Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 151 - 200 of 795 results

Title	Presenter Name	Presenter Surname	Area Sort ascending	Conference year	Keywords
Stable and Radiogenic isotopes in southern Mozambique: a window into groundwater recharge, mixing and vulnerability	Jared	van Rooyen	Southern Mozambique	2023	Isotopes, recharge, residence time, SADC, vulnerability
Abstract The use of radiogenic isotope tracers, produced through bomb testing (e.g. 3H and 14C), and the application of these isotopes is yet to be fully explored now that atmospheric abundances have returned to background levels. New isotope-enabled institutions and laboratories have recently been established in developing countries to apply isotopes in practical research. This study utilized several laboratories in South Africa and in Europe to compile a robust hydrochemical (major cations and anions) and isotope (d18O, d2H, 3H, 14C, 86Sr/87Sr) dataset of groundwater from 95 sample locations in the Maputo province of Mozambique. Groundwater is hosted in different aquifers and recharged through variable mechanisms ranging from direct infiltration of exposed alluvial soils to inter-aquifer transfer between fractured aquifer systems in the mountainous regions and the weathered bedrock in the lowlands. A combination of hydrochemistry and isotopes provided insight into the heterogeneous nature of recharge, mixing of modern and fossil groundwaters, and aquifer vulnerabilities when combined with other physical parameters in the region. However, it is also clear that grab sampling over a regional spatial extent and two sampling seasons (wet and dry) did not capture all the system variability, and more regular monitoring would uncover details in the system’s behaviour not captured in this study.
ion of multivariate statistical analysis as a support for the delineation of groundwater bodies: a case study in coastal plain areas of Campania Region (Southern Italy)	S	Stevenazzi	Southern Italy	2023	coastal aquifers, statistical analysis, volcanic areas, Water chemistry
Abstract The identification of hydrogeological boundaries and the assessment of groundwater’s quantitative and qualitative status are necessary for delineating groundwater bodies, according to the European Guidelines. In this context, this study tries to verify the current delineation of groundwater bodies (GWBs) through hydrogeochemical methods and multicriteria statistical analyses. The areas of interest are three GWBs located in the northern part of Campania Region (Southern Italy): the Volturno Plain, a coastal plain constituted of fluvial, pyroclastic and marine sediments; the Plain of Naples, an innermost plain of fluvial and pyroclastic sediments and the Phlegrean Fields, an active volcanic area with a series of monogenic volcanic edifices. Hydrogeochemical methods (i.e., classical and modified Piper Diagram) and multivariate statistical analyses (i.e., factor analysis, FA) were performed to differentiate among the main hydrochemical processes occurring in the area. FA allowed the handling many geochemical and physical parameters measured in groundwater samples collected at about 200 sampling points in the decade of the 2010s. Results reveal five hydrogeochemical processes variably influencing the chemical characteristics of the three GWBs: salinization, carbonate rocks dissolution, natural or anthropogenic inputs, redox conditions, and volcanic product contribution. Hydrogeochemical methods and FA allow the identification of areas characterised by one or more hydrogeochemical processes, mostly reflecting known processes and highlighting the influence of groundwater flow paths on water chemistry. According to the current delineation of the three GWBs, some processes are peculiar to one GWB, but others are in common between two or more GWBs.
Digging Deeper: Exploring the socio-environmental impacts of sand mining in Southern Africa	D	Walker	Southern Africa	2023	extraction industry, Governance, interdisciplinarity, livelihoods
Abstract Sand mining in southern Africa is on the rise, fuelled largely by rapid urbanisation. This creates a range of societal and biophysical challenges and supports livelihoods in regions with high unemployment. Relevant scientific studies are scarce. This study explores the impacts of sand mining from ephemeral rivers on Botswana, South Africa and Mozambique communities through field visits, interviews, modelling, remote sensing and legislative analysis. What was expected to be a hydrogeology project focussing on water resources identified a broader range of issues that should be considered. Initial results uncovered a range of negative biophysical impacts, including alteration of hydrological regimes, which in turn affect groundwater recharge and exacerbate drought and flood risks, destruction of riparian vegetation, increased erosion, damage to infrastructure (including bridges and roads), reduced water quality, and the spread of invasive plant species. Equally important are the range of social impacts, such as drowning people and livestock, loss of agricultural land, increased traffic, dust, noise and crime. Complex governance arrangements influence these social and environmental challenges. The findings highlight the need to adopt an inter- and trans-disciplinary approach that considers linkages between human and natural systems. This approach is essential for finding sustainable solutions for the provision of construction materials that limit detrimental impacts on water resources, ecosystems and livelihoods.
A review of slug tests analysis on South African aquifers in potential yield and transmissivity estimations	Rolene	Lubbe	South African	2023	Slug test; Potential yield; Transmissivity; Limitations; Modelling
Abstract Slug tests are preliminary tests applied to determine the hydraulic conductivity and whether it is necessary to perform a pumping test on the borehole under investigation and should never be recommended as a substitute for a pumping test. For this reason, slug tests cannot be related to sustainable yield because slug tests cannot detect boundary conditions. The aim was to develop a methodology to relate slug tests to a potential yield estimation, investigating and reviewing the applicability and accuracy of the slug test methodology in South Africa, applied on fractured rock aquifers as established in 1995. The aim was achieved by reviewing the methodology applied for slug tests that are related to potential yield estimations, identifying the limitations of slug tests, investigating the possibility of updating the potential yield estimation method of 1995, and investigating the possibility of relating slug tests, to potential yield and transmissivity estimations through groundwater modelling. The investigation revealed that using transmissivity values determined through slug test homogenous modelling can be utilised to estimate the potential yield of a borehole under investigation by implementing correlation statistics. Note that this is not an absolute and is subject to limitations.
The Role Of Brackish Groundwater In Water Security	Kevin C	Pietersen	South Africa, USA	2019	brackish water, groundwater management, Licence conditions
Abstract Brackish groundwater resources could become an option to diversify the water supply-mix in the future when coupled with desalination or other evolving and cost effective water treatment technologies. This paper discusses regulatory and management responses dealing with brackish groundwater in international jurisdictions to form a basis for decision-making in groundwater management in South Africa. Recent literature and research on brackish groundwater was reviewed to reflect on efforts by other jurisdictions (California, Texas - USA) to regulate and manage brackish groundwater and to formulate desirable goals for brackish groundwater management for South Africa. The regulatory responses in international jurisdictions include pollution prevention, permitting, underground disposal control and differentiated groundwater use. The groundwater management responses include adaptive management, optimized groundwater abstraction, demand management approaches, managed aquifer recharge and alternative technologies. Based on the review the following strategic objectives are defined for South Africa: (i) implement responsible brackish groundwater use in areas with low salinity groundwater; (ii) promote brackish groundwater supplies for desalination; (iii) establish rules for the protection of brackish aquifers from activities in the subsurface; and (iv) create regulatory certainty about the use of brackish groundwater resources. There are several beneficial uses of brackish groundwater resources. In the USA and Canada, brackish groundwater is now the norm in unconventional gas development whereas in water-scarce areas, drinking water is being produced by desalination of brackish groundwater. In Texas - USA, municipalities choose to pay for the cost of advanced treatment rather than incur the cost of building additional water transportation infrastructure (dams, canals, and pipelines) or securing additional water rights. Some industries may use brackish groundwater with minimum or no treatment. Untreated, low-salinity brackish water may be used for irrigation, and higher-salinity waters may be used for the cooling of power plants. Groundwater is a public good in South Africa which requires an authorization for its sustainable abstraction, and It is therefore important to stipulate the correct licence conditions for sustainable brackish groundwater. Critical are the conditions for discharging brine concentrate resulting from desalination processes. It is unlikely that apart from the coastal areas, there may be deep saline aquifers to dispose the brine and these areas require detailed hydrogeological studies - this knowledge is currently not available.
An assessment of hydrogeophysics application for groundwater resource assessment in Kalahari sands aquifers and crystalline basement aquifers with case studies from Namibia and South Africa	I	Muchingami	South Africa, Namibia	2023	Crystalline basement, Hydrogeophysics, Kalahari sand aquifer, groundwater assessment, groundwater controls
Abstract Integrated geophysical methods can be useful tools in mapping the subsurface characteristics likely to control groundwater occurrence and hence are useful in identifying potential drill targets in different aquifer formations in Southern Africa. This study applied hydrogeophysical methods (natural, electrical, and electromagnetic) to identify potential groundwater-bearing targets within the Kalahari sand aquifers in Namibia and the crystalline basement aquifer system in Namibia and South Africa. The results suggest that hydrogeophysical assessments in Kalahari sandstone aquifers could clearly show that the system exhibits a well-defined layered aquifer formation likely recharged from surface water. On the other hand, crystalline basement formations could be combined with geological observations and used to identify groundwater controls like lineaments and depths to fractured zones. The magnetic method, horizontal and vertical frequency domain electromagnetic geophysical methods presented herein managed to delineate the main dykes and lineament features associated with groundwater occurrence in typical crystalline basement aquifers, while the natural magneto telluric investigations managed to delineate the deep and shallow aquifer formation in Kalahari sandstone aquifer formation. The study also advocates for integrating geophysical methods with local and regional geology for groundwater evaluation to provide a more detailed approach to resource assessment in some of the vulnerable aquifer systems in Southern Africa. Results from this study are useful for technical groundwater management and promoting the utilization of groundwater as a climate-resilient strategy in Southern Africa.
Exploring Danish experiences for Groundwater mapping in South Africa	Anker Lajer	HØjberg	South Africa, Denmark	2021	mapping , fractured geology, SAGMAA, guidelines
Abstract Kürstein, J; Thorn, P; Vermaak, N; Kotzé, YL; Pedersen, PG; Linneberg, MS; Fourie, F; Magingi, A Water supply relies entirely on groundwater in Denmark. A national groundwater mapping programme was established in 2000 to protect this valuable resource. It builds on a thorough and holistic understanding of the hydrogeological settings, obtained through an extensive data collection, culminating with an identification of threats and aquifer vulnerablility. As part of the programme, new approaches, methods, and instruments have been developed, such as airborne geophysical survey by Sky-TEM that allows the mapping of large areas in a fine resolution. Another key element in the mapping is the development of three-dimensional hydrogeological and numerical models. These are used to understand the groundwater flow paths and delineate wellhead capture zones as well as infiltration areas, which, depending on the assessed vulnerability, may be subject to protective measures. The Danish mapping approach have been tested at selected South African sites through the Strategic Sector Cooperation (SSC) between Denmark and South Africa. The approach was applied in a study supporting Umgeni Water to identify groundwater resources to supply numerous villages near the town of Ladysmith. The study illustrated a high potential for adapting relevant parts of the Danish approach to South Africa, but also revealed some challenges, e.g. related to the fractured geology, where groundwater recharge can be concentrated along dykes, a process very different from what is generally observed in Denmark. The SSC has initialised the project “South African Groundwater Mapping and Assessment Approach (SAGMAA)” to share knowledge gain through the national groundwater mapping programme in Denmark with South Africa and explore the possibility of adapting elements from the Danish approach to South African conditions in a broader context. The objective of the project is to provide recommendations to South African guidelines, and the paper will present results from the comparison of approaches in the two countries and preliminary recommendations to guidelines.
Can Danish Groundwater Assessment Be Used In South Africa?	MS	Linneberg	South Africa, Denmark	2017	Vulnerability mapping, Strategic Water Sector Cooperation Program
Abstract Denmark is a small country in the northern part of Europe. The water supply in Denmark is solely reliant on groundwater. In the past 40 years Danish groundwater management has undergone a major development. A key aspect of this, which could be of relevance in South Africa, is The Danish Groundwater Vulnerability Mapping. During a 15 year period, Denmark has spent 2.7 billion DKK (App. 385 million USD) on mapping 40 % of Denmark, in order to conduct a thorough vulnerability mapping and proper delineation of catchment areas and groundwater protection zones. The mapping has been developed intensively through the years. The approach includes development of key components as practice oriented guidance documents on all the professional areas of groundwater mapping, geophysical methods, groundwater modelling etc. As an example the airborne geophysical method of Sky-TEM which is a spin-off from the mapping can be mentioned. Other key tools in the groundwater mapping is geological modelling in GeoScene3D and groundwater modelling in GMS/MODFLOW and MIKE SHE. The foundation for Danish Groundwater Mapping is access to data. In Denmark almost all subsurface data is made available in publicly accessible databases. There are dedicated databases for; boreholes (JUPITER), geophysical data (GERDA), geological and groundwater models (Model database) and groundwater reports (Report database). In recent years Denmark has increased its focus on sharing this knowledge with other countries, including South Africa, China and the United States. Through the Strategic Water Sector Cooperation Program (SSC) on Water between the South African Department of Water and Sanitation and the Danish Ministry for Environment and Food, the Danish method of Groundwater Mapping is being tested on two case studies, in South Africa. One is of an alluvial aquifer in Western Cape, which has similarities to the Danish geological setting. The other is in a fractured rock setting which is widespread in South Africa, but seldom seen in Denmark.
Managed aquifer recharge in South Africa (MARSA)	Jens	Aamand	South Africa, Denmark	2021	Pollutants, Reclaimed water, Anaerobic aquifer, Anaerobic degradation, Nitrate, Nitrospine, Nitrification, Compost, Contaminant, Infiltration, Pathogens
Abstract Managed aquifer recharge (MAR), the purposeful recharge of water to aquifers for subsequent recovery, is used globally to replenish over-exploited groundwater resources and to prevent saltwater intrusion. Due to increased water shortage worldwide, there is a growing interest in using unconventional water resources for MAR such as reclaimed water or surface water impaired by wastewater discharges. This, however, raises major concerns related to pollution of our drinking water resources. MARSA is a new Danish-South African research project aiming at developing MAR technologies allowing a broader span of water resources to be used for MAR, including storm water, river water, saline water, and even treated wastewater. It is hypothesised that improved removal of organic pollutants, nitrogen species, antibiotic resistance, and pathogens can be achieved by establishment of reactive barriers or creation of different redox environments through injection of oxidizing agents to anaerobic aquifers during recharge. In MARSA we will carry out feasibility studies, as flow-through columns, first in Denmark and later in South Africa, to investigate the capacity of South African aquifer sediments to remove organic pollutants, nitrogen species, antibiotic resistance genes, and pathogens. Then, based on these studies, MAR options will be further investigated at field conditions in South Africa using real source water from MAR sites. For this presentation we will give an overview of the MARSA-project and show results from previous feasibility studies investigating the potential of reactive barriers to remove organic micropollutants and ammonium. These studies have shown that establishment of reactive barriers will cause oxygen depletion, but also more efficient ammonium and organic micro-pollutant removal. MARSA is funded by the DANIDA fellowship centre, Ministry of Foreign Affairs of Denmark. Project no. 20-M03GEUS.
Southern African Pre-Cretaceous Deep Groundwater Flow Regimes: Evidence And Drivers	Eddie	Van Wyk	South Africa, Botswana, Namibia	2013	groundwater flow, deep drilling
Abstract After drilling technology improvements in South Africa in the early 1900s, several deep (>300 m) exploratory drilling programmes were conducted to explore for pressurised groundwater resources. The results were not significant, except for the Cretaceous Uitenhage Artesian Basin and recent investigations in folded Table Mountain Group Aquifer systems. Large sedimentary units in Southern Africa do have the structural geometry to drive regional artesian systems; however, diverse climate and aquifer hydraulic limitations counteract these conditions to such a level that sustainable basin- like deep flow mechanisms are probably non-existing, except where enhanced by deep mining activities. On the contrary, several deep drilling projects in South Africa, Botswana and Namibia have undoubtedly proven the existence of pressurised groundwater strikes below 300 m (northern Kalahari) to as deep as 3 000 m (western Karoo Basin). Given the regional hydrogeological characteristics of these systems, the availability of sufficient recharge zones required to drive sustainable artesian flow or semiartesian conditions becomes a challenge. The existence of isolated pressurised compartments as a result of the lithostatic pressurisation in the deeper sections of many of the sedimentary successions may prove to be a more realistic explanation for these pressurised water strikes observed during deep drilling operations in Southern Africa.
HALF FULL OR HALF EMPTY ? Groundwater surface water interactions – An ever-increasing focus for water resource management.	Sonia	Veltman	South Africa various	2021	Gw-Sw interaction, wellfield testing, resource management, numerical model
Abstract More often these days we hear concerns from water users regarding “how much water is the newly drilled borehole of a neighbor extracting from “their” river water”. These are serious question with serious repercussions for sustainable use and economic development. No one wants to lose what they have invested in. On the other hand, from a groundwater perspective, this is very one sided. Numerical modelling solutions are often proposed to clients as a more accurate method of determining the groundwater surface water interaction, with the addition of volumes removed from the modelling domain, to present to decision makers the changes in volumes of discharge into streams or volumes of infiltration of stream water into the aquifer. However, this is an expensive and time-consuming exercise, and will most likely incur additional costs to accumulate sufficient meaningful data sets for input into these detailed models. A robust combination of analytical and numerical solutions is proposed, while keeping aquifer assumptions conservative, where a lack of regional data exist. This is useful in quantifying this interaction and associated volumes better without the full time and cost associated with calibrated regional flow and transport models. Analytical calculations assist in the quantification of the aquifer’s hydraulic and physical properties and is used to conceptualize flow better and determine the inputs for a conservative well field scale numerical model, in which the change in flow between groundwater and surface water system are also evaluated. The well field scale model is calibrated in a fraction of the time as a conventional flow model (less than 20%), while volumes derived is defendable and based on measurable data. This combination is viewed to be a critical step in providing time effective solutions
eSymon - An Innovative Solution to Monitoring Data Management	Tarika	Isaac	South Africa various	2021	eSymon, Monitoring, data management, data visualization, data security
Abstract The year 2020 will forever be synonymous with the Covid-19 pandemic and the immeasurable impact it has had on all our lives. During this time, there was one avenue that reigned supreme: technology. Whether it was Zoom calls or Netflix, online consultations or video conferencing at work, technology took charge. In light of this, GCS (Pty) Ltd started exploring ways that technology could assist with the most common problem identified in the Water and Environmental sectors, which is the management of large volumes of geodata. Thus, the invention of eSymon. Monitoring of the environment usually generates a significant amount of data. If this data is not systematically stored, problems often arise with: • Limited access to historical data due to poor storage; • Different formats of stored data (if they are kept in digital form at all); • Continuity and integrity of the data; and • Security of the data. Therefore, years of historical data cannot be used or trusted. The solution was to develop eSymon, which is an acronym for Electronic Data Management System for Monitoring. eSymon is primarily designed to: • Systematically import, store, view and manipulate large volumes of monitoring data; • Provide remote and instantaneous access to site-specific information; • Allow data visualization using an interactive GIS interface; and • Create various outputs such as time series graphs, geochemical diagrams and contour maps. The main idea of the software is to have all historical data for a site on one platform and have it be accessible and functional at the touch of a button. This results in several key benefits, including saving time, providing accurate and up to date information, not having to wait for technical reports to assess trends and compliance, providing several means of data visualization and, most importantly, ensuring data security.
What is in a - groundwater - map?	Nicolette	Vermaak	South Africa various	2021	Mapping methodologies
Abstract A map is a symbolic or diagrammatic representation of an area of land or sea, showing physical features and the relationship between these elements. It often reduces a three-dimensional world to two dimensions. Maps are generally static – fixed to paper or some other medium. Maps are produced for different reasons, leading to different types of maps, e.g., roadmaps, topo-cadastral maps and the groundwater maps – with the latter the topic of this article. There is a lot of work going into maps. This includes collecting all the data, doing evaluation and analysis of the data and selecting the data to use on the map. It is not possible to present all the information on a map and maps are often a generalisation. Different kinds of groundwater maps include availability, quality, vulnerability and protection. The selection of symbols to represent the information and the rendering of the maps are important in producing understandable, useful maps, but need explanations. The success in representing the information on a map will determine the usefulness of a map, but it is still often misused. At the end of this long and tedious process where conflict management skills were well developed, you may find that the information on the map is outdated before the ink on the map is dried properly. The production of maps should be an iterative process, where new data can be incorporated as soon as it becomes available. It is an expensive process and cannot be repeated too often. This article will look at the processes that helped to shape the current series of hydrogeology maps of South Africa, and how to use it optimally while mindful of limitations. It will also briefly touch on recent research that aims to help with the production of improved groundwater maps for South Africa.
Latest approaches and examples illustrating the key role of numerical modelling in sustainable groundwater use in South Africa	Annalisa Sagra	Vicente	South Africa various	2021	numerical modelling, recharge
Abstract Imrie, S. Groundwater in South Africa has great potential to supplement our country’s water demands. Currently, studies show that less than 10% by volume of the Average Groundwater Exploitation Potential is abstracted on an annual basis. The 2017 drought has aided in creating awareness of the importance of this resource towards building water resilience. If managed correctly, groundwater is commonly viewed as a sustainable source. Oftentimes, the ‘sustainability’ of a groundwater resource is an ‘open-ended’ definition based on the hydrogeologist’s interpretation of aquifer pumping test data alone. This approach often discounts the cumulative impact of environmental factors (including drought and climate change) and other users on groundwater. The use of numerical groundwater models to support and inform the conceptual models provides the mechanism to bridge this gap. This paper discusses various approaches and examples of where numerical modelling plays a key role in supporting groundwater usage in a sustainable and informed manner. In particular, this includes: •Inclusion of impact from other anthropogenic activities and groundwater users, with model scenarios that show the potential impact of each on the other, as well as the combined result to groundwater (levels and water quality) •Consideration of extreme climatic events (e.g. 1 in 100-year drought and/or flood), including the use of uncertainty analysis and consideration of dynamic groundwater management, such as the possible varying of sustainable pumping rates to suit the prevailing conditions •Identification of groundwater receptors and appropriate assessment of potential impacts to those receptors from groundwater usage, including “target-audience” thinking in the post-processing and reporting of numerical model results, so as to convey clear messages to the interested and effected parties and stakeholders •Use of multiple methods and technologies to calculate and model surface water / groundwater interaction and recharge, including uncertainty analysis, and intelligent challenging of traditional methods of estimating groundwater recharge
Using the Groundwater Level Status approach for climate Impacts	Fanus	Fourie	South Africa	2023	Groundwater level; Status; water level fluctuation; risk; climate change; recharge
Abstract South Africa is known for droughts and their effect on groundwater. Water levels decrease, and some boreholes run dry during low recharge periods. Groundwater level fluctuations result from various factors, and comparing the levels can be challenging if not well understood. Fourie developed the “Groundwater Level Status” approach in 2020 to simplify the analysis of groundwater level fluctuations. Groundwater levels of two boreholes within different hydrogeological settings can thus be compared. The “Status” can now indicate the severity of the drought and thus be used as a possible groundwater restriction level indicator. The reasons for the groundwater level or the primary stress driver can only be determined if the assessment is done on individual boreholes and the boreholes according to hydrogeological characteristics. The analysis is used to identify areas of risk and inform the authorities’ management to make timely decisions to prevent damage or loss of life or livelihoods. The applicability of this approach from a borehole to an aquifer level is showcased through practical examples of the recent droughts that hit South Africa from 2010-2018.
Pock Marks as a Nature-based solution for enhancing water availability in African marginal drylands?	D	Kibirige	South Africa	2023	Pockmarks, Groundwater, nature-based solutions
Abstract Nearly 1.9 billion people live in marginal environments, including drylands, semiarid, arid, and hyperarid environments. Obscure but ubiquitous circular pockmark depressions dot these lands. These circular depressions can range from a few meters to kilometers, and the depth of these depressions varies from a few centimeters to over 10 m. However, the genesis of the circles has been investigated among scientists for many years because of their obscure nature. Some researchers believe that termites cause fairy circles, while others believe they are caused by plants competing for water and nutrients. This study documented the Africa-wide prevalence and extent of the pockmarks for the first time, and it further classified the pockmarks according to their genesis and hydrological roles. We further investigated their relevance in serving as nature-based solutions to overcome water scarcity in dryland regions. So far, field evidence in Ethiopia and Somalia showed that these features potentially have water security significance in a) organizing surface water flows over arid/semi-arid landscapes, b) serving as the site of temporary surface water storage, and c) serving as the site of focused groundwater recharge into the underlying aquifers. This presentation will highlight the spatial prevalence, extent, and genesis model of the pockmarks across the drylands in Africa (South Africa, Namibia, Somalia, Ethiopia, Kenya, Chad, Senegal, Mali, Niger, etc.).
From monitoring networks to near real-time groundwater forecast. A case study in Cape Town Table Mountain Aquifer, South Africa	J	Nicolas	South Africa	2023	Gardénia, MétéEau Nappes, Table Mountain Group, forecast, groundwater monitoring, modelling, near real-time
Abstract Groundwater level monitoring is essential for assessing groundwater’s availability, behaviour and trend. Associated with a modelling tool, groundwater level fluctuations can be predicted in the short to middle term using precipitation probabilities or meteorological forecasts. This is the purpose of the MétéEAU Nappes tool implemented by BRGM for the City of Cape Town (CoCT) in the Table Mountain Group Aquifer (TMGA). This case study shows how near real-time groundwater level monitoring can support the municipality in managing its future groundwater withdrawals. The TMGA is an important source of groundwater in the Western Cape region of South Africa. The upper Nardouw Sub-Aquifer of the TMGA is an unconfined aquifer recharged by rainfall. It had been monitored in the Steenbras area for over 10 years before CoCT started groundwater production from the Steenbras wellfield in 2021. The MétéEAU Nappes forecasting tool is already implemented on many observation wells of the French national piezometric network, where it is used for decision-making by the French administration. It allows, in particular, to anticipate several threshold levels of drought and take appropriate measures. It combines real-time water cycle measurement data with a groundwater level lumped model (e.g. Gardenia model) and extrapolates observations for the next 6 months from statistical meteorological scenarios completed with abstraction scenarios. This tool can help protect the Steenbras wellfield as a critical water source for CoCT in the TMGA. This study was financed by the French Agency for Development (AFD).
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.
Dynamic groundwater modelling of Lake Sibaya	M	Maseko	South Africa	2023	Groundwater/surface-water relations, Climate change, groundwater model, land-use landcover, surface-water model
Abstract The Lake Sibaya groundwater-dependent catchment in uMhlabuyalingana (KwaZulu-Natal) has been the focus of hydrological research since the 1970s. The continuous decline in lake water levels and groundwater stores has prompted recent efforts. To increase confidence in the relative attribution of known causes of declines, an existing MODFLOW groundwater model was updated based on reviewed and extended hydrological input datasets and more accurate land-use and land cover (LULC) change data. A novel approach was used in this study, which involved running the ACRU surface-water model in distributed mode to provide dynamic recharge outputs for the groundwater model. This approach considers LULC changes, improved spatial and temporal distribution of climatic data, and land-surface hydrological processes. The refined groundwater model provided satisfactory simulations of the water system in the Lake Sibaya catchment. This study reports on the advances and limitations discovered in this approach, which was used to reassess past to current status quo model simulations for the region. The model was then used, as part of a multidisciplinary project, to assess the response of the lake water system under various LULC preferences based on inputs from local communities under two future climate scenarios (warmer wetter and warmer drier) in the current ongoing WRC project. The ultimate goal is to advise water resources management in the catchment.
Groundwater-dependent ecosystem dynamics in transboundary aquifer settings - a case study in the Tuli-Karoo aquifer	Kwazikwakhe	Majola	South Africa	2023	Groundwater-Dependent Ecosystem, Interactions, Transboundary aquifer
Abstract Knowledge of the nature and extent of groundwater-dependent ecosystems (GDE) at an aquifer scale enables incorporating ecological water requirements in integrated groundwater resource management activities, including transboundary aquifer cases (TBA). This way, sustainable groundwater management and functional ecosystem services can be achieved. Therefore, understanding groundwater- ecosystems-surface water interactions is crucial for assessing resources’ resilience or susceptibility towards certain impacts. Unfortunately, this subject is widely under-researched with fragmented information, especially in southern Africa. This study was thus initiated to understand groundwater processes controlling the maintenance of Tuli-Karoo TBA (Botswana, South Africa, Zimbabwe) GDEs towards developing a model that can be utilised in impact assessments, especially in climate change. The employed approach included stable isotope analysis (mainly 2 H and 18O) for groundwater, streams, springs, rainwater, vegetation, and soil; spatial imagery and GIS classification (incl. NDVI, NDRE, NDWI); and plant moisture stress techniques. Identified GDEs in the study area (characterized by intergranular alluvium aquifer underlain by the Karoo sandstone of intergranular and fractured secondary aquifer type) are riparian vegetation, floodplain and depression wetlands, and springs. Precipitation recharged alluvium aquifer’s contribution to Limpopo River baseflow is negligible as the discharge is mainly through springs and evapotranspiration. Monitoring data scarcity and skewed availability among sharing countries hamper research and its output applicability to TBA’s entirety. Therefore, data generation, exchange, and joint databases development are crucial for sustainable comanagement of groundwater and supported ecosystems and science-based decision-making.
Urban Groundwater Development and Management for Metropolitan Areas in South Africa	K	Mahlahlane	South Africa	2017	urban water supply, Integrated Development Plans, Water Sensitive Design, spacial development frameworks
Abstract The freshwater resources of the world are under pressure to meet the growing demands of rapidly increasing populations and their various activities. South Africa receives less than the world’s average annual rainfall and this suggests that it is a potential candidate for water stress. Rising demand for increasingly scarce water resources is leading to growing concerns about future access to water, particularly in urban areas. Groundwater is generally not utilised as a significant source of water supply in urban areas. Currently, groundwater makes up only small portion (up to 6%) of the supply in those metropolitan municipalities that use it. Water supply generally comes from local resources as urban areas establish, and is replaced by imported water as cities grow. Further to groundwater not being widely used for supply in urban areas, it is generally being mis-used or at least indirectly used with negative consequences. Urban areas have surfaces that are sealed preventing infiltration and recharge, generating massive surface runoff and stormwater which is discharged downstream of the urban area. Leakage of the reticulation and sewer network causes an increase in recharge. The associated contamination and water quality impacts may render the groundwater resources in the urban areas not fit for supply. The sustainability challenge for urban water management is to remediate or at least isolate poor water quality, whilst making use of the local resources. To overcome these challenges, and specifically to address the contradictory nature of urban (ground) water resources, the role of groundwater in town planning (Spatial Development Frameworks), in development planning (Integrated Development Plans), and in Water Sensitive Design (WSD) must be strengthened. This paper summarises preliminary findings from a Water Research Commission project aimed at to improving urban groundwater management practices and developing a research strategy for developing and managing urban groundwater resources. The current state-of- the-art for urban groundwater resources use and management are assessed leading to the preliminary identification of gaps.
Cape Flats Aquifer Management Scheme – the City of Cape Town’s groundwater abstraction and MAR scheme for a resilient future (South Africa)	D	McGibbon	South Africa	2023	groundwater supply, Managed aquifer recharge, primary aquifer, Resilience, urban
Abstract In response to the Western Cape’s worst drought experienced during 2015-2018, the City of Cape Town implemented various projects to augment its water supply, including desalination, re-use and groundwater. The Cape Flats Aquifer Management Scheme (CFAMS) forms one of the groundwater projects that includes groundwater abstraction and managed aquifer recharge (MAR). The Cape Flats Aquifer (CFA) is a coastal, unconfined, primary aquifer within an urban and peri-urban environment. As such, it is well situated to take advantage of enhanced recharge using high-quality advanced treated effluent but also has challenges related to seawater intrusion (SWI) and risk of contamination. MAR is currently being tested and implemented with a three-fold purpose: (1) to create hydraulic barriers against seawater intrusion and other contamination sources, (2) to protect groundwater-dependent ecosystems harbouring biodiversity, and (3) to increase storage and improve water quality to enhance resilience to effects of drought. As no legislation for MAR exists in South Africa, international guidelines are used to determine water quality requirements related to clogging environmental and health concerns. Further consideration includes aquifer-scale design, the interaction of multiple abstraction and injection wellfields within an area, and the design of individual boreholes to enhance yield and limit clogging. We aim to present progress made to date that includes exploration, wellfield development, monitoring, numerical modelling, aquifer protection, and the lessons learnt.
The Structural Hydrogeology of a Gold Mine	Stephen	Fonkem	South Africa	2015	gold mining, fractures, hydrogeological models
Abstract Gold mineralization in study area is structurally controlled. The geomorphology of the local drainage system is highly controlled by the fault architecture. Surface water flowed through, and eroded open fractures in exposed damaged zones (zone of subsidiary structures surrounding a fault). Previous conceptual hydrogeological models of groundwater system suggested is a two-aquifer system, consisting of a fractured aquifer overlain by a weathered aquifer, where groundwater flow mimics surface topography. Based on recent drilling and reassessment of historic geological and hydrogeological data, the groundwater system cannot only be described in terms of an elevation or stratigraphic units, as traditional aquifers are, but instead in relationship with the folds and faults. The fractured aquifer system around the mine pit is structurally compartmentalized both laterally and vertically, as depicted by the variance in static hydraulic heads and borehole yields over short distances. The un-fractured mass has very low drainable porosity. Virtually all water is contained in fractures. The main fracture zones north and west of the pit typically yield 1.3 to 2 L/s
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
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.
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.
Understanding the pattern of spatial and temporal variations of groundwater levels using long-term monitoring data	P	Fuku	South Africa	2023	Groundwater decline, Hydrological stresses, long-term monitoring data
Abstract Monitoring regional groundwater levels provides crucial information for quantifying groundwater depletion and assessing environmental impacts. Temporal variation of groundwater levels is the response of the groundwater system to natural and artificial stresses in terms of groundwater recharge and discharge. The complexity and extent of the variation rest on the nature and storage properties of the aquifer system. High groundwater levels are usually found in the recharge zones and low in the discharge zones, resulting in groundwater flow from recharge areas to discharge areas. Continuous decline of groundwater levels has been observed in some of the monitoring boreholes within the National Monitoring Network. Groundwater level decline has been caused either by over-exploitation or reduction of groundwater recharge. Generally, the pattern of spatial and temporal variations of groundwater levels is the consequence of incorporating climatic, hydrological, geological, ecological, topographical, and anthropogenic factors. Therefore, understanding the pattern of spatial and temporal variations in groundwater levels requires a combined approach. A combination approach of National long-term groundwater level monitoring data, Hydrological stresses, Anthropogenic interferences, and characteristics of the groundwater system was used to understand the continuous decline of groundwater levels in selected monitoring stations across the country.
Contaminated soil and groundwater: Vacuum Enhanced Recovery as an alternative method	Ernest	Rambau	South Africa	2015	Vacuum Enhanced Recovery, hybrocarcon contamination
Abstract Vacuum Enhanced Recovery (VER) has widely been applied in many hydrocarbon contaminated site to recover liquid hydrocarbon from the subsurface Hydrocarbon contamination to groundwater and soil is usually as results of leak or release. Different technologies and method exist to treat contaminated groundwater and soil through hydrocarbon. This paper focuses on the efficiency of VER as alternative method to the site where over 6 000 litres of petrol leaked to the subsurface over a period of time. The application of VER involves creating a capture zone in a particular monitoring well by increasing the hydraulic gradient towards that particular well or set of wells affected by hydrocarbon.
Monitor and determine local groundwater impacts from increased mining activities in the Kalahari iron manganese field of the Northern Cape, South Africa.	Gawie	van Dyk	South Africa	2023	aquitards, environmental impacts on groundwater, increased water demand, Monitoring, primary aquifers, reduced recharge
Abstract The Kalahari iron manganese field (KIMF) in the Northern Cape, South Africa, was historically exploited by only three mines, with Hotazel the only town and the rest of the area being largely rural, with agricultural stock/ game farming the major activity. Since 2010, mining activities have increased to more than 10 operational mines with increased water demand and environmental impacts on groundwater. The area is within catchments of the Matlhwaring, Moshaweng, Kuruman and Gamogara rivers that drain to the Molopo River in the Northern Cape. All the rivers are non-perennial, with annual flow occurrence in the upstream areas that reach this downstream area once every 10 years. The area is semi-arid, with annual evaporation nearly five times the annual precipitation. The precipitation is less than 300mm, with summer precipitation in the form of thunderstorms. Vegetation is sparse, consisting mainly of grasslands, shrubs and some thorn trees, notably the majestic camel thorns. The Vaal Gamagara Government Water Supply Scheme imports 11 Ml/d or 4Mm3 /a water for mining and domestic purposes in the KIMF section. The area is covered with Kalahari Group formation of 30 to 150 m thick with primary aquifers developed in the basal Wessels gravels and Eden sandstones for local use. The middle Boudin clay forms an aquitard that isolates and reduces recharge. Water levels range from 25 to 70m, and monitoring indicates local dewatering sinks and pollution. This study will report on the water uses, monitoring and observed groundwater impacts within the current climatic conditions.
Combined Use of Environmental and Artificial Tracers to Characterise the Vadose Zone	Yazeed	van Wyk	South Africa	2023	vadose zone, contaminant transport processes, environmental and artificial tracers
Abstract Water and contaminant transport processes in the vadose zone through preferential flow paths can be understood using environmental and artificial tracer methods. Further improvement in tracer techniques can be achieved by applying numerical modelling techniques of both water and solute transport, accounting for additional information on water movement and the matric potential of the vadose zone. The vadose zone is often ignored as a key component linking the land surface to the groundwater table, even though it acts as a filter that removes or stores potential contaminants. The water transit time between the surface and the groundwater table is frequently investigated using artificial tracers that normally show conservative behaviour. The main advantage is that the input function can be clearly defined, even though artificial tracers can generally only be applied over a relatively small area. The research is expected to provide insight into the selection and use of environmental and artificial tracers as markers for detecting and understanding the contaminant transport processes and pathways of contaminants in altered vadose zone environments (open-pit quarry). The impact is improved characterisation of the pathways, transport and migration processes of contaminants, and residence times, leading to the development of appropriate conceptual and numerical models of vadose zone flow processes that consider various contaminant sources. The principal aim is, therefore, to systematically examine the transport mechanisms and associated pathways of different environmental and artificial tracers in an open-pit quarry.
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 Citizen Science Approach to Design Implementation of Science-Policy Interaction Plan for Optimal Use and Protection of Groundwater Resources at Quaternary Scale, South Africa	Stanley	Nzama	South Africa	2017	Citizen-science, ecological model, adaptive management, groundwater resource directed measures, resource directed measures, science-policy interaction
Abstract Using citizen science approach to influence implementation of science-policy interface concept leads to optimal use and protection of groundwater resources that ensures sustained research for practical policy dialogue. Mere determination of water resource classes, the reserve and resource quality objectives within the resource directed measures (RDM) concept for protection of groundwater water resources without considering implementation aspects, propels for defiance in policy implementation at local scale. Although water resource classes and resource quality objectives have not yet been implemented at any catchment at this stage, however findings indicate that in some areas challenges have been experienced with preliminary Reserve implementation at local level, especially in water use license applications. There is a need for an orthodox link between RDM and Source Directed Controls (SDC) to complement current methods used and processes followed in GRDM projects for uncontested RDM implementation to ensure sustainable groundwater resource protection especially at local site where the resource reside. The argument in this paper is that a feasible implementation for GRDM at local level provides science-policy interface platform for the sustained operation of the science-citizen approach. The objective of study was to design a field-tested conceptual model of science-policy interaction that monitors and evaluates GRDM intervention. How policy implementation and evaluation utilizes scientific research outputs at local level were examined using ecological model. Key findings indicated that (i) systems analysis approach was lacking at local level (ii) practical assessments of GRDM at local specific quaternary catchment scale was not adequate (iii) optimal reserve determination methodology for uncontested water utilisation was not clear to provide proper guidance for water use license application (iv) Reflective operational plan (GRDM monitoring) to enhance science-policy interaction was not available at quaternary catchment scale (v) Best practices of adaptive management principle to sustain groundwater resource protection were limited at local level. From these results, it can be said that the up scaling of the current approach for RDM especially GRDM requires refinement for practical uptake of scientific results. The study recommended that a feasible implementation plan for GRDM at local level that provides science-policy interface platform for the sustained operation of the science-citizen approach need to be designed, implemented, monitored and evaluated with citizens to inform reflective policy implementation. Although, the results of this study are not conclusive, the insights as a starting point for proactive buy in approach is provided to ensure that science-policy interaction remain practical and relevant to scientists and policy makers as well as society.
Numerical groundwater modelling of the Windhoek Aquifer (Namibia) for wellfield management	Jannie	Weitz	South Africa	2023	MODFLOW, Windhoek Aquifer, numerical groundwater modelling
Abstract The City of Windhoek in Namibia has developed wellfields and a managed aquifer recharge scheme within the fractured Windhoek Aquifer to ensure a sustainable potable water supply to the city during drought. A three-dimensional numerical groundwater model of the aquifer was developed using the finite-difference code MODFLOW to determine the potential impacts of varying pump inlet depth elevations and varying production borehole abstraction rates for optimal wellfield and aquifer management. The initial steady-state numerical model was calibrated to September 2011 groundwater levels, representing the best approximation of “aquifer full” conditions (following a good rainfall period and best available data). The subsequent transient numerical model was calibrated against groundwater level fluctuations from September 2011 to August 2019, the period after steady-state calibration for which data was available (and during which monitored groundwater abstraction occurred). The calibrated transient model was used to run various predictive scenarios related to increased emergency groundwater abstraction and estimate potential impacts on the Windhoek Aquifer. These predictive scenarios assessed groundwater level drawdown and recovery, aquifer storage potential, and potential abstraction rates under different pump elevations. Model results indicated a sharp initial groundwater level drop followed by a gradual decrease as groundwater levels approached the 100 m saturated depth mark. Pumping elevations were subsequently updated with recommended abstraction rates and volumes for the entire Windhoek Aquifer. The numerical groundwater model, in association with extensive groundwater monitoring, will be used to assess/manage the long-term sustainable and optimal utilisation of the Windhoek Aquifer.
Integration of water simulation modelling for water conservation and demand management in the mining sector (a case study)	Fanie	Botha	South Africa	2015	legislative challenges, integrated modelling, WUL
Abstract This paper outlines and presents out-of-the-box theories as examples to highlight some of the challenging restraints within the current legislative environment preventing scientists, engineers and other operational personnel to take theory into action and implementation. Key to this is the very static nature of the water use license (WUL)and associated process. The first example shows how integrated dynamic water modelling can be utilized to create an integrated water and waste management plan within the mining sector. The models developed using principles from Government Notice 704, the Best Practice Guidelines (BPGs) and the principles of water conservation and demand management. Ultimately it keeps clean and dirty water flows separate and optimises the use of dirty water in order to reduce raw/potable water off-takes through this process. The objective of these models are to optimise the water use and develop strategies to ultimately enable mines to optimize it's internal non-potable water resources therefor relieving pressure on the limited potable systems, as well as aiding surrounding communities, in which they operate, with potable water. Results from the model provides for 1 or 20 years simulation data that differs year-on-year based on numerous factors, i.e. rainfall, run of mine (ROM) feed and growing/declining surface run-off areas. The variability of the results makes it almost impossible to utilize within application documentation as it is too complex and it does not align with the application figures as required in the WUL process. This resulting in a fairly simplistic and sometimes unrealistic static model that is submitted as part of the application.
The impacts of climate change on groundwater in South Africa	Zaheed	Gaffoor	South Africa	2023	CMIP6, GRACE data, groundwater recharge potentia
Abstract Climate change is expected to have a significant impact on freshwater resources across the globe. Changes in the distribution and quantities of rainfall over the coming decade will impact various earth systems, such as vegetation, contributions to streamflow, sub-surface infiltration and recharge. While groundwater resources are expected to act as a buffer, changes in rainfall will ultimately impact the recharge process and, thus, groundwater reserves. Understanding these changes is a crucial step to adapt better and mitigate climate change’s impacts on water resources. This is valid in South Africa, where much of the population depends on groundwater as a freshwater supply. Hence, this research presents the status quo regarding climate change’s impacts on South Africa’s groundwater resources. Reviewing relevant literature, the impacts on recharge, groundwater quantity (storage changes), discharge and groundwater-surface water interactions, groundwater quality, and groundwater-dependent ecosystems are discussed. In addition, utilizing factors such as rainfall, slope and vegetation cover collected from CMIP6 climate projections, changes in groundwater recharge potential from the past through the present and future are demonstrated. The findings illustrate uncertainty over the long-term impacts of climate change on groundwater for different regions and various aquifers. However, global warming could lead to reduced recharge, which impacts groundwater reserves.
The Seven Deadly Sins of Numerical Modelling	Andries	Wilke	South Africa	2021	numerical modelling, recharge
Abstract Pope Gregory defined the seven deadly sins in order to guide the Catholic Church in the 6th century. The past 20 odd years in the industry has shown that there are several mistakes that are repeatedly made by numerical modelers. Although we all acknowledge that any numerical model is a non-unique solution, and that there exists and infinite number of solutions, there are several sins that will prevent the model from giving an accurate representation. This paper will provide the most common mistakes made in a format that is accessible to numerical modelers as well as other practitioners. Issues covered will include boundary conditions, model complexity and recharge.
Contributions To The Characterisation Of The Vadose Zone For Hydrogeological Applications	Matthys A	Dippenaar	South Africa	2017	vadose zone, hydraulic parameters
Abstract Hydrogeologists have moved past merely investigating for water supply and quantification of sustainable yields. In the 21st century, and with rapid urbanisation and climate change, hydrogeologists are expected to work in cross-disciplinary fields of geochemistry, aquatic biodiversity, surface water – groundwater interaction, groundwater economics, law and management. In addressing important hydrological parameters such as recharge, recharge rates, advection of contaminants and interflow, the role of the vadose zone becomes increasingly important. A series of case studies and physical models were used to evaluate the movement of water at variable saturation through media with primary, secondary and tertiary porosity. Scales of models varied based on different volumes of observation and relevance from discreet fractures to regional hillslopes. Centrifugal acceleration was employed in some of the models to scale predetermined variables. Models included consolidation of heterogeneous soil successions, discreet fractures and their intersections, flow from soil into discreet rock fractures, and column testing of dolomite residuum. Advances are made in the qualitative and often quantitative assessment of interflow, soil-to-rock percolation, discrete fracture flow, and flow through dolomite residuum. Further to this, insight is gained into empirical quantification of hydraulic parameters through, for instance, the cubic law; the relevance of flow regimes (turbulent versus laminar) at various Reynolds numbers; and breaching of interfaces to promote vertical percolation of water stored in partially saturated geological media. Applications include improved understanding of pore water pressure distributions in media, induced seepage under consolidation, ingress water eroding soil into bedrock cavities resulting in sinkholes or surface subsidence, drainage of slopes and cuttings, water influencing infrastructure, indirect and localised recharge rates, aquifer susceptibility to contamination from surface, and urban hydrology in general. The paper addresses some key findings and examples within the context of an extensive series of publications and research reports.
Test-pumping derivative analysis to improve conceptual understanding and abstraction yields in a complex fractured aquifer: Steenbras Wellfield (Western Cape, South Africa)	K	de Bruin	South Africa	2023	Table Mountain Group, conceptual model, derivative analysis, fractured aquifer, groundwater resource management, recommended yield, test-pumping
Abstract Test-pumping drawdown curves do not always sufficiently indicate aquifer characteristics and geometry and should never be analysed in isolation. Using derivative analysis and flow dimension theory, inferring the regional geometries and flow characteristics of fractured aquifers that are otherwise unknown or inconclusive is possible. As the drawdown and/or pressure front propagates through the aquifer, it reaches various hydrogeological objects that influence flow regimes and imprints a sequence of signatures in the drawdown derivative curve. The conjunctive interpretation of these flow regime sequences and hydrogeological data results in a robust, well-informed conceptual model (in terms of both local groundwater flow and the aquifer), which is vital for sustainable groundwater resource management. Derivative and flow regime analysis was applied to the test-pumping data of confined and unconfined Nardouw Aquifer (Table Mountain Group) boreholes within Steenbras Wellfield (Western Cape). Major NE-SW trending folding and transtensional Steenbras-Brandvlei Megafault Zone, in association with cross-cutting faults/fractures and younger False Bay Suite dykes, make the Nardouw Aquifer (and deeper Peninsula Aquifer) hydrogeologically complex. The sequential flow regime analyses reveal domains of conceptual flow models, including open vertical fractures, T-shaped channels, double (triple) porosity models, and leaky/recharge boundary models, amongst others. Appropriate analytical flow models (type curve fitting) are then applied for accurate aquifer parameter estimations, which are used to evaluate recommended long-term yields through predictive pumping scenarios. The outcome is an improved hydrogeological understanding and enhanced conceptual model of the aquifer, which informs numerical modelling, ecological protection, and groundwater resource management.
Integrated Modelling of the Hydrological Dynamics of the Semi-arid Hout-Sand Catchment, South Africa	E	Bjerre	South Africa	2023	drylands, conceptual flow model, integrated dynamic hydrological modelling, water resources, assessment and management
Abstract The interaction between dryland hydrological fluxes and the high spatial and seasonal climate variability is inherently complex. Groundwater recharge is episodic, and rivers are ephemeral. When flow occurs in the river network, water is lost through the riverbed, giving rise to focused recharge, which could be a significant part of total recharge. We have used the integrated and physically based MIKE SHE modelling system to analyze the hydrological processes and fluxes in the 7,715 km2 Hout-Sand catchment in the South African part of the Limpopo River Basin. The discharge hydrograph measured at the outlet station is highly episodic, with a small baseline flow component superimposed by high flow events in response to intense rainfall. Likewise, the groundwater hydrographs from the area are characterized by rapid increases in groundwater levels in response to high rainfall events with recurrence intervals of several years. Due to the scarcity of basic measurements and information, we used data products from satellite platforms to supplement the information on rainfall, evapotranspiration, soil moisture, land use and irrigated areas. We applied MIKE SHE to test different conceptual flow models of the catchment by calibrating the different models against direct measurements of river discharge and groundwater levels and indirect estimates of evapotranspiration and soil moisture from satellite products. By analyzing the simulated model dynamics and the resulting values for the calibration parameters, we identified the most plausible conceptual model, which then forms the basis for water resources assessment and management recommendations for the Hout-Sand catchment.
To Be, Or Not To Be – A Career In Hydrogeology: Some Anecdotes And Advice From Adventure And Exploration Over The Past 30 Years	R	Morris	South Africa	2017	Experience, career, profession
Abstract A hydrogeologist studies the ways that groundwater (hydro) exists within and moves through the soil and rock of the earth (geology). How we use this knowledge for the good of the environment and society will lead to our success as hydrogeologists and environmental game-changers. Within the broad field of hydrogeology there exist several specialist domains. One may be more of a specialist in groundwater supply, resource management and monitoring issues. Or one may concentrate on subsurface contamination issues. Or be more slightly removed in areas such as geophysics and specialised modelling. Field experience as a young hydrogeologist is essential to establish a foundation for good science. Early specialisation is however occurring to the detriment of first understanding the essentials of basic hydrogeology. Data collection, collation, interrogation and interpretation all contribute to the report. It is the presentation of the findings in a manner that can be understood by the layman, general public and authority groups that is important. For the field of hydrogeology to obtain the recognition it deserves in South Africa, the hydrogeological fraternity will need to become more ‘heard’ and ‘active players’ in managing the country’s scarce water resources. It is one thing to develop a groundwater supply scheme, but the role of the hydrogeologist must continue with the long term monitoring and management of that supply scheme to ensure its success. This presentation draws on the more than 30 years of experience that the author has had as a practising hydrogeologist in South Africa. The oral presentation of this paper has as its intention to excite passion for the profession of hydrogeology. Reminisces made will show the pleasure of experiences gained and provide guidance to young entrants to the profession. Being a hydrogeologist provides one with the opportunity to be a ‘player in the field’ and contribute to sustainable life and societal well-being. Being a player is more exciting than being a spectator, so engage in how you can enjoy your game.
FrackSA: A tool to aid in the enforcement of groundwater regulations during unconventional oil and gas extraction	Charissa	Worthmann	South Africa	2021	Poster, Unconventional gas, hydraulic fracturing, Regulations, enforcement, civic informatics, mobile application, groundwater protection
Abstract South Africa is currently considering unconventional oil and gas (UOG) extraction as an additional energy resource to improve the country’s energy security. In a water-scarce country such as South Africa, which has experienced more frequent and more intense climate extremes due to climate change, the water-related impacts of UOG extraction is a concern. The South African government is however determined to proceed with UOG development as soon as regulations to protect natural resources have been drafted. The country’s intricate governance system can however not enforce such regulations effectively, as it experiences repeated inter-departmental miscommunication, fails to collaborate with stakeholders effectively, and lacks human and financial resources for enforcement. A lack of transparency in fracking operations and between stakeholders is another challenge for enforcing UOG extraction regulations. Poor regulatory enforcement presents an obstacle for the protection of groundwater resources if fracking were to commence. This study, therefore, focuses on addressing the enforcement challenges of UOG regulations aimed at protecting groundwater resources. It proposes the use of civic informatics on a technology platform, specifically via a mobile application (FrackSA), to assist with on-the-ground enforcement of these regulations. While many UOG mobile applications are used internationally, they mostly focus only on UOG related aspects (news, information, pricing, geological information, and fracking well information). FrackSA uses civic informatics to address both groundwater monitoring and management as well as UOG extraction operations in a single platform, to enable regulators to protect groundwater resources more effectively during UOG extraction, while simultaneously enhancing transparency in the UOG industry.
Assessment of the state of potable water supply system in selected communities ofVhemb District Municipality, Souh Africa	Tuwani	Malima	South Africa	2021	community supply, local municipality, main source, Groundwater Quality, distance to source, reliability
Abstract Water is regarded as a source of life and access to potable water supply delivery remains the building block to improving and maintaining the community member’s health and productive life. The demand for water supply has been increasing due to population growth and climate change phenomena. Hence, there is need to assess the current state of potable water supply system in selected rural areas of Vhembe District Municipality (VDM), South Africa. About 14 villages in VDM were visited to assess the state of water supply. Interview were held with three municipal officials who deals with water supply systems and 14 focus group discussions were held in each village with the communities and their leaders. 448 head of households, 14 councillors completed the questionnaires on potable water supply situation in their area. The results indicated that the main sources of water supply are boreholes followed by tap water from dams. In areas where the two sources are not available, the rivers, fountain and the water tankers were also the main sources. In terms of water usage, the boreholes recorded the highest responses of 45% from households, followed by the tap water from dams at 35%, 4% from rivers, 5% from fountain and 10% from water tankers. In addition, about 53.6% of participants collect water once a week from the main source (boreholes and tap water from dams). Rural communities of Vhembe District Municipality were not satisfied with the quantity, distance and reliability of boreholes. Therefore, this article recommended that the municipality, communities, councillors and traditional leaders should work together in addressing the pressing water issues. Part of which include provision of more sources of water to complement growing population. In addition, village water committees need to be established to assist in water provision management.
Recharge under review: Implications for Water Resources Management	Nicolette	Vermaak	South Africa	2023	Recharge; groundwater availability; groundwater management
Abstract Recharge is an important factor in Water Resources Management as it is often used as a measure for sustainable groundwater abstraction and resource allocation. The recharge estimation is, however, linked to a specific time, area and conditions and then generalised over seasons and years. Current climate change estimations predict a warmer and drier future for western parts of southern Africa. Groundwater recharge estimation methods do not consider changes in climate over the short term and do not consider the longer trends of a changing climate. This article looks at the various methodologies used in recharge estimations and their application in a changing world, where rainfall period, pattern and intensity have changed, where higher temperatures lead to higher actual evapotranspiration and where there is a greater need for water resources for use in agriculture, industry and domestic use. Our study considers the implications of current recharge estimation methods over the long term for water allocation and water resources management of groundwater resources from local and aquifer catchment scale estimations.
The application of artificial intelligence techniques to support groundwater management in Southern Africa	Z	Gaffoor	South Africa	2023	Big data analytics, Machine learning, transboundary aquifers
Abstract The beneficial groundwater use in the Southern African Development Community (SADC) is well documented. Groundwater plays a vital role in the freshwater supply mix and, in some cases, is the only source of freshwater, especially in the arid region of SADC. However, the management of this resource is hampered by numerous challenges, such as lack of data, limited tools to leverage available data, lack of resources, institutional mismanagement, and climate change, amongst others. Of these challenges, the lack of data and the tools needed to transform this data into information has consequences for the decision-making process. Hence, this research attempts to address this challenge by demonstrating the use of big data and artificial intelligence (AI) to fill data gaps with new unconventional sources and model groundwater processes to transform data into actionable information. The presentation focuses on introducing the landscape of groundwater big data in SADC, followed by a review of regional AI applications. After that, novel approaches to using AI in various aquifers across SADC are demonstrated in their applicability to support groundwater management. Finally, the challenges facing the use of AI in SADC are discussed, followed by opportunities for new research based on the current state-of-the-art AI techniques. The results illustrate that AI can be a helpful tool for supporting groundwater management in SADC. However, the need for enhanced data collection is evident for these techniques to be generally applicable.
Characterisation of the Lower Berg River Aquifer System, Western Cape, South Africa	A	Parker	South Africa	2023	Lower Berg River, aquifer, Discharge, Geophysics, Groundwater, Isotopes, recharge, Tritium
Abstract The Lower Berg River Aquifer System, situated in the Western Cape province of South Africa, is important to the towns that overlay it, as they rely on the aquifer for water supply, which supplements industrial development and residential growth. This aquifer system is important because surface water resources in the area are finite and fully allocated. Despite studies on the Lower Berg River Aquifer System since 1976, knowledge of the geological layers, recharge and discharge areas, and groundwater flow paths remain limited. This study aimed to provide greater insight and understanding of the aquifer to assist in better management. Investigations included a Time Domain Electromagnetic airborne geophysical survey, the assessment of groundwater levels, infiltration tests, hydrochemical analyses, and stable and radioactive isotope analyses. These methods allowed for the identification of the aquifer’s layers and extent, determination of water quality in different parts of the aquifer, delineation of flow paths through the saturated and unsaturated zones, identification of inter-aquifer flow, as well as different modes of recharge.
Characterisation and Protection of Deep Aquifers in South Africa: Potential Resources	Amy	Allwright	South Africa	2017	Deep aquifers, aquifer protection
Abstract The importance of groundwater in South Africa has become evident over the past decades, especially as pressure on surface water resources intensifies in response to increasing water supply demands. Research has significantly progressed on the shallow groundwater resources conventionally used for water supply, and leading on from this deeper groundwater resources have become a focus point as a future water source. This focus on deep aquifers is driven by new developments, such as shale gas development, injection of brines into deep aquifers, carbon sequestration and geothermal energy. The understanding of deep groundwater in South Africa is often limited due to insufficient data at these depths. To develop a body of knowledge on deep geohydrology in South Africa, an investigation on the currently available information was launched to assess potential deep groundwater resources. The investigation formed part of the larger WRC Project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). The geology of South Africa was reviewed from a deep groundwater perspective to provide an initial analysis of potential deep groundwater aquifers. The main potential deep aquifers were identified for further investigation using a ranking system, where Rank 1 shows a positive indication, Rank 2 shows some indication, Rank 3 shows a neutral indication, and Rank 4 shows a negative indication for deep groundwater systems. The Rank 1 geological groups include (in no particular order): the Limpopo Belt, Witwatersrand Supergroup, Transvaal Supergroup, Waterberg and Soutpansberg Groups, Natal Group, Cape Supergroup, Karoo Supergroup. In a number of the identified potential deep aquifers, the indicator for deep groundwater flow systems was the presence of thermal springs. Additionally, deep groundwater occurs below the traditionally exploited weathered zone, and the importance of fractured aquifers becomes paramount in the investigation of potential deep aquifers. In conclusion, three main components were considered for the investigation of potential deep aquifers systems, 1) geological groups; 2) thermal springs and 3) depth of fractures. These three components should be used holistically going forward to best characterise the potential deep aquifers of South Africa.
Unconventional Gas Regulations for Water Use by DWS Unconventional gas	Lebogang	Malefane	South Africa	2021	Unconventional gas, UCG, CMB, contamination, Regulations, NWA 1998
Abstract Unconventional gas development in South Africa consists of but not limited to shale gas extraction commonly known as “fracking”, Underground Coal Gasification (UCG), Coalbed Methane (CBM), to extract natural gas from geological formations is a new, rapidly expanding industry in the world and in South Africa. However, there are general concerns that these operations could have large negative impacts such as groundwater contamination. This article maps out the development of regulations for unconventional gas operations, according to Section 26(1) (9) of the National Water Act, 1998 (NWA) and read together with Government Notice 999 (Government Gazette No.: 39299, of 16 October 2015). The objectives of the published DWS regulations include, augmenting the NWA and its existing regulatory framework, providing for a step-wise process for authorising all unconventional gas operations to allow for informed decision making, to set prohibitions and restrictions for protection of water resources, and requirements for disclosure on chemicals to be used during the operations. The objectives of DWS regulations are aligned to the NEMA, and MPRDA requirements for exploration and production of these operations, and are further supplemented by the minimum information requirements for water use licensing application and as part of integrated water resource management. In conclusion, DWS proposes thoroughly consulted and fit-for-purpose regulatory framework that seeks to propose water use law and requirements for unconventional gas operations based on the National Water Act (1998). With these proposed regulations DWS ensures that it plays its critical role in the development of a regulatory framework for unconventional gas operations.
ome Trans-disciplinary Legal Options to Ensure the Protection of South Africa’s Utilisable Groundwater Resources	Carin	Bosman	South Africa	2023	Groundwater governance; water law; protection; land use activities; hydrogeology; aquifer protection zones
Abstract South Africa faces serious water scarcity challenges not only because it is a semi-arid country but also due to climate change. One of the most significant effects of climate change is an increase in temperature, which inevitably increases evaporation. Increased evaporation directly reduces the availability of surface water resources. Groundwater is less susceptible than surface water resources to evaporation and thus offers resilience against the impacts of climate change. Many South African cities, communities, and farmers depend on groundwater for domestic or other socio-economic purposes. This implies that groundwater resources which are currently or potentially utilisable should be identified, and suitable legal measures should be implemented to protect these resources from potential risks of harm or damage posed by anthropogenic activity. First, This article evaluates the effectiveness of the country’s existing regulatory framework to effectively protect South Africa’s groundwater resources and finds that the framework can be improved significantly. Secondly, it explores regulatory opportunities within the existing legal framework to strengthen South Africa’s groundwater governance regime, including using land use planning instruments to facilitate the implementation of groundwater protection zones
Delineating wellhead protection areas and aquifer vulnerability in the Cape Flats, South Africa	Brynn	Hunink	South Africa	2023	Aquifer vulnerability mapping, groundwater sustainability, Resource protection, Source protection, Wellhead protection areas
Abstract Prevention of threats to the quality and quantity of groundwater supply is critical to ensure its sustainability. Several African studies have shown that contamination of aquifers is primarily caused by improper placement of land-based human activities. Therefore, adequate preventative measures are required to safeguard the water quality of African aquifers to avoid long-term deterioration. Spatially explicit, 3D numerical groundwater modelling is a common methodology to assess contaminant transport. However, model development is time-consuming and complex. Contrastingly, DRASTIC-L is a 2D, GIS-based aquifer vulnerability mapping technique. The method is simple to apply, but analyses are qualitative and subjective. The study aims to compare both methods and to combine their strengths using GIS overlay. Overall, aquifer vulnerability was determined using the DRASTIC-L method, while wellhead protection areas were delineated using steady-state numerical modelling. This study focuses on the Cape Flats area due to its rapid development and growing municipal water supply supplementation needs. DRASTIC-L mapping revealed that aquifers in the Cape Flats are highly vulnerable to contamination due to the region’s unconfined hydrogeological properties, shallow water table and high-risk land use types. Moreover, groundwater vulnerability mapping combined with the delineation of wellhead protection areas allows for reduced uncertainty in the contamination potential of delineated groundwater protection zones. As a result, this study highlights the need for overall resource protection of the Cape Flats aquifers and provides insights into mapping out potential source protection areas of existing water supply wells.
anaged aquifer recharge (MAR) suitability mapping Using GIS-MCDA: The South African perspective	L	Nhleko	South Africa	2023	Managed aquifer recharge, multi-criteria decision analysis, Regional Scale, Suitability mapping
Abstract To increase the security of groundwater resources, managed aquifer recharge (MAR) programs have been developed and implemented globally. MAR is the intentional recharge and storage of water in an aquifer, which will be recovered later. It was previously known and implemented as Artificial Recharge (AR). In South Africa, the documented practice dates back 40 years. There are five main MAR methods: Well-Shaft-Borehole, Spreading-induced bank infiltration, In-channel modifications, and Runoff harvesting. Two regional-scale MAR suitability maps for the Spreading Method (SM) and the Well-Shaft-Borehole (WSB) Method were compiled for South Africa, using the Geographic Information System combined with Multi-Criteria Decision Analysis (GIS-MCDA) methodology. Parameters used to compute the maps included the nature of the different aquifers, groundwater level, water quality (EC), distance to river, terrain slope, mean annual rainfall, land cover, soil moisture availability and clogging (Fe-iron content). To create a suitability map, the parameters were combined using the weighted overlay method and the Analytic Hierarchy Process (AHP – specifically the pairwise comparison). The site suitability maps indicated that most areas in South Africa are suitable for the Spreading and Well-Shaft-Borehole methods. The results were verified with the location of existing MAR schemes and were found to agree. However, these maps are not applicable for siting projects at a local scale but can serve as a guide and screening tool for site-specific studies looking for highly suitable or target areas for MAR implementation