Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 201 - 250 of 795 results

Title	Presenter Name	Presenter Surname	Area Sort ascending	Conference year	Keywords
Literature review on methodologies used to assess surface water and groundwater interaction	Aashna	Bissoon	South Africa	2023	Groundwater, case studies, methodologies, surface water, sustainable
Abstract A major surface water–groundwater interaction difficulty is the complex nature of groundwater resources due to heterogenic aquifer parameters. Wholistic research is needed to inform the conceptual understanding of hydrological processes occurring at surface and groundwater interfaces and their interactions at watershed scales. Sustainable water resource use and protection depend on integrated management solutions involving cross-disciplinary studies and integrated hydrological modelling. Choosing appropriate methods such as spatial and temporal scales, measurable indicators, differences in software parameters, and limitations in application often results in uncertainties. The study aims to conduct a comparative literature analysis, integrating case studies focusing on surface water–groundwater interaction. Literature reviews from case studies focus on several factors, including soils and vegetation studies, hydrochemical signatures, hydrodynamics of the main stem channels, desktop land use assessments, surface water quality profiling, conceptual hydrogeological modelling and numerical modelling in support of understanding surface water – groundwater interaction and highlight the challenges of methods used to indicate baseflow transition. This paper considers the methodologies demonstrated in the literature and their use in numerical modelling to obtain measurable indicators related to the two hydrological disciplines comprising (i) the surface water component and (ii) the groundwater component. These outcomes should be used to inform the potential future impacts on water quality from activities such as mining, irrigation, and industrial development. Water management protocols related to integrated surface water and groundwater studies for the future are critical in ensuring sustainable water management methods on a catchment scale.
Development Of The Training Manual For Groundwater Resource Management And Groundwater Governance For Municipalities In South Africa	George G	Molaolwa	South Africa	2017	Municipalities, Training manual, Training needs assessment
Abstract In order to establish sound groundwater resource management within towns and Municipal areas the development of a training manual on groundwater resource management and groundwater governance for Municipalities is of utmost importance. A Training Manual can be extensively used for capacitating municipal official, technicians, managers, and decision-makers, as well as communities where villages and towns are partially or solely reliant on groundwater resources. Increased knowledge and skills will not only lead to more effective groundwater resource management, but also to more sustainable groundwater use and protection of groundwater resources. This also forms part of provisions made by the National Water Act 1998 (Act 36 of 1998). Before a training manual can be compiled, training needs assessments of all reachable training institutions in South Africa and Free State Municipalities and Northern Cape Municipalities as identified as pilot areas in the proposal of the Training Manual for Groundwater Resource Management and Groundwater Governance for Municipalities in South Africa needed to be performed. Training needs assessment determines if a gap exist regarding available training and training needs on Groundwater Resource Management and Groundwater Governance. If a gap exists then it proofs that the development of a Training Manual on Groundwater Resource Management and Groundwater Governance for Municipalities in South Africa is required, as well as the accessibility to such a training course is of utmost importance.
Modelling Of Cumulative Mine Dewatering And Flooding Impacts	Kai T	Witthueser	South Africa	2017	mine life cycle, regional flow model, water balances, post-closure liabilities
Abstract Many of South Africa’s coal fields are characterised by a complex lateral and vertical pattern of mine voids, targeting different lease areas and coal seams, and applying different mining methods such as open cast (strip) and underground (board and pillar) mining. Many are at different stages in their life of mine from exploration to closure stage. Despite the general recognition that the water management or absence thereof at neighbouring mines influences each other (evident for example in the recognition of inter-mine flow in the overall water balance for a site), and the requirement of cumulative impact assessments, very few studies actually attempt to tackle and quantify cumulative impacts of numerous mines on the ambient groundwater environment. While the parameterisation and calibration of a groundwater model for a single mine is often hampered by environmental data scarcity, the absence of cumulative impact assessments is mostly related to the unwillingness of neighbouring and competing mines to share these data. Soft- and hardware as well as budget limitations pose additional challenges for the development of regional groundwater models taking cognisance of complex mining environments. This paper describes a regional groundwater flow model that takes into account five surface and underground mining areas. The different start and closure dates for the opencast and underground mining areas result in a complex mining schedule, with groundwater abstractions and inflows for the different areas potentially influencing each other during life of mine and post-closure and requiring therefore a simultaneous simulation thereof. A further complication in the model development was the explicit consideration of cut-and-fill operations, necessitating alterations of the model topography to reflect annual cuts as free seepage boundaries, and to reflect rehabilitated backfilled areas with topography different from the pre-mining environment. The case study has led to numerical model software developments to enable transient changes in layer elevations over a simulation period. While the model attempted to simulate the cumulative impact of the mines, it was also used to predict the impact of a new mining development on the life of mine and post-closure water balances for the remainder of the neighbouring mines. The model outcomes could therefore theoretically inform apportionment of post-closure liabilities.
he complexity and importance of the intermediate vadose zone - Local-scale, Pore-scale, and Discrete Scale	Matthys A	Dippenaar	South Africa	2023	adhesion, saturated zone, capillarity, cohesion, fracture flow, moisture content
Abstract The intermediate vadose zone underlies the plant root zone and comprises soil and rock. Different soils have different hydraulic and mechanical properties, and the vertical and spatial distributions are variable at a small scale. In South Africa, except for the Cenozoic and Quaternary deserts and coastal deposits, rock forms most of the vadose zone, and the rock fractures exacerbate the complexity. The vadose zone is observed at a small scale and dictates what happens in large scale, as adhesion to mineral surfaces happens first, and cohesion between water molecules is next. The original consideration of the intermediate vadose zone was a black box approach measuring what goes in from the surface and what goes out as groundwater recharge, not accounting for the movement of the vast majority of the freshwater supplied through precipitation. That doesn’t address the preferential flow, velocity, and pore water changes in the medium. Soil science addresses the soil or plant root zone very well. This zone governs the vertical movement of water and controls the ecosystems and biodiversity. However, all evapotranspiration disappears below this zone, and capillarity and gravity both move water into and through the intermediate vadose zone. Movement is no longer solely vertical and will be affected by soil types, intergranular porosity in soil and rock, changing water content, and secondary fractures with different properties in rock. This presentation will cover concepts and advances in this field, emphasising how and why water moves in the intermediate vadose zone.
Using analytical models to examine groundwater abstraction impacts on surface water levels	N	Maluleke	South Africa	2023	groundwater-surface water interaction, streamflow depletion, model coupling
Abstract Studies have examined the effects of groundwater pumping on nearby streams. Groundwater pumping affects streamflow, surface water rights, and aquatic ecosystems. This study investigates the impact of groundwater abstraction on surface water bodies. A secondary objective aims to develop a conceptual model to evaluate alternative approaches for streamflow depletion. The study area is a previous UFS/WRC test site along Modder River, Free State, South Africa. Streamflow depletion was simulated using four (4) analytical solutions, i.e., Jenkins (1968), Hantush (1964), Hunt (1999) and Hunt (2003). STRMDEPL08 analytical computer program tool is used to evaluate streamflow depletion. The aquifer parameters: distance of the boreholes to the stream; pumping periods analyzed in steady states conditions for a simulation period of 1 year; transmissivity with an average of 71 m/d; storativity of 0.02; specific yield of the aquitard range between 0.1 to 0.3; and abstraction rate of 2 l/s are defined for the hypothetical model. The average distances tested range from 10 m to 6,000 m. Pumping rate scenarios for an order of magnitude lower (0.2 l/s), 1 l/s; 4 l/s, and an order of magnitude larger (20 l/s) were simulated. Simulated graphs indicate that streamflow depletion rates are largest if the borehole is closer to the stream and decrease as the distance of the pumped borehole from the stream increases. Cumulative volume graphs for both analytical solutions decrease streamflow depletion volume
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.
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.
Groundwater Dependent Ecosystems or wetland dependent groundwater systems: A case study	N	Vermaak	South Africa	2023	Wetlands; groundwater-dependent ecosystems; recharge; groundwater surface water interaction
Abstract The interaction between groundwater and wetlands is poorly understood, even though it has been the topic of many research projects, like the study done at the Langebaan Lagoon. This interaction is complex as it lies at the intersection between groundwater and surface water, but each situation is unique, with different conditions regulating the interaction. Wetlands can be the source of water that recharges groundwater systems on the one hand, while the other is dependent on the groundwater systems. This interaction became part of the project looking at how to implement Managed Aquifer Recharge for Saldanha Bay Local Municipality without having a negative impact on the groundwater-dependent ecosystems, such as the springs and wetlands in the area. Ten wetlands were identified on the Langebaan Road Aquifer Unit, and a monitoring programme was developed. The purpose of the monitoring was to determine the status of the wetlands as a baseline before the implementation of managed aquifer recharge and to determine the level of groundwater dependence. The latter was done by hydrochemical analysis of rainwater, groundwater and water from the wetlands and stable isotope analysis. The ability of the wetlands to act as a recharge point to the groundwater system will be investigated through column experiments and lithostratigraphic analysis of soil columns taken at the wetlands. Groundwater levels will also be plotted as contour lines to determine the intersection of the water table with the wetlands in the area.
Development Of A Conceptual Understanding Of Hydrogeological Relationship Between The Skurweberg Aquifer And Wetlands In The Steenbras Catchment	Sinawo	Jack	Skurweberg Aquifer, Steenbras Catchment	2019	Drought, City of Cape Town, Steenbras, Skuweberg Aquifer, Groundwater Abstraction, Ecosystems
Abstract The City of Cape Town (CoCT) commenced a study into the feasibility of the Table Mountain Group aquifers (TMGA) for augmenting the water supply to the city in 2002. It comprised drilling of exploration boreholes in several target areas and the establishment of a hydrogeological and ecological monitoring network. Due to the prolonged drought and associated water crisis, the CoCT decided to fast-track the TMGA development in 2017. The first wellfield is currently developed within the catchment area of the Steenbras Dam comprising production boreholes targeting the Skurweberg and the Peninsula aquifers of the TMGA. Since groundwater abstraction from the Peninsula and Skuweberg aquifers might have a short-term or long-term impact on aquatic ecosystems (i.e. streams and wetlands) that are linked to the TMGA. As a result, evaluation of the potential impact of groundwater abstraction from this aquifer system requires an understanding of the nature and extent of groundwater dependency of the ecosystems. A variety of data sets and parameters have been measured over the last decade at ecological monitoring sites across the study area, of which two sites are located within the Steenbras catchment that are probably connected to the Skurweberg Aquifer. Recently further boreholes and monitoring sites have been added. This paper describes the various methods used and results of the analysis towards a conceptual understanding and quantification of the groundwater dependency of the selected ecosystems. While groundwater contribution is only one factor in ecosystem functioning, sustainable and adaptive management of the groundwater use must be based on the conceptual model and ongoing monitoring of the ecosystem responses.
Effective Open Cast Pit Dewatering And Groundwater Management At Sishen Mine By Utilizing Software And Technology.	Franszo	Faul	Sishen Mine	2019	dewatering, software
Abstract It's been said that you cannot manage what you cannot measure. This is especially true with groundwater management; where we have limited data allowing us to 'see' the underground source. All over the world, people are spending aquifers full of money (bucket loads) on monitoring programmes and hydro census's. They capture borehole locations, water levels, abstraction rates, rainfall measurements and water quality analysis, then typically store the product, the deliverable, their valuable data, in a massive amount of spreadsheets. They have measured, but struggle to manage effectively because the data has not been stored in a centralised, consolidated fashion. Join us for a journey through Dagbreek, an open cast pit at Sishen mine, one of the largest open cast iron ore pits in the world and certainly part of the biggest dewatering project in South Africa. See how Sishen utilised technology to eliminate manual, paper-based data collection and spreadsheets. See how they utilised a cloud-based information management system to centralise and consolidate their data before transforming the data into valuable visualised information. See how this is equipping Sishen's decision makers with easy to interpret and up-to-date information, empowering them to make more effective operational and management decisions about their dewatering and groundwater management strategy
Conceptual Model Based Numerical Groundwater Flow Modelling of the Simbithi Eco-Estate, Kwazulu-Natal, South Africa	Jacqueline	Roux	Simbithi Eco-State, Kwazulu-Natal, South a	2017	hydrogeological conceptual model, MODFLOW, numerical groundwater flow model, saltwater intrusion, Simbithi Eco-Estate, Monitoring
Abstract Water stress is frequently experienced in many parts of South Africa. To ensure the longevity of the country’s water resources, particularly groundwater, accurate quantification of the resource and prediction of the responses of each water resource unit to natural and anthropogenic stresses are necessary. To this endeavour, Simbithi Eco-Estate, located at Shaka’s Rock, KwaZulu-Natal requires the implementation of a Water Management Plan that includes a hydrogeological investigation. A hydrogeological conceptual model was developed for the eco-estate, based on which a numerical groundwater flow model was calibrated to simulate the impacts of different rates of groundwater abstraction within the estate. Hydrometeorological information, subsurface geology, hydraulic head, hydraulic characteristics of the aquifer units and hydrochemical data were analysed to develop a two-layer hydrogeological conceptual model. The conceptual model was used as the main input to the numerical groundwater flow model. The calibrated steady-state numerical model, developed using the finite-difference groundwater modelling code, MODFLOW, was used to determine the sustainability of groundwater abstraction within the eco-estate. During calibration, the hydraulic conductivities of the hydrostratigraphic units, and recharge were varied. The Model calibrated recharge was 5.5 % of the mean annual precipitation (MAP). The five abstraction scenarios considered were: Scenario 1, which is the sustainable abstraction rate determined from the analysis of pumping test data, and Scenario 2 to 5 which are assigned progressively increasing abstraction rates of Scenario 1, by a factor of 20%, 50%, 100%, and 1000%, respectively. The numerical model simulations indicate that Scenario 1 is most sustainable in terms of groundwater level drawdown and saltwater intrusion. The simulated groundwater drawdown progressively increased throughout the succeeding four scenarios. The simulation results of the 5th scenario indicate that part of the model domain within the vicinity of the northern boreholes becomes dry and subsequent application of forward particle tracking on the simulation results predicts saltwater intrusion from the Indian Ocean towards the south eastern boreholes. It is accordingly recommended that groundwater resource development should be limited to below the abstraction rates of Scenario 4. Additionally, continuous monitoring of all boreholes within the eco-estate is recommended to generate time-series groundwater level information, which would be used to improve the predictive capabilities of the current steady-state model through a transient numerical groundwater flow model. To that end, an immediate establishment of a groundwater level and specific electrical conductivity (EC) monitoring network, equipped with data loggers, is recommended.
Chemical and Microbial Quality of Groundwater in Siloam Village: Implications for Domestic Use	J.O.	Odiyo	Siloam Village, South Africa.	2017	Chemical Quality, Microbial quality
Abstract This study assessed the chemical and microbial quality of groundwater and potential risks to human health in Siloam Village, South Africa. Due to lack of access to potable water, residents in rural areas drill private boreholes within their homesteads without considering the potential sources of groundwater pollution. This exposes them to health risks associated with groundwater pollution. Water samples from 11 boreholes were collected from August 2013 to January 2014. pH and EC were measured using a multimeter and turbidity was measured using a turbidity meter. Non-metals and metals were analysed using Ion Chromatography and Atomic Absorption Spectroscopy, respectively. Colilert quanti-tray method was used to determine total coliforms and Escherichia coli. Descriptive statistics were used to determine the overall water quality status. Potential risks to human health were inferred based on Department of Water and Sanitation guidelines for domestic use. Water quality parameters found to have serious potential health effects on human beings were correlated with selected water quality parameters at a significance level (α) of 0.05 to understand the nature of correlation and possible sources of contamination. The study determined that nitrates and fluorides were the only parameters with excessively high concentrations in groundwater which are associated with health effects on human beings. Correlation of fluoride with calcium and pH indicated that further investigations are required to identify the local sources and fluoride control mechanisms in the study area. Correlation of nitrate with chloride and potassium indicated that faecal contamination and fertilisers are sources of nitrate pollution in the study area, though faecal contamination was the dominant source. Faecal contamination was confirmed from total coliforms and E.coli in most boreholes. The study identified the need to educate borehole owners in such villages of possible strategies to minimise groundwater pollution.
Investigation Of Possible Fluoride Source In Groundwater: A Case Study Of Siloam Village	Tobiloba	Onipe	Siloam Village	2019	Fluoride
Abstract Siloam, a village in the Northern province of South Africa (SA) has groundwater reportedly characterised by concentration of fluoride greater than the permissible limit of 1.5 mg/L by the World Health Organization (WHO). In response to reported high incidences (80%) of dental fluorosis in Siloam, sources of fluoride in the groundwater of Siloam village was investigated. Earlier hypothesis suggest that the source of fluoride could be fluorite. Physicochemical parameters were determined using a combined multimeter; while total fluoride (TF) was determined using Ion Chromatograph and Fluoride Ion Selective Electrode. Mineralogy of the rocks and soil in the village was determined using X-ray Fluorescence and X-ray diffraction, respectively. Results revealed that groundwater fluoride concentration ranged from 3.92 to 4.95 mg/L, which are far above the WHO permissible limit and South African National standard. Na-Cl water type was found to be dominant in the water samples which could be due to the heavy weathering of plagioclase present in the parent rocks. TF content of the rocks and soils of the village ranged from 10 to 2000 mg/L. Leachates were obtained by soaking the pulverised rocks and soil in de-ionized water over a period of 24 hours. TF in leachates ranged from 0.27 to 14.88 mg/L and 0.05 to 10.40 mg/L at induced, and non-induced temperature, respectively. Although, previous research hypothesize fluorite to be the possible source of fluoride in the village, this research shows that the main contributors of fluoride to groundwater in Siloam were smectite clays and the muscovite present in the sandstone, Investigation also revealed that the geothermal temperature of groundwater in the area is also a major factor enhancing the release of fluoride from the clay material into the groundwater.
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.
Hydrogeological Characterization of a Methyl-Tertiary-Butyl-Ether (MTBE) Plume	Bamanye	Takashe	Saudi Arabia	2021	contamination, MTBE, TOC, remediation
Abstract The proximity of aquifer systems to sources of contamination exposes them to severe environmental threats. Pollutants that leak from petrol stations, industrial areas and landfills eventually seep through the vadose zone to reach shallow groundwater, leading to groundwater contamination. One of these pollutants is Methyl Tertiary-Butyl Ether (MTBE), which is a polar organic compound that is volatile at room temperature. As a result of its high solubility compared to other gasoline additives, MTBE can cause serious environmental issues. The aims of this study were to characterize the extent of MTBE in groundwater and characterize natural attenuation in a Saudi Arabian MTBE and methanol manufacturing company. The aims were achieved by analyzing monthly MTBE concentrations (to observe the seasonal changes of MTBE) and annual MTBE concentrations (to observe long-term changes) in 5 out of 18. Groundwater samples were collected, and in each year the MTBE, Total organic carbon (TOC) and Electrical conductivity (EC) concentrations were recorded. Because of inconsistency in the data, the results for the monthly data were from 2007 to 2010, and from 2007 to 2012 for the annual data. The results indicated a positive relationship between MTBE and TOC, and as a result TOC can be used to monitor and indicate the presence of MTBE. There was plume growth in 2 of the 5 wells (well 4 and well 14) with well 4 recording the highest MTBE concentration in all years. The reason for the high concentration might be because of spillages during truck loading. The other 3 wells showed signs of natural attenuation. Results from seasonal data suggested that temperature influences MTBE concentrations and therefore the rate of natural attenuation. There are many methods to remediate MTBE and each of them is site specific, but bioremediation was recommended for this site due to its cost-effectiveness.
Water Use Registration: A reflection of Groundwater Governance of the Verlorenvlei Catchment in the Sandveld	Imelda	Haines	Sandveld	2015	patato, RAMSAR, good governance
Abstract Introduction: Verlorenvlei catchment in the renowned potato Sandveld area is shared by three main towns where agriculture is a primary economic activity. This semi-arid catchment, receives low winter rainfall, but has a dynamic groundwater system providing almost all water services in the catchment and sustaining the acclaimed Verlorenvlei RAMSAR site. There have been recurring concerns of land use as a potential threat to water resources and the sustainability of Verlorenvlei RAMSAR site. The Minister of Water and Sanitation as custodian of water resources requires that surface water use less than 18 250 m3 and ground water use less than 3 650 m3/a to be granted under general authorization. All water use above such general authorization volumes is to be registered (Government Gazette No. 20526 of 1999). Water use registration, is identified as a tool used to achieve the effective management and governance of water resources. Water use above general authorization, is associated with larger scale land use activity, which may have an impact on water resources and the environmental at large. The following study, seeks to examine and compare catchment water use for land uses, to catchment water availability using water use registration data. Comparing water allocation and catchment capacity, this study further seeks to explore the effectiveness of water use registration in achieving good governance of water resources. Purpose: The purpose of this study was to determine effectiveness of water use registration in promoting good governance in the Verlorenvlei catchment Results: Of 124 registered water users identified in the Verlorenvlei catchment, only two of these water users are within the legislative limit outlined by Government Gazette No. 20526 of 1999. Overall, permissible water use is 447 547 259.5 m3/a, over 10 times the catchment capacity of 40 000 000 m3/a. Conclusion: Overall, excessive water use for land use activity is observed within the catchment, despite provision of legislature guiding against excessive water use. Increased water use registration, does however correlate with improved land use practices for agricultural production (Potato SA, 2014) suggesting probability of good governance. Lastly, there is a need for monitoring; improved water and land use efficiency, Integrated Water Resources Management and good governance in the catchment.
Conjunctive use of water resources	Jan	KÜrstein	Saldanaha Bay	2021	Groundwater protection; recharge, Drawdown
Abstract Surface water has traditionally been the primary resource for water supply in South Africa. While relatively easy to assess and utilise, the surface water resource is vulnerable to climatic conditions, where prolonged periods of drought can lead to an over-exploitation and eventually water shortness and supply failure. Following the drought in 2018, more focus has been given to the groundwater resource to supplement the water supply in South Africa. In the Saldanha Bay municipality the water supply is based on a combination of surface water and groundwater, with plans to supplement this with desalination and managed aquifer recharge (MAR) in the future. For an efficient and sustainable utilisation of the different water resources, a Water Supply Management System is developed that can be used to manage water mix from multiple resources. The system builds on top of a flexible WaterManager system developed for operation of complex water supply infrastructures, which in the study is extended by implementing operational rules for optimal management. The operational rules provide recommendations for the day-to-day management, but also consider seasonal and long-term utilisations. To achieve this, the rules will rely on real-time monitoring data combined with results from hydrological modelling, providing estimated system response to selected scenarios to which the water supply must be resilient. In the present study the combined Water Supply Management System is developed and tested using synthetic data, which will be presented in the paper.
Aquifer structure and extent based on Airborne Geophysical investigation: A case study based in Saldanha Bay Local Municipality, West Coast.	Angelo	Johnson	Saldanah Bay	2021	Poster, Skytem, 3D mapping survey, MAR, interpretation, aquifer management
Abstract Saldanha Bay Local Municipality appointed Skytem to conduct an airborne geophysical 3D aquifer mapping survey. As part of improving the sustainable management of the groundwater resources and exploring the options of Managed Aquifer Recharge, a better understanding of the aquifers is required. The Skytem technology unlocked a rich understanding of the subsurface geology and the groundwater contained in it. Before the main survey commenced, a trial survey was conducted to investigate the quality of the data that may be expected from the main survey. The trial survey was conducted over the existing water supply wellfield where there were existing groundwater data including borehole lithology from drilling and ground geophysics. Consequently, the main survey commenced and consisted of the following: 1) Magnetic survey providing information regarding bedrock composition and where it changes due to faults or deposition, 2) Time Domain Electromagnetic survey providing conductivity/resistivity of the subsurface, 3) Detailed elevation along flight paths, and 4) 50Hz signal to understand where interferences can be due to power lines. The survey interpretation showed the following important aquifer characteristics that will be useful for future management of the aquifer system: 1) Bedrock elevation and paleo topography, 2) Areas with different bedrock composition, 3) Geological faults in the bedrock, 4) Bedrock below the surface, 5) Areas with thick dry sand, 6) Clay layer extent and area without clay, 7) Areas with different water quality, and 8) Areas with very high concentrations of salt. The survey output and interpretations are regarded as very useful for the update of the conceptual models for the area. Data can now be used to update the numerical models and improve the management of the wellfields.
An investigation of the natural groundwater recharge and discharge of the Saldanha Bay Aquifer Systems, South Africa	Aqeela	Parker	Saldanah Bay	2021	Bulk water supply, recharge, Discharge
Abstract Saldanha Bay is partially dependent on groundwater as part of their bulk water supply, as surface water resources in the area are extremely limited and fully allocated. Due to this, there is lots of pressure on the groundwater resources by industrial development and residential growth. Despite studies being conducted on these aquifer systems since 1976, they are still poorly understood especially with regards to their recharge and discharge processes. This study aimed at providing better insight and understanding on the natural groundwater recharge and discharge processes in order to assist in the better management of groundwater resources in Saldanha Bay. Recharge investigations included a Time Domain Electromagnetic airborne geophysical survey, the assessment of groundwater levels, infiltration tests, hydrochemical analyses as well as stable and radioactive isotope analyses. These methods allowed for the delineation of the geological layers and extent, determination different water quality spatially across the aquifer, determination of flow paths through the saturated and unsaturated zones, identification of inter-aquifer flow as well as different recharge processes in the area. The results of this study showed that is highly likely that the Saldanha Bay Aquifers are mainly recharged via deep flow paths from the Aurora Mountain Range and Moorreesburg region. Investigations also showed that it is unlikely that the Aquifer Systems are recharged by local rainfall due to thick unsaturated sands and low annual rainfall, except for runoff at the foot of granite hills through focused recharge processes. The Berg River, Langebaan Lagoon and the Atlantic Ocean were identified as being the main discharge zones for the area. It is recommended that further hydrogeological investigations are conducted in the Moorreesburg region in order to get a fuller picture of the regional groundwater recharge processes and flow to Saldanha Bay.
Characterisation Of Groundwater Potential In The Northern Parts Of The Limpopo Province, South Africa: Results From Integrated Geophysical Studies Across The Sagole Hot Spring	PK	Nyabeze	Sagole Hot Spring, Limpopo Province	2013	groundwater potential, Geophysics, investigations
Abstract The Sagole hot spring is located in the northern Limpopo Province of South Africa. Investigations were carried out in order to investigate the groundwater aquifer and water chemistry. Results were envisaged to the understanding of the geothermal potential of the area. Regional scale airborne magnetic data and geology were used for identifying structures and lithological boundaries that are associated with thermal groundwater aquifers. Detailed ground follow-up and verification surveys were carried out across the target, using magnetic, electrical resistivity tomography (ERT), frequency-domain electromagnetic (FDEM) and radiometric methods. Water samples were collected from the spring eye and archival groundwater data was analysed. The interpretation of the airborne magnetic data revealed the presence of west to east, northwest and intersecting lineaments at the hot spring. From magnetic data, the groundwater aquifer was found to be capped by basalt with heat rising to the surface along possible geological contacts, faults or fractures. The FDEM profile data across the aquifer zone had peak values above 100 mS/m. The inversion of ERT data defined a highly electrical conductive, low resistivity with thickness of about 60 m. Chemical analysis of the ground water revealed that the water does not have any indication of pollution. The thermal water was found to be of meteoric origin. The drilling of artesian thermal boreholes through the capping basalt should be explored. The hot-water boreholes will be utilised by the community for domestic, irrigation and possible development of micro-geothermal systems.
Groundwater recharge in sub-humid drylands under different agricultural systems	D	Mudimbu	SADC (Malawi, Zambia, Zimbabwe)	2023	groundwater recharge, basement aquifers, Southern Africa Development Community (SADC
Abstract Groundwater is a strategic long-term water resource used by an estimated 70% of the populations in sub-Saharan Africa for drinking, irrigation and a wide range of economic activities. Understanding groundwater recharge processes is key for effectively using and managing water resources. Very few studies have used direct groundwater observations to assess the impact of different farming systems on groundwater recharge processes. This study focused on assessing basement aquifer recharge in 4 instrumented catchments in Malawi (Chitedze), Zambia (Liempe and Kabeleka) and Zimbabwe (Domboshawa) within the SADC region between 2019-2022. Employing a range of methods, including direct field observations (groundwater hydrographs, precipitation data, stable isotopes, chloride mass balance and residence time tracer data), we quantify the amount of groundwater recharge as well as the timing and nature of recharge processes under both conservation and conventional tillage systems in these four study sites. Groundwater recharge was measured in most years across the study sites. The study reveals the strong climate controls on seasonal groundwater recharge volumes, the influence of low permeability layers in the unsaturated zone, and the likely magnitude of impact from different farming practices. Groundwater residence times are high (i.e. low fractions of modern recharge, interquartile range 1-5%, n=46), even in shallow piezometers, suggesting these unpumped systems may be highly stratified. The results provide an evidence-based suite of data that reveals much about key controls on groundwater recharge in basement aquifers in sub-humid drylands and will inform the development and management of such groundwater systems.
Stampriet Transboundary Aquifer System	Joyce T	Leshomo	SADC	2015	IAH, Unesco-IHP, transboundary aquifers
Abstract The International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial, sustainable aquifer development and management. The Stampriet Transboundary Aquifer System was selected as one of the three case studies funded by UNESCO. The Stampriet Aquifer System is located in the arid part of the countries (Botswana, Namibia and South Africa) where groundwater is a sole provider for water resource. The area is characterised by the Kalahari (local unconfined aquifer) and Nossob confined aquifer
Managing Transboundary Groundwater Resources: The Case of the Ramotswa Aquifer	Nicole	Lefore	SADC	2015
Abstract What are the key institutions, both formal and informal, that determine actual groundwater use in the Ramotswa aquifer? Are current institutions at regional, national and sub-national levels adequate to collaborate for equitable benefit-sharing for the future? These are the questions that the paper will address based on early findings of a project aimed at determining the role the Ramotswa aquifer can play in addressing multiple-level water insecurity, drought and flood proneness, and livelihood insecurity. Groundwater resources are critical in the SADC region
The Role of GRACE data in mapping groundwater drought in the Southern African Development Community: Updating the groundwater drought risk map	Zaheed	Gaffoor	SADC	2021	Drought, GRACE, SADC, Groundwater storage, mapping
Abstract Pietersen, KC; Musekiwa, C; Chevallier, L Groundwater plays an integral role in the fresh water supply for both rural and urban populations of the Southern African Development Community (SADC). However, the sustainable use of groundwater is negatively impacted by persistent and recurring droughts in the region. Understanding the characteristics of drought and the risk to groundwater, will contribute towards better planning and management of water supply in the region. In this study, a novel approach is demonstrated, that uses data from the Gravity Recovery and Climate Experiment (GRACE) to map and characterise the risk to groundwater storage from drought, across the SADC region. In addition, this study also demonstrates and evaluates the inclusion of this new feature, groundwater storage sensitivity, as an additional input into a revised Groundwater Drought Risk Mapping and Management System (GRiMMS), in-order to update the SADC groundwater drought risk map developed in 2013. Specifically, the GRACE Groundwater Drought Index is calculated and used to characterise the total length, average intensity and trend, in groundwater storage drought conditions. These three factors are then combined into a new layer, groundwater storage sensitivity, and validated through comparison with groundwater level data. The groundwater storage sensitivity, which represents the risk to groundwater drought associated with groundwater storage deviations, is then included at the modular level in the GRiMMS algorithm. The inclusion of the GRACE derived groundwater storage sensitivity further highlights regions of known hydrological drought, emphasising the impact groundwater storage plays in mitigating drought risk. In conclusion, GRACE provides a unique tool that can be used to map the impact of drought across the SADC region.
Effectiveness of Groundwater Governance in the Southern African Development Community (SADC) Countries	Kevin C	Pietersen	SADC	2017	Southern Africa Development Community
Abstract Water security is pivotal for economic growth, sustainable development and poverty reduction in SADC. Increasing aridity and dwindling surface water supplies are resulting in new opportunities for groundwater as a source for domestic, agricultural and industrial use. We carried out an assessment of groundwater governance in the SADC region to determine the effectiveness of provisions to regulate groundwater. Numerous sources of information were solicited, reviewed, and data was mined using framework analysis and qualitative context analysis approaches. This provided a systematic model for managing and mapping the data. There is a good understanding of aquifer systems at the regional level. Transboundary aquifers have been delineated and areas prone to groundwater drought have been identified. Information systems to manage groundwater data, however, are disparate throughout the region and institutions to manage groundwater are inadequate and are functioning within an environment of scarce financial and human resources. The hydrogeological capacity in public institutions such as government departments is a major concern and regulations to protect groundwater resources are often not in place. This includes instruments to control groundwater abstraction and potentially polluting activities. Where regulatory instruments are in place, often no enforcement or sanctions of unlawful activities are taking place. There is also limited coordination with other sectors such as energy and mining. Furthermore, the implementation of groundwater management action plans, where developed, is weak. Overall, groundwater management in the SADC region was found to be poor. Whilst the groundwater governance challenges are great, there are opportunities to support diagnostic analysis of transboundary aquifer systems, competency development, establishing regional groundwater monitoring networks, strengthening institutional frameworks, and development of groundwater resources, e.g. to clear the backlog in access to improved water supply.
Understanding Groundwater Geochemsitry Of A Plunging Syncline South Of Robertson, Western Cape, South Africa	Neville	Paxton	Robertson, Western Cape, South Africa	2017	Groundwater Geochemistry, Plunging Syncline
Abstract The use of groundwater in the Robertson area, Western Cape, specifically to the south of the town is underdeveloped. The Breede River is the primary source for irrigation of vineyards and livestock watering through various channels and waterways. In an attempt to secure an additional water supply, small scale groundwater exploration was conducted which has culminated into an extensive network of boreholes with varying yields and geochemical signatures. As demand for usable water increases, a better understanding of the quality of the groundwater is as significant as the quantity of groundwater available for informed decision-making. This study area overlies a plunging asymmetrical syncline which comprises of the Rietvlei sandstones of the Table Mountain Group (TMG) and the younger Bokkeveld Group. The TMG forms mountain ranges on the southern and northern limbs of the syncline. Boreholes of higher blow yields were selected to undergo yield tests to determine sustainable yields. Higher yielding boreholes with an average yield of 7.4 L/s were drilled into the highly fractured and quartz-rich sandstones, while lower yielding boreholes with an average yield of 2.2 L/s were drilled into the Bokkeveld Group. The only existing borehole in use, situated on the northern limb of the syncline along the Sewefontein Fault, had a higher yield than neighbouring boreholes and a significantly better groundwater quality, somewhat of an anomaly in this section of the study area. In an attempt to access groundwater from the same formation, additional geophysical exploration, drilling and testing was conducted. The results however indicated low blow yields and poor quality groundwater. AQTESOLV software was used to further characterise and classify aquifer parameters. Descriptive statistics together with graphical hydrological methods were used to characterise the geochemical composition of the groundwater. The lithology of the study area indicates that the syncline has been extensively fractured as a result of post depositional folding and faulting. Fractures with a primary strike direction of 120° to 140° provide flow paths across the different formations, indicated by geological logs and borehole connectivity. Mean transmissivity values for the TMG are almost double that of the Bokkeveld Group, and salinity of the latter is significantly higher than that of the TMG. Transmissivity provides an indication of residence time (with an inverse relation) and thus leads to the assumption that groundwater flow rate is slower in the Bokkeveld Group. Elevation also plays a role, with a negative correlation to salinity. Recharge is delayed in lower lying areas which are predominantly underlain by Bokkeveld Group rocks, and clay rich derivative soils. Water readily ponds here and undergoes increased evapouration. The resultantsalt precipitation gets flushed into the saturated zone during future rainfall events. Recharge that does reach the saturated zone increases in salinity along its flow path due to ion absorption and cation exchange with clay minerals. Higher lying areas have little to no soil cover, with the thin soils comprising almost solely of quartz grains - considered chemically inert. As groundwater flows from the TMG into the Bokkeveld Group, residence time increases and salinity levels increase significantly.
Application of Nanofiltration Membrane for Removal of VOCs and Heavy Metals in Groundwater, Ratchaburi, Thailand	Chunintorn	Chamathong	Ratchaburi, Thailand	2023	Heavy metals, Nanofiltration membrane, VOCs
Abstract he Namphu and Rangbua subdistricts in Ratchaburi province, in western Thailand, are affected by groundwater contamination. According to site characterization results, the aquifer has been contaminated with volatile organic compounds and heavy metals since 2014. Membrane filtration technology is an alternative method for treating groundwater to produce safe drinking water for household use. Nanofiltration membrane is a relatively recent development in membrane technology with characteristics that fall between ultrafiltration and reverse osmosis (RO). This study aimed to determine the hydrochemistry of contaminated groundwater and examine the efficiency of nanofiltration membranes for removing pollutants in groundwater and the potential implementation of the membrane. The membrane module used in this study is cylindrical in shape of 101.6 cm long and 6.4 cm in diameter, and the membrane surface charge is negative with monovalent rejection (NaCl) of 85-95%. The filtration experiments were conducted at a pressure of 0.4-0.6 MPa, which yielded flow rates of approximately 2 L/min. To examine the nanofiltration membrane efficiency, groundwater samples were extracted from four monitoring wells and were used as feed water. According to laboratory results, the nanofiltration maximum removal efficiencies for 1,2-dichloroethylene, vinyl chloride, benzene, nickel, and manganese were 97, 99, 98, 99, and 99%, respectively. However, the treatment efficiency depends on several factors, including pretreatment requirements, influent water quality and the lifespan of the membrane. Further research should be conducted to determine the maximum concentration of VOCs and heavy metals in the feed water before applying this treatment method to a large scale.
Can open-source remote sensing data be used to accurately downscale groundwater storage estimates?	C	Viviers	Pretoria, South Africa	2023	GLDAS-2.2, GRACE, Google Earth Engine, Machine learning
Abstract The lack of reliable groundwater level monitoring data hinders the comprehensive understanding and sustainable management of our aquifers. New remotely sensed data products could present novel possibilities to fill in situ data gaps. For example, continuous monthly groundwater storage anomaly estimates at a spatial resolution of 0.25° (28 km) are made available through the Global Data Assimilation System Version 2.2 (GLDAS-2.2) data products that assimilate Gravity Recovery and Climate Experiment (GRACE) data. In this study, it was hypothesised that the open-source, higher resolution Climate Hazards Group InfraRed Precipitation With Station Data (CHIRPS) precipitation data and Moderate Resolution Imaging Spectroradiometer (MODIS) evapotranspiration data could be used to downscale groundwater storage anomalies (GWSA) for local scale investigations. Using an intergranular and fractured aquifer, as well as a karst aquifer as case studies, both enclosed within the Steenkoppies Catchment (A21F), two respective random forest regression (RFR) models were developed to downscale GLDAS-2.2 GWSA. Sampling monthly training data without accounting for temporal lagging resulted in an increased correlation, index of agreement (IA) and improved RMSE for the intergranular and fractured aquifer. Where the correlation between the observed groundwater storage changes and the GLDAS-2.2 groundwater storage estimates were weaker, however, accounting for the temporal lags resulted in an improved RMSE. The final product is a 0.05° (5.5 km) grid of monthly time-series GWSA estimates that can improve groundwater resource assessments, understanding aquifer recharge, modelling accuracies and better overall decision-making regarding Integrated Water Resource Management (IWRM).
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.
Transboundary groundwater flows between Poland and Ukraine: The role of joint assessments and international frameworks on water resources management	T	Solovey	Poland, Ukraine	2023	Cross-border groundwater flow, numerical modelling, Sustainable exploitation, Transboundary aquifer, Mine water management
Abstract There is a transboundary groundwater reservoir on the Polish–Ukrainian borderlands, which is of key importance in shaping strategic groundwater resources. Due to the particular importance of this reservoir, the two neighbouring countries are obliged to undertake joint actions to protect it. One of the main difficulties in building a common platform for the management of TBAs in the Polish-Ukrainian border area is the differences in the approach to the identification of GWB, monitoring methodologies and assessment of the condition of GWB, and the inconsistent hydrogeological databases between the two countries. A transboundary numerical groundwater flow model was developed to support internationally integrated management. The model research helped diagnose potential problems by determining the scope of the area with cross-border flows and quantifying the flows between Poland and Ukraine. In addition, the numerical model was used to define the optimal cross-border management unit and the conditions needed to exploit the Lublin–Lviv Reservoir sustainably. Abstraction on a current level slightly increased the transboundary groundwater flow from Poland to Ukraine and minimally reduced the flow in the opposite direction but did not reverse the direction of water flow at the border. The simulated drawdowns do not have a transboundary range, but negative effects on surface water resources are noticeable. Joint management should focus on a broader legal consensus, improvement of institutional relations, and integration of monitoring and groundwater status assessment systems.
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.
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.
The pharmaceutical compounds diversity at two river bank filtration sites located in Warta River valley (Poland)	Krzysztof	Dragon	Poland	2023	pharmaceuticals compounds; river bank filtration sites
Abstract Emerging contaminants (e.g. pharmaceuticals or pesticides) are increasingly detected in aquatic environments. The most apparent contamination source of river water pollution by pharmaceuticals is sewage treatment plant stations that discharge treated sewage effluent to the rivers. The river bank filtration systems (RBF) can effectively remove these contaminants. The two RBF sites were examined for pharmaceuticals: Śrem and Gorzów waterworks. The water samples for pharmaceuticals investigation were taken from the river and four continuously pumped wells at each site. Two wells near the river were chosen at each site (40-50 m) and two at a greater distance from the river (70 m in Śrem and 110 m in Gorzów). A visible increase in pharmaceutical concentrations was observed along the river. The sum of pharmaceuticals concentration is 8151 ng/l in Śrem (upstream), while in Gorzów (downstream) concentration is 9142 ng/l. A very big differentiation in pharmaceutical occurrence was observed. In Śrem, the sum of pharmaceuticals concentration is between 657 and 3290 ng/l, while in Gorzów, despite the higher concentrations of pharmaceuticals in the river, these substances were detected only in one well located at a close distance from the river (two substances at a concentration of 92 ng/l). The research proves a very big differentiation of pharmaceutical concentration even on sites located at similar hydrogeological conditions and demonstrates the necessity of its monitoring, especially in groundwater strongly influenced by river water contamination (like at RBF sites). This work has received funding from the National Science Centre Poland (grant no. 2021/41/B/ST10/00094).
Validation of algorithms for estimating changes in groundwater storage from GRACE gravity satellite data for Poland	Tetyana	Solovey	Poland	2023	GRACE, groundwater storage assessment, validation
Abstract The development of satellite technologies creates more and more opportunities to build modern tools for monitoring the state of groundwater. The use of the GRACE satellites to monitor GWS changes has become widespread, but the degree of accuracy with which remote sensing data can estimate these changes is unclear. In this study, we quantified changes in the GWS in Poland from 2009 to 2022 using GRACE observations, in-situ data, and GLDAS. Long-term trends and seasonality were calculated and analysed for each time series. The correlation analysis between GRACE TWS, GWS obtained from GRACE and GLDAS, and GWS in situ was performed using linear regression. Pearson and Spearman’s methods show that GRACE performance is good in the region of shallow (up to 3 m) presence of thick (above 5 m) unconfined porous aquifers; however, performance is worse in a region with multiple aquifer systems, including fissured and karst aquifers. In addition, an unrepresentative groundwater GRACE signal is obtained in regions with surface water storage, such as the Baltic Sea area. It was also found that there is very high consistency between the GRACE observations and wells water level changes, while the GWS series obtained from GRACE and GLDAS do not provide adequate compatibility. According to the GRACE data, the results suggest that evapotranspiration and the hydrodynamic system have the greatest impact on the sensitivity of the GWS estimation. The results are important for better processing the GRACE data to obtain a representative signal for the GWS assessment.
A Groundwater Vulnerability Assessment Of The Greater Pietermaritzburg Region Using DRASTIC In A GIS Environment	Andy	Zwiers	Pietermaritzburg, KwaZulu-Natal	2013	Groundwater, Groundwater Vulnerability, GIS
Abstract POSTER All groundwater is vulnerable to contamination, and natural in homogeneity in the physical environment results in certain areas being more vulnerable to contamination than others. Inherent in the agricultural, domestic and industrial sectors of Pietermaritzburg, is the generation of contaminants which, upon reaching the aquifer, result in the deterioration of the quality of groundwater, thus resulting in the water no longer being fit for its intended use. The DRASTIC method is used to calculate the groundwater vulnerability of a 670 km2 region, including the city of Pietermaritzburg. The suggested ratings of each parameter are scrutinised and adapted, according to their relevance to the region and according to known geological occurrences. The use of this method enables the user to generate a regional scale vulnerability map of the groundwater in Pietermaritzburg. The vulnerability map generated has the ability to effectively highlight vulnerable areas to groundwater contamination, which is of critical importance in correct land-use planning, as well as in indicating areas of particular concern, where further detailed investigations are needed. The results of such an assessment are used as an input, together with a contamination inventory to assess the potential risk of groundwater pollution in a groundwater risk map. Furthermore, the result informs local decision-makers and enables proactive prevention of groundwater pollution, in accordance with section 13 of the 1998 National Water Act. The intrinsic vulnerability of the Pietermaritzburg region was found to range from low to very high. The area found to be highly vulnerable is the region northeast of Springbank which requires investigation at a local scale.
Hydrogeological Characterization Of The Pietermaritzburg Formation, Ecca Group: Case Study At The Ukulinga Research Farm, Pietermaritzburg.	Sphindile	Mtshali	Pietermaritzburg Formation, Ukulinga Research Farm	2019	Aquifer characterization, Environmental Isotopes, Groundwater level monitoring, Hydrochemistry, Ecca Group
Abstract Continued population growth, economic development and climatic change have increased the demand for water supply in South Africa. As a result, most surface water systems have been exhaustively developed, increasing dependency on groundwater, including on meager aquifers during dry spells. This study aims to characterize the hydrogeology of the Pietermaritzburg Formation, a poorly productive aquifer that has been targeted for borehole sitting during drought years though with poor success rate. Pumping test analyses, monthly monitoring of groundwater level, electrical conductivity (EC), pH, water temperature and environmental isotopes (?2H, ?18O) were undertaken in 2018. Analyses of the pumping test data of the pumping well using the Theis and Cooper-Jacob method has returned hydraulic conductivity (K), transmissivity (T) and storativity (S) values of 4.1210-6 m/day, 1.5610-4 m2/day and 1.5210-4, respectively. Analyses of observation well data located west 20 m from the pumping well gave K, T and S values of 1.7910-7 m/day, 6.9510-6 m2/day and 2.810-10, respectively. A second observation well located 33 m north from the pumping well did not show any water level response to the pumping. Additionally, the rate of water level recovery was very slow both in the pumped well and one of the observation wells. These test results indicate that the investigated aquifer is not only poorly productive but also heterogeneous, compartmentalized in nature and not feasible for sitting water supply wells. Rainfall recharge estimated using the water table fluctuation method (WTF) based on monitored groundwater level data is about 28 mm/a or 3.5% of mean annual precipitation (MAP). The groundwater level, temperature and EC monitoring indicate that as new rainfall recharge reaches the aquifer, the groundwater level and temperatures increases while the EC decreases as a result of salinity reduction because of dilution. Similarly, as the groundwater level declines as a result of prolonged dry seasons, the groundwater temperature drops, while EC increases due to increased salinity. Furthermore, monthly environmental isotope monitoring shows that all the samples plot along the local meteoric water line (LMWL) indicating that groundwater is recharged from local precipitation. The groundwater at the studied site is characterized by Ca-Na-HCO3 hydrochemical facies indicating an early stage of rock-water interaction
Aquifer Water Level Behaviour In Relation To Deluge And Drought At Eskom's Thyspunt Site, Oyster Bay, Eastern Cape	Desmond	Visser	Oyster Bay, Eastern Cape	2019	Drought, water levels
Abstract The paper presents the groundwater monitoring data collected at Eskom's Thyspunt Site over the eleven-year period from January 2008 to January 2019. The Thyspunt site is underlain by an upper unconfined intergranular aquifer of the Algoa Group sediments, called the Algoa Aquifer, and a deeper semi-confined fractured-rock aquifer of the Table Mountain Group, called the TMG Aquifer. In the Algoa Aquifer, the highest water levels were recorded after the very good winter rains of 2011 and 2012. Between 2013 and January 2019 the recorded water levels in this aquifer have been declining to the lowest measured levels since monitoring started in 2008. This decline varies from 11.0 m in the Oyster Bay dune field recharge zone to 0.8 m in the Langfonteinvlei discharge zone. The deeper TMG Aquifer shows a similar decline over the last four years ranging from 10.1 m in the inland recharge zone where the TMG outcrops to 1.3 m at the near coastal discharge zone.
Aquifer storage and recovery (ASR) applications to enhance drinking water supply security in the Sultanate of Oman	Harmen	van den Berg	Oman	2023	Aquifer Storage and Recovery, Oman, desalinated seawater, drinking water supply, groundwater flow modelling, Hydrogeology, recovery efficiency
Abstract Water scarcity has driven many countries in arid regions, such as Oman, to desalinate seawater for freshwater supply. Episodic problems with seawater quality (e.g., harmful algae), extreme weather events that affect energy supply and hence the desalination process have nurtured the urgent need to store desalinated seawater (DSW) in the aquifers for use during emergency and peak demand time. Aquifer Storage and Recovery (ASR) using injection wells is a possible strategic option for Oman Water and Wastewater Services Company (OWWSC) to augment aquifer storage using excess desalinated water during low demand times. ASR strategically serves as a water supply backup to optimize production capacities against seasonal demand patterns. The technical-economic feasibility of implementing ASR schemes was investigated in Jaalan, Oman, using hydrogeological and geophysical field measurements, groundwater flow and hydraulic modelling, and economic analysis. Analysis of modelled scenarios results revealed that the Jaalan aquifer is suitable for storing and recovering about 4,000 m3 /hr in 2045. Various well field designs have been tested and optimized numerically using MODFLOW 6, showing that with 160 dual-purpose wells, 7.9 Mm3 can be injected and abstracted within the constraints defined for a robust and sustainable ASR system. Simulations with the density-dependent flow model (MF6 BUY) show that the injected volume can be fully recovered considering the drinking water quality standard. Other sites were also studied. ASR capacity was found to be site-specific, and the groundwater developments near the ASR site governed its feasibility
Feasibility And Implementation Plan For Groundwater Resource Development Of The Malmani Dolomites Within The Olifants River Water Supply System	Kornelius	Riemann	Olifants River	2019	development
Abstract The Reconciliation Strategy for the Olifants River Water Supply System (ORWSS) indicated that the surface water resources in the Olifants Water Management Area are already overallocated, and recommended that the potential of the Malmani Subgroup dolomites along the Limpopo and Mpumalanga escarpment as an additional water resource be investigated. The Feasibility Study for Groundwater Resource Development of the Malmani Dolomites within the ORWSS considered among other aspects the hydrogeology, hydrology, artificial recharge potential, groundwater - surface water interaction and wellfield design options. A key aspect of the analysis and study findings was determining the amount of water that can be provided additionally, as the groundwater development was conceived as impacting on and reducing the ORWSS system yield. Hence, the implementation strategy was designed to address this mistrust in the groundwater potential and to allow for increasing the confidence in the yield estimates over time. The implementation strategy identified several possible recipients of the water, influencing the prioritisation of wellfield development. The scheduling of implementation should first address community water supply shortfalls in the area, followed by releases to the Olifants River to cater for environmental requirements and then direct development for bulk water supply schemes. Out of the twelve identified wellfield target zones (WFTZ), eleven are recommended for potential wellfield development. Seven Malmani Subgroup dolomite aquifer WFTZs have high groundwater development potential with proven high borehole yields (>10 l/s) and are recommended for priority full-scale wellfield development, through a phased monitor-model-manage approach. The total proposed groundwater development comprises 48 wellfields with a combined yield of >40 million m3/a. Although several organisations are suitable for implementing the scheme, or parts thereof, the DWS should maintain oversight function to ensure that the several parts of the scheme development are implemented in a coherent manner and in accordance to the implementation strategy.
Global potential groundwater recharge in response to climate variability and teleconnection	C	Moeck	Norway	2023	climate variability, global, groundwater recharge, teleconnections, unsaturated zone
Abstract Periodic climate variability, such as that caused by climate teleconnections, can significantly impact groundwater, and the ability to predict groundwater variability in space and time is critical for effective water resource management. However, the relationship between climate variability on a global scale and groundwater recharge and levels remains poorly understood due to incomplete groundwater records and anthropogenic impacts. Moreover, the nonlinear relationship between subsurface properties and surface infiltration makes it difficult to understand climate variability’s influence on groundwater resources systematically. This study presents a global assessment of the impact of climate teleconnections on groundwater recharge and groundwater levels using an analytical solution derived from the Richards equation. The propagation of climate variability through the unsaturated zone by considering global-scale climate variability consistent with climate teleconnections such as the Pacific-North American Oscillation (PNA) and the El Niño/Southern Oscillation (ENSO) is evaluated, and it is shown when and where climate teleconnections are expected to affect groundwater levels. The results demonstrate the dampening effect of surface infiltration variability with depth in the vadose zone. Guidance for predicting long-term groundwater levels and highlighting the importance of climate teleconnections in groundwater management is provided. The obtained insights into the spatial and temporal variability of groundwater recharge and groundwater levels due to climate variability can contribute to sustainable water resource management.
Harmonized groundwater data in International River Basins under the Water Framework Directive (2000/60/EC) – Challenges	Belinda	Flem	Norway	2023	Harmonized data; monitoring; sampling techniques; analysis
Abstract Transboundary aquifers in Europe are managed according to the Water Framework Directive (WFD) through international river basin districts (IRBD) management plans. Paragraph 11 in the WFD states that each Member State shall ensure the establishment of a programme of measures, PoM, for each river basin district, RBD, or part of an IRBD within its territory. Easy access to harmonized data from neighbouring countries part of the aquifer is essential to analyse the groundwater status and make proper PoMs. The datasets must be available in machine-readable format via an Application Programming Interface (API) and, where relevant, as a bulk download. The metadata describing the data shall be within the scope of the Infrastructure for Spatial Information in the European Community (INSPIRE) data themes set. The datasets must also be described in a complete and publicly available online documentation describing the data structure. Using a questionnaire survey of nine European countries, groundwater sampling and analysis routines are compared to evaluate if data are comparable and accessible across borders.
Hydrological processes in the Arctic catchment of Bayelva River (Western Svalbard-Norway)	Marco	Doveri	Norway	2023	Arctic hydrology, Climate change, groundwater-surface water evolution, melting water
Abstract Streamwater and groundwater are changing in the Arctic region because of significant climate warming. Arctic amplification has intensified the melting of snow cover, glaciers and permafrost, leading to a prominent variation in the annual discharge of rivers, the groundwater occurrence, and their relationships. In high-latitude regions, evaluating groundwater flux/storage and river discharge is challenging due to a lack of hydrogeological data. Changes in river flows and groundwater discharge will alter freshwater and terrigenous material flux, with implications for freshwater and marine ecosystems. Consequently, a more timely and accurate evaluation of surface and groundwater is required. In this framework, through the ICEtoFLUX project (MUR/PRA2021/project-0027), hydrology, geophysics and geochemical-isotopic surveys have been started during 2022 in the Bayelva River catchment (W-Svalbard) from its glaciers and periglacial/proglacial systems up to the Kongsfjorden. The study aims to quantify hydrologic processes and related transport of matter (solid transport, chemical solutes flux) and investigate how subsurface and surface waters interact during active layer development. The first results suggest that electrical conductivity and total suspended solids increase from glaciers to the Bayelva monitoring station, about 1 km from the coast. Seasonal evolution of physical-chemical features was also observed. Results from geophysics data and piezometers indicate that the underground flow is spatially and temporally heterogeneous, both quantitatively and from a physicochemical-isotopic point of view. Springwater characteristics testify to a deep and well-organized groundwater flow path system. This study highlights the high complexity of these systems and their high sensitivity to the meteo-climatic regimes.
A Case Study on Capacity Development in Rural Groundwater Supply in Acholiland, Northern Uganda	K	Robey	Northern Uganda	2023	Uganda, capacity development, Geophysics, handpump functionality assessments, rural groundwater supply, Water quality
Abstract Groundwater is the most important source of potable water in rural areas of Acholiland, a sub-region of northern Uganda. Installation of handpumps has been the focus of local government and international aid to provide safe drinking water in Uganda. However, non-functional handpumps are one reason for the abandonment of groundwater resources. For handpumps to be sustainable for years, appropriate siting and construction is required, as well as monitoring. This is common knowledge to specialists working in rural supply, but gaps in knowledge transfer and field skills may exist for the persons installing and maintaining handpump wells. This is a case study of a ten-day field campaign designed to train local participants who actively work in the rural groundwater supply sector. Nine non-functional handpump sites were identified for repair and hydrogeology and geophysical studies. A non-governmental organization, IsraAID, along with Gulu University implemented training by hydrogeology specialists to build local capacity. The training included handpump functionality tests, downhole inspections, electrical resistivity tomography surveys, and water quality sampling, including a novel Escherichia coli test that did not require an incubator. Functionality tests and downhole inspections provided simple but effective ways to assess handpump and well issues. Training in water quality empowered the participants to complete rapid assessments of the quality of the water and start monitoring programs. The success of the project was based on collaboration with multiple organizations focusing on the development of local capacity. The lessons learnt from this campaign should be considered for other rural groundwater supply scenarios.
Long-term evolution of groundwater/surface water interactions in the Indus and Upper Ganges	A	MacDonald	Northern India, Pakistan	2023	Groundwater surface water interaction; irrigation; groundwater abstraction; recharge; climate change
Abstract Northern India and Pakistan face some of the world’s most challenging surface water and groundwater management issues over the coming decades. High groundwater abstraction, widespread canal irrigation, increases in glacier melt and changes to rainfall impact the dynamics of surface water/groundwater interactions in the Indus Basin and Upper Ganges. Studies using newly available data from long-term hydrographs, high-frequency stable isotope sampling and campaign sampling for groundwater residence time indicators are shedding light on the complex interactions between groundwater, surface water and rainfall. Interactions vary spatially: (1) with distance down the catchment, related to the prevailing rainfall gradient, and (2) with position in the canal command, both distance from barrage and distance from feeder canals. Interactions are also observed to vary with time due to (1) the historical evolution of the canal network, (2) patterns in precipitation over the past 120 years, (3) changes in river flow due to glacial melting, and (4) increased pumping, which has also led to increased capture of surface water. Only by understanding and quantifying the different processes affecting groundwater/surface water coupling in the Indus and Upper Ganges is it possible to forecast future groundwater storage changes.
Update of regional groundwater flow models for the Vaal Gamagara SD1 and SD2 wellfields	Martin	Holland	Northern Cape	2021	Demand, exploitation potential, Simulations, CRD, Production rates, Prediction scenario, adaptive management
Abstract Wiegmans, FE The increasing water demand for the Northern Cape Province resulted in the detailed assessment of the exploitation potential of three groundwater development target areas namely SD1, SD2 and SD4, largely underlain by karst aquifers. Since 2014 the implementation of the wellfields was delayed pending authorisation. The potential impact on the groundwater resources was raised by several stakeholders as part of the process, resulting in the re-assessment of the SD1 and SD2 wellfields. The model update considered crucial data retrieved from several groundwater level loggers from April 2014 to December 2019. As a precursor to the model update the Cumulative Rainfall Departure (CRD) curves for the relevant rainfall stations for the study areas was updated. While for most sites a good relationship between rainfall and groundwater fluctuations was observed. A poor response of groundwater levels in comparison to the observed CRD curve suggests abstractions more than the recharge of the aquifer. Metered groundwater use is for most parts not available but was estimated based on the hydrocensus data. Once the models demonstrated to reproduce past behaviour, they were used to forecast the future behaviour. More importantly was to assess whether the 2014 proposed abstraction rates still held true after the re-calibration of the model. Several simulations were carried out iteratively to identify the optimal pumping rates and the temporal variability of the withdrawal period considering the impact on the groundwater resource. Based on the results the 2014 proposed production rates were reduced from 751,608 m3/month to 597,432 m3/month representing a 2019 mitigated (optimised) proposed abstraction scenario. The case study is an excellent example of adaptive groundwater management informed by crucial datasets and scenario modelling.
Development of regional groundwater flow models for the Vaal Gamagara well fields	Martin	Holland	Northern Cape	2015	flow models
Abstract The increasing water demand for the Northern Cape Province initiated the feasibility study to augment and/or upgrade the Vaal Gamagara Water Supply (VGWS) scheme. The study completed in 2011, recommended the upgrade of the total VGWS scheme to supply the water demand of users for the planning horizon to 2030. However, short term water demand and to augment the water from the Vaal River could also be sourced from groundwater and/or mine dewatering. This resulted in the detailed assessment of the exploitation potential of three groundwater development target areas namely SD1, SD2 and SD4, largely underlain by karst aquifers. The intrusive work done on the Vaal Gamagara target areas is arguably one of the largest groundwater investigations of modern time for South Africa. This paper describes the development of the 3-dimensional groundwater flow models for the three target areas as part of this investigation. The software code chosen for the modelling work was the program SPRING which uses the finite-element approximation to solve the groundwater flow equation. Each conceptual groundwater model developed was converted into a multi-layer numerical flow model for each groundwater development area and calibrated against observed heads, spring flows and long term water level monitoring data. Once the models demonstrated to reasonably reproduce past behaviour, they were used to forecast the outcome of future groundwater behaviour (i.e. abstraction from the well fields). Three large scale transient groundwater models have been built to analyse regional flow systems, to simulate water budget component changes, and to optimize groundwater development on a ‘sustainable’ basis. Different scenarios were developed for each target area to study the impact of different recharge scenarios and variable abstraction rates on the groundwater development of the area. Several simulations were carried out iteratively to identify the necessary number, optimal pumping rates and the temporal variability of the withdrawal period. While the proposed abstraction rates for all three groundwater regions (SD1, SD2 and SD4) of 13 million m3 / annum are considered as ‘sustainable’, by definition ‘sustainability’ has so determine the balance between economic, social and environmental interest. Perhaps a more applicable term for the long-term abstractions rates for the SD well fields is the maintainable aquifer yield which simply refers to a yield (volume/ time) that can be maintained by reduced discharge or enhanced recharge, without continually mining the aquifer or depleting aquifer storage.
Contaminant Source-Term Model Development For A Backfilled Opencast Coal Mine In The Karoo Basin	K	Lupankwa	Northern Cape	2013	Contaminant, opencast coal, Karoo
Abstract In South Africa salinisation of water resources by dissolved sulphates resulting from acid rock drainage (ARD) and metal leaching (ML) from surface coal mine spoils has a significant effect on water supply in the Gauteng Province. Predictions of mine water quality is required to select cost- effective rehabilitation and remediation measures to reduce future ARD and ML risks and to limit long-term impacts. A load balance model was developed in Microsoft Excel to simulated contaminant loads in a completely backfilled opencast mine in the Karoo Basin of South Africa after closure. The model calculated the balance between contaminant load into the pit water system from mainly pyrite oxidation processes in the spoils and load removed through decanting. Groundwater flow modelling data and simulated spoils seepage qualities for the mine site were used as input in the contaminant load calculations. The model predicted that the amount of contaminants added to the pit from spoils decrease considerably from the time of closure over a period of approximately 100 years. Thereafter the contaminant load decrease is gradual. This is due to a decrease in the volume of unsaturated spoils, as spoils at the bottom become permanently inundated as the pit fills up, thus limiting oxygen diffusion and oxidation. Cumulatively, the contaminant load gradually increases in the backfilled pit until the onset of subsurface and surface decant, when the contaminant load declines. This is due to removal of contaminants from the mine water system via decanting. Approximately 200 years after mine closure, 86% of the spoils are inundated. The model predicted that the quality of decanting water improves with time due to a decrease in load from spoils, removal of contaminants through decanting water and dilution effects of relatively clean groundwater inflows. Mass loads were used as input into the numerical groundwater model for the contaminant mass transport simulations to predict the migration of contaminant plumes with time. The geochemical model results assisted in developing conceptual water and waste management strategies for the opencast mine during operational and closure phase.
Groundwater Resource Development targeting major fault zones In Banded Iron Formations (BIF) for Augmentation of the Vaal Gamaga	Frans	Wiegmans	Northern Cape	2015
Abstract The mineral rich Northern Cape Province produces 84% of South Africa's iron ore, while the Kalahari basin holds 92% of the world's high grade manganese deposits, with diamond and lime mining operations to a lesser degree. Mining expansion programs and new mines planned in the Northern Cape drive the region's economic development and growth strategy. The planned mining expansion depend on water being available for mining water needs and related increased demands for domestic water supplies. Current water supplies consist of local groundwater resources (boreholes and mine dewatering) and bulk water supply from the Vaal Gamagara (VGG) Pipeline Scheme. In 1992 the Kalahari East water supply pipeline was incorporated to supply domestic and stock water to an area of approximately 1.4 million ha. The VGG scheme consists of 370 km pipes, was built in the late sixties and is nearing its useful life expectancy. Increased water supply interruptions are being experienced while operating at capacity. The pipeline has the capacity to convey and import water of approximately 15 million m3/a into the D41J and D41K quaternary catchments. Water demand projections show an increase to 40.1 million m3/a in 2030. Various options were investigated to upgrade the VGG water supply scheme. One option considers groundwater resources to augment the water from the Vaal River from four indentified target areas (SD1 to SD4). Major fault zones in Banded Iron Formations (BIF) are targeted for groundwater resource development in the SD4 area, located east of Hotazel. This area is largely covered by Quaternary age sand and located near the endpoint of the VGG scheme and therefore prioritized as investigation area. The primary objective of the hydrogeological investigation was to identify the existence of exploitable resources for additional source development. Secondary objectives were to assess the contribution groundwater can make to augmenting pipeline water; providing a source to an area and thus diminish reliance on the pipeline; and providing an independent source, which could prevent the need for pipeline extensions. The paper will discuss the use of an airborne magnetic and Time Domain Electromagnetic's (TDEM) survey combined with gravity ground surveys as a key success factor in adding to the geological and structural information of the area. The paper will also present the results of exploration drilling (> 60 boreholes) over a large area and related borehole test pumping with water sampling to identify a sustainable and potable water supply of 2.5 million m3/a.
A changing environment focussing on drought	Fanus	Fourie	Northern Cape	2021	Drought, community supply, groundwater behaviour, Pumping
Abstract The western part of South Africa is experiencing a prolonged drought. In many cases, the effects of drought have been noticed since 2011, putting the western part of the Northern Cape under severe stress to provide water to the communities. In the past 10 years, rainfall has also decreased, and in most cases, the catchments did not receive rain to help with the recharge of groundwater. Various lessons were learned from the change in the climate and environment. But a lot can be done to minimise the impact of these changes on the water supply to communities. This paper addresses what we are noticing in the environment that impacts the way we think groundwater behaves. The changes include the change in rainfall: patterns, lines, and type of rainfall. The collapsing of boreholes with water strikes closing when being over-pumped occurs more often in the last 3 years. Pump test recommendation changes with water level change – deployment output. A combination of the factors mentioned puts more stress on groundwater resources, and a mindset change is needed to give assurance of future supply to the communities.
Groundwater Resource Assessment For Water Supply To The Heuningvlei Socio-Economic Development Area	Collen	Monokofala	Northern Cape	2013	groundwater recharge, flow regime analysis, socio-economic development
Abstract The Heuningvlei pipeline scheme was built in the 1980s to supply water to rural communities in a low rainfall area (<300 mm/annum) – Northern Cape Province. In 2008, the Joe Morolong Local Municipality identified the need to refurbish and upgrade the pipeline scheme for socio-economic reasons. The safe yield and water quality information of existing sources supplying the scheme was unreliable. This was investigated by borehole test pumping and water quality sampling, which indicated reduced yields and deteriorating water quality since 1989. Water demands, which includes supply to communities for domestic use, schools, clinics and stock watering in the Heuningvlei area, was estimated at 2 380 m3/day or 868 700 m3/annum. The potable groundwater supply recommended from 11 existing boreholes is 316 937 m3/annum, leaving a deficit of 551 763 m3. The aquifers utilised for the existing water supply comprise fractured banded iron formations (BIF) and dolomite bedrock. Kalahari sedimentary and dolomite aquifers to the east of the pipeline scheme contain high saline water not suitable for domestic use. No surface water sources exist in the area and the feasibility of the socio-economic development project depends on establishing local groundwater resources that would not impact on existing sources. A target area was identified which is approximately 10 km south from the pipeline. This area is covered by the thick Kalahari sediments (up to 130 m) underlain by dolomite bedrock with a potable groundwater balance of 2.3 million m3/a. Both the associated primary (Kalahari) and secondary (Dolomite) aquifers contain potable water. The target area was not investigated in the past due to perceived poor water quality (elevated salinity) conditions, very low (<10 %) borehole exploitability prospect and difficult drilling conditions. The paper will discuss the importance of recharge estimate and understanding of flow regime at sub-catchment and local scale, use of an airborne magnetic survey in conjunction with ground geophysics, mapping of Kalahari sediment thickness, and successful drilling of exploration boreholes to exploit the deeper Kalahari sedimentary and dolomite bedrock aquifers. The successful development of localised potable water in a low rainfall area made it feasible to implement the Heuningvlei socio-economic development project.