Sabastian	Stenzl		2021	Microplastics
Abstract Globally, cumulative plastic production since 1950 is estimated to have reached 2500 Mt of plastic. It is estimated up 60% of this plastic is either resting in landfills or the natural environment, including groundwater settings. Microplastics are small pieces of plastic ranging between 1μm – 5mm in size and have been found in every ecosystem and environment on the planet. Much of the available literature on microplastics is focused on marine environments with few in comparison focused on freshwater environments, and even fewer on groundwater settings. The aim of this study is therefore to investigate the attenuation process responsible for influencing microplastic transport in saturated sands. This research will adapt colloid transport theory and experiments to better understand the movement of microplastics through sandy media. Saturated aquifer conditions will be set up and simulated using modified Darcy column experiments adapted from Freeze & Cherry (1979). Modified microplastics will be injected into the columns as tracers and the effluent concentrations measured by Fourier-transform infrared spectroscopy (FTIR). Breakthrough curves will then be plotted using the effluent concentrations to determine the attachment efficiency (α). It is expected the attachment efficiency will vary by microplastic type and size range. The Ionic strength of the solution flowing through the column and the surface charges of both microplastics and sandy surfaces are likely to influence the degree of attenuation observed. The relationship between different types of microplastics and collector surfaces from a charge perspective and their influence on the degree of attenuation will be evaluated. Given the lack of literature, its ubiquitous presence and postulated effects on human health, this research is significant. Through this research, the transport and attenuation of microplastics through sandy aquifers can be better understood, and in the process inform future research and water resource management.
Geochemical Behaviour Of Arsenic In Contact With Dolomite	Johan	Fourie		2017	Arsenic, geochemical, dolomites
Abstract Arsenic is a common contaminant typically found in effluent from gold mine operations and copper smelters throughout the world. The geochemical behaviour of arsenic in contact with dolomite underlying an arsenic containing waste rock pile was investigated. The interaction between the arsenic and the dolomite is an important control in the subsequent transport of the arsenic in the dolomitic aquifer. Rocks with varying dolomite content were tested to investigate the interaction between the arsenic and dolomite. From the modelling and test results it was estimated that in the aquifer, between 60 - 90% of arsenic is present in the solid phase under oxidation conditions at >50 mV. At 50 to -25 mV about 40 - 60% of the arsenic is estimated to be present in the solid phase and below -25 mV about 0 - 10% of arsenic will be present in the solid phase. Although some arsenic is removed by the dolomite in the aquifer the arsenic would still be present above acceptable guidelines for drinking water. The arsenic in the solid phase will be in equilibrium with the aquifer water and could be remobilised 1) under more reducing conditions or 2) with a decrease in arsenic in the aquifer.
A fresh look at the National Water Balance	Andries	Wilke		2015
Abstract The national water balance is primarily based on the availability of surface water and the historic allocation thereof. The changes that are required the next 20 years to ensure sustainable development of the nation will be painful, but is unfortunately at present not part of the public discussion, it is essentially ignored in favour of more "popular water topics".This paper intends to look at a few core aspects, they include the current water allocation in the national water balance, the relative value of the utilisation, the position of groundwater resources in changing the current relative allocation and the current groundwater utilisation. The paper further intends to be a less formal presentation of these aspects with the required data, references and conclusions available for distribution afterwards.
Practical Solutions for Academic Based Applications – Understanding the importance of correct aquifer test data interpretations	Jorette	Van Rooyen		2021	Gw-Sw interaction, test-pumping, FC, Monitoring
Abstract It has become increasingly apparent that understanding fractured rock mechanics as well as the interactions and exchanges between groundwater and surface water systems are crucial considering the increase in demand of each in recent years. Especially in a time where long term sustainability is of great importance for many water management agencies, groundwater professionals and the average water users. Previous callow experience has shown that there is a misunderstanding in the correct interpretation and analyses of pumping test data. The fracture characterisation (FC) method software provides a most useful tool in the overall understanding of a fractured rock aquifer, quantification of the aquifer’s hydraulic (flow regime and flow boundary conditions) and physical properties, only if the time-drawdown relationships are correctly interpreted and when the theoretical application principles are applied. Interpretation is not simply a copy and paste of the aquifer test data into the software to get a quick answer (especially when project time constraints are considered), however, recent experiences with numerous field examples, required intricate understanding of the geological environment, intended use and abstraction schedules coupled with the academic applications on which the software was based for correct interpretation. Through the application of correct interpretation principles, a plethora of flow information becomes available, of which examples will be provided in the presentation itself. By achieving this, flow can be conceptualised for inputs into a conservative scale three-dimensional numerical flow model and calibrated based on measurable data in a fraction of the time of a conventional regional model. Although higher confidence levels are achieved with these practical solutions, monitoring programmes are still required to provide better insight of the aquifer responses to long-term abstraction and recovery.
Temperature And Ec Stratification In The Gasification Zone And Surrounding Aquifers Of Underground Coal Gasification At The Majuba Pilot Plant	Lehlohonolo	Mokhahlane		2017	underground coal gasification, stratification
Abstract Underground coal gasification (UCG) is a chemical process that converts coal in-situ into a gaseous product at elevated pressures and temperatures. Underground coal gasification produces an underground cavity which may be partially filled with gas, ash, unburned coal and other hydrocarbons. In this study we assessed the stratification down the length of the boreholes. This was done by comparing the Electrical Conductivity (EC) profile of background boreholes to the verification borehole that were drilled after gasification was complete. Stratification was seen in all boreholes including the cavity borehole. The EC levels were lower in the cavity which may be due to the dilution factor induced by injecting surface water during quenching of the gasifier. The thermal gradient shows a steady increase in temperature with depth with higher temperatures measured in the verification boreholes. This increase in temperature may suggest that heat is still being retained in the cavity which is expected. This study serves as the preliminary investigation on the stratification of temperature and EC and will be proceeded with in depth surveys that covers all the groundwater monitoring wells that monitor different aquifers identified on site proceed.
GIS-PMWIN, A Preprocessor In ArcGIS For Groundwater Modeling With PMWIN	Haili	Jia		2015
Abstract PMWIN5.3 has been one of the most commonly used software for groundwater modeling because of its free source and the adoption of popular core program MODFLOW. However, the fixed formats required for data input and lack of GIS data support have posted big challenges for groundwater modelers who are dealing with large areas with complicated hydrogeological conditions. In South Africa, most geological and hydrogeological data have been captured and stored in GIS format during various national research projects such as WR2005, NGA and etc. Therefore, a proper linkage between PMWIN and ArcGIS is expected to do the preprocessing for modeling in PMWIN. Visual Basic for Application (VBA) embedded in ArcGIS 9.3 was used to develop the linkage. Based on the conceptualization of the study area, the model dimension, discretization and many value setting processes can be easily carried out in ArcGIS other than directly in PMWIN. Then the grid specification file and other input files can be exported as the PMWIN-compatible files. The functions of move, rotation, refinement, sub-model, deleting and inserting row(s) or column(s) of the model have also been developed to avoid the inconvenience aroused from model modification. The linkage can be used with a higher version of PMWIN or ArcGIS. It has been applied to several gold fields in the Witwatersrand gold basin to simulate the groundwater flow and mass transportation for various conditions and scenarios. One of the applications will be presented in this paper. It has been proved that the linkage is efficient and easy to use. {List only- not presented}
The value (or not) of measuring redox potential in groundwater: A case study	Meris	Mills		2015
Abstract The redox state of groundwater is an important variable for determining the solubility and mobility of elements which can occur in different redox states at earth surface conditions, such as Fe, Mn, Cr, As, U, N, S, V etc. Eh-pH diagrams are potentially invaluable for understanding and predicting the behaviour of these redox species yet, unlike pH, redox is seldom a routine field parameter due to the difficulties in measurement and interpretation. This paper discusses the potential use and limitations of field measurements of the redox state of groundwater with specific reference to the geochemical behaviour of dissolved iron in the Table Mountain Group (TMG) aquifer. As part of an investigation into iron cycling within the TMG aquifer, the redox state of groundwater was estimated through three different methods, namely direct in-situ measurement of Eh, direct measurement of DO and calculation from iron speciation in groundwater. Comparison of the results from the three methods highlights the potential value of collecting redox data, but also the complexity of controls on redox potential. The redox measurements allowed the determination of the controlling reactions on iron mobility within the TMG, but only by using the iron speciation method to calibrate the in-situ values and thereby identify which redox pair was controlling redox equilibrium. As this requires measurement of redox ion pairs in solution, it is unlikely to become a routine method for redox assessment, unless the specific redox state of an element is critical in understanding its mobility. For the majority of groundwater site investigations, measurement of the dissolved oxygen content of groundwater is probably sufficient as a first pass.
Reliability of laboratory testing of groundwater samples	Venetia	Mitchell		2015
Abstract Resources required for groundwater sampling includes but not limited to pumping equipment, trained manpower and technical resources specific to the sampling function. Bearing these expenses in mind, choosing a laboratory for testing the water samples collected should be a carefully considered purchase. Choosing a testing facility that cannot deliver an efficient, reliable and technically sound service could render the sampling futile. Water samples submitted to a laboratory for testing are received from third party sources more than ninety percent (90%) of the time and sampling techniques and sample integrity cannot be verified by the laboratory. However, the validity, reliability and integrity of the laboratory testing are within the control of the testing facility. These aspects of a laboratory are usually controlled within a quality management system where established policies and procedures form the basis of such a system. This system maintains a foundation for technical competence and customer service at the laboratory. There are numerous testing facilities available to Consultants requiring chemical and microbiological groundwater testing, each with varying levels of integrity and technical ability. It is imperative to maintain confidence in the validity of results of analyses from a laboratory and this assurance can be understood through an examination of a facility's management system. An established quality management system would comprise a policy statement, associated technical methods and technical and administrative procedures. This system would be formally documented and audited as part of the on-going laboratory's management system. In some instances, laboratories formalise this into an accreditation of the laboratory to an international standard, such as ISO 17025:2005. The assurance that the results of analyses from any laboratory are of sound technical integrity would depend on factors such as - personnel training, - accommodation and environmental conditions under which the tests are carried out, - validation of the methodology applied (including the uncertainty of measurement), - the calibration and maintenance of the equipment used, - understanding the traceability of and measurement undertaken, - handling and preservation of the sample on receipt and while in the laboratory. Each of these factors plays a critical role in the integrity of results of analyses and should be interrogated when trying to understand the reliability and competence of the laboratory of choice.{List only- not presented}
A Decision Support System to Assess Climate Change Impacts on Rural Communities	Musiiwa	Luruli		2015
Abstract Climate change contributes to the way in which people live. Natural resources such as groundwater, wood and surface water form a great part of livelihood in rural communities and are used extensively in rural areas where basic services have not yet been provided. The effect of climate change to all these natural resource may impact the lives of those in rural communities. Climate change is already starting to affect some of the poor and most vulnerable communities around the world. The aim of the dissertation is to develop a framework to assess the vulnerability of rural communities to climate change, with a specific focus groundwater and issues relating to gender. A questionnaire and interviews were used to collect data about rural communities' level of awareness climate change, their attitudes toward coping with climate change impact, level of education, income scale and how does this affect their security. Hyrodocensus was taken around the village to determine the rivers, dams, boreholes, abandoned boreholes and wells. Water samples were collected and analysed. The response rate was higher in females than in male's stakeholders (54% vs 46%).the results show that woman were mostly doing the hard work to complete daily basic activities. Education was found to be of high school level and incomes were low. The framework was developed with basic need showed that the area was at risk of poverty .Boreholes was found and water quality was analysed to be adequate for drinking water purpose. More information will be discussed on presentation.
Water Monitoring in the Mining Industry: An Overview	Callie	Pickering		2015
Abstract Water monitoring is a key aspect in the mining industry, in terms of gathering baseline data during the pre-construction stage, identifying potential areas of concern and mitigating source pollutants during the operational stage. A proper water monitoring program assists in the monitoring of plume development and water level rebound during the closure phase. The data made available through consistent long term monitoring should not be underestimated. Monitoring the effect that coal mine operations have on the water quality and quantity of surface and groundwater resources is a complex and multidisciplinary task. Numerous methodologies exist for monitoring of this kind. This paper will supply an overview of the water- rock chemistry associated with coal mine environments and the key indicator elements that should be focused on for water monitoring as well a review of the Best Practice Guidelines requirements in terms of water monitoring. Two case studies of coal mines in KwaZulu Natal will be reviewed, the key challenges outlined and mitigation measures implemented. The impact of requirements such as those set out by the Department of Water and Sanitation in terms of strict water quality limits for water containment and waste facilities as specified by Water Use Licences has also created unrealistic non-compliance conditions. The initial approach to creating a water monitoring programme should involve first identifying gaps in previous datasets and delineating potential sources of contamination. The sampling frequency will depend primarily on the water resource being monitored and the water quality analysis will depend on the type of facility. The facilities required for a specific situation will depend on the type and amount of waste generated, potential for leachate formation, vulnerability of groundwater resources and potential for water usage or resource sensitivity.
The importance of rainfall data in water resource planning and risk management	Nicolette	Vermaak		2015	rainfall data
Abstract Water resource management and risk management rely heavily on the availability of data and information. This includes the volumes of water needed, the volumes of water available, where the available water is and where it would be needed, etc. Historical records help to determine past use and gives a way to predict future use in the case of water resource planning while it helps to predict the possibility of floods and droughts when it comes to risk management. Rainfall data can provide valuable data for both water resource planning and risk management, since it is the input to the hydrologicalcycle. It is possible to determine dry and wet cycles using the cumulative deviation from mean that is calculated from the measured rainfall data. This was done for the Gnangara Mound in Australia, with the results giving a fair representation of the dry and wet cycles in the area. Data measured over a period of about 30 years for the Zachariashoek sub-catchment analyzed in the same fashion provided wet-dry cycles of about 8 years. The rainfall measurements had been taken at various settings around the catchment, and varied from place to place and differed from that measured at the WeatherSA stations in the vicinity. This article will draw a comparison between the Zachariashoek data and the WeatherSA data to determine whether the WeatherSA data followed the same patterns for the wet-dry cycles observed in Zachriashoek. It will then analyse the longer data record available for the WeatherSA data from 1920 to 2012. It is expected that the shorter wet-dry cycles seen in Zachariashoek will become part of longer wet-dry cycles that can be used in water resource planning and risk management. Rainfall is also dependent on a number of factors
Effects of artefacts other than horizontal groundwater flux on a single-borehole tracer dilution test: Field evidence	Modreck	Gomo		2015
Abstract This article present field evidence on the effect of artefacts other than the horizontal groundwater flux on the single-borehole tracer dilution test. The artefacts on the tracer dilution were observed during two single-borehole tracer dilution tests conducted in an alluvial channel aquifer in the main Karoo Basin of Southern Africa. Field evidence shows that early time of the tracer dilution plot can be affected by artefacts other than the horizontal groundwater flux. These artefacts have great potential to increase the early time gradient of tracer dilution curve leading to overestimation of the horizontal groundwater flux. A qualitative approach that can be used to isolate and remove portion of the dilution plot that has resulted from artefacts other than the groundwater flow prior to calculating the horizontal groundwater flux is proposed.
Effects of Urbanization and Agricultural activities on Aquifer storage and Groundwater quality	Athenkosi	Matshini		2015
Abstract POSTER Aquifer stress arising from urbanization and agricultural activities, these two factors affect aquifer properties when prolonged. Increase in urbanization especially those situated on top unconfined or semi-confined aquifer results in pressure on natural resources, this includes water resources, and changes of land use for agricultural purposes with high economic benefits has an effect on groundwater quality to due to application of Nitrogen- fertilizers during crop rotation and this is largely experienced in developing countries. The effects ranges from groundwater quality to aquifer storage as prolonged aquifer withdrawals due to irrigation, construction, manufacturing affects groundwater storage. Assessment of urbanization and agricultural effects on groundwater requires a complex analysis as integration approaches needs to be discovered for a better analysis of the two more specially when assessing groundwater pollution. The study was conducted to assess the impacts of urbanization and agricultural activities on aquifer storage and groundwater quality: by (a) determining the relationship between the occurrence of contamination due to urbanization by assessing contaminants present in the study area (b) develop groundwater protection, and if any offer recommendation for groundwater management. Multiple-well tests were conducted observing the behavior of drawdown and recovery for assessing groundwater storage. Two aquifer properties were observed to yield information about any changes in aquifer storage (transmissivity and storage coefficient) and groundwater quality lab test focusing on TDS, nitrate and pH were conducted. Historical results reflect that before industrial and urban revolution the groundwater contained small amounts of TDS compared with the present results. Increase in nitrate and pH concentrations observed in location closer to agricultural areas. Prolonged aquifer withdrawals increases expansion of cone of depression and therefore increases aquifer vulnerability and the risk of aquifer being polluted, and this increases storage coefficient. This study can be used to formulate protection zones for water resources and practice towards groundwater management.
Integrated Modelling: A Tool For Urban Groundwater Management On The Cape Flats, Cape Town	Benjamin	Mauck		2015
Abstract There is growing concern that South Africa's urban centres are becoming increasingly vulnerable to water scarcity due to stressed surface water resources, rapid urbanisation, climate change and increasing demand for water. Given South Africa's water scarcity, global trends for sustainable development, and awareness around the issues of environmental degradation and climate change, there is a need to consider alternative water management strategies. Water Sensitive Urban Design (WSUD) is an approach to sustainable urban water management that attempts to achieve the goal of a 'Water Sensitive City'. The concept of a Water Sensitive City seeks to ensure the sustainable management of water using a range of approaches such as the reuse of water (stormwater and wastewater), exploiting alternative available sources of supply, sustainable stormwater management and improving the resource value of urban water through aesthetic and recreational appeal. Therefore, WSUD attempts to assign a resource value to all forms of water in the urban context, viz. stormwater, wastewater, potable water and groundwater. However, groundwater is often the least considered because it is a hidden resource, often overlooked as a form a water supply (potable and non-potable) and it is often poorly protected. The management of urban groundwater and understanding the impacts of WSUD on groundwater in South African cities is challenging, due to complex geology, ambiguous groundwater regulations and management, data limitations, and lack of capacity. Thus, there is a need for an approach to assess the feasibility of management strategies such as WSUD, so that the potential opportunities and impacts can be quantified and used to inform the decision making process. An integrated modelling approach, incorporating both surface and subsurface hydrological processes, allows various urban water management strategies to be tested due to the complete representation of the hydrological cycle. This integration is important as WSUD is used to manage surface water, but WSUD known to utilise groundwater as a means of treatment and storage. This paper assesses the application, calibration and testing of the integrated model, MIKE SHE, and examines the complexities and value of establishing an integrated groundwater and surface water model for urban applications in South Africa. The paper serves to demonstrate the value of the application of MIKE SHE and integrated modelling for urban applications in a South African context and to test the models performance in Cape Town's unique conditions, accounting for a semi-arid climate, complex land use, variable topography and data limitations. Furthermore, this paper illustrates the value of integrated modelling as a management tool for assessing the implementation of WSUD strategies on the Cape Flats, helping identifying potential impacts of WSUD interventions on groundwater and the potential opportunities for groundwater to contribute towards ensuring to Cape Town's water security into the future.
Groundwater governance: where science, economics and politics meet	Nicolette	Vermaak		2015	groundwater governance
Abstract POSTER Researching a subject on the internet the slogan "Water flows upstream to money" popped up. The context was drought, and the meaning clear. If politics come into play as well, it would seem that science is relegated to a distant third place. The proclamation of the National Water Act, of 1998 (Act 36 of 1998), recognized the importance of groundwater and its role in the hydrological cycle and water supply issues. Groundwater governance has grown since then and is becoming increasingly important. One of the most important tenets on which groundwater based is the concept of sustainability. Various definitions of sustainability is used with the best know being "?development which meets the needs and aspirations of the present generation without compromising the ability of future generations to meet their own needs." Even though the basic understanding of sustainability may have been around for much longer than the term, it is the application of the theory in our current context that present us with challenges. Concepts like the precautionary principle, corporate governance and other buzz words that is being used does not always ensure good groundwater governance. One of the greatest problems is often the lack of scientific understanding and knowledge. Groundwater systems tend to be more complex and thus more difficult to manage than surface water. Understanding how groundwater and surface water interact, and that it is actually a linked water resource adds to the complexity. Add to this its importance in the functioning of groundwater dependent ecosystems that is still poorly understood. This article will look at principles for good groundwater governance and the tools that are needed to achieve it. It will finally look at real case studies where scientific considerations fall by the wayside for the requirements of the economy and political goals.
Identification and Assessment of LNAPL Hydrogeological Conditions to Refine Conceptual Site Models.	Adolf	October		2015
Abstract LNAPL present in a monitoring well forms part of the broader groundwater system and is effectively influenced by hydrogeological conditions, which are always changing. Monitoring of LNAPL is therefore of utmost importance to identify and assess the LNAPL hydrogeological conditions. Both groundwater and LNAPL can exist as unconfined and confined. Groundwater is unconfined when the upper boundary is the water table and is confined as a result of the presence of a confining layer with a relatively low vertical hydraulic conductivity that inhibits the flow of all liquids. LNAPL becomes unconfined when the apparent free product thickness increases with a decreasing groundwater elevation and confined when apparent free product thickness increases with an increasing groundwater elevation. The LNAPL is confined as a result of the difference between the capillary properties of the mobile LNAPL zone and its confining layer. Specifically, LNAPL is confined when it cannot overcome the pore entry pressure of the confining unit. Consequently, LNAPL may be confined when groundwater is not. The paper attempts to describe the hydrogeological conditions in case histories of both primary and fractured aquifers and illustrate how to identify and assess the conditions. Data such as free phase and groundwater level monitoring, well logs, sieving of soil and LNAPL bail tests are used as assessment tools. The additional required data is gathered and integrated in the conceptual site model, followed by a revision of the CSM and a refinement of decision goals over time. Thus the CSM matures and enables an improved understanding of the site characteristics and the re-adjustment of decision criteria. {List only- not presented}
Hydrocarbon plume delineation using a Hydrogeological and Geophysical approach	Albert	Kruger		2015
Abstract Simple and cost-effective techniques are needed for land managers to assess and quantify the environmental impacts of hydrocarbon contamination. During the case study, hydrocarbon plume delineation was carried out using hydrogeological and geophysical techniques at a retail filling station located in Gauteng. Laboratory and controlled spill experiments, using fresh hydrocarbon product, indicate that fresh hydrocarbons generally have a high electrical resistivity, whilst biodegraded hydrocarbons have a lower resistivity. This is attributed to the changes from electrically resistive to conductive behaviour with time due to biodegradation. As such, it should be possible to effectively delineate the subsurface hydrocarbon plume using two-dimensional (2D) Electrical Resistivity Tomography (ERT). As part of the case study, two traverses were conducted using an Electric Resistivity Tomography (ERT) survey with an ABEM SAS1000 Lund imaging system. The resultant 2D tomographs were interpreted based on the resistivity characteristics and subsurface material properties to delineate the plume. Localised resistivity highs were measured in both models and are representative of fresh hydrocarbons whereas areas of low resistivity represented areas of biodegraded hydrocarbons. More conventional plume delineation techniques in the form of intrusive soil vapour and groundwater vapour surveys as well as hydrochemical anlayses of the on-site monitoring wells were used to compare the results and to construct the detailed Conceptual Site Model. During the investigation, four existing monitoring wells located on the site and additional two wells were installed downgradient of the Underground Storage Tanks (USTs) in order to determine the extent of the plume. In conclusion, a comparison was found between the groundwater results and geophysical data obtained during the case study and it was concluded that ERT added a significant contribution to the Conceptual Site Model.
Hydrogeochemical processes in the shallow aquifer of the Lubumbashi river basin: multivariate statistical approach	Lumu	Moussa Antoine		2015
Abstract Understanding the hydrogeochemical processes that govern groundwater quality is important for sustainable management of the water resource. A study with the objective of identifying the hydrogeochemical processes and their relation with existing quality of groundwater was carried processes in the shallow aquifer of the Lubumbashi river basin. The multivariate statistical approach includes self organizing maps (SOM'S) of neural networks, hierarchical cluster (HCA) and principal component analysis of the hydrochemical data were used to define the geochemical evaluation of aquifer system based on the ionic constituents, water types, hydrochemical facies and groundwater factors quality control. Water presents a spatial variability of chemical facies (HCO3- - Ca2+ - Mg2+, Cl- - Na+ + K+, Cl- - Ca2+ - Mg2+ , HCO3- - Na+ + K+ ) which is in relation to their interaction with the geological formation of the basin. The results suggests that different natural hydrogeochemical processes like simple dissolution, mixing, weathering of carbonate minerals and of silicate weathering and ion exchange are the key factors. Added to this is the imprint of anthropogenic input (use of fertilizers, septic practice poorly designed and uncontrolled urban discharges). Limited reverse ion exchange has been noticed at few locations of the study.
A scientific method of assessing the groundwater contribution to lakes and wetlands	Roger	Parsons		2015
Abstract The intangible nature of groundwater provides challenges when trying to understand and quantify the role of groundwater in the hydrology of lakes and wetlands. This task is made even more difficult by the frequent absence of data. However, by adopting a scientific approach, it is possible to assess the hydrogeological contribution
Optimizing borehole performance through dynamic flow and chemistry profiling	Steve	Kalule		2021	Drinking water standards, Groundwater Quality, supply boreholes, remediation system, optimised well design, well profiling
Abstract Stringent drinking water standards for constituents like chromium, arsenic, and nitrates, combined with continually higher demand for groundwater resources have led to the need for more efficient and accurate well characterization. Many boreholes are screened across multiple aquifers to maximize groundwater production, and since these aquifers can have different water qualities, the water produced at the wellhead is a blend of the various water qualities. Furthermore, the water entering a well may not be distributed equally across the screened intervals, but instead be highly variable based on the transmissivity of the aquifers, the depth of the pump intake, the pumping rate, and whether any perforations are sealed off due to physical, chemical, or biological plugging. By identifying zones of high and low flows and differing water qualities, well profiling is a proven technology that helps optimize operational groundwater production from water supply boreholes or remediation systems. This frequently results in increased efficiencies and reduced treatment costs. By accurately defining groundwater quantity and quality, dynamic profiling provides the data needed to optimize well designs. Conventional exploration methods frequently rely on selecting well screen intervals based on performing and analyzing drill stem tests for one zone at a time. Using dynamic flow and water quality profiling, the transmissivity and water quality can be determined for multiple production zones in a matter of one to two days. It also allows the location and size of the test intervals to be adjusted in the field, based on real-time measurements. In this paper we discuss dynamic well profiling techniques with project case examples of characterization different types groundwater boreholes for a variety of applications and industries resulting in significant cost saving and sustainable water abstraction.
Impact of urbanization on groundwater quantity and quality in Kabul city, Afghanistan	A	Farahmand	Afghanistan	2023	Kabul basin, Urbanization, ground subsidence, Groundwater Quality, land use, land cover
Abstract Groundwater quantity and quality of shallow aquifers have deteriorated in recent years due to rapid development that has created an increased demand for drinking water, which is increasingly being fulfilled by groundwater abstraction. The study evaluates the hydrogeological framework of the Quaternary aquifer of the Kabul basin, Afghanistan, and the impact of urbanization on the groundwater resources around the Kabul city plain. Time series of Landsat satellite LCLU images indicate that the urban area increased by 40% between 2000 and 2020, while the agricultural area decreased by 32% and bare land decreased from about 67% to 52% during this period. The assumed groundwater overdraft 2019 was 301.4×103 m3 /day, while the recharge was 153.4×103 m3 /day, meaning a negative balance of about 54 million cubic meters (MCM) this year. Due to the long-term decline of water levels at 80 90 cm/year, and locally (Khairkhana, Dasht-e-Barchi) 30-50m during 2005-2019, a considerable groundwater drawdown is shown. Groundwater quality, on the other hand, reveals that chloride concentrations and salinity increased throughout the aquifer between 2005 and 2020. The nitrate concentration decreased in most Kabul Plain places over the period. In conclusion, the quantity and quality situation of urban groundwater in Kabul is worrying; urgent scientific and sustainable solutions and measures should be considered to manage this situation.
Combined effects of seawater intrusion and nitrate contamination on groundwater quality in the coastal agricultural area of El-Nil River, Algeria	Lamine	Boumaiza	Algeria	2023	Coastal aquifer, Groundwater Quality, nitrate contamination, Seawater Intrusion, stable isotopes
Abstract This study focuses on the coastal agricultural area of El-Nil River (Algeria), where anthropogenic activities heavily impact groundwater resources. A multi-tracer approach, integrating hydrogeochemical and isotopic tracers (δ2HH2O, δ18OH2O, δ15NNO3 and δ18ONO3), is combined with a hydrochemical facies evolution diagram and a Bayesian isotope mixing model (MixSIAR) to assess seawater contamination and distinguish the nitrate sources and their apportionment. A total of 27 groundwater samples and 7 surface water samples distributed over the entire study area were collected. Results show classic inland intrusion combined with an upstream seawater impact through the river mouth connected to the Mediterranean Sea. Results from nitrate isotopic composition, NO3 and Cl concentrations, and the MixSIAR model show that nitrate concentrations chiefly originate from sewage and manure sources. Nitrate derived from sewage is related to wastewater discharge, whereas nitrate derived from manure is attributed to an excessive use of animal manure to fertilise agricultural areas. The outcomes of this study are expected to help decision-makers prepare suitable environmental strategies for effective and sustainable water resources management in the study area.
Micro pore-pressure sensor (MEMs) and analysis technologies – towards a future of multi-scale groundwater monitoring	W	Timms	Australia	2023	multi-scale, pore pressure, sensors, analysis
Abstract Micro-electro-mechanical system (MEMs) technologies coupled with Python data analysis can provide in-situ, multiple-point monitoring of pore pressure at discrete and local scales for engineering projects. MEMs sensors are tiny, robust, inexpensive, and can provide wireless sensing measurements in many electrical and geomechanical engineering applications. We demonstrate the development of MEMs pressure sensors for pore pressure monitoring in open boreholes and grouted in piezometers. MEMs sensors with a 60 m hydraulic head range and centimetre vertical resolution were subject to stability and drawdown tests in open boreholes and in various sand and grouts (permeability 10-8 to 10-2 m/s). The resulting accuracy and precision of the MEMs sensors, with optimal calibration models, were similar to conventional pore pressure sensors. We also demonstrate a framework for estimating in-situ hydrogeological properties for analysis from vented pore pressure sensors. This framework method included Python code analysis of hourly pore pressure data at the millimetre vertical resolution, which was combined with barometric data and modelled earth tides for each borehole. Results for pore pressure analysis in confined boreholes (>50 m depth) included specific storage, horizontal hydraulic conductivity and geomechanical properties. Future improvements in the vertical resolution of MEMs pore pressure sensors and combined these two technologies will enable groundwater monitoring at multiple scales. This could include the deployment of numerous MEMs, at sub-meter discrete scale in boreholes and evaluating local site scale variations in pore pressure responses to recharge, groundwater pumping and excavations in complex sub-surface geological conditions.
Potential land use changes and wildfires effects over the spatiotemporal distribution of groundwater recharge at a regional scale: RAPReHS indicator accounting for SDG-13 in Bolivia	Monica Ximena	Guzmán Rojo	Bolivia	2023	Climate change, groundwater recharge, SDG
Abstract Having knowledge of spatiotemporal groundwater recharge is crucial for optimizing regional water management practices. However, the lack of consistent ground hydrometeorological data at regional and global scales has led to the use of alternative proxies and indicators to estimate impacts on groundwater recharge, enabling effective management of future water resources. This study explores the impact of land use changes and wildfires on groundwater recharge at a regional scale in Bolivia, using an alternative indicator to estimate variations in groundwater recharge rates. Based on a study by de Freitas L. in 2021, the methodology developed the annual groundwater recharge reduction rate (RAPReHS) utilizing remotely sensed data from the FLDAS and TERRACLIMATE datasets. The RAPReHS employs a simplified version of the water balance equation, estimating direct vertical groundwater recharge by considering the difference between precipitation, evapotranspiration, and runoff. The methodology was upscaled to improve data processing and analysis efficiency using an open-source cloud-computing platform (Google Earth Engine) over a 20-year period. The first results reveal a strong correlation between decreasing groundwater recharge rates and natural vegetation in the eastern region. By utilizing the RAPReHS index, forest preservation strategies can be prioritized. This study is in the framework of SDG 13 (Climate Action), which aims to mitigate the impacts of climate change on the environment and society. By exploring the impact of land use changes and wildfires on groundwater recharge at a regional scale in Bolivia, this research contributes to the inclusion of groundwater in policy guidelines for sustainable water management