Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 101 - 150 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort descending	Keywords
Comparison Of Analytic And Numerical Estimations Of Groundwater Drawdown Evolution For Open Pit Dewatering	Jaco	Nel	Kolwezi, Democratic Republic of the Congo	2013	dewatering, Drawdown
Abstract A new mining site situated near Kolwezi in the Democratic Republic of the Congo plans to develop a pit in phases over a period of six years. The mine requires dewatering volume estimates of the pit as well as a constant water supply to the plant. Hydrogeologic data available at the site during the scoping phase was limited to a few water level measurements and blowout yields from only five hydrological boreholes. Hydraulic properties from reports at neighbouring sites were extrapolated to the geological units at the site. The depth to water level at the site is about 20 m, with a planned final pit depth of approximately 180 m below surface. Based on the limited data available an analytical approach to estimate the inflow into the mine was adopted. Analytical calculations proposed by Marinelli and Niccoli (2000) were used to estimate the inflow into the Pumpi mine pits. The analytical calculations consider recharge, depth of mining vertical and horizontal hydraulic conductivities. Drawdown evolution of pit dewatering are obtained by using different mining depths at different mine stages. The output results from the analytical calculations are the maximum extent of influence of the pit as well as the volume of water inflow into the pit. Limitations of the analytical equations are that they, amongst others, cannot consider complex boundaries. Drilling and pump testing to obtain local hydraulic properties and boundary conditions are planned during the first quarter of 2013. The numerical model will be set up after the drilling and pumping tests, using the new data for calibration. The numerical model will contain as much of the physical layer definitions and potential internal boundaries as possible with model boundaries incorporated along far field fault zones and hydraulic boundaries. The numerical model should improve the reliability of estimates of pit inflow and water supply to the plant. The results between the analytical and numerical approaches can then be compared to improve future dewatering estimates with limited data. It is expected that the reliability of the analytical predictions will reduce after year 4, where the role of boundaries are expected to influence the drawdowns and related flow towards the pit.
An Innovative Application Of The Mixing Cell Model To Quantify Surface Water–Groundwater Interaction	Amy	Allwright	National	2013	Innovation, groundwater resource management, baseflow
Abstract The significance of a reliable groundwater resource assessment is of growing importance as water resources are stretched to accommodate the growing population. An essential component of a groundwater resource assessment is the quantification of surface water–groundwater interaction. The insufficient amount of data in South Africa and the apparent lack of accuracy of current estimates of the groundwater component of baseflow lead to the investigation of a new method. This applicability of this new approach, the Mixing Cell Model (MCM), to quantify the groundwater contribution to baseflow is examined to assess whether the method would be of use in further groundwater resource assessments. The MCM simultaneously solves water and solute mass balance equations to determine unknown inflows to a system, in this application the groundwater component of baseflow. The incorporation of water quality data into the estimation of the surface water–groundwater interaction increases the use of available data, and thus has the ability to increase the confidence in the estimation process. The mixing cell model is applied to datasets from the surface water–groundwater interaction test site developed by the University of the Free State, in addition to data collected along the middle Modder River during a fieldwork survey. The MCM is subsequently applied to a set of quaternary catchments in the Limpopo Province for which there are available calibrated estimates of the groundwater component of baseflow for the Sami and Hughes models. The MCM is further applied to the semi-arid quaternary catchment D73F to assess the applicability of the mathematically-based MCM in a flow system within a regionally-defined zero groundwater baseflow zone. The results indicate that the MCM can reliably estimate the groundwater component of baseflow to a river when sufficient data are available. Use of the MCM has the potential to evaluate as well as increase the confidence of currently determined groundwater baseflow volumes in South Africa, which will in turn ensure the responsible and sustainable use of the countries water resources.
How Good Is Your Consultant? A Laymens’ Guide To Critically Assessing Consultants	ME	Convery	National	2013	Consultant
Abstract With increasing focus on wasted expenditure within local government and recent media reports on the money spent on poor quality service, it is becoming progressively important for those in a position of engaging consultants, either for groundwater supply or environmental work, to have confidence in the company or person they have employed. This paper focuses on how to assess consultants before they walk through the door based on qualifications, CVs, professional registrations and previous work experience. It goes through the project lifestyle, explaining in a non- technical fashion the different processes involved in a groundwater supply or groundwater contamination assessment and provide simple indicators of good practice that should be evident in the consultant's work. Topics covered include assessing proposals, gathering background information, health and safety, appointing sub-contractors, data quality, the use of appropriate published procedural guidelines, the use of relevant quality guidelines and what deliverables should be provided.
Hydrocarbon Remediation – Practical Low Cost And Low Maintenance Solutions	Jennifer A	Pretorius	National	2013	Hydrocarbon, contamination
Abstract In recent years there is an increased awareness of hydrocarbon contamination in South Africa, and the need for remediating sites affected by these contaminants. Hydrocarbon contamination of groundwater can be caused by a large variety of activities at industrial, mining or residential areas. Once these contaminants are discovered in groundwater where it poses risks to human health and/or the environment, remediation is often required. Remediation of groundwater has become a booming industry for groundwater practitioners and often there is an attitude of more sophisticated and expensive solutions are better. This paper will show that this attitude is not always the best solution, but rather recommend an approach where a combination of low cost/low maintenance system need to be investigated and applied to reach clean-up goals. Determination of natural attenuation potential and on-going monitoring forms an integral part of this type of solution.
Characterisation And Development Of A Carbonate Rock Aquifer For Large Scale Irrigation In Zambia (A Case Study)	Kobus	Troskie	Zambia	2013	aquifer, case study, Groundwater
Abstract Limestones and dolomites form an important aquifer system in Zambia. The municipal water supplies for Lusaka and several population centres on the Copperbelt all depend on the carbonates for a substantial proportion of their water supply. Currently 155,912 ha of land are irrigated in Zambia, which is about 30 percent of the economical irrigation potential. Development of large scale irrigation schemes from carbonate rock aquifers proves to be a viable groundwater resource in Zambia. The Katanga carbonate rock aquifers are considered to have good groundwater potential, with high yielding anomalies of up to 60l/s common in certain areas of the country. A phased approach was adopted to characterise the Katanga Carbonates by means of quantifying the volume of groundwater available for abstraction within the geological boundaries. The first phases included geophysical surveys (mainly electrical resistivity and magnetic methods), exploration drilling and aquifer testing. Later phases included the drilling of production boreholes and wellfield development. Lessons learned during the exploration included the identification of high yielding drilling targets and the role of anomaly frequency in target selection. Further development of the Katanga aquifers for production provided challenges regarding production borehole construction and design. The feasibility of the optimum design of production boreholes versus the initial capital cost of the development of these carbonates proved to be an important consideration in this regard.
Sampling Protocol Optimisation Using Fluid Electrical Conductivity Logging	Candice	Lasher	National	2013	Electrical conductivity, Sampling Protocol
Abstract Characterisation of fracture positions is important when dealing with groundwater monitoring, protection and management. Fractures are often good conduits for water and contaminants, leading to high flow velocities and the fast spread of contaminants in these conduits. Best practice guidelines related to groundwater sampling suggest that specific depth sampling with specialised bailers or low flow purging are the preferred methodologies to characterise a pollution source. These methods require knowledge about the fracture positions and, more importantly, flow zones in the boreholes. Down-the-hole geophysical and flow logging are expensive, complicated and time consuming. Not all fracture zones identified with geophysical logging seem to contribute to flow through the borehole. An efficient and cost-effective methodology is required for the characterisation of position and flow in individual fractures. This research reviewed the use of Fluid Electrical Conductivity (FEC) logging to assist with the development of a monitoring protocol. FEC logging proved to be beneficial as it provided individual fracture positions, fracture yields and vertical groundwater flow directions. FEC logging proved to be fast, cost-effective and practical in deep boreholes. The technique allows the development of a site-specific sampling protocol. The information so obtained assists with the identification of the appropriate sampling depths during monitoring.
The Geohydrological Status Of The Vanrhynsdorp Karst Aquifer	Jana	Brits	Vanrhynsdorp	2013	Geohydrological, Aquafer
Abstract The aim of this study was to determine the geohydrological status of the aquifer within the boundaries of the Vanrhynsdorp Water User Association with emphasis on the central catchment, E33F. This will assist the Department of Water Affairs with the introduction of compulsory groundwater-use licensing and empowerment of the Vanrhynsdorp Water User Association to manage the resource. In this study emphasis was given to the determination of the water balance and groundwater reserve of the central catchment and the designing of a representative groundwater monitoring network. A literature study of five projects conducted since 1978 was done. Comparisons were made between the data and results of these studies. All the historical data from these studies, as well as the data from the current monitoring programme up until December 2012, were put together and analysed. A conceptual model and groundwater reserve determination, as well as a representative monitoring network, were produced. The study showed a general decline in groundwater levels over a 34-year period. It also showed an increase in rainfall over the last 20 years. Based on the reserve determination and the declining groundwater level in spite of increased rainfall and thus recharge, it was concluded that over-abstraction of groundwater in the study area is taking place. It is recommended that compulsory licensing should be put in place as soon as possible and that no additional groundwater-use licences should be granted in the study area. The installation of flow meters on all production boreholes should be stipulated in the licensing condition. This will assist the monitoring and regulation of groundwater abstraction volumes.
Towards The Effective Management Of Groundwater Resources During Unconventional Gas Mining	Surina	Esterhuyse	National	2013	Unconventional gas
Abstract Unconventional gas mining is a new and unprecedented activity in South Africa that may pose various risks to groundwater resources. According to legal experts, South Africa does not currently have the capacity to manage this activity effectively due to various lacunae that exist in the South African legislation. The possible impacts of unconventional gas mining on groundwater, as well as governance strategies that are used in countries where unconventional gas mining is performed; have been analysed and will be discussed. Based on possible impacts and strategies to manage and protect groundwater internationally, possible governance options for the management of South Africa’s groundwater resources are proposed
Characterisation Of A Large Light Non-Aqueous Phase Liquid (Lnapl) Plume Over A Fractured Gneiss Aquifer In Limpopo Province, South Africa; With Reference To An Ongoing Pump-And- Treat Remediation Technology	Mahlogonolo	Phahlamohlaka	Limpopo	2013	LNAPLS
Abstract Work is being conducted in Limpopo province following a large volume release of petroleum hydrocarbons that took place from a leaking underground pipeline, resulting in significant groundwater contamination. This is considered to be the largest petroleum hydrocarbon release recorded to date in South Africa. The leak took place for 15 years before it was discovered 13 years ago in 2000. From the pressure tests that were performed, 10-15 ML of A-1 Jet fuel is considered to have been released to the subsurface. Product bailing was the first method employed for the recovery of the free product, and was later replaced with a P&T system which was considered to be more effective. The village located about 6 km to the north of the spillage depends mostly on groundwater. This paper presents a progress update of works that have been conducted in support of developing a conceptual model which aims to determine the areal extent of the plume.
Establishment Of A Database And A Representative Groundwater Monitoring Network For The Vanrhynsdorp Water User Association	Brian	Dyason	Vanrhynsdorp, Western Cape	2013	groundwater monitoring, Geohydrological
Abstract The aim of this project was to establish a detailed geohydrological database and monitoring network for the karst aquifer within the boundaries of the Vanrhynsdorp Water User Association. An adequate monitoring network is necessary for the Vanrhynsdorp Water User Association to implement sustainable water use management as well as for the Department Water Affairs to ensure its mandate as trustee of all water resources. Hydrocensus projects were conducted in phases as the project escalated from historic town supply during 1978 towards a catchment driven water user association after implementation of the new National Water Act in October 1998 (Act 36 of 1998). With the successive hydrocensuses conducted, the monitoring network also evolved in regard to area monitored, point locations, monitoring schedules and parameters measured. Hydrocensus data were captured on the National Groundwater Archive, time series data on the Hydstra database and chemical analysis on the Water Management System. Time series graphs were compiled to analyse the monitoring data and to create a conceptual model of the karst aquifer. The study showed a general decline in groundwater levels and quality in the study area. The conclusion is that the aquifer is over exploited. It is recommended that an extensive management plan is developed and implemented to ensure sustainable use of this sensitive water resource. The installation and monitoring of flow meters on all production boreholes should be seen as urgent and stipulated as such in licensing conditions. This will ensure the effective management and regulation of this valuable groundwater resource.
Using gravity anomalies from GRACE to estimate changes in groundwater storage in the Vaal River Basin	Khuliso	Masindi		2015
Abstract The Gravity Recovery and Climate Experiment (GRACE) satellites detect minute temporal variation in the earth's gravitational field at an extraordinary accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores (snow, groundwater, surface water and soil moisture) due to increases or decreases in storage. The GRACE monthly TWS data are being used to estimate changes in groundwater storage in the Vaal River Basin for a period (2002 to 2014). The Vaal River Basin has been selected, because it is one of the most water stressed catchments in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands, it is critical to monitor and calculate changes in groundwater storages as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin were mostly localised focusing mainly on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, but many of these models do not take into account the groundwater component. Thus, there is a significant gap in the understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks are often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is a good approach to estimate changes in hydrological storages as it covers large areas and generates real time data. It does not require information on soil moisture, which is often difficult to measure. The accuracy of calculating change in groundwater storage lies in the processing of GRACE data and smoothing radii. For this study, smoothing radii of 1500, 900, 500, 300, 150 and 1 km are used. Currently the associated error with different smoothing radii is unknown. The preliminary results indicate that the study area experienced a loss in TWS of -31.58 mm equivalent water height over a period of 144 months in TWS at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamics, which will improve water management practices.
Understanding Site Hydrology of the Northern Kwa Zulu Natal Anthracite Coal fields	Hendrik	Botha	KwaZulu-Natal	2015	coal mining, AMD, mine closure
Abstract POSTER Investigations have shown that receiving water bodies, which mainly include rivers, streams and the more complicated geohydrological system, are part of the primary end receivers of harmful contaminants from identified coal mining waste bodies. Some of these potential dangers include acid mine drainage (AMD) and sulphur mine drainage (SMD) which have dire effects on the surroundings. The need for a cost effective methodology to assess site hydrology and geohydrology, to understand the associated legal responsibility of contaminated streams and aquifers, is recognised. In the compilation of this paper the unique nature of South African legislation and policies are implemented in the development of a logical approach towards mine closure specifically in the field of groundwater assessments. Furthermore, this paper explores co-disposal of discard and slurry material and the environmental impact of co-disposed wastes is assessed. The unique geological attributes of the KZN coal fields and the geochemical research results found indicates that on its own discard has great potential to produce long term SMD and that slurry has lower SMD potential. Co-disposed results are promising and buffering against long term chemical changes are noted. The final product of this approach constantly considered site hydrogeology, related impacts, risks and liabilities. This gave more clarity on aspects related to the principles followed to identify objectives for sustainable mine closure and to adopted a philosophy of mine closure as a hydrogeological concept. Overview of methods that could be used for mitigation of polluted aquifers and a brief site specific application is discussed with the aim to achieve the key deliverable which focuses on methods to scientifically assess sources, pathways and receivers. Ultimately this process has led to the development of a logical approach towards mine closure for groundwater assessment and remediation in the typical anthracite mine environment.
Hydrogeochemical characterization of groundwater and assessment of hydrological processes in the Mokolo catchment Limpopo	Corne	Engelbrecht	Limpopo	2015	ecological indicators, aquatic ecosystems, impacts
Abstract South Africa is facing a water supply crisis caused by a combination of low rainfall, high evaporation rates, and a growing population whose geographical demands for water do not conform to the distribution of exploitable water supplies. This situation is particularly critical in the river systems comprising the Limpopo River basin where every tributary river has been exploited to the limits possible by conventional engineering approaches. These attempts to meet society's demands for water for domestic, irrigation, mining and industrial uses have caused a progressive deterioration of the water resources as well as the aquatic ecosystems in these rivers. In addition to the pressure exerted by scarce water resources and deteriorating water quality, South Africa is facing a critical shortage of electrical power. There is an urgent need to address the country's electricity shortage through the building of new coal mines and coal fired power and the Waterberg area has been identified for these purposes. All of these new operations will be accompanied by a rapid growth in population which will put further stress on the water resources as well as the existing sewage plants. The Waterberg region is part of the Bushveld which can be classified as a hot and an arid region. Due to irrigation that currently exist in the region, which stems from the climate conductive to agriculture production and its current mining development, based on the vast mineral deposits present, the current water availability and water use in the Waterberg region is relatively in balance. Meaning that the available water resources in the Limpopo basin will not be able to meet the domestic and industrial demands for water that the new developments will pose and the flows in several rivers have already changed from perennial to seasonal and episodic. In order to satisfy the demand of water that will be required by the above mentioned projects, the Mokolo Crocodile Water Augmentation Project will supply additional water to the region. However, this area still contains a relatively high number of natural or near-natural ecosystems, and it is important that this natural capital is not significantly eroded in the development process. This is possible with effective environmental planning to limit and mitigate negative social, ecological and economic impacts. This project promotes science-based environmental assessment and planning by developing an understanding of key aquatic ecological indicators and their associated thresholds. The project vision is to promote improved outcomes for stream and river ecosystem health, and ultimately human health and well-being in the Waterberg area. The outcomes of the study will be used to detect existing processes of change in aquatic ecosystems and estimate the likely future changes that increased coal mining, human population and water transfers will cause.
Hydrocarbon plume delineation using a Hydrogeological and Geophysical approach	Albert	Kruger		2015
Abstract Simple and cost-effective techniques are needed for land managers to assess and quantify the environmental impacts of hydrocarbon contamination. During the case study, hydrocarbon plume delineation was carried out using hydrogeological and geophysical techniques at a retail filling station located in Gauteng. Laboratory and controlled spill experiments, using fresh hydrocarbon product, indicate that fresh hydrocarbons generally have a high electrical resistivity, whilst biodegraded hydrocarbons have a lower resistivity. This is attributed to the changes from electrically resistive to conductive behaviour with time due to biodegradation. As such, it should be possible to effectively delineate the subsurface hydrocarbon plume using two-dimensional (2D) Electrical Resistivity Tomography (ERT). As part of the case study, two traverses were conducted using an Electric Resistivity Tomography (ERT) survey with an ABEM SAS1000 Lund imaging system. The resultant 2D tomographs were interpreted based on the resistivity characteristics and subsurface material properties to delineate the plume. Localised resistivity highs were measured in both models and are representative of fresh hydrocarbons whereas areas of low resistivity represented areas of biodegraded hydrocarbons. More conventional plume delineation techniques in the form of intrusive soil vapour and groundwater vapour surveys as well as hydrochemical anlayses of the on-site monitoring wells were used to compare the results and to construct the detailed Conceptual Site Model. During the investigation, four existing monitoring wells located on the site and additional two wells were installed downgradient of the Underground Storage Tanks (USTs) in order to determine the extent of the plume. In conclusion, a comparison was found between the groundwater results and geophysical data obtained during the case study and it was concluded that ERT added a significant contribution to the Conceptual Site Model.
An Investigation Of Groundwater Recharge And Residence Time Using Noble Gases, Tritium, And Terrigenic Helium	Hugh	Klein	Utah, USA	2015
Abstract Noble gases are used in this study to investigate the recharge thermometry and apparent groundwater residence time of the aquifers on the eastern slope of the Wasatch Mountains in the Snyderville Basin of Summit County, Utah. Recharge to and residence time for the basin aquifer in the Salt Lake Valley, Utah, from the western slope of the Wasatch Mountain range by 'mountain-block recharge' (MBR), is a significant source of subsurface flow based on noble gas and tritium (3H) data. The Snyderville Basin recharge thermometry from 15 wells and 2 springs indicates recharge temperatures fall within the temperature "lapse space" defined by the recharge thermometry determined in the study of MBR for the Salt Lake Valley and the mean annual lapse rate for the area. Groundwater residence times for the Snyderville Basin were obtained using tritium and helium-3 (3He). The initial 3H concentrations calculated for the samples were evaluated relative to the 3H levels in the early 1950s (pre-bomb) to categorize the waters as: (1) dominantly pre-bomb; (2) dominantly modern; or (3) a mixture of pre-bomb and modern. Apparent ages range from almost 6 years to more than 50 years. Terrigenic helium-4 (4He) is also used as a groundwater dating tool with the relationship between terrigenic 4He in Snyderville Basin aquifers and age based on the apparent 3H/3He ages of samples containing water from only one distinct time period. The 4He is then used to calculate groundwater residence times for samples that are too old to be dated using the 3H/3He method. The mean groundwater residence times calculated with both methods indicate the water yielded by wells and springs in the Snyderville Basin generally ranges from 6 to more than 50 years. In addition, the calculated terrigenic 4He age for the pre-bomb component of many samples was found to exceed 100 years. While terrigenic 4He residence times are not as definitive as those calculated with the 3H/3He method, or chlorofluorocarbons (CFCs), age dating with terrigenic 4He allows initial estimates to be made for groundwater residence times in the Snyderville Basin, and is an important tool for establishing groundwater residence times greater than 50 years. Historic water levels from production wells indicate a declining water table. This trend in conjunction with precipitation data for the area illustrates the decline in the water levels to be a function of pumping from the aquifers. Groundwater residence times in the Snyderville Basin and declining water levels support the need for a groundwater management program in the Snyderville Basin to effectively sustain the use of groundwater resources based on groundwater age. {List only- not presented}
"Deriving groundwater recharge using Stronium isotopes: Oshivelo Aquifer, Namibia" - A step towards groundwater management	Henry	Beukes	Namibia	2015	Isotopes
Abstract In order to obtain a better understanding of a groundwater system, it is very important to understand the recharge mechanisms of such a system. Several intensive investigations have been done, documenting the different methodologies to derive recharge. Most of these studies have been centred on the detailed analysis and description of isotopes, which are either a characteristic of the water, the rock, or both. The isotopes of strontium, in particular the isotopic 87Sr/86Sr ratio, is one of such methodologies applied to drive the sources of recharge. The Oshivelo management area is part of the greater Owambo Basin, with no major rivers flowing through the project area, while the Omuramba Owambo, which crosses the area from east to west, bears water only rarely. This rural area therefore heavily relies on groundwater resources. Towards the end of the 20th century, through exploratory drillings an artesian aquifer in the southern part of the Owambo basin was discovered. Several investigation and water supply boreholes have been drilled, with the major findings summarised: - In the late 1990s DWA (DWA, 1999) drilled 12 exploration boreholes and six observation boreholes, showing high yields ranging between 40 and 200 m?/h. One of the boreholes yielded saline water, classified under the Oshivelo Artesian Aquifer and it was recognized that there may be a risk of saltwater intrusion when beginning to exploit the aquifer. It was assumed that the aquifer receives local recharge from the Etosha Limestone Member aquifer in the order of 3.75 MCM/a and additional unquantified recharge from the Otavi Dolomite Aquifer. - In the early 2000s KfW funded a study of the Tsumeb area, including the development of a groundwater flow model according to which an amount of 31 MCM/a would be leaving the Tsumeb area at the northern model boundary, i.e. flow into the Oshivelo Region. - The DWA plans to supply the north-western Oshikoto Region with water from the KOV2 aquifer via a pipeline in order to overcome water shortages there and to become more independent from surface water supplies from Angola. Though, through the groundwater model, a first estimate of groundwater resources availability has been established, the source of recharge is yet to be determined, including the flow mechanisms. Without, this vital piece of information, a valuable groundwater resource may be eventually utilized unsustainably. This presentation will focus primarily on the determination of groundwater recharge mechanisms, which would produce additional input to refine the existing groundwater flow model, concentrating on the Oshivelo Aquifer system. Upon the successful completion of this investigation, the next step would then be to evaluate the groundwater flow model and use it for a proper groundwater management plan. {List only- not presented}
The use Vegetable Oil Substrate's in the treatment of contaminated groundwater	Michelle	Pienaar		2015
Abstract Edible vegetable oil (EVO) substrates have been successfully used to stimulate the in situ anaerobic biodegradation of groundwater contaminated chlorinated solvents as well as numerous other anaerobically biodegradable contaminants like nitrates and perchlorates at a many commercial, industrial and military sites throughout the United States of America and Europe. EVO substrates are classified as a slow release fluid substrate, and comprise of food grade vegetable oil such as canola or soya bean oil. The EVO substrate serves as an easily biodegradable source of carbon (energy) used to create a geochemically favorable environment for the anaerobic microbial communities to degrade specific contaminants of concern. EVO substrate's can either be introduced into the subsurface environment as pure oil, in the form of light non aqueous phase or as an oil/water emulsion. The emulsified vegetable oil substrates holds several benefits over non-emulsified vegetable oil as the fine oil droplet size of the commercially manufactured emulsified oils can more easily penetrate the heterogeneous pore and fracture spaces of the aquifer matrix. The use of this technology to stimulate in situ biodegradation of groundwater contaminants is still relatively unknown in South Africa. This paper will give an overview of the EVO technology and its application, specifically looking at the advantages of using this relatively inexpensive, innocuous substrate based technology to remediate contaminated groundwater within fractured rock environments commonly encountered in South Africa. {List only- not presented}
Oudtshoorn Groundwater Project: Exploratory drilling results from the Blossoms Wellfield	Dylan	Blake	Eastern Cape	2015
Abstract {List only- not presented}
Acid mine drainage in the Witwatersrand: Unanswered questions	Henk	Coetzee	Witwatersrand	2015
Abstract Since the first decant of acid mine drainage in the West Rand in 2002, a great deal of effort has gone into researching the challenges which it poses there and in the adjacent Central Rand and East Rand Gold Fields. Short-term interventions have been implemented to maintain water at conservatively-determined safe levels and remove the worst contaminants from the water pumped from the mined. A feasibility study, looking at the long-term options has proposed treatment of water to a much higher standard, identifying a number of potential end-users of the treated water and highlighted the extremely high costs involved in responsible management. During the second half of 2010, a team of experts was convened to assess problems related to acid mine drainage in the Witwatersrand and propose solutions. A number of recommendations were made and the most urgent - the need for a short-term intervention to bring things under control and the the feasibility study for long-term management of the problems were undertaken. Nevertheless, despite the intense focus on the problem, a number of questions have remained unanswered. Throughout the period of min flooding, no detailed systematic monitoring of surface water flow has been undertaken, preventing the detailed apportionment of pollution between underground and surface sources. Ingress control measures have been proposed, but funding mechanisms, regulatory hurdles and challenges relating to long-term management have not all been comprehensively addressed. On a more positive note, the installation and operation of pumps to control the water level in the Western and Central Basins will start to provide valuable data regarding the response of the flooded mine workings to pumping, assisting in the characterisation of the hydraulic properties and behaviour of the large voids. This will facilitate the optimisation of pumping strategies and the refinement of environmental critical levels and assist in the development of more sustainable management options.
The National State of Water in South Africa - the Annual Reporting	Kwazikwakhe	Majola		2015
Abstract POSTER The Department of Water and Sanitation (DWS) is the custodian of South Africa's water and thus is imperative that it reports on its state as the National Water Act of 1998 requires regular reporting to Parliament by the Minister. Hence, the annual compilation of report entitled "The National State of Water in South Africa." This report aims to give an overview of the status and trends of water quality and quantity, further assisting with international water reporting obligations to SADC Region, African Continent, and Globally e.g. the United Nations Commission on Sustainable Development. This information empowers the public and provides knowledge to water managers for informed decision-making. The main purpose is to enhance quality, accessibility and relevance of data and information relating to the goal of Integrated Water Resource Management towards attaining holistic Integrated Water Management, and Integrated Water Cycle Management in future. Three distinct requirements for collecting data by DWS are: (i) assessing and comparing the status and trends for both quantity and quality; (ii) monitoring for water use and (iii) monitoring for compliance to licence conditions. Such information is further used to assess the effectiveness of policies implemented and identify the existing gaps. Various challenges to the country's water demand proper integrated water resources planning and management. The report is divided into Themes such as, Resource Management, Water Services/Delivery, Water Development and Finance, based on selected indicators. The indicators are strategically selected to provide a representative picture of the state, as well as the changes over time to the drivers, pressures, impacts and responses related to the chosen themes. These Indicators include: Climatic Conditions, Water Availability, Water Use, Water Protection, Water Quality, Water Service Delivery, Water Infrastructure, Water Finance, and Sanitation. The report for Hydrological Year 2013/2014 has been completed and it shows that the amount of water available varies greatly between different places and seasons, and from one year to another. The average total storage was around 85% of full supply capacity in September 2014. Surface water quality is generally facing a threat from eutrophication and microbial pollution emanating mainly from mismanaged water (and waste) treatment plants and related landuse activities. Groundwater quality is generally good except in some localised areas where mining and industrial activities are prevalent. With regards to infrastructure; vandalism, lack of maintenance & management skills reflect on/as non-revenue water, highlighting the need for more funding towards maintenance, especially in groundwater which is normally wrongly deemed as an unreliable resource. In the past 20 years, water services delivery to communities has improved as the Millennium Development Goals have been met and surpassed, while the sanitation access goals were likely to be met.
Unravelling the complex geohydrological structure of the Elandsfontein aquifer unit	Kezia	Smith	Western Cape	2015
Abstract The Elandsfontein aquifer is currently under investigation to assist with the management of the system and to ensure the protection of the associated Langebaan lagoon RAMSAR site. The Elandfontein aquifer unit is situated adjacent to the Langebaan Road aquifer in the Lower Berg River Region and is bounded by the Langebaan Lagoon, possible boundary towards Langebaan Road aquifer, the Groen River bedrock high and the Darling batholith. The study will investigate the boundaries and hydraulic characteristics of the different aquifers and aquitards (Elandsfontein clay layer) in the Elandsfontein unit and their relationship to the Langebaan Lagoon. A literature review and baseline study has been completed to determine groundwater flow patterns and the general distribution of water quality, using historic data to characterize the different aquifers and aquitards of the system. An initial conceptual model has been formulated based on this data. Pumping tests will be used to acquire hydraulic characteristics of the Elandsfontein aquifer where data gaps exist, together with water quality and stable isotope sampling. Future plans are to construct a groundwater numerical flow model of the Elandsfontein system to assist with the management of the complex relationships between the recharge areas, flow paths through the different aquifer layers and aquitards towards the Langebaan Lagoon discharge. Results will be presented using graphical methods such as time series graphs amongst the monitoring boreholes over the years, piper diagrams to show water type characterization (Na-Cl type water) and initial results from the groundwater flow model. The expected results are envisaged to advance knowledge on groundwater availability and quality to inform the decision about water resource protection and utilization. Therefore this study is designed to provide large-scale background information that will improve the knowledge and understanding of the Elandsfontein aquifer unit and provide a basis for potential future studies of a more-detailed nature.
The value (or not) of measuring redox potential in groundwater: A case study	Meris	Mills		2015
Abstract The redox state of groundwater is an important variable for determining the solubility and mobility of elements which can occur in different redox states at earth surface conditions, such as Fe, Mn, Cr, As, U, N, S, V etc. Eh-pH diagrams are potentially invaluable for understanding and predicting the behaviour of these redox species yet, unlike pH, redox is seldom a routine field parameter due to the difficulties in measurement and interpretation. This paper discusses the potential use and limitations of field measurements of the redox state of groundwater with specific reference to the geochemical behaviour of dissolved iron in the Table Mountain Group (TMG) aquifer. As part of an investigation into iron cycling within the TMG aquifer, the redox state of groundwater was estimated through three different methods, namely direct in-situ measurement of Eh, direct measurement of DO and calculation from iron speciation in groundwater. Comparison of the results from the three methods highlights the potential value of collecting redox data, but also the complexity of controls on redox potential. The redox measurements allowed the determination of the controlling reactions on iron mobility within the TMG, but only by using the iron speciation method to calibrate the in-situ values and thereby identify which redox pair was controlling redox equilibrium. As this requires measurement of redox ion pairs in solution, it is unlikely to become a routine method for redox assessment, unless the specific redox state of an element is critical in understanding its mobility. For the majority of groundwater site investigations, measurement of the dissolved oxygen content of groundwater is probably sufficient as a first pass.
Geohydrological update and numerical modelling of the Langebaan and Elandsfontein Aquifer Systems	Julian E	Conrad	Western Cape	2015	Elandsfontyn Aquifer System, Langebaan Road Aquifer Systemaquifer systems, numerical modelling
Abstract The Saldanha / Langebaan area is expanding at a significant rate, increasing the water demand for the area. The expansion comes from the industrial, residential and tourism sector. In addition there are economically viable deposits of silica and phosphate in the area. Ecosystem functioning in the area is also to a degree dependent on groundwater. All of these factors require an improved understanding of the geohydrology of the area. The geology of the area consists of basement Cape Granite and Malmesbury Group rocks that underlie the sediments of the Sandveld Group. The unconsolidated formations present, are (in order of oldest to youngest) as follows: - Elandsfontyn Formation (oldest): This formation overlies the bedrock in depressions and palaeo-channels in the bedrock. This formation is about 40 m thick and is composed of upward fining quartz sediments. - Varswater Formation: This formation is composed of marine deposits and is restricted to the western (seaward) parts of a bedrock depression to the east of the Langebaan Lagoon and Saldanha. The formation is characterized by rounded quartz grains. - Langebaan Formation: This formation consists of calc-arenites. The sediments are generally grey to cream coloured and consist of quartz and shell fragments, the grain size ranges from coarse to fine and the consolidation is variable. - Witzand Formation (youngest). This formation consists of light-coloured, calcareous, coastal dune sand that can be distinguished from the underlying consolidated Langebaan Formation. The Elandsfontyn Aquifer System (EAS) and the Langebaan Road Aquifer System (LRAS) are the main aquifer systems in the area. These aquifer systems are defined by palaeo-channels that have been filled with gravels of the Elandsfontyn Formation and represent preferred groundwater flow paths. Within each of these aquifer systems (EAS and LRAS) two aquifer units are present. Namely, the confined Lower Aquifer Unit (LAU) geologically consisting of the basal gravels of the Elandsfontyn Formation and the Upper Aquifer Unit (UAU) composed of consolidated sands and calcrete. The two units are separated by a clay aquitard. A numerical model has been established for the area, and extends from the Berg River to the Langebaan Lagoon. Granite outcrop and river system define the other boundaries of the model. Extensive logging of groundwater levels by the Department of Water and Sanitation (DWS) has enabled the accurate establishment of a model. In addition extensive field work and a detailed hydrocensus, as well as the capture of a lot of historical information has resulted in a comprehensive GIS which assists with the refinement of the numerical model. The model provides a valuable tool in modelling potential impacts whether they been from planned groundwater abstraction or artificial recharge. {List only- not presented}
Groundwater Monitoring During An Underground Coal Gasification Process	Johan	van Dyk		2015
Abstract Underground Coal Gasification (UCG) is an emerging, in-situ mining technology that has the advantage to access a low cost energy source that is currently classified as not technically or economically accessible by means of conventional mining methods. As such it offers significant potential to dramatically increase the world's non-recoverable coal resource. Groundwater monitoring in the South African mining industry for conventional coal mining as an example, is well established, with specific SANS, ASTM and ISO Standards dedicated for the specific environment, location and purposes. In South Africa a major impact of the coal mining industry can be a reduction in the groundwater quantity and quality. South-Africa's groundwater is a critical resource that provides environmental benefits and contributes to the well-being of the citizens and the economic growth. Groundwater supplies the drinking water needs of a large portion of the population; in some rural areas it represents the only source of water for domestic use. Utilization and implementation of groundwater monitoring programs are thus non-negotiable. The groundwater quality management mission, according to the Department of Water and Sanitation in South-Africa, is set in the context of the water resources mission and is as follows: "To manage groundwater quality in an integrated and sustainable manner within the context of the National Water Resource Strategy and thereby to provide an adequate level of protection to groundwater resources and secure the supply of water of acceptable quality." The scope of this paper is to propose an implemention strategy and a fit-for-purpose groundwater monitoring program for any Underground Coal Gasification commercial operation. It is thus important to pro-actively prevent or minimise potential impacts on groundwater through long-term protection and monitoring plans. A successful monitoring program is one that consists of (1) an adequate number of wells, located at planned and strategic points; (2) sufficient groundwater sampling schedules; and (3) a dedicated monitoring program and quality control standard. In order to have an efficient monitoring program and to prevent unnecessary analysis and costs, it is also critical to determine upfront what parameters have to be monitored for the specific process and site conditions.
Transport and Fate of chemical and microbial tracers at UWC campus site, Cape Flats aquifer of South Africa	Erin	Haricombe	Western Cape	2015	biological tracers, chemical tracers
Abstract Different biological and chemical transport results are evaluated in this study. Ecoli and PDR1 were selected as the biological tracers with salt and rhodamine as chemical tracers. The transport experiments were evaluated through the primary aquifer material found at the University of the Western Cape research site. A series of controlled experiments under laboratory and field conditions was conducted. Each provides a different kind of data and information. The results from laboratory studies could be used to better design the field studies. In both cases, the data collected was to provide information on fate and transport of microbes in groundwater. The field design phase of the experiment was an up-scaling of the laboratory phase of this project. The amount injected into the aquifer was increased in proportion to the size of the research site. Tracer tests using chemical and microbial tracers were carried out simultaneously. Results of laboratory tests show a 5 times slower transport of microbes, compared to salts.. The salts at field scale show a breakthrough occurring after 2 days whereas the microbes never managed to breakthrough with the experiment stopped after 45 days. A new borehole was drilled closer to reduce distance/ travel time, but this had no effect on field results for the microbes. {List only- not presented}
High Resolution Site Characterisation Assessment Of A Chlorinated Solvent Plume In A Shallow Unconfined Aquifer	Kate	Naude		2015
Abstract Identifying and characterising the vertical and horizontal extent of chlorinated volatile organic compound (CVOC) plumes can be a complex undertaking and subject to a high degree of uncertainty as dense non-aqueous phase liquid (DNAPL) movement in the subsurface is governed most notably by geologic heterogeneities. These heterogeneities influence hydraulic conductivity allowing for preferential flow in areas of higher conductivity and potential pooling or accumulation in areas of lower conductivity. This coupled with the density-induced sinking behaviour of DNAPL itself and the effects of groundwater recharge in the aquifer result in significant challenges in assessing the distribution and extent of CVOC plumes in the subsurface. It has been recognized that high resolution site characterization (HRSC) can provide the necessary level of information to allow for appropriate solutions to be implemented to mitigate the effects of subsurface contamination. Although the initial cost of HRSC is higher, the long-term costs can be substantially reduced and the remedial benefits far greater by obtaining a better understanding of the plume characteristics upfront. The authors will discuss a case study site in South Africa, where ERM has conducted HRSC of a CVOC plume to characterise the distribution of the source area and plume architecture in order to assess the potential risk to receptors on and off-site. The source of impact resulted from the use of a tetrachloroethene (PCE)-based solvent in an on-site workshop. The following methods of characterization were employed: - Conducting a passive soil gas survey to identify and characterise potential source zones and groundwater impacts; - Vertical characterisation of the hydrostratigraphy, contaminant distribution and speciation in real time using a Waterloo Advanced Profiling System (APS) with a mobile on-site laboratory; - Using the Waterloo APS data to design and install groundwater monitoring wells to delineate the vertical and lateral extent of contamination; and - Conducting a vapour intrusion investigation including sub-slab soil gas, indoor and outdoor air sampling to estimate current risk to on-site employees. In less than a year, the risk at the site is now largely understood and the strategies for mitigating the effects of the contamination can be targeted and optimised based on the information gained during the HRSC assessment.
Groundwater Resource Development targeting major fault zones In Banded Iron Formations (BIF) for Augmentation of the Vaal Gamaga	Frans	Wiegmans	Northern Cape	2015
Abstract The mineral rich Northern Cape Province produces 84% of South Africa's iron ore, while the Kalahari basin holds 92% of the world's high grade manganese deposits, with diamond and lime mining operations to a lesser degree. Mining expansion programs and new mines planned in the Northern Cape drive the region's economic development and growth strategy. The planned mining expansion depend on water being available for mining water needs and related increased demands for domestic water supplies. Current water supplies consist of local groundwater resources (boreholes and mine dewatering) and bulk water supply from the Vaal Gamagara (VGG) Pipeline Scheme. In 1992 the Kalahari East water supply pipeline was incorporated to supply domestic and stock water to an area of approximately 1.4 million ha. The VGG scheme consists of 370 km pipes, was built in the late sixties and is nearing its useful life expectancy. Increased water supply interruptions are being experienced while operating at capacity. The pipeline has the capacity to convey and import water of approximately 15 million m3/a into the D41J and D41K quaternary catchments. Water demand projections show an increase to 40.1 million m3/a in 2030. Various options were investigated to upgrade the VGG water supply scheme. One option considers groundwater resources to augment the water from the Vaal River from four indentified target areas (SD1 to SD4). Major fault zones in Banded Iron Formations (BIF) are targeted for groundwater resource development in the SD4 area, located east of Hotazel. This area is largely covered by Quaternary age sand and located near the endpoint of the VGG scheme and therefore prioritized as investigation area. The primary objective of the hydrogeological investigation was to identify the existence of exploitable resources for additional source development. Secondary objectives were to assess the contribution groundwater can make to augmenting pipeline water; providing a source to an area and thus diminish reliance on the pipeline; and providing an independent source, which could prevent the need for pipeline extensions. The paper will discuss the use of an airborne magnetic and Time Domain Electromagnetic's (TDEM) survey combined with gravity ground surveys as a key success factor in adding to the geological and structural information of the area. The paper will also present the results of exploration drilling (> 60 boreholes) over a large area and related borehole test pumping with water sampling to identify a sustainable and potable water supply of 2.5 million m3/a.
A fresh look at the National Water Balance	Andries	Wilke		2015
Abstract The national water balance is primarily based on the availability of surface water and the historic allocation thereof. The changes that are required the next 20 years to ensure sustainable development of the nation will be painful, but is unfortunately at present not part of the public discussion, it is essentially ignored in favour of more "popular water topics".This paper intends to look at a few core aspects, they include the current water allocation in the national water balance, the relative value of the utilisation, the position of groundwater resources in changing the current relative allocation and the current groundwater utilisation. The paper further intends to be a less formal presentation of these aspects with the required data, references and conclusions available for distribution afterwards.
Fluoride challenge in groundwater of the Ethiopian Rift Valley and adjacent highlands	Taddesse M	Bollollo	Ethiopia	2015	Fluoride
Abstract The urban and rural communities sources of water for domestic and other uses come from groundwater in most parts of Ethiopia. But the groundwater is not free from challenge. Fluoride is one of those critical problems which are affecting the health of inhabitants of this corridor. There are places where the fluoride contents reach more than 10mg/l. groundwater Treatment plants, changing the water scheme source from surface water and related efforts have been made so far to alleviation such challenges. Fluoride affects bones and teeth by changing its color and easily affected to a number of health complication in the rift valley of Ethiopia. {List only- not presented}
Hydraulic tests of strong artesian boreholes; wellhead construction and test design	Kornelius	Riemann		2015
Abstract Artesian boreholes are a common feature worldwide in confined aquifers, but the hydraulic testing of these boreholes, and estimation of aquifer properties from such tests, still poses a challenge for hydrogeologists. Common hydraulic tests, such as step-drawdown or constant-discharge rate tests require a static water level at the start of the test, and the measurement of drawdown (increasing over time) and abstraction rate (fixed for a period of time). Usually, when undertaking a pumping test in an artesian borehole, the drawdown is measured from ground level, and the drop in hydraulic head between static pressure and ground level is often ignored. This procedure also implies that the starting time of the test is not at the static water level. A constant-head test, set at ground level, is the other option. However, the decrease in flow rate is not only dependent on the hydraulic properties of the aquifer, but also masked by pipe hydraulic effects within the well. This kind of test would also limit the available drawdown to be utilized for the test. Hence, it was required to develop a method for undertaking hydraulic tests in strong artesian boreholes, allowing for the drawdown to fluctuate between levels both above and below ground and avoiding the pitfalls described above. The solution is a specially designed and constructed wellhead for the installation of the pump and monitoring equipment prior to the hydraulic test. The standard tests are slightly modified and are only undertaken after sealing the wellhead and reaching static hydraulic pressure. The recommended wellhead construction and subsequent hydraulic tests were implemented at a strong artesian borehole in the Blossoms Wellfield, south of Oudtshoorn in the Western Cape province of South Africa.
In situ iron removal: Innovative option for preventing production borehole clogging	Kate	Robey	Karoo	2015
Abstract Worldwide many aquifer systems are subject to hydrochemical and biogeochemical reactions involving iron which limit the sustainability of groundwater schemes. This mainly manifests itself in clogging of the screen and immediate aquifer with iron oxyhydroxides resulting in loss of production capacity of the borehole. Clogging is caused by chemical precipitation and biofouling processes which also manifests in South African wellfields such as the Atlantis and the Klein Karoo Rural Water Supply Scheme. Both wellfields have the potential to provide a sufficient, good quality water supply to rural communities, however clogging of the production boreholes has threatened the sustainability of the scheme as quality and quantity of water is affected. Repeated rehabilitation of the affected boreholes using techniques such as the Blended Chemical Heat Treatment (BCHT) method does not provide a long term solution. Such treatments are costly with varying restoration of original yields achieved and clogging recurs with time. Currently, the research, management and treatment options in South Africa have focused on the clogging processes which are complex and site specific making it extremely difficult to treat and rectify. This project attempts to eliminate the cause of the clogging which is elevated concentrations of dissolved iron. High iron concentrations in groundwater are associated with reducing conditions in the aquifer allowing for dissolution of iron from the aquifer matrix. These conditions can be natural- and/or human-induced. Attempts to circumvent iron clogging of boreholes have focussed on increasing the redox potential in the aquifer to prevent dissolution and facilitate fixation of the iron in the aquifer matrix. Various in situ treatment systems have been implemented successfully overseas for some time. However, in South African in situ treatment of iron has only been a theoretical approach. Based on experience from abroad the most viable option to research and apply elimination of ferrous iron in South African aquifer systems would be through the in situ iron removal treatment The objective of this paper is to set out the experience from abroad and to outline the initial results of this treatment. A pilot plant for testing the local applicability of this method was constructed at the Witzand wellfield of the Atlantis primary aquifer on the West coast of South Africa.
The North Lee County Reverse Osmosis Water Treatment Plant Injection Deep Injection Well Project	Hugh	Klein	Florida, USA	2015
Abstract The way in which groundwater is utilized and managed in South Africa is currently being reconsidered, and injection wells offer numerous possibilities for the storage, disposal and abstraction of the groundwater resource for municipalities, rural communities, mining, oil and gas, and a multitude of other industries. This presentation is about the North Lee County Reverse Osmosis Water Treatment Plant Injection Deep Injection Well project in southwest Florida in the United States. Water is plentiful in Florida, but it is not drinking water quality when it comes out of the ground. As such, treating water from wells is an important part of water supply in the coastal regions of the state. One form of treatment is reverse osmosis (RO), which generates a brine concentrate waste. The concentrate must then be disposed of, and a preferred method of disposal is an injection well because the disposal is not visible to the general public. The injection well project was associated with the construction of a large water treatment plant. The emphasis of this presentation is on the drilling and technical work in the field for this injection well, and to illustrate the rigorous requirements of drilling, constructing and testing a Class I injection well. Class I injection wells are permitted by the United States Environmental Protection Agency (US EPA) for injecting hazardous waste, industrial non-hazardous liquid, and/or municipal wastewater beneath the lowermost Underground Source of Drinking Water (USDW). Aquifer storage and recovery (ASR) wells are permitted as Class V injection wells by the US EPA. The permitting of an injection well is rigorous and requires state and federal approval before, during and after the field portion of the project. {List only- not presented}
Characterising surface water-groundwater interactions in the Vo?lvlei (Agulhas Plain), using a multi-disciplinary approach	Nabuweya	Noordien		2015
Abstract Coastal wetlands are complex hydrogeological systems in which groundwater have a significant influence on both its water balance and hydrochemistry. Differences in groundwater flow and groundwater chemistry associated with complex hydrogeologic settings have been shown to affect the diversity and composition of plant communities in wetland systems. A number of wetlands can be found across the flat terrain of the Agulhas Plain, of which the most notable is the Soetendalsvlei and the Vo?lvlei. Despite the ecological and social importance of the Vo?lvlei, the extent to which local, intermediate and regional groundwater flow systems influences the Vo?lvlei is poorly understood. The aim of this work is to characterize the spatial and temporal variations in surface water and groundwater interactions in order to demonstrate the influence of groundwater flow systems on the hydrology of the Vo?lvlei. The specific objectives of the study are; 1) to establish a geological framework of the lake sub-surface, 2) to determine the physical hydrological characteristics of the Vo?lvlei and 3) to determine the physical-chemical and isotopic characteristics of groundwater and surface water. Data collection will be done over the period of a year. Methods to be used will include the use of geophysical (electrical resistivity) to determine high water bearing areas surrounding the wetland, a drilling investigation (the installation of piezometers at 5-10m depths and boreholes at 30m depth, sediment analysis (grain size analysis, colour and texture), hydraulic (slug testing to determine hydraulic properties; hydraulic conductivity and transmissivity), hydrological (to estimate groundwater discharge; Darcy flux and hydraulic head difference between groundwater level and lake level), physical-chemical (electrical conductivity, temperature and pH) and stable environmental isotopic (oxygen and hydrogen) analysis of surface water and groundwater, to determine flow paths and identify processes. Thus far, results obtained for the geophysical survey has revealed that the sub-surface of this wetland system is highly variable. Three traverses were done on the South-Western, South-Eastern and Northern side of the wetland (See Figure 1). In VOEL1 (South west), the upper couple of meters show areas of very low resistivity, which is associated with clays, poor water quality and water which has high dissolved salts. The changing of medium to high resistivity values on the North-eastern side is usually indicative of weathered sandstone (Table Mountain Group). VOEL2 (South eastern), indicates that the subsurface is of low resistivity. These low values are the result of noticeable salt grains in the sand. VOEL3 (Northern), indicated upper layers of low resistivity, while the lower depth indicate areas of high resistivity. It is expected that the results of this study will provide a conceptual understanding of surface water-groundwater interactions and the processes which control these interactions, in order to facilitate the effective management and conservation of this unique lacustrine wetland.
Simulation of Underground Mine Flooding with EPANET and MODFLOW	Stephen	Fonkem	Free State	2015	mine shaft, flooding, modelling, MODFLOW
Abstract Underground mine water rebound prediction in its simplest form can be simulated linearly by comparing the volume of the mined ore with long-term average recharge rate to obtain an estimate of the time which will elapse before the workings are full to their decant elevation. This type of linear interpolation of rising water levels can lead to an over estimation or an underestimation of the date when mine voids will flood to the critical levels. This is due to the fact that this method cannot account for the variability and interconnection between different mine voids and also does not consider the change in storage over time which is an important factor. In an abandoned underground water environment, water is stored in flooded mine stopes (tanks) and flows through a network of haulages (pipes). Due to the dip and strike of the ore body, the mined stopes are extensively interconnected on multiple levels and bounded by faults and dykes, so that water rising within any one tank will display a common level throughout that tank. At certain elevations, adjoining tanks may be connected via a discrete "overflow point", which may be a holding or permeable geological features. Water level rise during flooding is a function of head-dependent inflows from adjoining mine aquifers and/or other tanks, and the distribution of storage capacity within the tank. The process of flooding occurs independently in two (or more) adjoining tanks until such time as the water level in one or more of the tanks reaches an overflow point. Inter-tank transfers of water will then occur until the difference in head between the two tanks either side of each overflow point is minimised. To apply the conceptual model stated above, EPANET 2 was used to predict the risk of flooding of a mine shaft, in the Free State Goldfields, if dewatering is discontinued. Considerations on stope volumetric calculations, haulage interconnections, modelling assumptions and predictions, are presented.
Decision making with web-based geo-spatial databases coupled to groundwater models	John	Wise		2015
Abstract Model calibration and scenario evaluations of 2D and 3D groundwater simulations are often computationally expensive due to dense meshes and the high number of iterations required before finding acceptable results. Furthermore, due to the diversity of modelling scenarios, a standardised presentation of modelling results to a general audience is complicated by different levels of technical expertise. Reducing computational time In this presentation we look briefly at the use of Reduced Order Models (ROM's), which is one of the recent developments in groundwater modelling. The method allows significant speed-up times in model calibration and scenario evaluation studies. In saturated flow for example, these approaches show speed-up times of >1000 when compared to full models created with Finite Element of Finite Difference methods. These methods are demonstrated to a case study in the Table Mountain Group, in which we show a simplified parameter calibration and scenario evaluation study. Standardising presentation In order to present the results to as wide an audience as possible, the use of a web-browser as a GUI is proposed, where the web-page is coupled to a geo-spatial database and data is presented in a spatial and numeric format. The use of the spatial database manager PostgreSQL with PostGIS is proposed. Through a browser interface, users can run modelling scenarios using the ROM, which is evaluated in near real-time. Following the evaluation of the model, we show how PostGIS can spatially present data on a base-map such as google maps. In keeping with the current trends in online map customisation, viewers can interactively choose to overlay the base-map with a data-type (such as pressure or hydraulic head contours or flow direction) that is most intuitive for their level of familiarity with the data. Conclusion In using advanced modelling techniques and a simplified browser based presentation of results, high-level decisions in water resource management can be significantly accelerated with the use of interactive scenario evaluations. Furthermore, by reaching a broader audience, public participation will be significantly enhanced.
Stampriet Transboundary Aquifer System	Kwazikwakhe	Majola		2015

Existing Springs in City of Cape Town and Environs: Spring Use Strategy	Louise	Soltau	Western Cape	2015
Abstract Cape Town... Home to over 3 and a half million people, the second most populated city in South Africa was born in the shadow of the Table Mountain. The mountain offered all the elements vital for human settlement... most importantly WATER. The reports of the abundance of fresh water and fertile land at the foot of the mountain and surrounds inspired the VOC to set up a refreshment station at the Cape. By the late-1800s, spring water was solely used for domestic supply to the settlers of Cape Town. Until the 1930s, the Stadsfontein or Main Spring was still being used as a source of drinking water but because of on-going concerns about the safety of the water for human consumption, and sufficient water being available from the new schemes like Steenbras and Wemmershoek, a decision was taken to discontinue using the Stadsfontein for drinking water purposes. Since then most of the water joined the stormwater to the sea, until 2010 when the City recommenced using the water for irrigation at Green Point Stadium and the Commons. City of Cape Town faces a number of water supply challenges. These include managing the ever increasing demands on the current water supply. The City of Cape Town Springs Study was born from this 2001 Water Demand Management study and it aims primarily to examine the possibility of using spring water as an alternative source of water for non-potable supply. Of these, the springs which hold the most potential for use are found in two areas - the CBD area of Oranjezicht, home to the Field of Springs
Groundwater Pollution Resulting From Environmental Impacts	Lwandisa	Fada	Western Cape	2015	Pollutants, Cape Flats aquifer, groundwater flow
Abstract POSTER Water resources are not just lakes, glaciers and polar ice caps and rivers; however one of the largest water resources is underground water well-known as Groundwater. Groundwater is one of the most important source of water as it the huge reservoir for freshwater. Groundwater can be defined as water existing underneath the earth surface in rock bodies known as aquifers. Approximately 140 communities in South Africa depend on groundwater as the source of water (Department of water affairs and forestry, 1998). Nevertheless groundwater is vulnerably to pollutants resulting from surrounding environmental effects which lead to poor groundwater quality. Numerous environmental effects have a huge impact in polluting groundwater such as pesticides, seawater encroachment, sewage effluent discharges to the ground and storage tanks underground; hence one need to identify, evaluate and come up with solutions on eradication of all these environmental effects that lead to groundwater pollution ( Hearth 1983). The objectives of the report will be based on minimizing the groundwater pollution at the source and to restore groundwater quality to extent that the beneficial users recognise its suitability. Inspection in University of the Western Cape (UWC) campus site and Rawsonville site will be conducted by BSc Environment and Water Science students of UWC in June using various tools in order to identify and monitor surrounding environmental effects towards groundwater pollution. UWC campus research site is located on top of the Cape Flats primary aquifer (unconfined sand aquifer); Cape Flat aquifer is overlain by an impermeable bedrock Malmesbury (shale) secondary fractured aquifer. Generally this borehole test will be based on testing on how the surrounding environmental impacts with various aquifer properties affect the groundwater quality or whether the surrounding environment interrupts the groundwater quality in Cape flats aquifer and Rawsonville site. The UWC campus site has low infiltration compared with Rawsonville site as it is surrounded by vegetation that plays role in trapping water from infiltrating therefore this aquifer is less likely to be contaminated by pollutants from the land surface, however with it being surrounded by residential areas and industries it is likely to be polluted. Rawsonville on the other hand is located in the grape farm which makes it easier for the site to be contaminated by fertilisers used for agricultural practice. The pumping test will further enable one in knowing the quantity of groundwater in UWC campus site and Rawsonville site thus extraction levels for municipal works, irrigation and so forth will be monitored in a correct manner (Department of water affairs and forestry, 1998). Finally groundwater models will be used to further investigation on the behaviour of groundwater systems.
Reliability of laboratory testing of groundwater samples	Venetia	Mitchell		2015
Abstract Resources required for groundwater sampling includes but not limited to pumping equipment, trained manpower and technical resources specific to the sampling function. Bearing these expenses in mind, choosing a laboratory for testing the water samples collected should be a carefully considered purchase. Choosing a testing facility that cannot deliver an efficient, reliable and technically sound service could render the sampling futile. Water samples submitted to a laboratory for testing are received from third party sources more than ninety percent (90%) of the time and sampling techniques and sample integrity cannot be verified by the laboratory. However, the validity, reliability and integrity of the laboratory testing are within the control of the testing facility. These aspects of a laboratory are usually controlled within a quality management system where established policies and procedures form the basis of such a system. This system maintains a foundation for technical competence and customer service at the laboratory. There are numerous testing facilities available to Consultants requiring chemical and microbiological groundwater testing, each with varying levels of integrity and technical ability. It is imperative to maintain confidence in the validity of results of analyses from a laboratory and this assurance can be understood through an examination of a facility's management system. An established quality management system would comprise a policy statement, associated technical methods and technical and administrative procedures. This system would be formally documented and audited as part of the on-going laboratory's management system. In some instances, laboratories formalise this into an accreditation of the laboratory to an international standard, such as ISO 17025:2005. The assurance that the results of analyses from any laboratory are of sound technical integrity would depend on factors such as - personnel training, - accommodation and environmental conditions under which the tests are carried out, - validation of the methodology applied (including the uncertainty of measurement), - the calibration and maintenance of the equipment used, - understanding the traceability of and measurement undertaken, - handling and preservation of the sample on receipt and while in the laboratory. Each of these factors plays a critical role in the integrity of results of analyses and should be interrogated when trying to understand the reliability and competence of the laboratory of choice.{List only- not presented}
Qualitative interpretation of groundwater flow distribution within the southern granite supersite of the Kruger National Park	Ashton	Van Niekerk	Mpumalanga	2015
Abstract Understanding the hydrogeology of fractured or crystalline rocks could be complicated because of its complex structure and a porosity that is almost exclusively secondary. These types of geologies are known to exhibit strong heterogeneities and irregularities contrasted in hydraulic properties, spacing and flow distribution within fractured rock aquifers. Therefore it is important to develop a conceptual model based on site specific data such as the hydraulic roles between groundwater and nearby hillslope/surface water bodies in order to understand its movement within the environment. Therefore this study intends to develop a hydrogeological conceptual model to qualitatively interpret the dominant groundwater flow processes at a 3rd order scale within southern granite supersite of the Kruger National Park (KNP). Key findings based on actual subsurface results in the form of Electrical Resistivity Tomography (ERT) surveys, borehole drilling logs, water levels and hydraulic data suggest that two aquifer types exist on the southern granite supersite namely, a weathered low resistivity of 3-75 ?m (average depth ranging 383-328 mamsl) and hard rock high resistivity of 1875-5484 ?m (average depth ranging 364-299 mamsl) granite/gneiss aquifer. The weathered aquifer flow system responds to localized processes such as piston recharge, indirect surface water recharge and groundwater water discharge via interflow. This was due to the relatively rapid response time of 2-3 weeks in groundwater levels to the major sequence of rainfall events over the hydrological year. The hard rock aquifer is part of a regional groundwater flow system. This is owed to the lengthy response time lags of 2-3 months in groundwater levels to the major sequences of rainfall events over the hydrological year. Due to the generally low transmissivity (ranging 9.50E-08 to 11.2 m2/day) values obtained during the borehole pump and slug tests and inclining trend of groundwater levels after the wet season, suggest these ephemeral hillslope landscapes are likely to act as hydraulic boundary areas. In that they contribute during the dry season to the regional hydraulic head generating baseflow to perennial streams. Therefore from a management perspective certain reaches within these ephemeral streams contribute to recharge which in turn should receive attention as many of the ephemeral stream sand are used for grading tourist gravel roads. Furthermore these granite ephemeral landscapes are characteristic of generally low transmissive aquifer properties and therefore should be given careful consideration before including it in a water supply scheme scenario.
Investigating the impact of fertilizer spills on groundwater quality	Jacobus Wilhelmus	Haumann		2015
Abstract A groundwater assessment was conducted to identify and predict the contamination and transport properties of a groundwater system. The motivation for the study was the rising concern of a farm owner about the deteriorating water quality of the aquifer system. An investigation of the surface and groundwater quality indicated that two fertilizer dumpsites were the sources of pollution. Water analyses revealed elevated concentrations of Ca, Mg, K, F, NO3, SO4, Mn and NH4 within boreholes near the pollution sources. The NH4 and NO3 concentrations were exceptionally high: 11 941 mg/L and 12 689 mg/L, respectively. These high concentrations were the direct result of the dumping of fertilizer. The rise in these concentrations may also have been catalysed by the nitrogen cycle and the presence of the Nitrosomonas bacterium species. Due to the high solubility of NO3, and because soils are largely unable to retain anions, NO3 may enter groundwater with ease, and could migrate over large distances from the source. Elevated NO3 in groundwater is a concern for drinking water because it can interfere with blood-oxygen levels in infants and cause methemoglobinemia (blue-baby syndrome). A geophysical study was undertaken within the area of investigation to gain insight on the underlying geological structures. The survey indicated preferential flow paths within the aquifer system along which rapid transport of contaminant is likely to occur. Key words: aquifer system, groundwater quality analyses, fertilizer, nitrogen cycle, Nitrosomonas species, geophysics.
Estimation of evapotranspiration from pine plantations in the Lake Sibayi catchment and its effect on groundwater and Lake level	Mokhadi	Nchabeleng	KwaZulu-Natal	2015
Abstract POSTER Pine plantations require large amount of water for transpirational demand and the amount of water depend on the area of plantation and the rooting depth of plants. The large amount of water required may result in disturbance of the natural water table equilibrium to meet the demand and insure growth. The lake Sibayi catchment area is covered by the 65 km2 freshwater lake sibaya, 70km2 of pine and eucalypts woody plantations and crops. The lake is recharged dominantly from groundwater and it is a water resource for local communities. A large extraction of groundwater by plantations will decrease the water table and the lake level and that will decrease the amount of water available for local residences. The main aquifer is composed of tertiary to quaternary age sediments which form a thin covering which blankets most of the Maputaland coastal plain and rests on a cretaceous system. Shallow marine and beach deposits of tertiary origin overly the cretaceous aged silt, while the quaternary age sediments which constitute most of the cover are predominantly of Aeolian origin. The Uloa formation of tertiary age is identified to be the most promising aquifer in the region consisting of coarse grained shelly sandstone with calcarenite associated with it. The aquifer is approximately 40m in depth and it is recharged dominantly from rainfall through infiltration. Rainfall averages 900mm per annum over the catchment but varies between 1200mm per annum in the south east and 700mm per annum in the west and evaporation equals to ? 1420 mm per annum (Pitman and Hutchinson, 1975). Lake Sibayi is a freshwater lake of 65km2, in surface area and it is a water resource for surrounding communities and other inhabitants. The sandy substrate surrounding Lake Sibayi limit the amount of surface runoff and consequently the water level within the lake are maintained by groundwater recharge. The growth of plantations is influenced by the ability of trees to extract soil water from the intermediate zone below the root zone and the capillary fringe. The water supply depends on the depth of the water table and on the structure of deposited soil layers and the water table depth is determined by the rate at which vegetation extracts water for transpiration and the recharge rate of groundwater. The specific yield of a soil determines the amount of water that percolates to recharge groundwater and because vegetation extracts water from layers of soils above the water table they decrease the amount of recharge for groundwater.
Estimation of Groundwater Recharge Response from Rainfall Events in a Semi-Arid Fractured Aquifer: Case study	Phathutshedzo	Nemaxwi		2015
Abstract Estimating groundwater recharge response from rainfall remains a major challenge especially in arid and semi-arid areas where recharge is difficult to quantify because of uncertainties of hydraulic parameters and lack of historical data. In this study, Chloride Mass Balance (CMB) method and Extended model for Aquifer Recharge and soil moisture Transport through unsaturated Hardrock (EARTH) model were used to estimate groundwater recharge rates. Groundwater chemistry data was acquired from the Department of Water and Sanitation (DWS) and Global Project Management consultants, while groundwater samples were collected to fill-in the identified gaps. These were sent to Council for Geoscience laboratory for geochemical analysis. Rainfall samples were also collected and sent for geochemical analysis. An average value of rainfall chloride concentration, average groundwater chloride concentration and mean annual precipitation (MAP) were used to estimate recharge rate at a regional scale. Local scale recharge was also calculated using chloride concentration at each borehole. The results were integrated in ArcGIS software to develop a recharge distribution map of the entire area. For EARTH model, long term rainfall and groundwater levels data were acquired from the South Africa Weather Services and DWS, respectively. Soil samples were collected at selected sites and analysed. These were used to determine representative values of specific yield to use on EARTH model. 60% of the groundwater levels data for 5 boreholes was used for model calibration while the remaining 40% was used for model validation. The model performance was evaluated using coefficient of determination (R2), correlation coefficient (R), Root Mean Square Error (RMSE) and Mean square error (MSE). Regional recharge rates of 12.1 mm/a (equivalent to 1.84% of 656 mm/a MAP) and 30.1 mm/a (equivalent to 4.6% MAP) were calculated using rainfall chloride concentrations of 0.36 and 0.9 mg/L, respectively. The estimated local recharge rates ranged from 0.9-30.2 mm/a (0.14 - 4.6%) and 2 - 75 mm/a (0.3 - 11.4%) using chloride concentration of 0.9 and 0.36 mg/L, respectively. The average recharge rate estimated using EARTH model is 6.12% of the MAP (40.1 mm/a). CMB results were found to fall within the same range with those obtained in other studies within the vicinity of the study area. The results of EARTH model and CMB method were comparable. The computed R2, R, RMSE and MSE ranged from 0.47-0.87, 0.68-0.94, 0.04-0.34, 0.16-3.16, and 0.50-0.79, 0.68-0.89, 0.07-0.68, 0.15-8.78 for calibration and validation, respectively. This showed reasonable and acceptable model performance. The study found that there is poor response of groundwater levels during rainy season which is likely to be due to lack of preferential flows between surface water and groundwater systems. This has resulted in poor relationship between estimated and observed groundwater levels during rainfall season. Key words: ArcGIS, CMB, EARTH, Groundwater recharge, rainfall
Modelling groundwater recharge in the Upper Vaal River Catchment.	Gaelene	Kramers	Gauteng	2015
Abstract At a regional scale, groundwater recharge is often calculated using surface water models. Precipitation and surface water runoff are easier to measure than groundwater recharge, and evapotranspiration can be estimated with relative accuracy using indirect methods. In modelling, surface water measurements can be used for calibration, and groundwater is the residual term in the water balance of the catchment. This can give a good indication of regional trends, but provides limited scope for the accommodation of groundwater system characteristics and recharge processes. Recently, much research has been focused on the interaction of surface and groundwater models. The coupling of physically based surface and ground water models allows for calibration of the model using both surface and groundwater data while providing scope for improved insight into the processes which define the interaction of groundwater with the rest of the water cycle. For example: stream discharge, interflow, preferential flow through the unsaturated zone and interaction with surface water retained in dams and wetlands. One such model is GSflow (United States Geological Survey), which we are applying to the Upper Vaal Catchment. This model integrates the surface water model PRMS (Precipitation-Runoff Modelling System) with MODFLOW (Modular Groundwater Flow model). The model is initially being calibrated at quaternary catchment scale, starting with the surface water components and later adding the groundwater system. The quaternary catchment is subdivided into smaller, topologically defined hydrological response units. This scaling allows for a better understanding of how well the characteristics of the units are represented in the physical processes incorporated into the model, so that ultimately the sensitivity analysis can incorporate these processes. The results will be compared to current work on recharge being carried out using GRACE data and previous work done in the same area. Once the entire model has been calibrated, there will be scope to calculate future scenarios, allowing for climate and land-use changes. A brief overview of existing work as well as methods and initial results and sensitivity analysis will be presented.
Where AMD meets Karst, and Humans theorise (speculate?) whilst Nature acts	Phil	Hobbs	Gauteng	2015	AMD
Abstract The karst aquifer downstream of the actively decanting West Rand Gold Field (a.k.a. the Western Basin) has for decades been receiving mine water discharge. Evidence of a mine water impact in the Bloubank Spruit catchment can be traced back to the early-1980s, and is attributed to the pumping out of so-called "fissure water" encountered during active underground mining operations for discharge on surface. Rewatering of the mine void following the cessation of subsurface mining activities in the late-1990s resulted in mine water decant in 2002. The last five hydrological years (2009?'10 to 2013?'14) have experienced the greatest volume and worst quality of mine water discharge in the 45-year flow and quality monitoring record (since 1979?'80) of the Bloubank Spruit system, causing widespread alarm and concern for the receiving karst environment. The focus of this attention is the Cradle of Humankind World Heritage Site, with earlier speculation fuelled by an initial dearth of information and poor understanding of the dynamics that inform the interaction of surface and subsurface waters in this hydrosystem. Oblivious to these circumstances, the natural hydrosystem provides an invaluable beneficial function in mitigating adverse impacts on the water resources environment at no cost to society. The hydrologic and hydrogeologic framework that informs this natural benefaction is described in quantitative physical and chemical terms that define the interaction of allogenic and autogenic water sources in a subregional context before highlighting the regional benefit. The subregional context is represented by the Bloubank Spruit catchment, a western tributary of the Crocodile River, which receives both mine water and municipal wastewater effluent and therefore bears the brunt of poor quality allogenic water inputs. The regional context is represented by the Hartbeespoort Dam catchment, which includes major drainages such as the Crocodile River to the south and its eastern tributaries the Jukskei and Hennops rivers, and the Magalies River and its southern tributary the Skeerpoort River to the west. Each of these drainages contribute to the quantity and quality of water impounded in the dam, and an analysis of their respective contributions therefore provides an informative measure of the temporal mine water impact in a regional context. The result indicates that amongst other metrics, the total dissolved solids (TDS) load delivered by the Bloubank Spruit system in the last five hydrological years amounted to 11% of the total TDS load delivered to Hartbeespoort Dam in this period, ranking third behind the Jukskei River (49%) and the Hennops River (30%), and followed by the Magalies River (5%), Crocodile River (4%) and Skeerpoort River (1%). By comparison, the long-term record reflects changes only in the contributions of the impacted Bloubank Spruit (10%) and pristine Skeerpoort River (2%). The difference is attributed mainly to the intervention of Mother Nature.
An Analysis Of The Challenges For Groundwater Governance During Unconventional Gas Development In South Africa	Kevin C	Pietersen	National	2015	groundwater governance, Unconventional gas
Abstract The groundwater governance arrangements for the development of groundwater resources were analysed. The analysis highlighted gaps and barriers to overcome before unconventional gas (shale gas and coal bed methane) development can take place at an industrial scale. The following governance challenges were identified (i) setting baseline measurements to detect groundwater pollution and to determine resource status; (ii) review of licenses and setting conditions for the development of unconventional resources; (iii) compliance monitoring and enforcement systems in place (iv) dealing punitively with non-compliant operators (v) mitigation options in place to prevent groundwater pollution; (vi) goal-based regulatory framework in place rather than a prescriptive regulatory framework; (vii) disclosure of hydraulic injection fluid; (viii) coordination with other government departments and regulatory bodies; (ix) a framework for subsidiarity and support to local water management; and (x) an incentive framework that support good groundwater management. To overcome the challenges requires a decentralized, polycentric, bottom-up approach, involving multiple institutions to deal with unconventional gas development. This provides better conditions both for cooperation to thrive and for ensuring the maintenance of such institutions.
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.
Is potato cultivation negatively impacting the groundwater resources of the Sandveld, Western Cape?	Julian E	Conrad	Western Cape	2015	groundwater monitoring
Abstract Groundwater is used extensively in the Sandveld for the irrigation of potatoes. The groundwater resources are plentiful and of good enough quality for the production of potatoes, however there has been a significant increase in potato production especially from the period 1975 to 2008. The area planted has increased from 2 369 Ha to 6 715 Ha in this period. The rate of increase has reduced significantly since 2008 and is now quite consistent at approximately 6 800 ha/a. In the region groundwater is vital for the proper functioning of ecosystems and it is also the sole source of water for five towns in the area and supplies most of the domestic water for the farms in the area. Thus the abstraction of groundwater for agriculture needs to be carefully assessed to ensure impacts on other systems and users do not occur. For this reason Potatoes South Africa has taken the responsible approach of investing in the on-going monitoring of groundwater levels (quantity) and groundwater quality in the Sandveld. PSA appointed the groundwater consultancy, GEOSS to do this monitoring and they have continually committed to this monitoring for the past 10 years. The long term monitoring data has been very valuable in that it shows groundwater trends and the spatial distribution of the measured parameters. Regarding the trends it is clear that certain areas are being over-abstracted and groundwater levels are dropping. In the more critical areas, intervention has occurred - boreholes were closed down and the points of abstraction distributed over a much wider area. This region (Lower Langvlei River) is showing clear signs of recovery both in terms of groundwater levels and quality. The other localized areas where negative trends are evident the land owners have been informed and are aware of the problems. In some critical areas continuous groundwater level loggers have been installed to monitor trends. The long-term groundwater monitoring, has helped significantly in addressing the negative perception about the widespread impact on groundwater resources due to potato cultivation in the Sandveld. It is important the monitoring continues and regular feedback provided to land owners. The monitoring that the local municipality and the Department of Water Affairs do also needs to be integrated into a single database. It is evident that the initial abstraction of groundwater in the pioneer days of potato cultivation did impact groundwater resources and associated ecosystems in the Sandveld, however currently as the rate of expansion has reduced and stabilized, the groundwater resources closely mimic rainfall patterns and the areas that are being impact are localized, well known and being addressed.
A Systematic Approach To The Interpretation Of Conductivity Anomalies Across Intrusive Dolerite Dykes And Sills In The Karoo	Dakalo	Makhokha	Karoo	2015
Abstract South Africa is a semi-arid country. Its average rainfall of roughly 464 mm/a is much lower than the world average of 860 mm/a. Due to a shortage of surface water, groundwater plays an important role in the water supply to domestic, industrial, agricultural and mining users. Groundwater exploration has become increasingly dependent on the use of geophysical techniques to gain insight into the subsurface conditions to minimise the risk of drilling unsuccessful production boreholes. Dolerite dykes and sills are often targeted during groundwater exploration programmes in Karoo rocks. Due to the high pressures and temperatures that reigned during the emplacement of these structures, the sedimentary host rocks along the margins of the intrusive structures are typically strongly altered. These altered zones are often heavily fractured and, as a result, have increased hydraulic conductivities as compared to the unaltered host rock. The altered zones often act as preferential pathways for groundwater migration, making them preferred targets during groundwater exploration. In conjunction with magnetic methods, electromagnetic (EM) methods are the techniques most often used for groundwater exploration in Karoo rocks. In South Africa, the ground EM system most commonly used is the Geonics EM34-3 frequency-domain system. This system has already been in use for a few decades, yet a great deal of uncertainty still remains regarding the interpretation of anomalies recorded over geological structures associated with lateral changes in electrical conductivity. This uncertainty results from the fact that the Geonics EM34-3 system employs measurements of the out-of-phase components of the secondary magnetic field relative to the primary magnetic field to calculate an apparent conductivity for the subsurface. The apparent conductivity profiles across lateral changes in conductivity often do not make intuitive sense. This project focuses on the development of guidelines for the interpretation of anomalies recorded with the EM34-3 system across intrusive structures of geohydrological significance in Karoo rocks. Geophysical surveys were conducted across known dykes and sills in an attempt to systematically investigate the responses recorded across these structures. Data from magnetic and two-dimensional electrical resistivity tomography surveys, as well as from geological borehole logs in some cases, were used as controls to assist in the interpretation.
A Baseline Study of Scarce Groundwater Resources in Anticipation of Fracking in the Karoo	Divan	Stroebel	Eastern Cape, Karoo	2015	Shale gas, Fracking, sampling
Abstract The anticipated exploration and exploitation of Shale Gas in the Eastern Cape Karoo through hydraulic fracturing has raised considerable debate regarding the benefits and risks associated with this process for both the Karoo, and the country as a whole. Major concerns include the potential impact of hydraulic fracturing on ecological, environmental and especially scarce water resources. The Eastern Cape Karoo region is a water stressed area and with further climate change it will become increasingly so. Thus, effective and reliable groundwater management is crucial for sustainable development in this region. This research aims to hydrochemically characterise both the shallow groundwater (<500m) and deeper saline groundwater in the vicinity of the Shale Gas bearing formations, based on major and trace elements, as well as gas isotope analyses. Sampling will include water sampling and gas measurements from shallow boreholes (<300m), SOEKOR drillholes (oil exploration holes drilled in the 60's and 70's up to 4km deep) and thermal springs (source of water >500m). To-date, a desktop study includes the collation of information determining the areas with the highest potential for Shale Gas Exploration throughout the Eastern Cape Karoo, from which the research area has been determined. This includes the identification of the respective oil companies' exploration precincts. A Hydrocensus has been initiated across this area, which includes slug testing and electrical conductivity profiling of open, unequipped boreholes. Further borehole selection will be finalised from this acquired information. The boreholes will be sampled and analysed a minimum of three times per year, which will occur after summer (April/May) and winter (October/November), after which the hydrochemistry will be analysed. The sampling will be preceded by purging of all inactive boreholes. The possible hydraulic connectivity between the shallow and deep aquifers will be tested, particularly in those areas where dolerite intrusions as well as fault systems may enhance preferential flow of water, using the chemical forensics complemented with passive seismic profiling/imaging and deep penetrating Magneto-Telluric (MT) imaging. The data collected will form a record against which the impact of fracking can be accurately determined. The research is a critical first step towards the successful governance of groundwater in light of the proposed Shale Gas development. In its absence, effective regulation of the sector will not be possible.