Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 251 - 300 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year	Keywords
Optimized Groundwater Monitoring Design for Managed Aquifer Recharge Using Hybrid Numerical, Geophysical and Chemical modelling approach	Clinton W	Andries	West Coast, Western Cape	2021	MAR, AHP, Monitoring network design
Abstract Israel, S; Kanyerere, T Globally, surface waters are severely unsustainably exploited and under pressure in semi-arid coastal regions, which results in increasing demand for groundwater resources. Currently, Cape Town and its neighbouring towns along the West Coast of South Africa are facing water shortage related problems. Managed Aquifer Recharge (MAR) is a nature based solution to improve groundwater security in drought prone regions such as the West Coast. The objective of this study was to design a groundwater monitoring network using a hybrid hydrochemical, geophysical and numerical modelling approach to assess and mitigate the potential impacts of MAR for the West Coast Aquifer System (WCAS). An Analytical Hierarchy Process method was used to perform a Multi-criteria analysis employed in GIS (ArcMap 10.3). The factors of importance for optimized groundwater monitoring network design were based on available data and consultations with hydrogeologists and environmental scientist at stakeholder workshops. The factors which were considered included: elevation (m), geology, density of existing boreholes (wells/km2), electrical conductivity (mS/m), water rise (m), water level decline (m), transmissivity (m/day), saturation indices and lithological thickness (m). Factors were weighted based on their level of importance for the design of the groundwater monitoring network using Analytical Hierarchy Process (AHP). Priorities were calculated from pairwise comparisons using the AHP with Eigen vector method. The Consistency Ratio (CR) calculated was 5.2% which deems the weighting coefficients statistically acceptable. The results show that high priority monitoring areas occurs in the areas where there are fresh groundwater, high borehole density, elevated topography, higher recharge rates and decline in water levels are found. The monitoring network will include boreholes from the low priority areas to ensure that hydrogeological conditions are monitored and impacts are not worsened. Geophysical, numerical and chemical modelling aspects of the methodological approach will be incorporated into the initial groundwater monitoring network design.
Sharing water resources and the complexities around it: Three Case Studies from the Western Cape	Christel	Van Staden	Western Cape	2021	Water resource, De Doorns, Worcester, Drilling, Water level, Drawdown, abstraction, Irrigation, Quartzite bedding
Abstract With increasing population growth and a subsequently increased demand for food production, the agricultural sector has had to grow and develop continuously despite drought-stricken water resources in recent years. The expansion in this sector requires increasingly efficient water use management and increases in water supplies, which are often met through groundwater utilization. In the past several years the use of groundwater in the Western Cape has increased exponentially and thus has forced the sharing of resources. The question pertains to how an invisible water resource that is difficult to measure and quantify, can be shared. Issues of varying complexities can arise when submitting a water use licence application (WULA), such as historical water use debates, interactions between groundwater and surface water, seasonal stresses on resources, etc. In one case study in De Doorns, a WULA became side-tracked soon after initiation by a neighbour’s complaint that his production borehole was severely affected by the drilling of the applicant’s boreholes. In the second case study in the Hexriver Valley, a WULA was complicated by a gentleman’s agreement stating that no one in the valley is allowed to abstract groundwater from deeper than 6 m. This gentleman’s agreement stems from past disagreements regarding such practices. The final case study was not a WULA but arose out of concerns for dropping weir levels connected to a new borehole. The borehole was equipped with new casing to case off the alluvium; it was suspected to be the cause of the disturbance. The scientific method was used to evaluate the borehole’s impact on the weir. Case studies such as these will become more prevalent as the demand on water resources will increase. Hydrogeologists needs to more informed of the complexities that can and will arise in the future as a result of shared water resources.
Geochemical investigations to improve the prediction of mine water impacts: A case study in the Elandsfontein Aquifer System, West Coast.	Angelo	Johnson	West Coast	2021	Phosphate mine, waste sreams, mine water impacts, PHREEQC, geochemical
Abstract The impact of the future closure of the KROPZ phosphate mine in the West Coast on the various potential receptors including the underlying Elandsfontein Aquifer System (EAS), Langebaan Lagoon (RAMSAR-site) and wetlands were assessed. This abstract/paper describes the geochemical characterization and management options related to the waste streams from the mining activity, to assess the post closure contribution to groundwater flow from the mine towards potential receptors. The PHREEQC geochemical modelling code was used to predict potential mine water impacts. The input water quality parameters used in the model included: background groundwater quality, pit water and processed water generated from phosphate separation process at the mine. Various scenarios were simulated combining the different process water streams with the tailings and soft stockpile material at the mine. The geochemical predictions showed some management options that should be prevented, while also providing guidance to promising options where most of the chemical parameters does not exceed the WUL stage 1 thresholds. There is however, an increase in sulphate concentrations that need attending to before the mine goes into production phase. Currently there seems to be no immediate concern on the Lagoon relating to the prediction of mine water impacts post mine closure. Some of the management scenarios do however show low levels of potential impacts on SANParks property 100 years post closure. These predictions do however correlate to areas where limited calibration data is available. At the time of this abstract the sites for new boreholes have been selected and the initial boreholes are being drilled to confirm aquifer properties in areas with limited data.
Observation and monitoring of field parameters for springs and rivers of a Swiss alpine valley in relation to seasonality.	Cedric	Meier	Switzerland, France	2021	Monitoring, data management, data science libraries, Water security, Groundwater Sampling, training, municipal water supply
Abstract The study area is located in a Swiss alpine valley at the border between Switzerland and France and is situated in Valais. It is delimited by the hydrologic catchment of the river “La Vièze de Morgins”. The catchment area is situated in the Municipality of Troistorrents and of Monthey. Its population is approximately 4500 inhabitants. From the geological point of view, the valley “Val de Morgins” is mostly comprised of sedimentary rocks, amongst others breccia, schist, flysch, limestone, and quaternary sediments. The valley is affected by several natural hazards, such as landslides, rockfalls, and avalanches. Hydrogeologically, the valley contains few main springs that are outlets of porous and fissured aquifers. For this study, an inventory and monitoring of springs and rivers has been carried out since 2018 until April 2021. Particularly, more than 110 springs and rivers have been registered and observed during this time. The data includes GPS coordinates, photos, measurements of physical-chemical parameters and flowrates. Complementary to measurements, specific geological and topographical maps, and site information have been gathered. The analysis and interpretation of this huge set of hydrogeological data will be concluded with a new and innovative approach using different data science libraries that are implemented for the Python programming language. In this case study, groundwater sampling training is used to increase the understanding of the water quality. Four years of field measurements enable a better understanding of the parameter variability in relation to seasonality. Furthermore, new data analysis can aid the integrated resource management for the municipal water supply. The sampling and monitoring are key aspects to ensure water security, in terms of quality and volume. Additionally, it can also unlock prospective groundwater resources for municipal water supply. Case study data will also be compared with South African and other Swiss dataset of similar aquifer type.
Assessing groundwater dependence of wetlands and streams within the Table Mountain Group Aquifer: A Case Study from the Kogelberg	Dale	Barrow	Western Cape	2021	Ecosystems, datasets, conceptualisation, Monitoring
Abstract Ewart Smith, J; Snaddon, K; de Beer, J; Murray, K; Harillal, Z; Frenzel, P; Lasher-Scheepers, C Various analysis techniques are available for assessing the groundwater dependence of ecosystems. Hydrogeological monitoring within the Kogelberg and greater Table Mountain Group (TMG) aquifer has provided various datasets from multiple scientific disciplines (hydrological, hydrogeological, geochemical, climatic, ecological and botanical). Using a variety of analysis techniques, and using the Kogelberg as a case study, this paper assesses the groundwater dependence of several ecological sites (wetlands and streams). The starting point is a sound geological and hydrogeological conceptualisation of the site. The approach involves conceptualisation and analysis within each scientific discipline, but also requires bridging between areas of specialisation and analysis of a variety of datasets. This paper presents the data and analyses undertaken and the relevant results as they pertain to several sites within the Kogelberg.
Test Pumping: Comparing the Farmer Test, Constant Head Test and SANS 10299-4:2003 methodologies with regards to estimating groundwater abstraction. Data, analyses and recommendations.	Kes	Murray	Western Cape	2021	test-pumping, Irrigation, training, Water security
Abstract Estimating pumping rates for the purpose of equipping boreholes with suitable pumps that will not over abstract either the boreholes or the aquifer(s) that are intersected is often assessed through test pumping of the boreholes prior to pump selection. While the South African National Standard has guidelines on the methodologies and durations of these tests (SANS 10299-4:2003), many production boreholes in the agricultural and industrial sectors are still equipped based upon so called Farmer Tests or Pump Inlet Tests (PIT), often of a short (6-24 hour) duration. These tests are also frequently and incorrectly confused with a Constant Head Test (CHT), both of which are different in methodology to SANS 10299-4:2003 testing, which relies to a high degree on data collected during a Constant Discharge/Rate Test (CDT or CRT) and recovery thereafter. The study will assess differences in test pumping methodology, data collection, analysis methodology and final recommendations made between Farmer Tests and SANS 10299-4:2003 methodology tests for 20 boreholes in which both tests were performed. The selected sites cover a variety of geological and hydrogeological settings in the Western Cape. Test comparisons include boreholes drilled into the Malmesbury Group, Table Mountain Group and Quaternary alluvial deposits, with tested yields ranging from 0.5 – 25 L/s.
Analysis of groundwater sampling methods used within uranium-rich fractured rock aquifers of the Beaufort West region	James	Berkland	Beaufort West	2021	Poster, Monitoring, sampling, protocol, fractured rock
Abstract Maphumulo B; Mahed G Disastrous droughts sweeping across South Africa has led to the population turning towards groundwater as their primary source of water. This groundwater movement has increased the need for proper groundwater management in terms of both quality and quantity. Groundwater sampling is a crucial, and yet often overlooked, component of water quality assessment and management. This thesis evaluated the various groundwater sampling methods used within fractured rock aquifers in the Beaufort West region. Each sampling method was evaluated in terms of their precision and accuracy according to their hydrochemical results. Historical hydrochemical data from past reports was utilised to determine how various groundwater sampling techniques influence results. This helped gained a better understanding of the requirements required to correctly and accurately sample different water sources such as boreholes and windmills. These requirements include the importance of purging in order to remove stagnant water from windmills. By understanding these sampling techniques, it is possible to create a groundwater sampling protocol which should be followed when sampling fractured rock aquifer in order to ensure best possible results.
Combined use of Environmental and Artificial Tracers to Characterise the Vadose Zone.	Yazeed	Van Wyk		2021	Poster, vadose zone, isotopic tracers, recharge mechanisms, Protection, aquifer protection
Abstract Approximately 982 km3 /annum of the world’s groundwater reserve is abstracted, providing almost half of all drinking water worldwide. Globally, 70% is used for agricultural purposes while 38% for irrigation. Most water resources of South Africa are threatened by contamination caused by industrial, agricultural, and commercial activities, and many parts of the country face ongoing drought with an urgent need to find alternative freshwater sources, such as groundwater. Groundwater constitutes approximately 15% of the total volume consumed, hence it is an important resource that supplements insufficient surface water supplies across South Africa. Very little attention has been afforded to understanding the anthropogenically altered vadose zone as a potential source or buffer to groundwater contamination. This is evident from few research studies that has applied multiple isotopic tracers to characterise this zone. Most subsurface systems in South Africa are characterised by fractures, whereby flow and transport are concentrated along preferential flow paths. This study aims to evaluate the performance of different tracer classes (environmental and artificial) with one another, and create a better understanding of the hydraulic properties, mean residence time and transport mechanisms of these tracers. The influence of unsaturated zone thickness on recharge mechanisms will also be evaluated. Site visits will be conducted for the proposed study areas, and the neighbouring sources of contamination will be assessed. The matric potential and unsaturated hydraulic conductivities will be measured using various techniques. Water samples will be collected and analysed for the various tracers from the vadose zone using gravity lysimeters including suction cups. Several tracers will also be injected into boreholes where samples will be collected to calculate tracer residence times (BTC’s) and further constrain the hydraulic properties of the vadose zone. All samples will be analysed, interpreted, and simulated using the numerical finite-element modelling code SPRING, developed by delta h. The software derives quantitative results for groundwater flow and transport problems in the saturated and unsaturated zones of an aquifer. The research is expected to provide more insight into the selection and use of environmental and artificial tracers as markers for detecting, understanding the transport processes and pathways of contaminants in typical altered South African subsurface environments. The impact derived improved characterisation of the pathways, transport, and migration processes of contaminants, leading to groundwater protection strategies and appropriate conceptual and numerical models. The output from this study will determine the vertical and horizontal flux for both saturated and unsaturated conditions.
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.
Sustainable Groundwater Development Perspectives: Differences in sustaining individual abstraction rates based on test pumping data analysis with recharge based firm yield estimations for an aquifer or localised area.	Kes	Murray	Karoo	2021	development, water balance, groundwater budget
Abstract As populations, agricultural and industrial demands grow with time, increasing attention is placed on developing groundwater resources in a sustainable manner. At the small, local scale, this tends to involve exploration (scientific and otherwise) and test pumping (also subject to more and less scientific methods). While there can be some subjectivity in the analysis of scientific test pumping data (the selection of representative periods of drawdown stability, the inclusion of potential boundary conditions and the estimation of available drawdown), published methodologies such as the FC method (2001) and the Q20 (1959) and R20 (2006) concepts attempt to calculate sustainable abstraction rates based on these tests. At a larger catchment or aquifer scale, water balance estimates of inflows, storage and outflows are also used to estimate the effects of groundwater abstraction within such a “water budget”. This can be done conceptually, but is often also through a numerical model. A drawback of such methods is the difficulty in estimating representative annual inflow volumes, such as groundwater recharge. One such methodology is the Aquifer Firm Yield Model (2012) which assesses sustainable groundwater supplies based on threshold recharge inflows, baseflow and evapotranspiration outflows, and a 5 m aquifer saturated fluctuation limit. While this was intended for use at a preliminary stage of investigations, before sufficient hydrogeological data would be available for a numerical model, it nonetheless provides an estimate of the available groundwater for abstraction based on a water budget concept rather than test pumping data analysis. A comparison of the results of these two approaches is provided for several newly developed municipal production boreholes in the Karoo to compare where the assumptions inherent to each approach may be highlighted by noticeable differences in results.
Strengthening South Africa’s groundwater regulatory framework: The case of the unprotected dolomitic aquifer of Delmas	Carin	Bosman	Delmas	2021	Governance, aquifer protection, Regulations, WUA, abstraction, Water quality, SPLUMA
Abstract Governing groundwater in a way that does not deplete the source of water, nor cause any form of degradation is a global challenge. In South Africa, scholarship shows an extensive history of groundwater governance doctrines. Yet, the country’s groundwater remained a poorly governed resource. A recent regulatory regime change culminated in the National Water Act 36 of 1998 (NWA), which was specifically promulgated to ‘provide for fundamental reform of the law relating to water resources’. While the NWA provided an ideal opportunity for the judicious governance of South Africa’s groundwater, groundwater governance remain problematic. The regulatory focus is still very much on surface water. In fact, up to date, no regulations have been made to specifically protect vulnerable aquifers, or aquifers on which communities depend as a source of water supply, or aquifers that supports large scale agriculture. This paper sets out to achieve three objectives: to assess South Africa’s existing regulatory approach to the protection of groundwater; to identify gaps in the regulatory framework; and to explore regulatory opportunities to strengthen groundwater governance. The discussion follows a focussed approach, and hinges on the case of the dolomitic aquifer of Delmas. The Delmas case study is expected to show why policy makers and planners need to be more concerned about groundwater. It will also introduce, explain and propose an established international or foreign legal measure that may be incorporated to strengthen the regulatory status of the Delmas aquifer. The paper concludes with recommendations for strengthening South Africa’s groundwater regulation.
Water Quality Guidelines: Which to use and where applicable?	Lerize	Van Wyk		2021	Poster, Water quality, guidelines, SAWQG, SANS, WHO, WUL
Abstract When conducting water quality monitoring, questions arise on which water quality guidelines to use and where to apply them. For example, the use of South African Water Quality Guidelines (SAWQG) for Domestic usage compared to the use of the South African National Standards (SANS) for Potable Water Quality when monitoring drinking water quality. The World Heath Organization (WHO) published a set of water quality guidelines for drinking water which can also be used instead of SANS. Using various water quality guidelines to assess water quality can give different outcomes on the state of water quality of a particular site. For example, SANS water quality guidelines are less strict when compared to the SAWQG target values, however, SAWQG are comprised of different sets of standards for different usages. SAWQG distinguish between drinking water, livestock and irrigation, aquatic systems and industrial usage while SANS are only used for potable or bottled water. The International Finance Corporation (IFC) that is part of the World Bank Group published the Environmental, Health, and Safety (EHS) Guidelines for Environmental Wastewater and Ambient Water Quality, guidelines set specifically for wastewater and ambient water quality. Utilizing this poster, I will explain when to use which guidelines with different types of water samples. I will also discuss the stringent water use license limits applied at some sites compared to the national standards of South Africa.
Investigating groundwater and surface water interactions using stable isotopes and hydrochemistry in the Notwane River Catchment, South East Botswana.	Piet	Kenabatho	Botswana	2021	Gw-Sw interaction, Isotopes, Hydrochemistry, HCA
Abstract Modie LT; Stephens M Stable isotopes and hydrochemical analysis were undertaken to investigate groundwater-surface water (GW-SW) interactions and their possible implications on the quality and quantity of water in the karstified dolomite-dominated Notwane River Catchment (NRC) in semi-arid South East (SE) Botswana. Stable isotopes (δ18O & δ2H) and other hydrochemical parameters were analyzed from water samples (groundwater, river water and rain) collected in the upstream, middle stream and downstream of the Ramotswa Wellfields to investigate the potential GW-SW relationship in the study area. In addition field observation were also undertaken to support results obtained through stable isotopes and hydrochemical methods. Similarity in isotopic signatures taken during the dry and wet seasons respectively for groundwater (δ18O -1.4‰, δ2H -10.8‰; δ18O 1.4-‰, δ2H -10.9‰) and surface water(δ18O -2.04‰, δ2H -6.2 ‰; δ18O -2.56‰, δ2H -7.1‰) suggests groundwater recharge through the streambed at a site further downstream in the study area. In upstream study sites the average groundwater isotopic signature values of (δ2H -24.1,δ18O -4.1) suggests a more direct link to the Meteoric Water Line(MWL) indicating possibility of a rapid infiltration and quick watershed response to heavier rainfall events(δ2H -51.7, δ18O -8.6) rather than recharge through the riverbed. A further assessment on the GW-SW hydrochemistry was provided using Hierarchical Cluster Analysis (HCA) to investigate the influence of groundwater on stream water. The median EC values from the clusters are in an increasing order Cluster A-B2-B1 indicating cluster A(all river samples) as the most dilute samples with the shortest resident time relative to the groundwater clusters(B2 and B1). These results therefore rules out groundwater discharge through the streambed into the river as not a dominant process for GW-SW interaction in the study area. The study has concluded that GW-SW interactions in the NRC part under study vary from connected to no connection from one site to another.
A redescription of groundwater amphipods (Crangonyctoidea: Sternophysingidae) from karstic aquifers in Gauteng, South Africa	Kimberley	Murray	Gauteng	2021	Groundwater ecology, scientific illustration, zoology
Abstract Sternophysingids are a group of stygobitic amphipods that inhabit groundwater networks characterised by large fractures, cracks and voids, as well as smaller pores, fissures, cavernous openings and interstitial spaces. Two species occurring in Gauteng, South Africa, Sternophysinx filaris and Sternophysinx calceola, were studied using morphological descriptions and molecular analyses to elucidate the distribution, evolutionary history, phylogeny and population structure. The population structure and distribution of stygobitic amphipods is a reflection of the physical structure of groundwater networks, and their evolutionary history can be used to understand the formation of groundwater bodies. S.filaris is a small and common inhabitant of aquifers in the northern regions of the country, while S. calceola occurs in many of the same locations but is much larger and rarer. No morphological differences were observed between individuals of different populations of S. filaris or S. calceola and detailed illustrations have been provided for each. This finding is not believed to be indicative of a high degree of connectivity within the subterranean groundwater network, lending to high rates of gene flow, instead, these morphological similarities are a symptom of cryptic speciation. Sternophysingids are likely to arise from an very ancient and widespread ancestor inhabiting much of Gondwanaland prior to its breakup. Using the COI gene, S. calceola collected from the type locality in Matlapitse Cave was successfully PCR-amplified and sequenced. Phylogenies were constructed using a limited variety of crangonyctoid sequences and the sternophysingids were confirmed to belong to the Crangonyctoidea superfamily, being most closely allied with the Western Australian paramelitids. The relationship between these groups is still distant and ancient; it is expected that the South African paramelitids would be more closely related, as well as other African, Madagascan and Indian crangonyctoids.
Development of an Aquifer Management Plan for the Polokwane Urban Complex	Sivashni	Naicker	Limpopo	2021	NWA 1998, wellfields, Aquifer management plan
Abstract The National Water Act, 1998 (Act 36 of 1998) requires water resources management be driven at a local level, in keeping with the local nature of water systems. Polokwane Local Municipality (PLM) as the Water Services Authority, is responsible for supplying adequate domestic water to 16 Rural Water Schemes and Groundwater Schemes. The Department of Water and Sanitation (DWS) Masterplan highlighted that the DWS, Catchment Management Agencies and Water Boards need to develop wellfields and management plans to ensure sustainable use of aquifers. The Aquifer Management Plan (AMP) for the Polokwane Urban Complex (PUC) within the Olifants-Sand Water Supply Scheme was developed with an overall aim of achieving integrated and adaptive management of the aquifer. This is to assist in confronting climate change challenges and water security at local level. The AMP forms part of the Integrated Water Resource Management and should be seen in the context of other related guidelines and activities, such as catchment management, water conservation and demand management, waste water management, and water resource planning and management. Extensive consultation with PLM and various other stakeholders as part of the Aquifer Management Plan was meant to foster a groundwater management relationship between the Department, PLM and other stakeholders to create an enabling environment for implementation of the Aquifer Management Plan. A set of goals, targets and actions were developed for the Aquifer Management Plan These goals and targets serve as steps that allow for ‘zooming’ into the more specific actions. During consultations with the PLM, relevant Professional Service Providers, the DWS Limpopo Provincial Office and numerous other stakeholders, 75 actions within the 10 goals were identified. Ultimately, an Aquifer Management Plan had to identify actions that can improve groundwater resource management within the Polokwane Urban Complex and develop a supportive cross-institutional relationship in which to pursue them.
HALF FULL OR HALF EMPTY ? Groundwater surface water interactions – An ever-increasing focus for water resource management.	Sonia	Veltman	South Africa various	2021	Gw-Sw interaction, wellfield testing, resource management, numerical model
Abstract More often these days we hear concerns from water users regarding “how much water is the newly drilled borehole of a neighbor extracting from “their” river water”. These are serious question with serious repercussions for sustainable use and economic development. No one wants to lose what they have invested in. On the other hand, from a groundwater perspective, this is very one sided. Numerical modelling solutions are often proposed to clients as a more accurate method of determining the groundwater surface water interaction, with the addition of volumes removed from the modelling domain, to present to decision makers the changes in volumes of discharge into streams or volumes of infiltration of stream water into the aquifer. However, this is an expensive and time-consuming exercise, and will most likely incur additional costs to accumulate sufficient meaningful data sets for input into these detailed models. A robust combination of analytical and numerical solutions is proposed, while keeping aquifer assumptions conservative, where a lack of regional data exist. This is useful in quantifying this interaction and associated volumes better without the full time and cost associated with calibrated regional flow and transport models. Analytical calculations assist in the quantification of the aquifer’s hydraulic and physical properties and is used to conceptualize flow better and determine the inputs for a conservative well field scale numerical model, in which the change in flow between groundwater and surface water system are also evaluated. The well field scale model is calibrated in a fraction of the time as a conventional flow model (less than 20%), while volumes derived is defendable and based on measurable data. This combination is viewed to be a critical step in providing time effective solutions
Conjunctive use of water resources	Jan	KÜrstein	Saldanaha Bay	2021	Groundwater protection; recharge, Drawdown
Abstract Surface water has traditionally been the primary resource for water supply in South Africa. While relatively easy to assess and utilise, the surface water resource is vulnerable to climatic conditions, where prolonged periods of drought can lead to an over-exploitation and eventually water shortness and supply failure. Following the drought in 2018, more focus has been given to the groundwater resource to supplement the water supply in South Africa. In the Saldanha Bay municipality the water supply is based on a combination of surface water and groundwater, with plans to supplement this with desalination and managed aquifer recharge (MAR) in the future. For an efficient and sustainable utilisation of the different water resources, a Water Supply Management System is developed that can be used to manage water mix from multiple resources. The system builds on top of a flexible WaterManager system developed for operation of complex water supply infrastructures, which in the study is extended by implementing operational rules for optimal management. The operational rules provide recommendations for the day-to-day management, but also consider seasonal and long-term utilisations. To achieve this, the rules will rely on real-time monitoring data combined with results from hydrological modelling, providing estimated system response to selected scenarios to which the water supply must be resilient. In the present study the combined Water Supply Management System is developed and tested using synthetic data, which will be presented in the paper.
"But is it 'pollution'?" - determining appropriate site-specific regulatory limit values for groundwater quality.	Carin	Bosman	National	2021	Groundwater Quality, WSA 108 of 1997, SANS, law, policy, Methodology
Abstract Because the quality of groundwater is influenced by the host rock through which it moves, it differs on a site-specific basis, and is often naturally brackish or even potentially harmful to people. In spite of this, many practitioners incorrectly use the SANS 241 Drinking Water Standard as “compliance requirement” to compare groundwater quality against. This standard only applies to water that has been purified to be suitable for potable purposes at a water treatment works in terms of regulations made under the Water Services Act 108 of 1997. The only circumstance in which it could be used to compare the quality of natural groundwaters against, is where such groundwater is (to be) used, for potable purposes (with or without treatment), and then only to provide guidance on the level of treatment required to facilitate suitability for such domestic use, and not to determine possible ‘unacceptable’ levels of contamination. Therefore, the comparison of groundwater quality results against the SANS 241 Drinking Water Standard is not only a scientifically flawed practice, it has no basis in law. It is furthermore a scientifically flawed practice to refer to groundwater quality as ‘good’, ‘bad’, or ‘poor’, as it reflects a judgemental anthropocentric perspective that has no place in modern discussions on judicious environmental management and monitoring. This then raises the question, what are, or should the limit values be against which groundwater quality results should be compared to determine if it has been negatively affected by anthropogenic activity to such an extent that a scientifically substantiated claim can be made that the groundwater has been ‘polluted’, an allegation with criminal liability implications? This paper aims to answer this question in the context of South African Framework law and policy, and propose a methodology to determine appropriate site-specific limit values for groundwater quality.
What is in a - groundwater - map?	Nicolette	Vermaak	South Africa various	2021	Mapping methodologies
Abstract A map is a symbolic or diagrammatic representation of an area of land or sea, showing physical features and the relationship between these elements. It often reduces a three-dimensional world to two dimensions. Maps are generally static – fixed to paper or some other medium. Maps are produced for different reasons, leading to different types of maps, e.g., roadmaps, topo-cadastral maps and the groundwater maps – with the latter the topic of this article. There is a lot of work going into maps. This includes collecting all the data, doing evaluation and analysis of the data and selecting the data to use on the map. It is not possible to present all the information on a map and maps are often a generalisation. Different kinds of groundwater maps include availability, quality, vulnerability and protection. The selection of symbols to represent the information and the rendering of the maps are important in producing understandable, useful maps, but need explanations. The success in representing the information on a map will determine the usefulness of a map, but it is still often misused. At the end of this long and tedious process where conflict management skills were well developed, you may find that the information on the map is outdated before the ink on the map is dried properly. The production of maps should be an iterative process, where new data can be incorporated as soon as it becomes available. It is an expensive process and cannot be repeated too often. This article will look at the processes that helped to shape the current series of hydrogeology maps of South Africa, and how to use it optimally while mindful of limitations. It will also briefly touch on recent research that aims to help with the production of improved groundwater maps for South Africa.
Evaluating changes in groundwater storage during the 2015-2018 drought in the Western Cape using GRACE data	Ritshidze	Nenweli	Western Cape	2021	Poster, Drought, GRACE, Groundwater storage
Abstract The frequency, intensity, and duration of droughts are increasing globally, putting severe pressure on water supply systems worldwide. The Western Cape Province suffered from a period of severe water shortages that began around January 2015 and lasted until about July 2018. During this recent drought, there was a forced reduction in water use, predominantly from the agricultural sector. Citizens also reduced water use and increasingly tapped into groundwater for their needs irrespective of whether the hydrogeology was considered favourable or not. Unmonitored and unregulated abstraction of groundwater, especially under unstable climatic conditions, poses a significant risk to the future water security of the Western Cape. We hypothesize that groundwater enabled the municipalities, residents, and industries of the Western Cape to survive the recent drought. Our aim is to evaluate the change in groundwater storage during the 2015 to 2018 drought and its subsequent recovery. To achieve this, we must gain a comprehensive understanding of the dynamics of separate components of the water cycle, as well as the overall water balance. While there is data on surface water use during the drought, the impact on groundwater resources has yet to be evaluated. However, the accurate assessment of groundwater use is difficult, especially in data-scarce regions, such as South Africa. In our study, we combine remote sensing from NASA’s Gravity Recovery and Climate Experiment (GRACE), the Global Land Data Assimilation Systems, groundwater level measurements from the National Groundwater Archive, and ancillary datasets from the City of Cape Town’s weekly water dashboard to assess the total change in groundwater storage in the Cape Town Metropolitan area and surrounding cities over an 8-year period, from 2012 to 2020. Preliminary results from GRACE data analysis show a steady decline in aquifer saturated thickness over the drought, indicative of an increase in groundwater use.
Impact of Engineered Tree Plantations on Water Transfer Through the Upper Vadose Zone and Implications on Vertical Groundwater Recharge	Hendrik	Botha	National	2021	Poster, tree plantations, impact, vertical recharge, water transfer, vadose zone, water balance
Abstract The main purpose of this paper is to present a case study where soil moisture and rainfall data were evaluated for engineered tree plantations, to understand the potential impact on vertical groundwater recharge. Soil moisture for probes within the tree plantation root zones and reference sites within the same soil types were evaluated, in context to site rainfall patterns. Water transfer from shallow to deeper soil zones for a dataset of 2 years are presented. Observations in terms of water movement in the root zone are made. A water balance is presented in the effort to conceptualise the impact on water transfer through the upper vadose zone and to quantify the significance in terms of potential vertical groundwater recharge reduction.
The fate and occurrence of pharmaceuticals in Cape Town’s water network	Mikyle	Cloete	Cape Town	2021	Poster, CECs, micropollutants, pathways, contamination, pharmaceuticals
Abstract Israel, S Thousands of pharmaceuticals, pesticides and microplastics are consumed and disposed of directly or indirectly into various waterbodies globally. They are collectively termed “contaminants of emerging concern” or CECs. Contaminants of emerging concerns are defined as micropollutants that are present in the environment that are not regulated and that can pose a risk to the health of both humans and wildlife. The spread of these CEC’s in water systems is not isolated to a specific place and is on the rise all over the world. This study aims to investigate the spatial and temporal distribution pattern of pharmaceuticals in Cape Town’s water network, in order to assess the occurrence, concentration levels and distribution of pharmaceuticals in various water bodies. The study focuses on the occurrence of eight pharmaceuticals which are most frequently used and occurs in various water bodies around the world, namely acetaminophen, diclofenac, carbamazepine, naproxen, rifampicin, tenofovir, progesterone, sulfamethoxazole. The research sites include six waste water treatment plants in Cape Town with receiving rivers and borehole sites nearby and downstream from the waste water treatment works. Liquid chromatography combined with mass spectrometry is the selected method used to analyse the analytes of interest in the collected samples. Preliminary results obtained during the summer period (January 2021) showed that pharmaceuticals had indeed spread from waste water treatment plants into receiving water bodies with concentrations ranging from 0.8 to ≤ 6400 ng/L in both surface and groundwater due to the inefficient removal of these compounds. Continued research will conclusively address the concentration levels as a function of time, and consider the spatial distribution and its seasonality. It can be concluded from the preliminary results, that pathways of contamination from waste water discharge points to surface water and groundwater do indeed exist for the 8 pharmaceuticals considered.
Managed aquifer recharge - evaluating the efficiency of the unsaturated zone to reduce contaminants. A case study of Atlantis aquifer	Londiwe	Ntshangase	Atlantis	2021	MAR, contaminants removal, unsaturated zone, prevention strategies
Abstract Surface water resources are under threat of depletion and quality deterioration due to various factors such as climate change, urbanization, and population expansion. Managed aquifer recharge (MAR) is a technique that has been successfully implemented over the last 4 decades to sustain the balance between water demand and availability. The unsaturated zone, where source water is introduced during infiltration, plays a major role in the reduction of contaminants present in water before it naturally percolates and reaches the aquifer. This research aims to evaluate the removal efficiency of contaminants by the unsaturated zone. Three objectives to be accomplished are; to determine and classify the chemical composition of the source water. Secondly, to determine the hydraulic properties of the soil in the area of interest. Lastly to evaluate the contaminants removal efficiency, by tracing the quality of water at the point of recharge and discharge. The Atlantis water resource management scheme in the Western Cape will be used as a case study, in order to assess the relationship between the unsaturated zone and the reduction of contaminants. The current study argues that during the artificial recharge of aquifers, contaminants present in the source water filter through the unsaturated zone, where natural processes, as well as resident microbes, reduce their concentrations to acceptable levels. Assessing the ability of the unsaturated zone to reduce contaminants, will allow for the early warnings of contamination potential and the execution of informed prevention strategies that can be used in decision making of the management and protection of water resources. Additionally, the advanced understanding of the role that the unsaturated zone plays in eliminating contaminants can be used to account for satisfactory groundwater quality in areas where groundwater is not constantly monitored and artificial remedies are not applied.
Test pumping derivative analysis to improve conceptual understanding in a complex aquifer: Steenbras Wellfield.	Kevin	De Bruin	Steenbras Wellfield, Cape Town	2021	flow regime analysis, flow models, test-pumping, drawdown derivative curve, hydraulic conductivity, Derivative data
Abstract Test-pumping drawdown curves are not always sufficiently indicative of aquifer characteristics and geometry. In fact, drawdown curves should never be analysed and interpreted alone. The derivative analysis (Bourdet et al., 1983) and flow dimension theory (Barker, 1988) make it possible to infer the regional geometries and flow characteristics of fractured aquifers which are otherwise often unknown or inconclusive when interpreting point-source borehole logs. The propagation of the drawdown and/or pressure front through the aquifer reaches distal hydrogeological objects which influence the flow regime and imprints signatures in the drawdown derivative curves. The conjunctive interpretation of these flow regime sequences and geological data results in a robust, well-informed conceptual model which is vital for resource management. A methodology similar to that of A. Ferroud, S. Rafini and R. Chesnaux (2018) was applied to the test-pumping data of 14 confined and unconfined Nardouw Aquifer boreholes in the Steenbras area, Cape Town, which has been under exploratory investigation since the early 2000’s. The Steenbras wellfield was developed following the major 2017-2018 Western Cape drought. The NE-SW trending open folds and dextral strike-slip Steenbras-Brandvlei Megafault Zone (with crosscutting faults and dykes) make the aquifer hydrogeologically complex. It is due to these complexities that the sequential flow regime analysis was undertaken to enhance the current conceptual understanding. The analyses reveal domains of flow models which include open vertical fracture, T-shaped channel, double(triple) porosity model, and leaky/recharge boundary amongst others. Poor data quality and noise issues are also highlighted. The outcomes of the sequential flow regime analysis allow for identification of applicable flow models for type curve fitting to avoid erroneous aquifer parameter estimations; improvement of the hydrogeological understanding of the aquifer; enhancements of the current conceptual model in order to inform on subsequent numerical modelling, groundwater resource management and ecological protection.
Latest approaches and examples illustrating the key role of numerical modelling in sustainable groundwater use in South Africa	Annalisa Sagra	Vicente	South Africa various	2021	numerical modelling, recharge
Abstract Imrie, S. Groundwater in South Africa has great potential to supplement our country’s water demands. Currently, studies show that less than 10% by volume of the Average Groundwater Exploitation Potential is abstracted on an annual basis. The 2017 drought has aided in creating awareness of the importance of this resource towards building water resilience. If managed correctly, groundwater is commonly viewed as a sustainable source. Oftentimes, the ‘sustainability’ of a groundwater resource is an ‘open-ended’ definition based on the hydrogeologist’s interpretation of aquifer pumping test data alone. This approach often discounts the cumulative impact of environmental factors (including drought and climate change) and other users on groundwater. The use of numerical groundwater models to support and inform the conceptual models provides the mechanism to bridge this gap. This paper discusses various approaches and examples of where numerical modelling plays a key role in supporting groundwater usage in a sustainable and informed manner. In particular, this includes: •Inclusion of impact from other anthropogenic activities and groundwater users, with model scenarios that show the potential impact of each on the other, as well as the combined result to groundwater (levels and water quality) •Consideration of extreme climatic events (e.g. 1 in 100-year drought and/or flood), including the use of uncertainty analysis and consideration of dynamic groundwater management, such as the possible varying of sustainable pumping rates to suit the prevailing conditions •Identification of groundwater receptors and appropriate assessment of potential impacts to those receptors from groundwater usage, including “target-audience” thinking in the post-processing and reporting of numerical model results, so as to convey clear messages to the interested and effected parties and stakeholders •Use of multiple methods and technologies to calculate and model surface water / groundwater interaction and recharge, including uncertainty analysis, and intelligent challenging of traditional methods of estimating groundwater recharge
Testing Danish groundwater mapping methodologies in South Africa, Case Ladysmith, South Africa	Jan	KÜrstein	Ladysmith, South Africa, Denmark	2021	Mapping methodologies, 3D models
Abstract Vermaak, N; Fourie, F; Awodwa, A; Metcalf, D; Pedersen, PG; Linneberg, MS; Madsen, T The Strategic Water Sector Cooperation (SSC) between Denmark and South Africa is a long-term bilateral cooperation, which amongst others are contributing to the South African water sector by demonstrating and testing different Danish groundwater mapping methodologies in South Africa in order to add long term value to the South African work on optimizing the utilization of groundwater and to increase the resilience against drought. One key aspect is to develop a South African groundwater mapping methodology, based on the detailed Danish methodology and South African specialized knowledge of the South African hydrogeology. In this case, the SSC has contributed to the work done by Umgeni Water in The District Municipality of uThukela in the KwaZulu-Natal (KZN) province of South Africa. The methodology that has been used is integrated modelling using 3-geological models built in GeoScene3D and groundwater modelling, which was based on existing data from Umgeni Water and Department of Water and Sanitation (DWS). Based on the outcome of the 3-D geological voxel model both known aquifers where the boundary has been adjusted, as well as new aquifers has been outlined. Good places for drilling production boreholes have been identified, followed by groundwater modelling of sustainable abstraction rates from existing and new potential well fields. Finally, recommendations were made for new data collection and how to modify the Danish mapping approach for use in South Africa, taking the differences in geology and water management into consideration. The Danish methodology for groundwater mapping is adaptable to South African conditions but it requires Danish and South African experts works closely together. The project has also shown that integrated 3-D geological modeling and hydrological modelling can contribute to a sustainable development of groundwater in South Africa, as well as the Danish methodology for modelling and monitoring sustainable abstraction rates.4
Science-Policy Nexus: Assessing role of groundwater resource directed measures in water resources protection practice, case of Schoonspruit-Koekemoerspruit River Catchment, South Africa	Stanley	Nzama	Gauteng, North West	2021	RDM, aquifer protection, knowledge sharing, policy implementation
Abstract The argument in this paper is that improved understanding of science-policy integration, where physical bases of natural science is combined with practice in managing water resource challenges, becomes critical in translating scientific knowledge into effective and sustainability solutions linked to groundwater resource protection. Such hypothesis should be attested at locally relevant scale where water resources reside and where water utilization takes place. This paper provides a practical case-study of how science-policy integration can directly impacts groundwater resource protection practice from a local, and national perspective using strategies of groundwater resources directed measures. A combination of literature surveys, and desktop record review methods were used for the purpose of data collection from published literature and publicly accessible national databases of the Department of Water and Sanitation (DWS). Collected data were analysed using document analysis, descriptive statistics, and case study analysis methods. Based on the analysis, three types of science-policy nexus theoretical models exist in practice, namely, 1) science-policy integration, 2) policy-science integration, and 3) mixed integration. From a national perspective, the analysis showed that South Africa is able to practically apply science-policy nexus in policy implementation practice for water resources protection, and that such practice depicts a mixed integration model of the nexus. Case study analysis of the Schoonspruit-Koekemoerspruit River Catchment provided insight on how localized operationalization of groundwater resource directed measures facilitates sustained groundwater resources protection for water availability and sustainable utilization. This study provides an exemplary for collaborations between researchers and/or scientists and policy makers to ensure that science research is answering policy-relevant questions and that results from scientific work are readily available for policy implementation. In addition, there is adequate evidence to indicate that science-policy nexus can be designed and prioritized to support sustainable development agenda on groundwater resilience, and visibility at various levels.
Measuring Hydraulic Conductivity Across Different Scales Using Varying Methods To Develop A Hydraulic Conductivity Model	Sispho	Dlakiya	Cape Town	2021	Poster, hudraulic conductivity, methods, scales, infiltrometer, vertical infiltration
Abstract This paper describes the calibration and testing processes of three methods of measuring hydraulic conductivity (slug test, mini disk infiltrometer and particle size distribution (sieves)) across varying scales (field and lab). The methods used in the field are the slug test and sieves which were used in four different wells of the Rietvlei wetland in Cape town and the mini disk infiltrometer was used in a grid developed in one of the Nelson Mandela University Reserve salt pans. The mini disk infiltrometer and the slug test are used to determine the saturated hydraulic conductivity (Ks) of altered or unaltered soil samples under controlled conditions in a laboratory, and that is a key parameter to understand the movement of water through a porous medium. The mini disk infiltrometer requires a small volume of water and has a compact size which makes it convenient for laboratory soil specimens, especially when studying vertical infiltration. Infiltration shows a dependence on the compaction and saturation of soil while hydraulic conductivity increases with depth in a simulated aquifer.
The Seven Deadly Sins of Numerical Modelling	Andries	Wilke	South Africa	2021	numerical modelling, recharge
Abstract Pope Gregory defined the seven deadly sins in order to guide the Catholic Church in the 6th century. The past 20 odd years in the industry has shown that there are several mistakes that are repeatedly made by numerical modelers. Although we all acknowledge that any numerical model is a non-unique solution, and that there exists and infinite number of solutions, there are several sins that will prevent the model from giving an accurate representation. This paper will provide the most common mistakes made in a format that is accessible to numerical modelers as well as other practitioners. Issues covered will include boundary conditions, model complexity and recharge.
Assessment of Concentration levels of contaminants in groundwater of Soutpansberg Region, Limpopo Province, South Africa	Lindelani	Lalumbe	Limpopo	2021	community supply, Drinking water standards, Groundwater Quality, skills transfer, knowledge sharing, health, Food security
Abstract Kanyerere, T Groundwater contribution towards improved food security and human health depend on the level of contaminants in the groundwater resource. In rural areas, many people use groundwater for drinking and irrigation purposes without treatment and have no knowledge of contaminants levels in such waters. The reason for such lack of treatment and knowledge is due to the parachute type of research which emphasizes on scientific knowledge and records only and do not develop skills and outputs on groundwater quality for improved human health and food security in communities. This study argued that parachute research type exposes groundwater users to health hazards and threaten food security of communities. Concentration levels of contaminants were measured to ascertain suitability of groundwater for drinking and irrigation use. 124 groundwater quality samples from 12 boreholes and 2 springs with physiochemical data from 1995 to 2017 were assessed. This study found high concentration levels of contaminants such F-, NO3-, Cl- and TDS in certain parts of the studied area when compared to international and national water quality standards. In general, groundwater was deemed suitable for drinking purposes in most part of the studied area. Combined calculated values of SAR, Na%, MH, PI, RSC and TDS determined that groundwater is suitable for irrigation purposes. The discussion in this paper showed that scientific knowledge generated on groundwater quality is not aimed at developing skills and outputs for improved human health and food security but rather for scientific publication and record keeping leaving communities where such knowledge has been taken devoid of knowledge and skills about the groundwater quality. In this study, it was recommended that skills and outputs on groundwater quality should be developed and shared with groundwater users through various initiatives as it will enhance the achievement of SDG’s.
An investigation of the natural groundwater recharge and discharge of the Saldanha Bay Aquifer Systems, South Africa	Aqeela	Parker	Saldanah Bay	2021	Bulk water supply, recharge, Discharge
Abstract Saldanha Bay is partially dependent on groundwater as part of their bulk water supply, as surface water resources in the area are extremely limited and fully allocated. Due to this, there is lots of pressure on the groundwater resources by industrial development and residential growth. Despite studies being conducted on these aquifer systems since 1976, they are still poorly understood especially with regards to their recharge and discharge processes. This study aimed at providing better insight and understanding on the natural groundwater recharge and discharge processes in order to assist in the better management of groundwater resources in Saldanha Bay. Recharge investigations included a Time Domain Electromagnetic airborne geophysical survey, the assessment of groundwater levels, infiltration tests, hydrochemical analyses as well as stable and radioactive isotope analyses. These methods allowed for the delineation of the geological layers and extent, determination different water quality spatially across the aquifer, determination of flow paths through the saturated and unsaturated zones, identification of inter-aquifer flow as well as different recharge processes in the area. The results of this study showed that is highly likely that the Saldanha Bay Aquifers are mainly recharged via deep flow paths from the Aurora Mountain Range and Moorreesburg region. Investigations also showed that it is unlikely that the Aquifer Systems are recharged by local rainfall due to thick unsaturated sands and low annual rainfall, except for runoff at the foot of granite hills through focused recharge processes. The Berg River, Langebaan Lagoon and the Atlantic Ocean were identified as being the main discharge zones for the area. It is recommended that further hydrogeological investigations are conducted in the Moorreesburg region in order to get a fuller picture of the regional groundwater recharge processes and flow to Saldanha Bay.
The Importance Of Reliable Monitoring Data	Shuaib	Dustay	National	2021	data management, numerical model, poor data
Abstract Imrie, S “Monitoring rounds”, “logging”, “quality checking”, “data collation” and “reporting” are terms all too familiar to groundwater field specialists. Yet, a full understanding of the true worth and the full lifecycle of data is often not appreciated. Field data form critical “ingredients” to groundwater conceptual and numerical models. Unfortunately, if can often be the case that the quality of field data is only tested once it has been processed and input to the model, which may be many years following collection. This case study highlights the time-consuming, budget-consuming and groundwater management difficulties that can arise from poor quality data, such as poor monitoring network designs, inconsistent data capturing, erroneous logging, poor borehole construction and gaps in data. The study area is an industrial complex with a highly contaminated groundwater system. The site is located on fractured sandstone and tillite, with major cross-cutting fault zones. The objectives of the numerical groundwater model are to assess the efficacy of the current remediation measures, likelihood of seepage due to artificial (contaminated) recharge, and prediction of the future potential contaminant plume footprint. Setbacks were encountered in the early stages of building the model. Although the site has a monitoring network of over 300 boreholes, less than 50 of these boreholes could be considered for model calibration, with those remaining including data with high uncertainty and multiple assumptions. The poor data resulted in lower calibration statistics which translated into lower model confidence levels. The modelling exercise proved useful for informing updates to the monitoring programme and identification of critical gaps where future drilling and testing will be focussed. However, the lack of reliable monitoring data led to a model of low confidence and high uncertainty, subsequently impacting the level of groundwater management, and thus impeding remediation efforts and future protection of our precious groundwater resource.
Analyzing the effects of episodic groundwater recharge caused by extreme events in a semi-arid region: a case study in Beaufort West, South Africa.	Aarifah	Williams	Beaufort West	2021	recharge
Abstract On a global scale, groundwater is seen as an essential resource for freshwater used in both socioeconomic and environmental systems; therefore forming a critical buffer when droughts occur. Due to its location in a dry and semi-arid part of South Africa, Beaufort West relies on groundwater as a crucial source of fresh water. Thus, proper management of their groundwater resources is vital to ensure its protection and preservation for future generations. Although fluctuations have occurred over the years, groundwater levels in the area have progressively dropped due to abstraction in well fields. However, in 2011, an episodic flooding event resulted in extreme groundwater recharge with groundwater levels North-East of Beaufort West recovering tremendously. This led to the overall groundwater levels of Beaufort West becoming relatively higher. The general flow of groundwater in the town, which is from the Nuweveld Mountains in the North to the town dyke in the South, is dictated by dykes occurring in the area. This study aims to expand on the understanding of episodic groundwater recharge around extreme climatic conditions of high precipitation events in a semi-arid region. This was done by analyzing historical data for the Gamka Dam spanning over 30 years; estimating recharge in the Beaufort West well fields caused by the flooding event; as well as studying the hydrogeological setting and lineaments in the area. It was found that sufficiently elevated recharge around the observed flooding event only occurred in areas where the correct climatic (precipitation, evaporation), geological and geographical conditions were met. Ultimately, gaining a better understanding of these recharge events should aid in the assessment of the groundwater development potential of Beaufort West.
Test pumping Well field analysis of a heterogeneous fractured rock aquifer.	Reuben	Lazarus	Cape Town	2021	Shales, wellfield testing, cluster connectivity
Abstract A Case study done in the heterogeneous Tygerberg shales underlying the northern section of the Cape flats aquifer. A well field consisting of five boreholes within a 1.6 Ha area was test pumped to determine aquifer parameters and sustainable yields for the well field. The wellfield located in a highly heterogeneous geological setting, proved to be an interesting scenario for wellfield analysis and determination of sustainable borehole yields. A variety of analytical methods were used to analyse the test pumping data including the Advance FC analysis and the Cooper Jacob Wellfield analysis, both producing different results. Through the test pumping data analysis, the wellfield could be divided into sub wellfield clusters based on drawdown interconnectivity during testing. Sub wellfield clusters were confirmed using groundwater chemistry, providing higher confidence in limiting uncertainty in long term cluster connectivity.
Using geophysics to detect water-hosting fractures in the Vredefort Dome: A training opportunity	Stephanie	Enslin	Vredefort Dome, Gauteng	2021	Field School, fractures, geophysical methods
Abstract Tamilo, T; Webb, S.J. The Vredefort Dome 120 km southwest of Johannesburg is a meteorite impact crater that formed at approximately 2 Ga. The region hosts farmland, and the town of Parys is situated in the northwestern part of the dome. The dome is the location of the annual Wits University/AfricaArray Geophysical Field School. The aim of the field school is to teach geoscience students several geophysical techniques while conducting scientific research in the area. A geophysical survey during the 2019 field school over an open field just outside of Parys revealed a buried fracture that hosts ground water. A 150 m long magnetic profile over the fractures shows a magnetic low (approximately 500 nT) that correlates with a low resistivity region on the inverted electrical resistivity data (dipole-dipole method). Euler deconvolution depth estimates and magnetic modelling estimate an overburden thickness of around 10 m and a similar fracture thickness. The magnetic low of the fracture is due to weathering and removal of any magnetic material in the granites in the region. Two existing boreholes that lie 618m due south and at a 10 m lower elevation have water levels of around 6.4 m. Both boreholes lie near a riverbed and vegetation, and appear to lie along an extension to the fracture. This fractures detected using geophysical methods seems to form part of a larger fracture system within the Vredefort Dome, that is linked to the formation of the dome. These fractures provide a vital source of water for the local farming community.
FrackSA: A tool to aid in the enforcement of groundwater regulations during unconventional oil and gas extraction	Charissa	Worthmann	South Africa	2021	Poster, Unconventional gas, hydraulic fracturing, Regulations, enforcement, civic informatics, mobile application, groundwater protection
Abstract South Africa is currently considering unconventional oil and gas (UOG) extraction as an additional energy resource to improve the country’s energy security. In a water-scarce country such as South Africa, which has experienced more frequent and more intense climate extremes due to climate change, the water-related impacts of UOG extraction is a concern. The South African government is however determined to proceed with UOG development as soon as regulations to protect natural resources have been drafted. The country’s intricate governance system can however not enforce such regulations effectively, as it experiences repeated inter-departmental miscommunication, fails to collaborate with stakeholders effectively, and lacks human and financial resources for enforcement. A lack of transparency in fracking operations and between stakeholders is another challenge for enforcing UOG extraction regulations. Poor regulatory enforcement presents an obstacle for the protection of groundwater resources if fracking were to commence. This study, therefore, focuses on addressing the enforcement challenges of UOG regulations aimed at protecting groundwater resources. It proposes the use of civic informatics on a technology platform, specifically via a mobile application (FrackSA), to assist with on-the-ground enforcement of these regulations. While many UOG mobile applications are used internationally, they mostly focus only on UOG related aspects (news, information, pricing, geological information, and fracking well information). FrackSA uses civic informatics to address both groundwater monitoring and management as well as UOG extraction operations in a single platform, to enable regulators to protect groundwater resources more effectively during UOG extraction, while simultaneously enhancing transparency in the UOG industry.
Towards a conceptual understanding of groundwater-ecosystems interactions in the Tuli-Karoo transboundary aquifer	Kwazikwakhe	Majola	Karoo	2021	Ecosystem, TBAs, Dependent, Aquatic, Vegetation, Wetlands, Interactions, Transboundary flow, Integration, recharge, Discharge, conceptualisation
Abstract Xu,Y; Kanyerere, T Currently, there is little understanding of the nature and extent of groundwater-dependent ecosystems (GDEs) at catchment or aquifer scale globally, making it difficult to protect and incorporate them in integrated groundwater resources management plans. Groundwater levels fluctuations could alter groundwater accessibility patterns to GDEs, potentially resulting in groundwater quality deterioration too. The understanding of groundwater-ecosystems interactions is generally poor since most historical research has been skewed to surface water-related ecosystems. There exists a research need towards the understanding of groundwater processes that control the maintenance of GDEs at local level, through conceptual modelling. A study has been initiated in the Tuli-Karoo transboundary aquifer (TBA) – shared between Botswana, South Africa and Zimbabwe in the Limpopo Basin - to address this scientific knowledge gap because of possible cross-border negative impacts on respective groundwater resources attributed to interlinked aquifer systems’ nature between riparian countries. Ecosystems’ protective measures here are country-specific, disregarding neighbouring countries activities and based on low-flow requirements through baseflow, largely excluding terrestrial GDEs. Groundwater resource co-management agreements are also non-existent among sharing countries, warranting a collaborative approach to research. Potential GDEs in this TBA include riparian vegetation along the main stem Limpopo River and its major tributaries (Shashe and Mzingwane); terrestrial vegetation of Mopane bioregion of the Savanna Biome; and seasonal and permanent wetlands, pans and springs. Isotope analysis have ascertained dependency partly in one country and therefore extended to cover the TBA. Tuli-Karoo is characterized by shallow unconfined alluvium aquifer systems of the Karoo sandstones and basalts of shallow to medium depths. A conceptual model developed will demonstrate interactions between groundwater, surface water and ecosystems; allowing for assessments of impacts on GDEs to ensure resilience. Although TBA focused, the findings will be applicable to similar national aquifers in terms of lithology, geology, geohydrology and ecosystems types.
An innovative approach to dealing with elevated iron concentrations at the Knysna Hospital	Roger	Parsons	Knysna	2021	Iron treatment, TMG, pumping rates
Abstract In response to the drought which started in 2017, the Western Cape Government set about securing water supplies to key facilities across the province, including the Knysna Hospital. Drilling and testing of two boreholes at the facility indicated it to be viable to establish a groundwater supply of 66 KL/d from the underlying Table Mountain Group Aquifer. Iron concentrations were low and the initial water chemistry analyses pointed to concentrations below the SANS 241 aesthetic limit. However, further to the implementation and operationalization of the groundwater supply schemes, significantly elevated iron concentrations of up to 6 mg/L were observed. This contributed to the difficulty in getting the Knysna Hospital’s alternative water supply operational. Best practice requires that as little oxygen as possible gets introduced into the groundwater system; and this can be achieved by pumping the borehole continuously at the lowest rate possible. It is not always possible to do this under operational conditions when the water demand varies. To counter the iron problem in the potable water and to prevent or retard an increase in the iron concentration in the abstracted groundwater, iron treatment was added to the treatment train and a dual pumping regime was adopted. Using the variable speed drives that had been installed with the pumps, two pumping rates were adopted – with the rate controlled by the level in the treated water storage tank. When the tank level is low, the borehole is pumped at a rate of 0.9 L/s. However, when the level fills to 70%, the pumping rate is reduced to 0.35 L/s and continues pumping even if the tank is full. The modified system was brought into operation in August 2019 and has continued to meet the water demand of the hospital.
Fracking regulations to protect groundwater resources during unconventional oil and gas extraction: Getting it right.	Surina	Esterhuyse	National	2021	Fracking, Regulations, enforcement
Abstract The South African government is actively pursuing unconventional oil and gas (UOG) extraction to augment energy supplies in South Africa, but it risks damaging water quality. The Department of Water Resources and Sanitation recently released regulations to protect water resources during UOG extraction for public comment. Regulations are one of the main tools that can be used to minimise UOG extraction impacts on water resources and enhance an environmentally sustainable economy. This tool must however be used correctly. Many states in the US and Canada have extensive regulations to protect water resources during UOG extraction but they are often ineffective, either because they were poorly drafted or because they are not properly enforced. Since South Africa is a water-scarce, groundwater-dependent country, we asked South African groundwater experts what regulations are needed and how to enforce them. Focusing on the interface between science and public policy, we critically analyse and recommend the most appropriate fracking regulations to protect groundwater resources. Additionally, we consider the enforcement mechanisms required to ensure the proper regulation of fracking. The results from this study can assist the government in ensuring that regulations that they are currently drafting and finalising, are appropriate to protect groundwater resources, and that they would be able to enforce them effectively.
Unconventional Gas Regulations for Water Use by DWS Unconventional gas	Lebogang	Malefane	South Africa	2021	Unconventional gas, UCG, CMB, contamination, Regulations, NWA 1998
Abstract Unconventional gas development in South Africa consists of but not limited to shale gas extraction commonly known as “fracking”, Underground Coal Gasification (UCG), Coalbed Methane (CBM), to extract natural gas from geological formations is a new, rapidly expanding industry in the world and in South Africa. However, there are general concerns that these operations could have large negative impacts such as groundwater contamination. This article maps out the development of regulations for unconventional gas operations, according to Section 26(1) (9) of the National Water Act, 1998 (NWA) and read together with Government Notice 999 (Government Gazette No.: 39299, of 16 October 2015). The objectives of the published DWS regulations include, augmenting the NWA and its existing regulatory framework, providing for a step-wise process for authorising all unconventional gas operations to allow for informed decision making, to set prohibitions and restrictions for protection of water resources, and requirements for disclosure on chemicals to be used during the operations. The objectives of DWS regulations are aligned to the NEMA, and MPRDA requirements for exploration and production of these operations, and are further supplemented by the minimum information requirements for water use licensing application and as part of integrated water resource management. In conclusion, DWS proposes thoroughly consulted and fit-for-purpose regulatory framework that seeks to propose water use law and requirements for unconventional gas operations based on the National Water Act (1998). With these proposed regulations DWS ensures that it plays its critical role in the development of a regulatory framework for unconventional gas operations.
The onset of iron biofouling in boreholes in and around Cape Town	Roger	Parsons	Cape Town	2021	Iron biofouling, Drought, Monitoring
Abstract Iron biofouling in boreholes drilled into the Table Mountain Group has been documented, with groundwater abstracted for the Klein Karoo Rural Water Supply Scheme and irrigation in the Koo Valley hampered by clogged boreholes, pumps and pipes. A similar phenomenon has been experienced at some boreholes drilled and operationalised by the Western Cape Government in response to the onset of the crippling drought in 2017. Monitoring of groundwater levels and pumping rates has yielded data showing a gradual decrease in groundwater level as the pumping rate reduced in response to the pump becoming biofouled, with possibly the same negative impact on the borehole itself. Methods are available to rehabilitate the boreholes (mechanical scrubbing, chemical treatment and jetting), but it seems difficult to destroy the bacteria and re-occurrence of biofouling appears inevitable. In the absence of better solutions, current experience suggests an annual borehole maintenance and rehabilitation budget of R 100 000 per borehole is required. This paper presents three case studies of boreholes drilled into the Malmesbury Group and Table Mountain Group and explores possible triggers of biofouling and its manifestation in the monitoring data.
Groundwater transport modelling: A fractional/fractal perspective	Amy	Allwright		2019	modelling
Abstract The complexity of real world systems inspire scientists to continually advance methods used to represent these systems as knowledge and technology advances. This fundamental principle has been applied to groundwater transport, a real world problem where the current understanding often cannot describe what is observed in nature. There are two main approaches to improve the simulation of groundwater transport in heterogeneous systems, namely 1) improve the physical characterisation of the heterogeneous system, or 2) improve the formulation of the governing equations used to simulate the system. The latter approach has been pursued by incorporating fractal and fractional derivatives into the governing equation formulation, as well as combining fractional and fractal derivatives. A fractal advection-dispersion equation, with numerical integration and approximation methods for solution, is explored to simulate anomalous transport in fractured aquifer systems. The fractal advection-dispersion equation has been proven to simulate superdiffusion and subdiffusion by varying the fractal dimension, without explicit characterisation of fractures or preferential pathways. A fractional-fractal advection-dispersion equation has also been developed to provide an efficient non-local modelling tool. The fractional-fractal model provides a flexible tool to model anomalous diffusion, where the fractional order controls the breakthrough curve peak, and the fractal dimension controls the position of the peak and tailing effect. These two controls potentially provide the tools to improve the representation of anomalous breakthrough curves that cannot be described by the classical-equation model. In conclusion, the use of fractional calculus and fractal geometry to achieve the collective mission of resolving the difference between modelled and observed is explored for the better understanding and management of fractured systems.
Airborne And Ground Geophysical Surveys To Investigate The Deep Geology And Geohydrology In The Beaufort West Area, Western Karoo, South Africa	Matome	Sekiba	Western Cape	2019	Geology, Geohydrology, Airborne, Magnetotelluric
Abstract A geoscientific research project is underway in the Western Karoo Basin near Beaufort West, South Africa. This area has been earmarked for possible gas exploration. The aim of the project is to improve the understanding of the deeper aquifer systems of the Karoo Basin to better predict potential impacts of geo-resource exploration activities on the deep groundwater systems. This paper reports on the airborne and ground geophysical surveys that were conducted in the study area to gain insight into the deep structural geology and its possible association with aquifer systems. Geophysical methods that were used in the investigations include: 1) the airborne magnetic method was employed to detect and delineate non-outcropping dolerite sills and dykes, as well as to map geological structures of regional extent, and 2) the deep-probing magnetotelluric (MT) technique was used to map conductivity contrasts at large depths that could be associated with prominent geological structures. The results of the geophysical surveys showed that the airborne magnetic method was very effective in mapping intrusive magmatic bodies and other major geological structures. The magnetotelluric results indicated the presence of very resistive layers that appear to be associated with dolerite intrusives. Furthermore, the vertical displacement of a conductive zone indicated the possible presence of large-scale faulting. Based on the results of the airborne geophysical investigations, two investigative boreholes were drilled at selected positions to depths of 516 m and 1 402 m to obtain information on the subsurface geological and geohydrological conditions, and to constrain the interpretation of the airborne geophysical data. Downhole geophysical surveys were conducted on these boreholes to obtain in situ geotechnical and structural information. The results of this project show that the combined use of airborne and deeper probing geophysical methods can greatly contribute to the understanding of the deep geological and geohydrological conditions in the Karoo Basin. The approach can be further utilised for similar investigations of other Karoo satellite basins in South Africa and neighbouring countries
Emergency Response To Drought - The City Of Cape Town's Groundwater Abstraction And MAR Scheme (South Africa)	David	McGibbon	Cape Town	2019	Drought, MAR
Abstract The Western Cape region in South Africa is currently experiencing its worst drought since 1904. As a result, the City of Cape Town (CoCT) implemented emergency response projects to augment water supply through desalination, re-use of treated effluent and groundwater abstraction from several groundwater systems. Amongst the targeted aquifers, the Cape Flats Aquifer (CFA) presents unique challenges and opportunities for abstraction and managed aquifer recharge (MAR). The CFA is a coastal unconfined primary aquifer within the urban and peri-urban environment. As such it is well situated to take advantage of enhanced recharge from treated effluent and urban stormwater. MAR is currently being tested and implemented with a three-fold purpose: (1) create hydraulic barriers against seawater intrusion and other contamination sources, (2) protect groundwater dependent wetlands and RAMSAR sites and (3) increase storage to enhance resilience to drought. Due to local hydrogeological characteristics and a high demand for open land, in the short term, high quality treated effluent will be injected directly through boreholes. Numerical modelling has supported siting and quantifying necessary injection rates. Current estimates indicate that available treated effluent will increase sustainable yields from the aquifer two-fold, as well as providing an additional storage volume equivalent to 2 to 3 years abstraction. In the future this is expected to be complemented with the re-design of urban water drainage to further enhance the recharge of stormwater. Given the time-constraints of an emergency response project, long-term testing and study of the system to support design and implementation have been significantly reduced and had to be replaced by a 'learn by doing' approach. We aim to present the on-going challenges of implementing MAR to complement an emergency response, as well as an overview of the scheme, new data and insights gained through the process.
Groundwater Sampling Errors: The Missing Link in the Broken Chain	Gaathier	Mahed	Karoo	2019	Sutherland, measurement uncertainty MU, theory of sampling TOS, chain of custody, hydrogeochemical processes
Abstract A hydrogeochemical analysis of multiple samples stemming from two fractured rock aquifers in the Karoo geological formation of South Africa was undertaken. The samples were taken using various sampling methods in numerous locations over varying time frames. The ion error balance for the groundwater samples from the previously mentioned secondary aquifers is further analysed. Graphical representation of the data, which includes a piper plot, gives insight into the groundwater geochemistry. Conclusions drawn highlight the precautionary measures to take into account when sampling in fractured rock aquifers in a South African context. The future recommendations include suggestions related to the entire chain of sampling in the context of the theory of sampling and measurement uncertainty for fractured rock hydrogeology in particular.
Groundwater development for Municipal water supply in response to drought of 2015 to 2019.	Dale	Barrow	Western Cape	2019	Drought, TMG
Abstract The geographic positioning of the Western Cape results in a Mediterranean climate - receiving majority of its rainfall during the winter months. A demand on the water supply throughout the year is typically met by storing water from winter rainfall in large dams. The Western Cape experienced a significant drought between 2015 and 2019. As a result, the supply dams have not been filled to capacity and drastic water restrictions had to be implemented. In the search for alternative water sources, groundwater exploration became a priority. Groundwater development projects were implemented rapidly in attempt to alleviate the implications caused by severe water restrictions and ultimately prevent running out of water. As a local groundwater institution, GEOSS got involved in several fast-tracked groundwater development projects for Department of local government, local municipalities, as well as other industrial and agricultural corporations. For obtaining the required water volumes, alternative measures were implemented. Previously under developed aquifers were targeted. In certain instances, in order to target the Table Mountain Group Aquifer (TMG), horizontal exploration drilling was conducted. The results of exploration and drilling yielded valuable learnings in terms of relevant hydrostratigraphy within the study areas. Additionally, there were learnings in terms of managing projects of this nature. In fast-tracked projects, careful management of the contractors, data collation (and storage) and public perception is critical to the success of the project. In this paper on water supply development for Municipalities, the various components of groundwater development are detailed along with relevant learnings from the recent emergency drought response measures.
Investigation The Effect Of Excess Pumping On The Groundwater Salinity In Semi-Arid Aquifers Using Predicted Future Scenarios	Mohammed	Seyam		2019	Hydrological Modeling, Groundwater Quality, Salinity, Prediction scenario
Abstract The groundwater quality in semi-arid aquifers can be deteriorated very rabidly due to many factors. The most important factor affecting the quality of groundwater quality in Gaza Strip aquifer is the excess pumping that resulting from the high population density in the area. The goal of this study to investigate the future potential deterioration in groundwater salinity using scenario analysis modeling by artificial neural networks (ANN). The ANN model is utilized to predict the groundwater salinity based on three future scenarios of pumping quantities and rates from the Gaza strip aquifer. The results shows that in case the pumping rate remains as the present conditions, chloride concentration will increase rapidly in most areas of the Gaza Strip and the availability of fresh water will decrease in disquieting rates by year 2030. Results proved that groundwater salinity will be improved solely if the pumping rate is reduced by half and it also will be improved considerably if the pumping rate is completely stopped. Based on the results of this study, an urgent calling for developing other drinking water resources to secure the water demand is the most effective solution to decrease the groundwater salinity.
Conceptual Hydrogeological Modelling Of The Thyspunt Area, Eastern Cape, South Africa.	Moneri Joel	Modiba	Thyspunt, Eastern Cape	2019	modelling
Abstract A conceptual hydrogeological and numerical groundwater flow modelling study is being undertaken around and within the proposed ESKOM Thyspunt Nuclear Site, located 120 km west of Port Elizabeth. The study aims to improve the understanding of the prevailing hydrogeological condition around the Thyspunt area. The area is characterized by folded and jointed geological conditions. The local geology comprises the Table Mountain Group (TMG) and the Bokkeveld Group rocks of the Cape Supergroup, and Quaternary to recent sand deposits of the Algoa Group. The study area receives mean annual precipitation (MAP) of 922.6 mm. The mean annual estimated evapotranspiration is 821 mm and the average annual recharge rate estimated using the Water Table Fluctuation method is about 71 mm. A robust conceptual hydrogeological model is developed through detailed aquifer characterisation including pumping test analyses, determination of groundwater occurrence, storage, and flow, hydrogeochemical and environmental isotope analyses. Groundwater occurs within intergranular of the Algoa Group and fractured quartzitic aquifers of the TMG. The depth to groundwater ranges from 4.5 to 28.9 m below ground level (b.g.l.) and though the local groundwater flow is complex, the general groundwater flow direction is from west to east, towards the Indian Ocean. The upper unconfined intergranular Algoa aquifer and the deeper semi-confined fractured TMG aquifer are characterised by wide range of hydraulic properties, including aquifer thickness (2.2 - 22.0 m and 18.0 - 138 m), hydraulic conductivity ( 4.5 - 19.1 m/d and 8.9x10-3 -1.58 m/d), transmissivity (108.3 - 275 m2/d and 0.4 - 44.0 m2/d), specific yield (1.5x10-2 - 0.1) and storativity (5.0x10-5 - 5.9x10-3), respectively. The main hydrochemical facies of groundwater in the shallow Algoa is Ca-Mg-HCO3 type and groundwater circulating in the deep TMG aquifers are Na-Cl type. Environmental isotope signatures (?2H, ?18O) results indicate groundwater - surface water interactions
Hydrogeological Mapping in the Kuruman River Catchment of Northern Cape Province, South Africa	Olma	Makonto	Northern Cape	2019	Poster, mapping
Abstract Hydrogeological mapping was first attempted in Kuruman River Catchment, Northern Cape Province, South Africa. The main geology underlying the area of study includes sediments of the Kalahari Group, limestone and dolomite of the Transvaal Supergroup, lavas of the Ventersdorp Supergroup, and Archaean granite and gneiss. The main objective of this study was to produce hydrogeological maps on a scale of 1/100 000. Demarcation of different aquifer types was done by analyzing factors that control groundwater occurrence. These factors include lithology, geological features such as fault and lineaments, groundwater levels, and groundwater chemistry. Four types of aquifers were identified: o - Intergranular aquifer, associated with alluvial and pluvial deposits. o - Intergranular and fractured aquifer, associated with weathered igneous and sedimentary rock. o - Fractured aquifer, dominated by basal formations. o - Karst aquifer, associated with the dolomitic formations. The groundwater quality in the four demarcated aquifers was assessed to determine the current groundwater status. Groundwater chemistry was measured by collecting groundwater samples from boreholes. Physical parameters such as pH, temperature and electrical conductivity were measured in-situ using an Aquameter instrument. The samples taken were analysed at MINTEK laboratory using Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, and Spectrophotometer for cations, anions and alkalinity respectively. The results obtained indicated sodium chloride water type in fractured aquifer, while calcium carbonate water type was identified in intergranular aquifer, karst aquifer, and intergranular and fractured aquifer. In conclusion, high concentration of Nitrate, Magnesium, and Calcium was seen in all the four aquifers. High concentration of nitrate is due to stock farming, whereas high concentration of Magnesium and Calcium is due to geology. Moreover, high concentration of mercury due to mining activities was picked in intergranular aquifers, karst aquifers, and intergranular and fractured aquifers.
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.