Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 551 - 600 of 795 results

Title Sort descending	Presenter Name	Presenter Surname	Area	Conference year	Keywords
Physico-Chemical Assessment of Groundwater in the Orange Water Management Area	Olma Tsakani	Makonto		2015
Abstract The groundwater quality of the Orange Water Management Area (OWMA) was assessed to determine the current groundwater status. Groundwater is of major importance in the Orange Basin and constitutes the only source of water over large areas. Groundwater in the OWMA is mainly used for domestic supply, stock watering, irrigation, and mining activities. Increase in mining and agricultural activities place a demand for the assessment of groundwater quality. The groundwater quality was assessed by collecting groundwater samples from farm boreholes, household boreholes, and mine boreholes. Physical parameters such as pH, temperature and Electrical Conductivity (EC) were measured in-situ using an Aquameter instrument. The groundwater chemistry of samples were analysed using Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, and Spectrophotometer for cations, anions and alkalinity respectively. The analyses were done at Council for Geoscience laboratory. The results obtained indicated high concentration of Nitrate (NO3), EC, sulphate (SO4), Iron (Fe), and dissolved metals (Chromium, Nickel, Copper, Zinc, and Lead). The concentrations were higher than the South African National Standards (SANS) 241 (2006) drinking water required guideline. The OWMA is characterised by the rocks of the Karoo Supergroup, Ventersdorp Supergroup, Transvaal Supergroup, Namaqua and Natal Metamorphic Province, Gariep Supergroup, and Kalahari Group. Groundwater is found in the sandstones of the Beaufort Group. Salt Mining occurs in the Namaqua Group, hence the high concentration of EC observed. High EC was also found in the Dwyka Group. The salt obtained from the pans underlain by the Dwyka Group rocks has relatively high sodium sulphate content, this probably results from oxidation of iron sulphate to sulphate. Therefore, high concentration of SO4 is due to the geology of the area. High concentration of NO3 is due to agricultural activities, whereas high concentration of EC, Fe, SO4 and dissolved metals is due to mining activities.
Planning for increased water security and preventing salinisation in coastal areas of the Netherlands: A study on the suitability for managed aquifer recharge and extraction of brackish water, including quantification of potential extractable volumes	I	de Groot-Wallast	The Netherlands	2023	Aquifer Storage and Recovery, Managed aquifer recharge, aquifer salinisation, brackish water extraction, suitability maps, Water supply
Abstract Year-round water security is at risk as socio-economic developments lead to increasing water demands, while climate change affects water availability through higher-intensity rainfall and prolonged periods of drought. Coastal zones and deltas with often high population densities experience additional risks of salinisation and land subsidence. These developments ask for creative solutions to secure sustainable and year-round access to fresh water. The subsurface provides storage capacity to actively infiltrate freshwater, bridging the time-gap between demand and supply. Combining infiltration with extraction and desalination of brackish water prevents the salinisation of aquifers whilst providing an additional water source. We call this COASTAR. A Dutch research consortium with partners like water companies and water boards develops COASTAR. Among COASTAR results are suitability maps for Aquifer Storage and Recovery (ASR) and Brackish Water Extraction (BWE) in the coastal zone of the Netherlands. The maps are based on geohydrological factors. A quick-scan analysis was also performed to quantify the nation-wide potential extractable ASR and BWE volumes. COASTAR develops case study models and local scale pilots on ASR and BWE. For two water supply regions, an analysis has been made to geographically match development in water demand with suitability for ASR and BWE as a step in the search for strategic locations to develop ASR and BWE. The suitability maps provide guidance for initiatives’ development and practical experiences from pilot projects; this provides important information for further upscaling of COASTAR approaches.
Platinum mines will leave behind a sustainable legacy which will form a vital building block to meet future water demands	Fanie	Botha		2015	aeration and aerobic storage facilities, Nitrate
Abstract Slightly more out of the box idea is the use of anthropogenic aquifers as storage and chemical conditioners. This concept was first introduce by Eland Platinum Mine(EPM) and reported on in previous papers. At EPM water is used through a serious of natural aeration and aerobic storage facilities to reduce nitrate levels. In 2013 another group introduced pilot studies by virtue of abstraction in support of the water conservation and demand management strategy; which has proven that it could enable the operations to overcome water shortage periods and reduce pressure on Rand Water (RW). The pilot sites would deliver water into the dirty water circuit, but within five to ten years it may further be used to overcome months with zero potable water supply. . In platinum mines the more the aquifers are used the cleaner the water becomes, simply because introduced pollutants are not constant sources and country rock is mostly inert. In the future these aquifers have the potential to become larger storage facilities protected from floods and limited evaporation losses. It is foreseen that some of the mines in the western belt may have more water stored in primary aquifers than water stored within major water dams. Yields from these aquifers for individual aquifers may be up to 450 m3/hour and storage of 18 Mm3. . Why then this paper if we are already using it? The issue is that the true value of these aquifers an only be unlocked when they are used as recharging aquifers and thereby actively storing dirty water within a dirty water aquifer. Once we are able to undertake this the positive environmental gains such of environmental overflows, condition dirty water, reduction of pollution and significant reduction of the use of potable water from RW. {List only- not presented}
Platinum-Group-Elements and Total Organic Carbon in hyperalkaline springs at the Ronda peridotites (Malaga, Spain) as proxies of the origin of dissolved methane gas	Lucia	Ojeda	Malaga, Spain	2023	Hyperalkaline springs, Methane, Platinum-Group-Elements, Ronda peridotites, Total Organic Carbon
Abstract The serpentinization of ultramafic rocks is a process in which minerals of ferromagnesian nature (e.g., olivine) are transformed into serpentine and produce groundwater with a very high pH. In these settings, CH4 can be produced by combining H2 from serpentinization and CO2 from the atmosphere, soil, carbon-bearing rocks, or mantle, although the microbial generation of CH4, mediated by methanogens utilizing CO2, formate and/or acetate can be another source in these aquifers. In this sense, the hydrochemistry of hyperalkaline springs can provide valuable information about gas origin. The Ronda peridotites (Malaga province, Spain) are one of the world’s largest outcrops of the subcontinental mantle (~450 km2). Hyperalkaline springs (pH>10) emerging along faults present a permanent low outflow (<1 L/s), Ca2+- OH- facies and residence times exceeding 2,000 years. The fluids, poor in Mg2+ and rich in K+, Na+, Ca2+ and Cl-, also contain significant concentrations of dissolved CH4 and other hydrocarbons. Water samples have been collected from eight hyperalkaline springs and analyzed for major, minor and trace elements, including Platinum Group Elements (PGE) and Total Organic Carbon (TOC). The most mobile PGEs (Pd and Rh) are present in all the springs, indicating the existence of potential catalysts for the abiotic synthesis of CH4. High TOC concentrations are observed in some studied springs where previous analyses (i.e., bulk CH4 isotopes) have indicated a microbial CH4 origin.
Pock Marks as a Nature-based solution for enhancing water availability in African marginal drylands?	D	Kibirige	South Africa	2023	Pockmarks, Groundwater, nature-based solutions
Abstract Nearly 1.9 billion people live in marginal environments, including drylands, semiarid, arid, and hyperarid environments. Obscure but ubiquitous circular pockmark depressions dot these lands. These circular depressions can range from a few meters to kilometers, and the depth of these depressions varies from a few centimeters to over 10 m. However, the genesis of the circles has been investigated among scientists for many years because of their obscure nature. Some researchers believe that termites cause fairy circles, while others believe they are caused by plants competing for water and nutrients. This study documented the Africa-wide prevalence and extent of the pockmarks for the first time, and it further classified the pockmarks according to their genesis and hydrological roles. We further investigated their relevance in serving as nature-based solutions to overcome water scarcity in dryland regions. So far, field evidence in Ethiopia and Somalia showed that these features potentially have water security significance in a) organizing surface water flows over arid/semi-arid landscapes, b) serving as the site of temporary surface water storage, and c) serving as the site of focused groundwater recharge into the underlying aquifers. This presentation will highlight the spatial prevalence, extent, and genesis model of the pockmarks across the drylands in Africa (South Africa, Namibia, Somalia, Ethiopia, Kenya, Chad, Senegal, Mali, Niger, etc.).
Policy and pragmatism in South African groundwater management	Jude	Cobbing	South Africa	2015	policy, water management organisations
Abstract Changes to South African water law and policy since the mid-90s have promoted integrated water resource management (IWRM) and the wider application of the principle of subsidiarity (decentralization), underpinned by the Constitutional emphasis on equity, human rights and redress. New water management organisations aim to promote equity, universal access to water, economic prosperity and gender equality but the reality, especially for groundwater, is less inspiring. The Water Act of 1998 envisages new organisations including Catchment Management Agencies (CMAs), Water User Organisations (WUAs) and Water Service Authorities (WSAs), but in many cases these organisations have inadequate capacity or do not exist at all. Only two of the nine (formerly nineteen) CMAs have been formed in more than fifteen years, and neither is yet financially self-reliant. The onerous process necessary to found a WUA and other disincentives have meant that fully-fledged WUAs as envisaged by the Water Act are rare. Hydrogeologists are unusual at Water Service Authority level, and the Department of Water and Sanitation (DWS) still assesses most groundwater resources. This has stoked argument between DWS and WSAs over long-term sustainable municipal water supplies. Our mandated organisations are not delivering the outcomes for groundwater that policy makers envisaged. Municipalities campaign for surface water instead of groundwater, yet groundwater is still the mainstay of rural water supply and has the most promise for underserved areas. Intractable problems with operation and maintenance are wrongly blamed on the primary groundwater resource, or on "shortages" of one kind or another. There is a need to emphasise function and outcomes rather than trust that these will follow automatically once "the right" organisations are in place. A hybrid of top-down expertise with a genuine focus on local outcomes is called for. We currently pay a considerable opportunity cost for delays, turf-wars and finger pointing - including reputational damage to groundwater as well as less reliable water supplies for the poorest South Africans.
Possible Wastewater Volumes Associated With Unconventional Oil And Gas Extraction In South Africa And The Management Thereof	RD	Williamson	Karoo	2017	Unconventional gas, Wastewater, Fracking
Abstract Several oil and gas companies have applied for licenses to extract unconventional oil and gas (UOG) resources in South Africa (SA) through a process known as hydraulic fracturing or fracking. The South African government is in the process of drafting regulations and procedures to allow the extraction of these resources. It is surmised, based on evidence from fracking examples around the world, that large volumes of wastewater may, however, potentially be generated during the extraction of these UOG resources. The issues arise when it comes to determining the actual volumes of wastewater that may be generated from this process, should it be used in SA, as well as the management of the wastewater. The volume of wastewater generated is dependent on a number of factors, with well properties, rock formation, basin properties and the number of fracturing stages within the well, being some of the dominant factors. In this project an extensive review of existing literature, reports and fracking databases was used to identify the methods used for determining wastewater volumes, which databases were used as well as the assumptions and challenges each data source faced. The data was analysed and interpreted in order to come up with various ranges and averages of wastewater generated through UOG extraction. The potential volumes of wastewater generated through fracking were then modelled into the hypothetical scenarios outlined in the Strategic Environmental Assessment (SEA) on Shale Gas Development in the Central Karoo. This allowed for the determination of potential volumes of wastewater associated with UOG extraction in SA from which management implications for wastewater in South Africa can be determined.
Possible recharge areas for two of the Lower Berg aquifers units, Western Cape	Nicolette	Vermaak	Western Cape	2015	groundwater recharge
Abstract The question about the natural recharge areas for two of the Lower Berg river aquifers units, Elandsfontein Aquifer unit and Langebaan Road aquifer unit, has been keeping geohydrologists working in the area without a definite answer. Tredoux and Engelbrecht have postulated that it must be from the higher grounds around Hopefield, while Woodford hinted that an offshoot fault from the Coleso fault system could also cause the systems to be recharged from the Darling hills. Isotope studies had been done for the proposed Hopefield recharge area, but none has so far been done for the possible Darling recharge system. This paper will look at the studies done up to date and evaluate the data available for the boreholes drilled in the area in an attempt to get a clearer understanding of the two possibilities. It will also identify possible gaps in our knowledge of the area and the steps that would make it possible to fill in the gaps.
Post Mining Aquifer Testing At A South African Coal Mine	Marnus	du Toit		2017	coal mine, dewatering, geochemistry, pumping test, analytical mocels
Abstract Mining site remnants are everlasting and impact the groundwater regime on a long term scale. An integrated approach to geoscience is necessary due to the complexity of nature and the unknown relationships that must be discovered to further the understanding of impacts on the natural environment. Furthermore, groundwater resources are negatively impacted by mining activities affecting the groundwater quality and quantity. Underground coal mining can be accompanied by roof failure events. This may change the matrix which subsequently alters the flow regime; leads to variations within the water chemistry, provided there is inter- aquifer connectivity; and alters the recharge rate. Dewatered mine voids are in direct contact with oxygen initiating oxidation reactions, depending on the geology of the specific site. A change in water chemistry was analyzed, and this coincides with a roof failure event as interpreted from water level measurements. Concentrations of Mg, Ca, and alkalinity indicate anomalous changes that are still in effect, five to six years after the majority of water levels had stabilized. The changes in the system coincides with and correlates to events of roof failure and different parameters. The latter changes are applied as extra tools when interpreting different site specific anthropogenic induced impacts on the system. Also within this study, constant rate pumping tests were conducted for the interest of the hydraulic properties, using three farming boreholes. The results put forward a range of 0.21 – 0.44L/s and 6.5 – 11.5m2 /d, for sustainable yield and transmissivity, respectively. Furthermore, it is recommended that a better understanding can be gained on system behaviors if chemistry correlations can be gathered through certain events causing specific systems to be in disequilibrium. It is also recommended that additional pumping tests will allow more insightful interpretation and delineation between the abovementioned chemical and water level changes. Finally, the combination of parameters during events can aid in deciding the most appropriate analytical models used for further analysis.
Potential Impacts Of Fracking On Groundwater In The Karoo Basin Of South Africa	Gerrit	Van Tonder	Karoo	2013	potential impact
Abstract Determining impacts associated with the production of shale gas in the semi-arid Karoo on groundwater is vital to people living in the Karoo. On the one hand shale gas can be a game-changer for energy supply, but on the other it may have a devastating effect on the environment. Knowing the potential impacts of shale gas mining beforehand, the government can set appropriate regulatory protocols and tools in place to mitigate potential risks. This paper describes research done on the potential impact that hydraulic fracturing could have on groundwater in the Karoo. A wild card that only exists in the Karoo Basin of South Africa is the numerous dolerite intrusions. These dolerite structures are associated with relative high-yielding boreholes because of the fractured contact aureole that exist between solid dolerite and the adjacent Karoo sediments. Compromised cement annuli of gas wells are the major preferential flow paths along which methane and fracking fluid can escape into shallow, freshwater aquifers. This study focused solely on the impact of compromised cement annuli of gas wells. The Karoo Basin is under artesian conditions which imply that any pollutant will always try to migrate upwards in the Karoo. The hot-water springs in the Karoo indicate that upward velocities of water are relatively high (the spring water take only days to travel from deep down to the surface). The cubic law was used to estimate potential upward leakage rates from gas wells (during production, but after cessation thereof as well, when pressures will rebuild because of artesian behaviour of the Karoo formations). Potential leakage rates along faulty annuli of a well can vary between a value close to zero to two liters per second in the case of an aperture of 0,5 mm. These leakage rates were used as input to a 2D numerical groundwater flow and mass transport model. The 2D model was run for 30 years and the movement of pollution from the gas wells on the pad simulated. The model indicates that an area of 300 ha could be contaminated over a period of 30 years in a downstream groundwater flow direction. If an abstraction borehole drilled along a fault zone or a dyke, intersecting the fracked reservoir, is introduced into the model, results predict that the pollutant will reach the borehole in less than two months if the borehole is situated six kilometres from the well-pad. The total impact that fracking will have on the groundwater in the Karoo, is a function of the total area that will be fracked. The outcomes of this research clearly show that fracking in South Africa cannot be done in the same way than it is currently done worldwide. A rule that will force gas companies to disclose fracking fluid contents is non-negotiable. Companies should also be required to measure pressures in the fracked gas reservoir after closure. An additional requirement to enforce sealing of the entire fracked reservoir with a very dense material like bentonite or a mud with a very high density to capture the fracking fluids deep down in the gas reservoir should not be negotiable.
Potential for co-disposal of fly-ash and coal discard: Results from geochemical modelling and laboratory studies	Meris	Mills		2015
Abstract Geochemical investigations for a planned coal mine indicated that the coal discard material that would be generated through coal processing would have a significant potential to generate acid rock drainage. A power station is planned to be developed in close proximity to the coal mine, and the potential for co-disposal of coal discard with fly-ash material required examination. Fly-ash is typically highly alkaline and has the potential to neutralise the acidic coal discard material. In order to investigate whether this was a viable option, the geochemical interaction between the coal discard and fly-ash was investigated. Geochemical data, including acid-base accounting, total chemical compositions, leach test data and kinetic test data, were available for the coal discard material and the fly-ash. Using these data as inputs, a geochemical model was developed using Phreeqci to predict the pH of leachate generated by mixing different ratios of coal discard and fly-ash. The ratio of coal discard to fly-ash was established that would result in a leachate of neutral pH. Using this prediction, a kinetic humidity cell test was run by a commercial laboratory for a total of 52 weeks using the optimal modelled ratio of discard and fly-ash. Although leachate pH from the kinetic test initially reflected a greater contribution from fly-ash, the pH gradually decreased to the near-neutral range within the first 20 weeks, and then remained near-neutral for the remainder of the 52-week test. During this period, sulphate and metal concentrations also decreased to concentrations below those generated by either the fly-ash or coal discard individually. The addition of fly-ash to the coal discard material provided sufficient neutralising capacity to maintain the near-neutral pH of the co-disposal mixture until the readily available sulphide minerals were oxidized, and the oxidation rates decreased. At the end of the test, sufficient neutralising potential remained in the humidity cell to neutralise any remaining sulphide material. The results of this investigation suggested that, under optimal conditions, co-disposal of fly-ash with coal discard is a viable option that can result in reduced environmental impacts compared to what would be experienced if the two waste materials were disposed of separately.
Potential land use changes and wildfires effects over the spatiotemporal distribution of groundwater recharge at a regional scale: RAPReHS indicator accounting for SDG-13 in Bolivia	Monica Ximena	Guzmán Rojo	Bolivia	2023	Climate change, groundwater recharge, SDG
Abstract Having knowledge of spatiotemporal groundwater recharge is crucial for optimizing regional water management practices. However, the lack of consistent ground hydrometeorological data at regional and global scales has led to the use of alternative proxies and indicators to estimate impacts on groundwater recharge, enabling effective management of future water resources. This study explores the impact of land use changes and wildfires on groundwater recharge at a regional scale in Bolivia, using an alternative indicator to estimate variations in groundwater recharge rates. Based on a study by de Freitas L. in 2021, the methodology developed the annual groundwater recharge reduction rate (RAPReHS) utilizing remotely sensed data from the FLDAS and TERRACLIMATE datasets. The RAPReHS employs a simplified version of the water balance equation, estimating direct vertical groundwater recharge by considering the difference between precipitation, evapotranspiration, and runoff. The methodology was upscaled to improve data processing and analysis efficiency using an open-source cloud-computing platform (Google Earth Engine) over a 20-year period. The first results reveal a strong correlation between decreasing groundwater recharge rates and natural vegetation in the eastern region. By utilizing the RAPReHS index, forest preservation strategies can be prioritized. This study is in the framework of SDG 13 (Climate Action), which aims to mitigate the impacts of climate change on the environment and society. By exploring the impact of land use changes and wildfires on groundwater recharge at a regional scale in Bolivia, this research contributes to the inclusion of groundwater in policy guidelines for sustainable water management
Practical Solutions for Academic Based Applications – Understanding the importance of correct aquifer test data interpretations	Jorette	Van Rooyen		2021	Gw-Sw interaction, test-pumping, FC, Monitoring
Abstract It has become increasingly apparent that understanding fractured rock mechanics as well as the interactions and exchanges between groundwater and surface water systems are crucial considering the increase in demand of each in recent years. Especially in a time where long term sustainability is of great importance for many water management agencies, groundwater professionals and the average water users. Previous callow experience has shown that there is a misunderstanding in the correct interpretation and analyses of pumping test data. The fracture characterisation (FC) method software provides a most useful tool in the overall understanding of a fractured rock aquifer, quantification of the aquifer’s hydraulic (flow regime and flow boundary conditions) and physical properties, only if the time-drawdown relationships are correctly interpreted and when the theoretical application principles are applied. Interpretation is not simply a copy and paste of the aquifer test data into the software to get a quick answer (especially when project time constraints are considered), however, recent experiences with numerous field examples, required intricate understanding of the geological environment, intended use and abstraction schedules coupled with the academic applications on which the software was based for correct interpretation. Through the application of correct interpretation principles, a plethora of flow information becomes available, of which examples will be provided in the presentation itself. By achieving this, flow can be conceptualised for inputs into a conservative scale three-dimensional numerical flow model and calibrated based on measurable data in a fraction of the time of a conventional regional model. Although higher confidence levels are achieved with these practical solutions, monitoring programmes are still required to provide better insight of the aquifer responses to long-term abstraction and recovery.
Prefeasibility Study for Managed Aquifer Recharge within the Greater Kruger National Park, Limpopo Province, South Africa.	Michael	Holloway	Limpopo, KNP	2021	MAR, Doleritic Dyke Swarms, Prefeasability Study
Abstract Lourens, PJ West of the world-renowned conservation site, Kruger National Park, lies the larger extent of the Greater Kruger National Park within the Limpopo province. Boreholes have been drilled here in the last few decades to century for the provision of water supply to game lodges, large resorts, watering holes for game viewing and also historically for agriculture and livestock. The area contains both primary and secondary aquifers classified as having yields between 0.5 and 5.0 l/s, based on the geological setting which consist of gneiss intruded by dolerite dyke swarms. A geohydrological assessment of the area revealed that groundwater quality within the project area is characterised as having an EC of 100 - 450 mS/m, which seems to link to borehole proximity to surface water systems. The Makhutswi Gneiss and Doleritic Dyke swarms are the major controlling geology of the area, with higher yielding boreholes located in close proximity to dykes and major structural lineaments (faulted / weathered zones) of the Gneiss. A major concern identified through geohydrological assessment and hydrocensus observations is that boreholes frequently dry up after a few years and require either deeper drilling / redrilling or drilling a new borehole and that the very aggressive calcium hardness in the water frequently damages equipment and leads to overall higher maintenance costs. This project investigates the feasibility of increasing recharge to the aquifer with seasonal flooding / rainfall events by constructing artificially enhanced recharge locations overlaying several doleritic dykes. This is expected to decrease the salinity and hardness of the groundwater, which will reduce operational costs. Water security will also be increased through enhanced long-term sustainability of the groundwater by balancing some of the current annual abstraction.
Preliminary Hydrogeological Investigation Of The Natal Group Sandstone, South Africa	Molla	Demlie	KwaZulu-Natal	2013	Hydrogeological, investigations, Boreholes
Abstract The Paleozoicage Natal Group Sandstone (NGS) that outcrops from Hlabisa (in the north) to Port Shepstone (in the south) and Greytown (west) to Stanger (east) in the Province of KwaZulu-Natal, South Africa, is investigated in terms of its hydrogeological characteristics. This sandstone group, which comprises a lower Durban and an upper Marrianhill Formations, is a secondary/fractured aquifer system that has variable but good productivity across its members. It is characterised by variable borehole blow yields ranging from 0.2 l/s to as high as 20 l/s, with more than 50% of the boreholes having blow yield > 3 l/s. Preliminary analysis of these boreholes yields indicates that higher yielding boreholes are associated with a network of intersecting fractures and faults, and are recommended targets for future water well-siting in the area. Groundwater in the NGS is of good quality in terms of major and trace element composition and it has a total dissolved solids (TDS) composition of <450 mg/l. It was observed that the specific electrical conductivity (EC), TDS and major ions composition of groundwater within the sandstone decrease from north to south, which appears to be controlled by the geochemical composition of the aquifer material and an increase in the rate of recharge. Depth to groundwater is also found to decrease southwards because of an increase in the rate of recharge. Groundwater hydrochemical facies are generally either Na-HCO3 or Na-HCO3–Cl, and environmental isotope data (2H, 18O, Tritium) indicates that the groundwater gets recharge from modern precipitation. Furthermore, the EC increases from inland to the coastal zone, indicating maritime influences and the general direction of groundwater flow is eastwards, to the Indian Ocean.
Problematic modelling and setting compliance values for contaminated groundwater in fractured rock aquifers -South Africa	Morne	Burger		2015	industrial risk, contamination
Abstract Industrial Management Facilities represent a hazard to the down gradient surface water and groundwater environment. The assessment of the risks such facilities pose to the water environment is an important issue and certain compliance standards are set by regulators, particularly when the potential for an impact on the water environment has been identified. This paper will aim to describe how the contamination was conceptualized, estimated, limitations and how it is technically not feasible to establish one limit or compliance value of known contamination in different aquifers.
Protecting groundwater resources in an era of geological carbon sequestration: A fractional stochastic model to predict pressure buildup due to CO2 injection into a saline aquife	H	Mbah	National	2023	Carbon Capture and Storage, CCS, CCS fractional operator, geological heterogeneity., injectivity, pressure buildup, saline aquifer
Abstract Carbon Capture and Storage (CCS) in deep saline aquifers is a viable option for Green House Gas (GHG) mitigation. However, industrial-scale scenarios may induce large-scale reservoir pressurization and displacement of native fluids. Especially in closed systems, the pressure buildup can quickly elevate beyond the reservoir fracture threshold and potentially fracture/ reactivate existing faults on the cap rock. This can create pathways, which could act as conduits for focused leakage of brine and/or CO2 up-dip and mobilization of trace elements into capture zones of freshwater wells. Careful pressure management can ensure the reservoir’s hydraulic integrity. This can theoretically be achieved through simulation with appropriate mathematical tools. This research aims to quantify pressure buildup at a CO2 injection well by applying fractional derivatives to the pressure diffusivity Differential Equation (PDE). A numerical solution has been developed to (1) predict and assess the consequence of pressure buildup within the storage formation on groundwater flow in shallow aquifers and (2) assess the impact of pressure-mobilized contaminants (CO2 , brine and/or trace elements) on the quality of usable groundwater, if there is a leakage. The efficiency of each derivative is shown to depend on the type of reservoir heterogeneity. The Caputo derivative captured the long tail dependence characteristic of fracture flow, while the ABC derivative was able to model the cross-over from matric into the fracture flow. The numerical tools presented here are useful for successful risk assessments during geo-sequestration in basins with freshwater aquifers.
Protection, Management And Governance Of Groundwater Resources In Transboundary Aquifers – Stampriet Transboundary Aquifer System (STAS) Case Study	Kwazikwakhe	Majola	Central America, Central Asia, Botswana, Namibia, South Africa	2017	transboundary aquifers, Water security, transboundary cooperation, resource management
Abstract The UNESCO-IHP initiated a project on “Governance of Groundwater Resources in Transboundary Aquifers” in 2013. Three aquifers were selected for case studies: Trifinio (Central America), Pretashkent (Central Asia), and the Stampriet Transboundary Aquifer System (STAS) in southern Africa shared between Botswana, Namibia and South Africa. The project aimed to conduct a detailed assessment of the characteristics, current state and management of transboundary aquifers and to lay the foundations for a multi-country consultation body. It is expected that this will lead to enhanced water security, transboundary cooperation in groundwater management, and improved environmental sustainability in the aquifer region. Phase 1 of the project focused on desktop activities to acquire existing data and information with respect to three components: Hydrogeological, Socio-economic & Environmental, and Legal & Institutional. The integrated assessment determined that the recharge is taking place in Namibia during heavy rain periods, and that is where the resource is mostly used - Namibia (91.2%), Botswana (8.6%), South Africa (0.2%). Lack of time-series data made it difficult to determine aquifer properties. Groundwater quality is mainly impacted by agricultural activities and geological properties. The STAS area depends mainly on groundwater since the rivers are ephemeral. The Information Management System was developed in order to encourage information sharing among countries and to store interpreted and processed data from the assessment of the groundwater resources for use as a tool to support decision makers and relevant stakeholders’ actions. Water Diplomacy training offered involves hydro-politics of water to support cooperative agreements and increasing institutional capacity of sharing countries to reduce conflict and enhance cooperation over shared resources. This formed basis for the development of a Multi-Country Consultation Mechanism, a body that will provide the vision and direction towards governance and sustainable management of the STAS. The project is on-going with Phase 2 expected outcomes including numerical model, among other outcomes, using FREEWAT which is openly available. It is anticipated that ultimately, a joint governance model shall have been drawn amongst the three countries to ensure a mutually sustainable resource management.
Qualitative interpretation of groundwater flow distribution within the southern granite supersite of the Kruger National Park	Ashton	Van Niekerk	Mpumalanga	2015
Abstract Understanding the hydrogeology of fractured or crystalline rocks could be complicated because of its complex structure and a porosity that is almost exclusively secondary. These types of geologies are known to exhibit strong heterogeneities and irregularities contrasted in hydraulic properties, spacing and flow distribution within fractured rock aquifers. Therefore it is important to develop a conceptual model based on site specific data such as the hydraulic roles between groundwater and nearby hillslope/surface water bodies in order to understand its movement within the environment. Therefore this study intends to develop a hydrogeological conceptual model to qualitatively interpret the dominant groundwater flow processes at a 3rd order scale within southern granite supersite of the Kruger National Park (KNP). Key findings based on actual subsurface results in the form of Electrical Resistivity Tomography (ERT) surveys, borehole drilling logs, water levels and hydraulic data suggest that two aquifer types exist on the southern granite supersite namely, a weathered low resistivity of 3-75 ?m (average depth ranging 383-328 mamsl) and hard rock high resistivity of 1875-5484 ?m (average depth ranging 364-299 mamsl) granite/gneiss aquifer. The weathered aquifer flow system responds to localized processes such as piston recharge, indirect surface water recharge and groundwater water discharge via interflow. This was due to the relatively rapid response time of 2-3 weeks in groundwater levels to the major sequence of rainfall events over the hydrological year. The hard rock aquifer is part of a regional groundwater flow system. This is owed to the lengthy response time lags of 2-3 months in groundwater levels to the major sequences of rainfall events over the hydrological year. Due to the generally low transmissivity (ranging 9.50E-08 to 11.2 m2/day) values obtained during the borehole pump and slug tests and inclining trend of groundwater levels after the wet season, suggest these ephemeral hillslope landscapes are likely to act as hydraulic boundary areas. In that they contribute during the dry season to the regional hydraulic head generating baseflow to perennial streams. Therefore from a management perspective certain reaches within these ephemeral streams contribute to recharge which in turn should receive attention as many of the ephemeral stream sand are used for grading tourist gravel roads. Furthermore these granite ephemeral landscapes are characteristic of generally low transmissive aquifer properties and therefore should be given careful consideration before including it in a water supply scheme scenario.
Quantification of river-aquifer interactions using multiple measuring methods for improved water abstraction in the Lower Vaal River catchment, South Africa	Lucky	Baloyi	South Africa	2023	baseflow, discharge areas, Hydrochemistry, multi-methods approach, stable isotopes
Abstract Previous studies have shown that river-aquifer connectivity exists. However, an integrated approach that consists of multiple measuring methods to quantify and characterise such connectivity still needs improved scientific understanding due to the underlying principles and assumptions of such methods, mainly when such methods are applied in a semi-arid environment. Three techniques (hydrogeochemistry, stable water isotopes, and baseflow separations) were applied to quantify and characterize river-aquifer interactions. The study’s objective was to improve knowledge and understanding of the implications of the results from the three methods. Field measurement, laboratory assessment, and record review were used to collect primary and secondary data. Results showed that Na- HCO3 water type dominated the upper stream, discharging onto the surface and forming stream sources. Na-HCO3 water type was an outlier when the area’s geology and land use activities were assessed. The isotope results showed that the studied aquifer had 9% recently recharged water. Being the upstream, the freshwater in such a mountainous aquifer was expected. The baseflow index (BFI) results showed that the dependency of the total river flow to aquifer discharge contributed 7.24 % in the upper stream, 7.31% in the middle stream, and 7.32% in the lower stream. These findings provided empirical evidence that hydrochemistry, stable isotopes, and baseflow separation methods provide key insights into aquifer-stream connectivity. Such findings inform choosing appropriate and relevant measures for protecting, monitoring, and allocating water resources in the catchments.
Quantifying Groundwater Resources In Alluvial Aquifers Of The Omaruru River; Simplifying Decision Making For Aquifer Management	W	Kabinda	Namibia	2017	Alluvial aquifer, IWRM, Bulk water supply, modelling, recharge potential
Abstract The Omaruru River Basin encompasses an area of approximately 19 625 km2 in central west Namibia. The headwaters extend to the area north of the Etjo Mountains, ephemeral surface runoff and groundwater flow is generally directed south-westward until they reach the Atlantic Ocean. Annual rainfall decreases steadily from 380 mm at the headwaters to <50 mm at the river mouth implying that majority of runoff is generated in the upper headwaters. The alluvial aquifer is recharged indirectly from seasonal floods whose runoff reduces significantly towards the coastal aquifers by transmission losses. Groundwater abstraction is controlled through a permitting system by the Department of Water Affairs, embracing the principles of Integrated Water Resource Management. The alluvial aquifer is a major contributor to bulk water supply in the basin. Four bulk water schemes were established along the aquifer for domestic and industrial use while the alluvial aquifers also sustain riparian and sensitive ecosystems established along the river. The current water demand of the Omaruru River Basin has been estimated at 12.7 Mm3 /a, of which 59 % is abstracted from the alluvial aquifer. An integrated geohydrological model was developed using dynamic system modelling software. Hydrological and geohydrological information was made available to highlight runoff and groundwater recharge as key indicators for integrated water resources management. River compartments were defined adopting the concept that the ephemeral rivers are characterised by pools and ridges formed by basement highs. Therefore, groundwater levels are regulated mostly by flood recharge, evapotranspiration and groundwater abstraction and to a lower extent by groundwater through-flow from the alluvium upstream. Sub-basin parameters such as rainfall, basin size, alluvial aquifer compartment length, width and depth were derived to estimate surface runoff produced per sub-basin, transmission losses and first estimate of groundwater recharge to the alluvial aquifer. Model results indicated total volume of saturated alluvium to approximately 377 Mm3, with recharge from transmission losses amounting to approximately 14.8M m3 for the entire basin. Groundwater recharge potential is highest in the upper part and decreases significantly towards the coast. Groundwater abstraction needs to be reconciled with the protection of sensitive ecosystems established along the ephemeral river. The model results have implications on management of the entire alluvial aquifer. The Geohydrological model provides fast assessment of the impact of groundwater abstraction on water levels and available water resources in downstream compartments. This can be a great benefit to the Department of Water Affairs and Forestry in processing abstraction permits as well controlling abstraction in times of prolonged drought. The resulting model shows that abstraction strategies downstream the river should be optimized to protect the aquifer against over-abstraction. In its simplicity the model can be adapted to other strategic alluvial aquifers.
Quenching A Thirsty Country	Fanus	Fourie	National	2013	Groundwater, strategy, Boreholes
Abstract Only 40% of all the available groundwater resources are developed in South Africa and the development of surface water are becoming more costly and challenging. The Minister of Water and Environmental Affairs acknowledge this and identified the need to increase the use of groundwater as one of the interventions to address the increasing water requirement of towns and communities. Over the last seven years the Department of Water Affairs developed many reconciliation strategies for the area of water management, the big metro municipalities and for the smaller towns and villages in South Africa. The reconciliation strategies entails, among other things, sustainable ways to source additional water supplies for the selected towns/metro’s or villages. Groundwater played a major role in the recommended interventions. The challenges are now the implementation of the groundwater schemes and sustainable management of the groundwater resources. Or differently put: the balancing act between selling of groundwater and the prevention of over-abstraction. The bankability of regional schemes, the credibility of groundwater as a bulk scheme source, poor management of boreholes/well-fields, institutional responsibility, acceptable quality and treatment of groundwater, still challenge the use of groundwater development. Groundwater need to play its role in addressing the future water needs of South Africa, or can it?
Questions Of Scale And Measurements	Nicolette	Vermaak		2019	scale
Abstract Until 1998 groundwater was managed separately from surface water and was seen as a private resource. The National Water Act of 1998 (Act 36 of 1998) (NWA) was forward thinking in that it saw groundwater as an integrated part of the water resource system and as a common resource to be managed by the Department of Water and Sanitation (DWS) as custodian. Various tools had been provided to manage the water resources equitably, sustainably and efficiently. A limited understanding of groundwater and the prevalence to revert to engineering principles when managing water resources had led to an Act that is mostly written with surface water in mind. The tools and principles that had been tested for surface water was used directly for groundwater without considering the practicalities in applying and enforcing the NWA. This did not provide too many problems, as groundwater was not considered a viable, sustainable water resource, and the use of groundwater was mostly limited to private use for garden irrigation, in agriculture for irrigation and for bulk supply in a number of small towns where surface water was not available. This has changed drastically during the recent drought that affected the whole country, but especially the Western Cape. Groundwater was suddenly seen as the solution to the problem of water availability. The problem was that the understanding of groundwater has not increase sufficiently over the years, and water resources management is still skewed to hydrology principles that apply to surface water. Groundwater sustainability is at the heart of the questions of scale and measurements. The Department has been flooded by the large number of water use licence applications that have been submitted by municipalities, industries and agriculture as a result of the drought. This article will look at groundwater resource assessment and allocation methodology in a South African context.
Radical evolution of the Geneva transboundary aquifer agreement: an example for the sustainability of TBA governance?	Gabriel	de los Cobos	Switzerland	2023	Geneva aquifer, MAR, Climate change, Governance, transboundary aquifer agreement
Abstract The Geneva aquifer is internationally recognized for its transboundary resource management agreement between Switzerland and France, described as the first groundwater management agreement in the world. Signed in 1978 and renewed in 2008, this agreement on managing a shared underground resource has long been an example for establishing other agreements worldwide, particularly by UNESCO and its hydrological program via the TBA commission of the IAH. Like many countries worldwide, Switzerland and France experienced a critical summer of 2022 concerning the use of water resources, both surface and underground. The system applied in the cross-border agreement for using the aquifer involves French participation in the costs of managing aquifer recharge (MAR), depending on the total pumping. It shows that the French part, having consumed more water to compensate for the extreme drought of 2022, has seen its bills increase considerably. Development plans show that the population of Greater Geneva will increase considerably by 2030-2040, requiring significant medium-term water availability (30% additional water). Therefore, the French institutions’ political leaders have formally asked the authorities of the canton of Geneva to review the conditions linked to the quotas and calculation methods included in the 2008 agreement. A new agreement could be a real example of positive cross-border coordination for decision-makers finding themselves in a blocked or even conflicting situation due to differences in managing a shared resource revived by the effects of climate change.
Radon-222 in Thermal Springs of Limpopo Province, South Africa	Humberto	Saeze	Limpopo	2015
Abstract Studies have shown that the use of natural water (drinking and bathing) with high level of 222Rn concentration may contribute to negative health effect in human beings. Thermal springs located in Limpopo province were sampled for the determination of 222Rn concentration by gamma ray spectrometry. The spring water has been used for domestic purposes: drinking and bathing, and for recreation bathing mainly. 19 samples were collected between thermal springs emanation points and swimming facilities (out and in doors). Radon-222 concentration found in these water ranges from 0.2 to 624 Bq/l. These results indicate that 7 thermal springs may represent increasing risk on bathing or inhalation of radon gas, leading to an increased risk of healthy.
Re-inventing the Wheel - The Iterative Development of Groundwater Sustainability in Southern Africa.	Jeffrey	Davies		2015
Abstract The SADC Grey Data archive http://www.bgs.ac.uk/sadc/ provides a chronology of groundwater development within the constituent countries of the SADC region. Early reports show how groundwater development progressed from obtaining water by well digging to the mechanical drilling of boreholes for provision of water for irrigation, township development, transport networks and rural settlement. During the 1930s steam driven drilling rigs were supplanted by petrol engine driven cable tool percussion drilling. Dixey (1931), in his manual on how to develop groundwater resources based on experiences in colonial geological surveys in eastern and southern Africa, describes aquifer properties, groundwater occurrence and resources as well as water quality and groundwater abstraction methods. Frommurze (1937) provides an initial assessment of aquifer properties in South Africa with Bond (1945) describing their groundwater chemistry. South African engineers transferred geophysical surveying skills to the desert campaign during World War II. Paver (1945) described the application of these methods to various geological environments in South Africa, Rhodesia and British colonial territories in eastern and central Africa. Test pumping methods using electric dippers were also developed for the assessment of groundwater resources. Enslin and others developed DC resistivity meters, replacing early Meggar systems, produced data that when analysed, using slide rules with graphs plotted by hand, identified water bearing fractures and deeply weathered zones. Tentative maps were drawn using interpretation of aerial photographs and heights generated using aneroid altimeters. The problems faced by hydrogeologists remain the same today as they were then, even though the technology has greatly improved in the computer era. Modern techniques range from a variety of geophysical surveying methods, automated rest level recorders with data loggers to GPS location systems and a whole host of remotely sensed data gathering methods. Worryingly, using such automated procedures reduces the ability of hydrogeologists to understand data limitations. The available collection of water level time series data are surprisingly small. Surrogate data need to be recognised and used to indicate effects of over abstraction as demand grows. As the numbers of boreholes drilled per year increases the number of detailed hydrogeological surveys undertaken still remains seriously small. Has our knowledge of hydrogeological systems advanced all that much from what was known in the 1980s? Case histories from Malawi, Zimbabwe and Tanzania illustrate a need for groundwater research with well-judged sustainability assessments to underpin safe long-term groundwater supply for the groundwater dependent communities in the region.
Real-time iFLUX sensors reveal rapidly changing groundwater flow dynamics in wetland ecosystems	N	Van Putte	Poland, Belgium	2023	Internet of Things, ecohydrology, groundwater flow, sensor development, wetland conservation
Abstract Shallow groundwater dynamics play a crucial role in wetland ecosystems and are key to climate change resilience. Therefore, conserving and restoring wetland areas requires excellent knowledge of groundwater flow dynamics, which are often rapidly changing following extreme weather events and anthropogenic impacts such as groundwater extraction. Traditional methods to estimate groundwater flow require extensive modelling or rely on point measurements, missing the effect of crucial short-term events and impeding quick actions to conserve the wetlands’ ecohydrological status. Here, we present a newly developed sensor that can measure real-time groundwater flow velocity and direction. The sensor probe consists of two bidirectional flow sensors that are superimposed. It is installed in a dedicated pre-pack filter and can measure a broad range of groundwater flow velocities from 0.5 cm/ day to 2000 cm/day. With an IoT (Internet of Things) system, sensor data is wirelessly transmitted and visualized in real-time on an online dashboard. In addition, we show a selection of results from a case study in the Biebrza National Park (Poland) and a nature reserve in Damme (Belgium). In both ecosystems, we could capture changes in groundwater flow velocity and direction resulting from precipitation and evapotranspiration events. As such, we are confident that our sensors provide new insights into rapidly changing groundwater dynamics and will become an invaluable tool in ecohydrological studies worldwide, ultimately leading to more integrated management strategies to protect and conserve remaining wetlands.
Recent Advances In Numerical Groundwater Modelling Of The Atlantis Aquifer, South Africa	Jannie	Weitz	Atlantis Aquifer	2019	numerical modelling
Abstract The City of Cape Town (CoCT) metropolitan municipality seeks to identify and develop alternative water resources for the augmentation of surface water to ensure more robust and sustainable water supply to the CoCT and its inhabitants. A 3-D finite-element numerical model of the Atlantis Aquifer was developed using the commercial code FEFlow 7.1 to support the assessment of the impact of groundwater abstraction from the aquifer which has been identified as one of the target zones to develop sustainable alternative water resources as part of the CoCT water reconciliation strategy. The numerical model acts as a decision support tool to assist in planning and management of the rehabilitation and potential expansion of the groundwater abstraction and managed aquifer recharge scheme. The numerical model is to be applied in determining the impact of additional abstraction as well as assess the maximum sustainable yield from the wellfields without negatively impacting on surface water sources and other groundwater dependent users. The model improves upon previous modelling work and represents the latest and most comprehensive knowledge in terms of three-dimensional aquifer geometry, location and rates of anthropogenic groundwater users, spatial distribution of recharge, hydraulic parameters and location of aquifer boundary conditions. Model parameters have been successfully calibrated under steady-state conditions to provide a realistic representation of long-term groundwater levels across the system (R2=98%). Abstraction scenarios and their impact on groundwater levels were assessed using the calibrated numerical model. Scenarios were simulated of three phases of abstraction (approximately 15, 25 and 40 Ml/d) to determine drawdown around the wellfields, the impact on spring discharge, and the possibility of saline intrusion. Model results show drawdown to be mostly confined to the associated wellfields, with minor drawdown experienced in the vicinity of Silwerstroom. Simulated hydraulic heads indicate that seawater intrusion is unlikely to occur under all scenarios.
Recent Developments in The Understanding Of Karoo Aquifers And The Deeper Underlying Formations	Peter	Rosewarne	Karoo	2013	Shale gas, Karoo Groundwater Atlas
Abstract The possibility of large reserves of shale gas underlying the Karoo and their exploitation has focused attention on the groundwater resources and aquifers of this region. Much is known about the relatively shallow aquifers (<300 m) which supply many local municipalities and farmers with water for domestic, stock and irrigation use (mostly from boreholes <150 m in depth). Conversely, little is known about the deeper formations (>500 m) and associated groundwater occurrences and their possible interconnection to the shallow aquifer systems. This paper covers a desk study of the southern Karoo, mostly above the Great Escarpment, carried out by a group of hydrogeologists/geochemists with a cumulative experience of about 250 years. The main consideration at this stage has been the collation and analysis of existing information, using GIS, conceptualisations, and identification of knowledge gaps. A Karoo Groundwater Atlas was published in 2012 and Volume 2 has been released at this conference, which present a summary of the main analyses. Borehole yield, recharge and quality in the shallow aquifer tend to improve, and water levels become shallower, from west to east, associated with higher rainfall and increased percentage of dolerite and sandstone. Aquifer yield, quality, lithology and presence of dolerites constitute 60% of a groundwater attributes ratings classification; 54% of the study area has a high rating. Twenty four percent of the study area has a high vulnerability rating. Knowledge of the characteristics of groundwater associated with the deeper formations is restricted to a few thermal springs and sparse data from some deep hydrocarbon exploration wells. Weak artesian flows were recorded from two such wells in the Dwyka Group below the Great Escarpment, with Total Dissolved Solids of up to 10 000 mg/L and temperatures of up to 77 oC, from depths of 2 347 to 3 100 m. Further work and cooperation with other researchers/institutions is on-going and planned to fill in knowledge gaps and assess the risks to groundwater of shale gas exploration.
Recharge under review: Implications for Water Resources Management	Nicolette	Vermaak	South Africa	2023	Recharge; groundwater availability; groundwater management
Abstract Recharge is an important factor in Water Resources Management as it is often used as a measure for sustainable groundwater abstraction and resource allocation. The recharge estimation is, however, linked to a specific time, area and conditions and then generalised over seasons and years. Current climate change estimations predict a warmer and drier future for western parts of southern Africa. Groundwater recharge estimation methods do not consider changes in climate over the short term and do not consider the longer trends of a changing climate. This article looks at the various methodologies used in recharge estimations and their application in a changing world, where rainfall period, pattern and intensity have changed, where higher temperatures lead to higher actual evapotranspiration and where there is a greater need for water resources for use in agriculture, industry and domestic use. Our study considers the implications of current recharge estimation methods over the long term for water allocation and water resources management of groundwater resources from local and aquifer catchment scale estimations.
Refinement of a 3D Finite Element Mesh Model, Bela-Bela, South Africa	Tshegofatso	Mophatlane	North West	2015
Abstract This paper follows on current research taking place in the Springbok Flats Basin focusing on Carbon Dioxide Geological Sequestration within coal seams. The research, commissioned by ESKOM, began in 2012 and has a primary aim of producing a hydrogeological risk assessment for carbon dioxide geological sequestration operations scheduled for national pilot testing within the basin. One of the fundamental tools used in the assessment has been finite element mesh modeling. A 3D finite element mesh model of the study area, that has 11307 nodes, has been generated using FEFLOW algorithms. Portions in the study area without linear and point physical features have been modeled with the Advancing Front Algorithm, while the Grid Builder Algorithm has been used to model portions with linear and point features. This paper has investigated the node angle accuracy and precision of the mesh model by generating a map of the maximum interior angle of triangles. Approximately 70 % of the triangles have equilateral angles, while the remainder triangles have obtuse angles. The majority of the equilateral triangles occur within the portions modeled with the Advancing Front Algorithm. Half of the obtuse triangles have been refined to equilateral triangles with the FEFLOW refinement tools while the other half has been refined manually with the node digitizing features. FEM models perform better with dense triangle matrices with equilateral angles, as they influence the accuracy of the FEM.
Regional Scale Groundwater Monitoring Status Reporting: A mapping series within the Vanrhynsdorp aquifer system	Ashton	van Niekerk	South Africa	2023	Aquifer scale, groundwater availability, Groundwater Quality, spatial-temporal, trend analysis
Abstract A mapping series was generated using the Vanrhynsdorp aquifer system to illustrate an improved standardization groundwater monitoring status reporting, that includes a progressive conceptual site model linked with spatial and temporal groundwater monitoring network assessment on an aquifer scale. The report consists of 4 segments: Base map provides a conceptual site model of a groundwater resource unit (GRU) delineating an area of 1456 km2 representing the geology and geological structures that make up the Vanrhynsdorp aquifer system. The Groundwater Availability Map illustrated over a long-term trend analysis, the measured water levels indicate an 83% decreasing trend over an average period of 21.83 years, the water levels have declined by an average linear progression of 11.54 m (ranging 0.48-35.76 m) or 0.64 m per year, which equates to an estimated decline in storage of 218 Tm3 - 21 Mm3 within the GRU. The Groundwater EC map illustrated over the long-term analysis of an average period 24 years the average EC ranged between 57 - 791 mS/m, with certain areas tracking at a constant increasing trend beyond 1200 mS/m. The Groundwater Quality Characterization map provides EC contours and spatial Stiff diagram plots. The Stiff diagrams illustrate three aquifer water types namely, Na-Cl (Table Mountain Group Sandstones), Na-Cl with high SO4 concentration (Blouport and Aties Formation) and Na-Cl-HCO3 (Widouw Formation). These four segments of information products inform Resource Quality Objectives and the need for surveillance monitoring in conjunction with annual compliance monitoring and enforcement groundwater use audits.
Regional-scale identification of recharge or discharge using remote sensing and GIS: Implications towards groundwater-surface water interactions	Kawawa	Banda	Zambia	2023	Barotse Floodplain, Groundwater-Surface water, Zambezi River, Zambia, Ecosystems
Abstract Identifying groundwater recharge and discharge areas across catchments is critical for implementing effective strategies for salinity mitigation, surface water and groundwater resource management, and ecosystem protection. This study seeks to identify potential GW-SW discharge and recharge areas around the Barotse Floodplain. The results of remote sensing analysis using the Normalised Difference Vegetation Index (NDVI) show that the vegetation is sensitive to the dynamics of groundwater level, with shallower levels (< 10 m) in the lower reaches compared to deeper levels (>10 m) in the upper catchment). These zones are further investigated and likely represent geological variability, aquifer confinement and the degree of GW-SW interactions. GW-SW interactions likely are influenced by an interplay of factors such as water levels in the groundwater and surface level and hydrogeological conditions. Based on the findings, the wetland hosts riparian vegetation species responsive to the groundwater dynamic. NDVI can thus be used as a proxy to infer groundwater in the catchment. Therefore, effective water resources management of the floodplain should be implemented through conjunctive management of groundwater and surface water.
Regulating the regulations for managing groundwater use to improve water security in Southern Africa: Reflection on water use licence application process in South Africa	Mfundi	Biyela		2019	water entitlement, Regulations, WARMS, Southern Africa, South Africa
Abstract In the management of water resources especially groundwater resources, implementing existing regulations is one of the much needed aspects ensuring water security through the regulated use. However, such regulations are not regulated to ensure that they served the intended purpose in their original formulation. In South Africa, a study was carried out to assess the relevance and efficient of adhering to procedural requirements during water use licence application (WULA) process. Lived-experiences and observation methods were used to collect data. The department of water and sanitation was used as a case study. Interpretative analysis approach was used to provide the meaning on the analysed information. The WARMS database was accessed where the number of days that WULA process was extracted. The regulation No. 40713 about WULA process was analysed. The five-year-data prior and post the promulgation of regulation No. 40713 were extracted from WARMS database and evaluated in terms of the duration each application took to be processed for WULA. Data on water use for abstractions from all the regions were obtained from WARMS database and assessed. Dates when applications were submitted and when such applications were finalised were analysis per month and per years for temporal analysis. The number of entitlements received during the particular period and the number of applications recommended to be declined and issued were assessed using exploratory data analysis methods. Graphical method was adapted to increase results visualisation on water use entitlements. Key results showed that the process of WULA was generally slow and reasons were provided for such outcome. However, the temporal analysis revealed an increasing trend in the post promulgation of regulation No. 40713 suggesting that regulations when re-regulated serve its intended purpose. Although such findings are not conclusive but they inform a basis for re-regulating enforcement regulations in Southern African countries with issues similar to South Africa on water entitlement.
Reliability of laboratory testing of groundwater samples	Venetia	Mitchell		2015
Abstract Resources required for groundwater sampling includes but not limited to pumping equipment, trained manpower and technical resources specific to the sampling function. Bearing these expenses in mind, choosing a laboratory for testing the water samples collected should be a carefully considered purchase. Choosing a testing facility that cannot deliver an efficient, reliable and technically sound service could render the sampling futile. Water samples submitted to a laboratory for testing are received from third party sources more than ninety percent (90%) of the time and sampling techniques and sample integrity cannot be verified by the laboratory. However, the validity, reliability and integrity of the laboratory testing are within the control of the testing facility. These aspects of a laboratory are usually controlled within a quality management system where established policies and procedures form the basis of such a system. This system maintains a foundation for technical competence and customer service at the laboratory. There are numerous testing facilities available to Consultants requiring chemical and microbiological groundwater testing, each with varying levels of integrity and technical ability. It is imperative to maintain confidence in the validity of results of analyses from a laboratory and this assurance can be understood through an examination of a facility's management system. An established quality management system would comprise a policy statement, associated technical methods and technical and administrative procedures. This system would be formally documented and audited as part of the on-going laboratory's management system. In some instances, laboratories formalise this into an accreditation of the laboratory to an international standard, such as ISO 17025:2005. The assurance that the results of analyses from any laboratory are of sound technical integrity would depend on factors such as - personnel training, - accommodation and environmental conditions under which the tests are carried out, - validation of the methodology applied (including the uncertainty of measurement), - the calibration and maintenance of the equipment used, - understanding the traceability of and measurement undertaken, - handling and preservation of the sample on receipt and while in the laboratory. Each of these factors plays a critical role in the integrity of results of analyses and should be interrogated when trying to understand the reliability and competence of the laboratory of choice.{List only- not presented}
Remediation of Groundwater at AngloGold Ashanti South Africa	Gawie	van Dyk		2015
Abstract Gold Mining activities the past 60 years at AngloGold Ashanti polluted the groundwater underlain by 4000 ha of land at the Vaal River and West Wits operations in South Africa. Sulphide material in Tailings Storage Facilities, Waste Rock Dumps and extraction plants produce Saline Mine Drainage with Sulphate, minor salts and metals that seep to the groundwater and ultimately into surface water resources. Water regulation requires mines to prevent, minimise/ reduce or eliminate pollution of water resources. The waste philosophy has matured from tolerate and transfer to treat and termination of pollution sources. The impact of the pollution was determined and possible technologies to treat the impact were evaluated. Source controls of proper water management by storm water management, clean dirty water separation, lined water conveyance structures and reduced deposition of water on waste facilities is crucial. The aquifer character determines the possible remediation technology. From the possible technologies phytoremediation, physical interception and re-use of this water was selected. In future possible treatment of the water would be considered. This paper explain the strategy and report on the phased implementation of these plans and the expected results. The establishment of 750 ha of woodlands as phytoremediation, interception trenches of 1250 m, 38 interception boreholes and infrastructure to re-use this water in 10 water management areas is planned. The total volume of 15 Ml/day would be abstracted for re-use from the boreholes and trenches. The woodlands can potentially attenuate and treat 5 ml/day. The established woodlands of 150 ha proof successful to intercept diffused seep over the area of establishment and reduce the water level and base flow. The 2 implemented trenches of 1000 m indicate a local decline in the water level with interception of shallow groundwater within 1-2 m from surface. The 2 production interception well fields abstracting 50 and 30 l/s respectively indicate a water level decline of between 2 to 14 m with regional cones of depression of a few hundred meters to intercept groundwater flow up to 20 meter. Predictions from groundwater modelling indicate that these schemes can minimise pollution during the operational phase and protect downstream water resources. Predictions from modelling indicate that the pollution sources need to be removed to ensure long term clean-up to return the land to save use. The gold and uranium prize is securing the removal of the sources through re-processing of the tailings and waste rock dumps. After removal of the sources of pollution the remediation schemes would have to be operated for 20 years to return the groundwater to an acceptable standard of stock watering and industrial water use. The water quality is observed by a monitoring network of approximately 100 observation boreholes.
Research-based exploration of deep groundwater within the eastern limb of the Bushveld Complex	Amy	Allwright	Bloemfontein, South Africa	2023	Bushveld Complex, Deep groundwater, deep scientific drilling
Abstract The current understanding of groundwater within the larger Bushveld Complex (BC) is evaluated to gauge the potential for deep groundwater, specifically emphasising the lesser investigated eastern limb. From the review of publicly available literature and data, geohydrological databases and statistical analyses are presented as a collation of the current understanding of groundwater in the eastern limb of the BC. Unfortunately, information on deep groundwater (> 300 m) is scarce due to the cost associated with deep drilling, mining exploration holes often neglecting hydrogeological data collection, or lack of public access to this information. Nevertheless, the conceptual model developed from the available information highlights deep groundwater’s variable and structurally controlled nature and the uncertainty associated with groundwater characterisation of the deeper groundwater systems. This uncertainty supports the need for research-based scientific drilling of the deeper fractured lithologies in the eastern limb of the Bushveld Complex. The Bushveld Complex Drilling Project (BVDP) established an opportunity to perform such research-based drilling and was funded by the International Continental Scientific Drilling Program (ICDP). While the main focus of the BVDP is to produce a continuous vertical stratigraphic sequence of the BC, there is a sub-component to collect geohydrological information. The planned borehole, 2 500 m deep, will provide an opportunity to collect information from the deeper systems within the Bushveld Complex and the underlying Transvaal Supergroup, which will inform on the connection between shallow and deeper groundwater.
Researching Fracking in the Karoo: Summary of lessons learned	Fde	Lange	South Africa	2023	Challenges, Fracking, Independent, policy, Precautionary, Regulatory, Research, risks, scale, stakeholders
Abstract Research on Fracking in the Karoo basin yielded results that, if not considered “unexpected”, can be considered as “should have been foreseen”. Some aspects substantially impacting research on fracking are often overlooked when undertaking scientific research on an emotional topic such as fracking. This presentation aims to provide insights and recommendations based on the experiences and outcomes of current research on hydraulic fracturing or “fracking” in the Karoo basin of South Africa. Fracking has been a subject of significant research and debate over the past decade. Topics, each with its challenges, include 1) The scale of exploration/production extent (Site specifics), 2) Importance of robust and independent research, 3) Need for stakeholder engagement and participation, 4) The complexity of environmental risks and impacts, 5) The need for a precautionary approach, 6) Regulatory and policy challenges. Several methodologies can be relied upon to compare outcomes of different aspects of fracking research in the Karoo, such as 1) Comparative analysis, 2) Meta-analysis, 3) Stakeholder mapping and analysis and 4) Data visualisation. A combination of these methodologies can be used to compare outcomes of different aspects of fracking research in the Karoo and provide insights and recommendations for future decision-making and planning. Ultimately, the decision to allow Fracking should be based on a balanced assessment of potential risks and benefits, considering long-term impacts on the environment, economy, and communities.
Review of Groundwater Use in Varying Climatic Conditions	Lindelani	Lalumbe		2019	Poster, Climate
Abstract Groundwater levels in E33F quaternary catchment are at their lowest level ever. The impact of climatic variation and increasing abstraction were determined to be the main factor. There are 115 registered groundwater users in E33F and the monthly abstraction volumes are not being measured. There is a need to use land use activities as well as the population to estimate groundwater use. The main objective is to use non-groundwater monitoring data to estimate groundwater use in order to protect the aquifer and ecosystem in general in varying climatic condition. Land use activities information was used to estimate groundwater use in E33F quaternary catchment. The estimated groundwater use volumes were compared to allocated and measured volumes. For domestic groundwater use estimation, population data and an estimation 100 litre per person per day were used. The water requirements for the types of crops being cultivated together with the area (m2) were used to estimate groundwater use volumes for irrigation. The number and type of live stocks were used with the water requirements for each livestock type to estimate the groundwater use volumes. 96 % of groundwater users are using groundwater for irrigation purposes with 9 966 105 m3/a allocated for irrigation. Mining, industries, domestic and livestock are allocated 100 200 m3/a. The estimated groundwater use volume for irrigation is 30 960 000 m3/a, which is three times higher than the allocated volume. Groundwater use volume for domestic use is estimated to be 38 225 m3/a which is higher than the 31 000 m3/a allocated. The total estimated groundwater use volume in E33F is estimated to be 30 998 225 m3/a, which is three times higher than the allocated groundwater use volume of 10 066 305 m3/a. This estimation could be higher as only registered boreholes were used and estimations from mining, Industries and live stocks were excluded due to lack of data
Review of In-Situ and Remote Sensing-Based Indices and Their Applicability for Integrated Drought Monitoring in South Africa	M	Mukhawana	South Africa	2023	multivariate drought indices; PDSI; SWSI; SPI; SPEI; VCI; SSI; SGI; GRACE
Abstract The devastating socioeconomic impacts of recent droughts have intensified the need for improved drought monitoring in South Africa (SA). This study has shown that not all indices can be universally applicable to all regions worldwide, and no single index can represent all aspects of droughts. This study aimed to review the performance and applicability of the Palmer drought severity index (PDSI), surface water supply index (SWSI), vegetation condition index (VCI), standardised precipitation index (SPI), standardised precipitation evapotranspiration index (SPEI), standardised streamflow index (SSI), standardised groundwater index (SGI), and GRACE (Gravity Recovery and Climate Experiment)-based drought indices in SA and provide guidelines for selecting feasible candidates for integrated drought monitoring. The review is based on the 2016 World Meteorological Organization (WMO) Handbook of Drought Indicators and Indices guidelines. The PDSI and SWSI are not feasible in SA, mainly because they are relatively complex to compute and interpret and cannot use readily available and accessible data. Combining the SPI, SPEI, VCI, SSI, and SGI using multi-index or hybrid methods is recommended. Hence, with best fitting probability distribution functions (PDFs) used and an informed choice between parametric and non-parametric approaches, this combination has the potential for integrated drought monitoring. Due to the scarcity of groundwater data, investigations using GRACE-based groundwater drought indices must be carried out. These findings may contribute to improved drought early warning and monitoring in SA.
Revision Of The Groundwater Quality Reserve	Ndivhuwo	Netshiendeulu	National	2013	Groundwater Quality
Abstract The groundwater quality component of the Reserve serves as guidance for groundwater quality requirements when assessing water use license applications. The Reserve is the quantity and quality of water required to satisfy the basic human needs and protect the aquatic ecosystem in order to ensure ecologically sustainable development and use of water resources. This component provides guidance when assessing the suitability of groundwater for drinking purposes. The current groundwater quality was based on the Quality of domestic water supplies, assessment guide (vol. 1,2nd ed., 1998). The parameters that were assessed in the current template include chemicals: sodium, magnesium, calcium, chloride, sulphate, nitrate and fluoride; and physical parameters: pH and electrical conductivity. The above-mentioned ions cater for most water uses applied for, whereas the revised template will also include microbiological (escherichia coli), toxics (zinc, manganese, iron, cadmium, cobalt and copper) for local government and mining commodity/by- product specific water use applications. The current water quality basic human needs values will also be replaced with SANS 241 (2011) guidelines. Inputs and suggestions are therefore requested from various end users/stakeholders.
Rigorous Methodology For Sustainable Yield Estimation Using Groundwater Numerical Modelling Validation To Detailed Long Term Pumping Test Data	Shuaib	Dustay	Port Alfred	2017	numerical modelling, WUL, large-scale abstraction, Monitoring
Abstract Groundwater numerical models are commonly used to determine the impact that groundwater abstraction has on the ability of surrounding areas to supply water, and thus to inform Water Use Licence (WUL) Applications. However, data available is often limited to that generated by relatively short-term geohydrological studies and pumping tests. In most cases this data and the degree of defined uncertainty in the model results are sufficient. However, for large scale abstractions (such as municipal abstraction) and in sensitive or complex geological areas, a more rigorous approach to calculating the impact from pumping is recommendable. The study area is located on a syncline consisting of two sandstone aquifers. However, there was a lack of data to quantify the connectivity between the two aquifers. SRK Consulting (South Africa) (Pty) Ltd undertook a rigorous, long-term approach, which included a 3- year monitoring plan of the area, input from stakeholders, extending the hydrocensus to the entire catchment and monitoring of pumping in the area. Using this comprehensive data set, the existing numerical groundwater model was updated, re-calibrated and validated such that predictive scenarios could be run to assess the long-term potential impact of the municipal wellfield. These results were submitted for the final allocation of the WUL. Along with mitigation measures, recommendations could also be made on where to focus monitoring and future testing. This rigorous methodology and the use of long- term comprehensive monitoring data is recommended for future use in similarly complex environments to decrease uncertainty on the expected impacted area from large-scale abstractions.
Risk-Based Operating Rules For Groundwater Supply: A Case Study Of Siloam Village, South Africa	Rachel	Makungo	Siloam Village	2019	operating rules
Abstract This study developed operating rules for groundwater supply from a probabilistic (risk-based) approach. Groundwater supply systems are often operated without relating groundwater yield/availability to demand which makes groundwater resource planning and management challenging and unpredictable. Risk-based approaches for developing groundwater operating rules comprehensively incorporate assurance of supply and also account for uncertainty due to model inputs, model structure and climate variability. A groundwater resource unit (GRU) was delineated and its hydrogeological conceptual model developed. A program for generation of monthly groundwater levels for the GRU was coded in FORTRAN based on the GW-PITMAN model. The model was calibrated using groundwater levels from a neighbouring borehole due to lack of observed representative data for the GRU. Validation was done by establishing the realistic nature of simulated runoff, recharge and groundwater levels. A Variable Length Block (VLB) bootstrapping model was used for simultaneous generation of stochastic inputs (rainfall, evaporation and groundwater levels) of the operating rules model. Operating rules were developed from statistical analysis of 100 base yields for the GRU simulated from 5-year long stochastically generated inputs. The hydrogeological conceptual model indicated presence of faults and diabase dykes which influence preferential flow paths and storage of water in the aquifer. Majority of the historical statistics were mostly well preserved by VLB, except for skewness. Superimposing the cumulative demands on the base yield curves and analysis of percentages of water demands that can be supplied indicated that the groundwater system could not meet the water demands at all times. The operating rule curves indicated that if priority classification is used all water demands are met up to a maximum groundwater level of 25 m. The operating rule curves are therefore expected to improve water supply to both domestic and productive water uses, if they are adequately implemented and hence improve livelihoods.
Risk-corrected contaminant detection probability of monitoring well networks for flow towards pumping wells in heterogeneous aquifers	T	Sarris	New Zealand	2023	Contaminant transport, Dispersion, Groundwater Contamination, Heterogeneity, monitoring networks, Risk corrected detection rate
Abstract A groundwater monitoring network surrounding a pumping well (such as a public water supply) allows for early contaminant detection and mitigation where possible contaminant source locations are often unknown. This numerical study investigates how the contaminant detection probability of a hypothetical sentinel-well monitoring network consisting of one to four monitoring wells is affected by aquifer spatial heterogeneity and dispersion characteristics, where the contaminant source location is randomized. This is achieved through a stochastic framework using a Monte Carlo approach. A single production well is considered, resulting in converging non-uniform flow close to the well. Optimal network arrangements are obtained by maximizing a weighted risk function that considers true and false positive detection rates, sampling frequency, early detection, and contaminant travel time uncertainty. Aquifer dispersivity is found to be the dominant parameter for the quantification of network performance. For the range of parameters considered, a single monitoring well screening the full aquifer thickness is expected to correctly and timely identify at least 12% of all incidents resulting in contaminants reaching the production well. Irrespective of network size and sampling frequency, more dispersive transport conditions result in higher detection rates. Increasing aquifer heterogeneity and decreasing spatial continuity also lead to higher detection rates, though these effects are diminished for networks of 3 or more wells. Earlier detection, critical for remedial action and supply safety, comes with a significant cost in terms of detection rate and should be carefully considered when a monitoring network is being designed.
Risks related to groundwater resources in the Murray-Darling Basin, Australia	Andrew	Ross	Australia	2023	Groundwater, Murray-Darling Basin Plan, Ecosystems, implementation, policies, research priorities, risks, surface water
Abstract Groundwater governance and risk management in the Murray-Darling Basin in Australia (MDB) are being challenged by the increasing demand for water and the growing scarcity and variability of water supply owing to climate change. Over the past 20 years, consideration of risk related to groundwater in the MDB has evolved from concerns about the impact of groundwater extraction on surface water resources to an integrated assessment of risks to connected water resources and ecosystems. The Basin Plan includes a comprehensive framework for assessing risks to Basin water resources and ecosystems, but further scientific and policy developments are required to implement the plan. Consistent definition and improved assessment of groundwater-surface water connectivity are required, together with longer planning timeframes. Multi-year planning rules and policies must be developed to exploit opportunities for integrated management of groundwater and surface water resources and storage to manage droughts and floods. Risks to groundwater quality and groundwater-dependent ecosystems must be adequately assessed and monitored to avoid adverse impacts on communities and long-term loss of ecosystem services. Further improvements can be made in assessing cumulative risks from coal seam gas and coal mining. Additional research can be targeted towards knowledge gaps and uncertainties that pose the greatest risk to connected groundwater and surface water resources and ecosystem viability. Most importantly, further training and capacity building in water management agencies is critical to enable effective and transparent monitoring and management of Basin water resources.
Robust Hydrogeological Conceptual Models Through Interdisciplinary Characterisation – A Case Study	Zandri	Rademan	South Africa	2023	conceptual model, Geophysics, geotechnical, hydraulic testing, interdisciplinary
Abstract The basis of a hydrogeological conceptual model is the comprehensive characterisation of the groundwater system. This ranges from discrete hydraulic feature analysis to local-scale testing to integrated regional-scale aquifer system conceptualisation. Interdisciplinary data integration is critical to each level of characterisation to gain a realistic, yet simplified representation of the hydrogeological system based on various data sources. Incorporation of geological datasets, including (but not limited to) structural and lithological mapping, geotechnical core logs and geophysical surveys, in conjunction with a tailored selection of hydraulic testing techniques, are often underutilised by hydrogeologists. Yet, the contribution of these alternative hydraulic datasets cannot be overstated. A recent hydrogeological assessment and feasibility study forming part of the planned expansion project for a base-metal mine in the Northern Cape, South Africa, offers an ideal, practical example. The localised nature of the project area and the inherently complex geological setting required a more detailed conceptual model and hydrostratigraphic domaining approach. Highly heterogeneous stratigraphy and strong structural aquifer controls necessitated characterisation by reviewing, testing and analysing various datasets. Exploratory core datasets, hydraulic aquifer tests, geological and downhole geophysical datasets, and statistical Rock Quality Designation—hydraulic conductivity relationships were interpreted to produce meaningful, refined hydraulic process identifications. A comprehensive local groundwater framework, discretised into various hydrostratigraphic units and structural domains with specified hydraulic parameters, was incorporated to provide a novel, more robust conceptual understanding of the unique hydrogeological system.
Role of regional scale dykes in the flow of groundwater in the Otavi Mountainland karst aquifers	D	Sarma	Namibia	2023	Namibia, Otavi Mountainland, compartmentalization, conceptual model, dykes, groundwater flow, karst
Abstract The work presented relates to the influence of regional scale dykes in groundwater flow in karst aquifers of northern Namibia’s Otavi Mountainland around the towns of Tsumeb, Otavi and Grootfontein. The aquifers are well studied and are an important water source locally and for populated central areas of the country during drought. The area has parallel, eastwest trending elongated valleys and ranges shaped by the underlying synclines and anticlines of folded carbonate units of the Damara Supergroup. The role of the regional scale dolerite dykes that cut across the dolomitic aquifers has not been fully appreciated till recently. Aeromagnetic data is effective in mapping the dykes in detail. The dykes trend in a north-easterly to northerly direction into the Otavi Platform carbonate rocks. The dykes are normally magnetised with the odd remanent dyke. They consist mainly of dolerite, although in some cases are described as tectonic with hydrothermal magnetite and no dolerite material. The dykes appear to focus southwest of the Otavi Mountainland near the Paresis Alkaline Intrusive (137Ma). Examination of existing hydrogeological data reveals different characteristics of the dykes that influence groundwater flow, forming: a) conduits that enhance flow along contact zones, b) barrier to flow with compartmentalization and c) partial barrier to flow. An advantage has been taken of the understanding gained to manage mines’ dewatering and pumped water management. Future water resources management and contaminant studies will need to recognise the compartmentalised nature of the aquifer
Saline Groundwater Generation From Paleo-Termite Mounds In The Buffels River Valley, South Africa	Jani	van Gend-Muller	Buffels River Valley	2019	saline, development
Abstract Saline groundwater in semi-arid to arid areas is typically ascribed to evaporative concentration of salts on or near the surface followed by dissolution of salts during episodic rainfall events and then percolation of saline downwards. This has been previously postulated for large parts of the west coast of South Africa where groundwater electrical conductivity (EC) ranges between 804 ?S/cm and 21 300 ?S/cm. However, due to the spatial variability of groundwater salt concentrations, it is unlikely that simple evaporation is the only process leading to elevated salinity levels in this region. Palaeo-termite mounds, known as heuweltjies (meaning little hills), are common surface features along the west coast of South Africa, covering an estimated 14 to 25% of the land surface. These structures consisting of aerated and nutrient-rich sediments, containing elevated levels of micro- and macro elements, including salts, compared to the surrounding sediments. For this reason, it is postulated that heuweltjies are an important source of groundwater salts. In the Buffels River valley, exchangeable ions from sediments in the centre of the heuweltjies are up to 20 times higher than in the inter-heuweltjie material and are consistent with elevated heuweltjie salts determined via in-situ EM38 scanning. 36Cl/Cl ratios are highly variable ranging between 25.94 x10-15 and 156.19x10-15, indicating that recharge occurs inland. Groundwater 87Sr/86Sr ratios in the same area are extremely elevated, up to 0.78240, suggesting a direct link to the underlying radiogenic granitic gneisses but decrease to the west suggesting interaction or mixing between different water sources. We propose that in this case, the two water sources are older groundwaters mixing with direct recharge that contains elevated salts but lower 36Cl/Cl and 87Sr/86Sr ratios derived from preferential flow paths through the heuweltjies.
Sampling Protocol Optimisation Using Fluid Electrical Conductivity Logging	Candice	Lasher	National	2013	Electrical conductivity, Sampling Protocol
Abstract Characterisation of fracture positions is important when dealing with groundwater monitoring, protection and management. Fractures are often good conduits for water and contaminants, leading to high flow velocities and the fast spread of contaminants in these conduits. Best practice guidelines related to groundwater sampling suggest that specific depth sampling with specialised bailers or low flow purging are the preferred methodologies to characterise a pollution source. These methods require knowledge about the fracture positions and, more importantly, flow zones in the boreholes. Down-the-hole geophysical and flow logging are expensive, complicated and time consuming. Not all fracture zones identified with geophysical logging seem to contribute to flow through the borehole. An efficient and cost-effective methodology is required for the characterisation of position and flow in individual fractures. This research reviewed the use of Fluid Electrical Conductivity (FEC) logging to assist with the development of a monitoring protocol. FEC logging proved to be beneficial as it provided individual fracture positions, fracture yields and vertical groundwater flow directions. FEC logging proved to be fast, cost-effective and practical in deep boreholes. The technique allows the development of a site-specific sampling protocol. The information so obtained assists with the identification of the appropriate sampling depths during monitoring.
Sampling procedures for PFAS and pharmaceuticals –Recommendations vs. reality	A	Kuczyńska	Poland	2023	emerging contaminants, groundwater monitoring, sampling protocols
Abstract PFAS and pharmaceuticals in groundwater are two of many synthetic compounds currently under the attention of many researchers and environmental administration in Europe, especially in light of the revision of the EU Groundwater Directive 2006/118/EU. The two types of substances were first included in the voluntary groundwater watch list and were first formally regulated at the EU scale. This regulation implies that they will be obligatory to be monitored within national monitoring programmes for groundwater body status assessment procedures across the EU. While there is no doubt about the need to regulate the presence of these substances in groundwater, sampling procedures and QC/QA protocols may be challenging to implement as no official guidelines exist. Although scientific literature allows us to define protocols usually based on precautionary principle, these may be too difficult and expensive to implement at the national scale monitoring. This article describes a work that the Polish Geological Institute – National Research Institute undertook to define an optimal sampling process for PFAS and pharmaceuticals in groundwater. Experimentally tested factors included cleaning pumps between sampling sites, the need for using protective suits during sampling and the influence of ambient air on sample quality. Results showed that sampling protocols for PFAS and pharmaceuticals do not need to be modified concerning current protocols as these seem to be sufficient to protect groundwater samples from unintentional cross-contamination.