Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

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Abstract

In 2009 it was announced that South Africa and Australia would be in competition for the race of the Square Kilometre Array (SKA). In 2009 the MeerKAT project was started in the Karoo near the core site of the SKA, which set out to demonstrate that South Africa was able to build the infrastructure of the SKA. The SKA required water for the building of roads, the dishes and the foundations of the dishes at the MeerKAT site. This poster explains the groundwater monitoring that is being performed at the MeerKAT site from 2011 till present in order to illustrate how good monitoring and management of groundwater can ensure sustainable groundwater use at sites like these. {List only- not presented}

Abstract

Because the quality of groundwater is influenced by the host rock through which it moves, it differs on a site-specific basis, and is often naturally brackish or even potentially harmful to people. In spite of this, many practitioners incorrectly use the SANS 241 Drinking Water Standard as “compliance requirement” to compare groundwater quality against. This standard only applies to water that has been purified to be suitable for potable purposes at a water treatment works in terms of regulations made under the Water Services Act 108 of 1997. The only circumstance in which it could be used to compare the quality of natural groundwaters against, is where such groundwater is (to be) used, for potable purposes (with or without treatment), and then only to provide guidance on the level of treatment required to facilitate suitability for such domestic use, and not to determine possible ‘unacceptable’ levels of contamination. Therefore, the comparison of groundwater quality results against the SANS 241 Drinking Water Standard is not only a scientifically flawed practice, it has no basis in law. It is furthermore a scientifically flawed practice to refer to groundwater quality as ‘good’, ‘bad’, or ‘poor’, as it reflects a judgemental anthropocentric perspective that has no place in modern discussions on judicious environmental management and monitoring.

 This then raises the question, what are, or should the limit values be against which groundwater quality results should be compared to determine if it has been negatively affected by anthropogenic activity to such an extent that a scientifically substantiated claim can be made that the groundwater has been ‘polluted’, an allegation with criminal liability implications?

This paper aims to answer this question in the context of South African Framework law and policy, and propose a methodology to determine appropriate site-specific limit values for groundwater quality.

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}

Abstract

For a long time, professionals regarded social media as a superficial, unprofessional platform where internet users would submerge themselves in a virtual world, detached from real-life issues. Slowly, the myths and stigmas surrounding the use of social media has faded as more and more professionals and scientists have realized that these social platforms could be positively exploited in a professional manner which could be beneficial. In a digital age where information at our fingertips is the norm, professionals should co-evolve and ensure that their work is just as accessible and appealing, without the unnecessary jargon. Currently, science is mostly restricted to a very particular audience and conveyed in one direction only. Using a social media platform such as Twitter-which limits messages to only 140 characters-challenges scientists to convey their work in a very concise manner using simpler terminology. Furthermore, it dismisses the usual one-way form of communication by opening dialogue with fellow Twitter users. At conferences, Twitter can serve as a useful tool for active engagement which will not only "break the ice" between delegates but also ensure that important information is communicated to a much wider audience than only those in attendance. This idea was tested at the 2014 Savanna Science Network Meeting held in Skukuza, Kruger National Park, where the hashtag #SSNM was used. More than 63% of the Twitter users who participated in the #SSNM hashtag were actually not present at the conference. These external "delegates" were interested individuals from five different continents and in different professions besides Science. This highlights how social media can be exploited at conferences to ensure that key messages are conveyed beyond the immediate audience at the event.

Abstract

South Africa is a country at the forefront of the solar energy revolution. Each solar energy plant implementation results in further supply of clean renewable energy to the South African electric grid, thus playing a part in helping South Africa meet its renewable energy targets, in addition to stimulating long-term economic development and creating new jobs. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Particular focus has recently been on the use of concentrated solar power technology which is better able to address the issues of scalability and electric storage. The process includes the use of a liquid salt solution and also requires a reliable water source. When applying for a new solar energy plant, a geohydrological assessment is required to inform the Environmental Impact Assessment. SolarReserve South Africa (Pty) Ltd responsibly take this one step further by requesting detailed geohydrological assessments including drilling and field testing, numerical modelling and simulations, and detailed impact analysis. Of particular consideration in these assessments is the potential for groundwater to meet the plants water needs, as well as the assessment of risk and potential groundwater contamination impact from failure in the lining of the evaporation ponds. This paper describes the 'best practice' approach that has been formulated and undertaken for some previously proposed sites, and is now recommended for future use in the groundwater impact assessment of future proposed solar energy plants in South Africa. It makes use of a SolarReserve case study example, located at the farm Kalkaar near Jacobsdal in the Free State Province, to explain the main steps in the process and how the results of using this approach are important inputs in the assessment of impacts, decision-making regarding go/no-go, technology used, infrastructure and site layout, and responsible management and monitoring of the groundwater in the future.

Abstract

As part of supporting the National Development Plan (NDP) vision 2030, Council for Geoscience has been tasked by the Department of Mineral Resources to embark on an integrated and multidisciplinary geoscience mapping programme to systematically map South Africa in a more detail manner. With the idea of groundwater resource development and preservation purposes, a 1:100 000 geohydrological map, explanatory booklet, geohydrological data base for all data obtained from various sources and an ISO document was produced. The map is situated in the middle reach of Kuruman River and covers an area of 2750 km2. Mapping process commenced by sorting existing geological and hydrogeological data sourced from the Council for Geoscience database, Department of Water and Sanitation, Department of Agriculture and Kuruman municipalities. The process also includes filling identified gaps through extensive hydrocensus which entailed site surveying, hydrocensus, measuring and groundwater sampling, determination and demarcating of groundwater units, legend standardization and GIS cartography. Different aquifer types were categorised by analysing factors which control groundwater occurrence in the area; these factors includes lithostratigraphy, groundwater quantity, geological and linear structures. These were later used as datasets in Arc GIS for map processing. Before being used to determine aquifer media and geohydrological boundary conditions, these factors were closely studied through different approaches by interpreting geological and remotely-sensed data, field verification and survey of historical information. Four aquifer types were identified, namely; Intergranular aquifer covering an area of 152.9 km2; Intergranular and fractured aquifer which covers 696.4 km2 area; Fractured aquifer which covers an approximate area of 408.5 km2 and Fractured karst aquifer with a total size of 1486.1 km2. The insert groundwater quality map show completely unfit water (Class 4) for use in the central and south-eastern side of the map. Electrical conductivity in most parts of the map fall within recommended operational limit.

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.

Abstract

Amongst groundwater users, the importance of a scientific borehole yield test is often highly underrated. From experience, a vast number of groundwater users make use of a method of yield testing known as the ‘farmer test’ or even just the air lift yield obtained when the borehole is drilled. In many cases, a scientific yield test is only conducted so that the borehole can be licensed with the Department of Water and Sanitation. A recent yield test undertaken near Stellenbosch demonstrated the importance of a scientific yield test, and the short comings associated with the “farmer method”. The case study pertains to a borehole where the air lift yield was much higher than expected for the area. The borehole was drilled into a high transmissivity aquifer of limited extent. As such, the yield testing was able to quite quickly detect and demonstrate impacts from aquifer boundary conditions. The case study demonstrates the need for hydrogeological conceptualization of the aquifer and flexibility in designing and modifying the yield test. The safe yield potential of this borehole was reduced from an expected 15 L/second to 0.5 L/second. Aquifer boundary conditions occur at most boreholes to some degree, and this case provides a demonstration of the effect on yield testing.

Abstract

The North West Province has produced a large portion of South Africa’s inland alluvial diamonds. Kimberlite intrusions are typically the parent source for the alluvial diamonds. Diamondiferous kimberlite intrusions were eroded over time by surface run-off and streams which transport the diamondiferous sediments downstream to depositional regimes. The diamondiferous alluvial deposits around Schweizer- Reneke were mostly deposited on magmatic rock of the Ventersdorp Supergroup. Formal alluvial mining in the area often requires a considerable amount of overburden material to be removed in order to access the coarser gravel beds which contain the economic grade diamonds. Diamond production from secondary sources in this region totalled approximately 14.4 million carats up to 1984, and small scale production persists today.

The case study focuses on the impacts of alluvial diamond mining operations on surface- and groundwater resources in the North West Province, South Africa. To recover diamonds from the sediments, the industry is currently focussing on using modern processing methods and a more clinical approach to increase the sustainability of mining, therefore minimizing the impact on the environment. Wastewater from the screening and the fines management phase is delivered to the primary water treatment phase where up to 70% of process water is recirculated to the processing plant, minimising the volumes of fresh water required. The settled sludge or waste is deposited on a tailings storage facility. Alluvial diamond mining operations, unlike many other industrial processes and types of mining, have a lower environmental hazardous risk associated with waste material, however, it is a possibility that leachate emanating from tailings often have a high salt content. The process raw water to these operations are supplied from both surface- and groundwater sources from the local area. Supplying processing raw water in a sustainable manner is often a challenge in drought stricken areas with limited surface flow and low aquifer potential.

Abstract

Climate change contributes to the way in which people live. Natural resources such as groundwater, wood and surface water form a great part of livelihood in rural communities and are used extensively in rural areas where basic services have not yet been provided. The effect of climate change to all these natural resource may impact the lives of those in rural communities. Climate change is already starting to affect some of the poor and most vulnerable communities around the world. The aim of the dissertation is to develop a framework to assess the vulnerability of rural communities to climate change, with a specific focus groundwater and issues relating to gender. A questionnaire and interviews were used to collect data about rural communities' level of awareness climate change, their attitudes toward coping with climate change impact, level of education, income scale and how does this affect their security. Hyrodocensus was taken around the village to determine the rivers, dams, boreholes, abandoned boreholes and wells. Water samples were collected and analysed. The response rate was higher in females than in male's stakeholders (54% vs 46%).the results show that woman were mostly doing the hard work to complete daily basic activities. Education was found to be of high school level and incomes were low. The framework was developed with basic need showed that the area was at risk of poverty .Boreholes was found and water quality was analysed to be adequate for drinking water purpose. More information will be discussed on presentation.

Abstract

The past few years hydraulic fracturing has been a hotly researched topic. Currently, most published documents are just speculation of what can happen if hydraulic fracturing is to take place in South Africa. There is very little work done to firstly establish a baseline on the current groundwater quality and secondly look at the current state of the groundwater around the Soekor wells. For these reasons a geochemical investigation was launched looking at the Soekor wells and the surrounding boreholes to determine a valid baseline.

Looking at the two Soekor wells; geochemical analyses was conducted on water, soil and rocks. The drill core of the wells; soils from the waste ponds and water at or nearby the wells were sampled and analysed. By making use of XRF; XRD, Stable Isotopes and water chemistry analyses, a better picture of these wells and groundwater can be developed to give better guidelines to what should happen during the monitoring of hydraulic fracturing wells.

Abstract

Groundwater in the South Western Karoo is of critical importance in the overall freshwater supply. However groundwater sustainability is vulnerable to natural as well as anthropogenic influence. Groundwater monitoring scheme are employed to provide the necessary information during decision making situations. Groundwater monitoring thus performs in important role in groundwater management and protection. Interest in exploiting potentially vast reserves of shale gas in the deep geological formations in the region, has been met with concerns that can negatively impact the groundwater system. The current monitoring network is not adequately designed to capture the necessary level of information. Hence in this paper a revised monitoring network is designed. A novel geostatistical hydrogeological approach is applied to a case study area in the South Western Karoo. Kriging methods are used to determine required density of the new network using the spatial autocorrelation of water levels in the case study area. Using the spatial autocorrelation range a hexagonal sampling grid is developed. Using key hydrogeological features, such as contaminant pathways and zones of favourable water resources monitoring points are systematically positioned within the sampling grid. Using thus approach the current monitoring network is expanded from 34 points to a total of 95 monitoring points. The new network shows an increase in optimization by lower overall kriging prediction standard error than the current network. This allows more efficient monitoring of baseline conditions and detection monitoring.

Abstract

It has been shown over many years that the efficient management of water resources is almost impossible without a database containing historical and up-to-date information and data of high integrity. When it comes to groundwater the situation is even worse as groundwater was often not seen as a viable resource, and if it was used, then in many cases, it was poorly managed due to the lack of monitoring and poor data collection. This has changed in recent years as groundwater now forms a large part of the used water resources in several communities, towns and metros. Therefore, the need for properly managed groundwater data has increased tremendously, leading to urgent requirements for a water database in whatever form. Unfortunately off-the-shelf groundwater databases relevant to the South African market did not really exist for many years, while international packages are expensive and need a lot of adaptation to work for South African conditions. Therefore, most groundwater practitioners used various forms of database software and/or spreadsheets without much integrity leading to data hosted on various computers around South Africa, but not one central system available to be accessed by groundwater managers, scientists or even the public. The Water Research Commission therefore Initiated a research project for the "Development of an integrated Groundwater Database and visualisation tools for the City of Cape Town and Environs", a system that should be so versatile that it could also be applied in other metros, provincial or national offices. This research project will have a huge impact on water resources decision making for the City of Cape Town, as the recent drought has put the City water managers under immense pressure, which was increased by the need to start using more and more groundwater resources, especially for critical City and province institutions like hospitals, clinics and care centres around the Western Cape. The outcome of the project is a "complete" groundwater resources database with links to surface water and meteorological stations and a number of visualisation tools, including an online web-based mapping tool, which is fed by live data from the database and may be used even by the public for groundwater education purposes.

Abstract

POSTER All groundwater is vulnerable to contamination, and natural in homogeneity in the physical environment results in certain areas being more vulnerable to contamination than others. Inherent in the agricultural, domestic and industrial sectors of Pietermaritzburg, is the generation of contaminants which, upon reaching the aquifer, result in the deterioration of the quality of groundwater, thus resulting in the water no longer being fit for its intended use. The DRASTIC method is used to calculate the groundwater vulnerability of a 670 km2 region, including the city of Pietermaritzburg. The suggested ratings of each parameter are scrutinised and adapted, according to their relevance to the region and according to known geological occurrences. The use of this method enables the user to generate a regional scale vulnerability map of the groundwater in Pietermaritzburg. The vulnerability map generated has the ability to effectively highlight vulnerable areas to groundwater contamination, which is of critical importance in correct land-use planning, as well as in indicating areas of particular concern, where further detailed investigations are needed. The results of such an assessment are used as an input, together with a contamination inventory to assess the potential risk of groundwater pollution in a groundwater risk map. Furthermore, the result informs local decision-makers and enables proactive prevention of groundwater pollution, in accordance with section 13 of the 1998 National Water Act. The intrinsic vulnerability of the Pietermaritzburg region was found to range from low to very high. The area found to be highly vulnerable is the region northeast of Springbank which requires investigation at a local scale.

Abstract

POSTER Water is an invaluable resource without which life would cease to exist. Supply in South Africa has become limited due to increases in demand brought upon by population growth, urbanisation and industrialisation. In Southern Africa, water systems are considerably degraded by mining, industry, urbanisation and agricultural activity and a large amount of the fresh surface water has already been utilised. The stresses on this resource will unlikely make the current usage sustainable in years to come. In order to provide for basic needs for the future, groundwater as a resource will have to play a major role. It is for this reason that groundwater integrity needs to be preserved. 

Hydrocarbon contamination is a huge threat to groundwater as it contains toxic substances that are insoluble in water. These toxins are carcinogenic and mutagenic, and have a major impact on human health and ecosystem stability. When spilled, hydrocarbons will move downward through the unsaturated zone under the influence of gravity and capillary forces, trapping small amounts in the pore spaces. Accumulation will result in added weight along the water table, forcing the entire surface to be displaced downward. Some of the components can dissolve in the groundwater and move as a plume of contaminated water by diffusion and advection within the saturated zone. The transport of contaminants from petroleum hydrocarbon spills needs to be described in terms of a multiphase flow system in the unsaturated zone, taking into account contaminant movement in each of the three phases: air, water and free light non-aqueous phase liquid. Petroleum hydrocarbon behaviour in the subsurface is additionally complicated by the presence of multiple compounds, each with different properties. The net result is that some hydrocarbon fractions are transported faster than others and a contamination plume of varying intensity may spread over a large area.

The aim of this study is to develop a methodology to map and simulate the movement of groundwater that has been contaminated by hydrocarbons and to determine the fate of the water quality through decomposition. Associated remediation options will be determined thereafter.

Abstract

Water scarcity is a global challenge, particular in South Africa, which is a semi-arid country. Due to the continuing drought, appropriate groundwater management is of great importance. The use of groundwater has increased significantly over the years and has become a much more prominent augmentation component to the supply chain especially in rural communities. However, the approach used to develop groundwater resources, specifically in rural areas, can be improved in numinous ways to ensure drilling of successful boreholes that could meet water demands. A recent study done in the Thaba Nchu area focused on an adapted approach, which resulted in drilling successful boreholes that would be able to sustain their augmentation role in the long term. The adapted approach involves (i) a hydro-census that includes local knowledge and focused field observations, (ii) study of aerial photographs and geological maps on a regional scale, rather than on a village scale area, (iii) an optimised geophysical investigation to identify and map geological structures to drill production boreholes, (iv) conducting aquifer pump test to determine an optimum sustainable yield, (v) collecting water samples to determine if water quality is suitable for its specific use (vi) providing a monitoring program and abstraction schedule for each borehole. The adapted approach highlights the following improvements: (i) drilling of new production boreholes during times of bounty to allow for better time management on the project; (ii) including an experienced geohydrologist during planning phases, (iii) including a social component focussing on educating local communities on the importance of groundwater and introducing them to the concept of citizen's science, (iv) establishing a communication channel through which villagers can report any mechanical, electrical, quantity or quality issues for timeous intervention. Through applying these small changes to established components of development of groundwater resources, budgets and time management were optimised and additional communities could be added to the project without additional costs. This approach not only emphasised ways to improve the awareness and potential of groundwater resources, but also affects the economical-, social- and environmental welfare in rural communities.

Abstract

An understanding of the movement of moisture fluxes in the unsaturated zone of waste disposal sites play a critical role in terms of potential groundwater contamination. Increasing attention is being given to the unsaturated or vadose zone where much of the subsurface contamination originates, passes through, or can be eliminated before it contaminates surface and subsurface water resources. As the transport of contaminants is closely linked with the water flux through the unsaturated zone,  any quantitative analysis of contaminant transport must first evaluate water fluxes into and through this region. Mathematical models have often been used as critical tools for the optimal quantification of site-specific subsurface water flow and solute transport processes so as to  enable  the  implementation of management practices that minimize  both surface water  and groundwater pollution. For instance, numerical models have been used in the simulation of water and solute movement in the subsurface for a variety of applications, including the characterisation of unsaturated zone solute transport in waste disposal sites and landfills. In this study, HYDRUS 2D numerical simulation was used to simulate water and salt movement in the unsaturated zone at a dry coal ash disposal site in Mpumalanga, South Africa. The main objective of this work was to determine the flux dynamics within the unsaturated zone of the coal ash medium, so as to develop a conceptual model  that  explains  solute  transport through  the unsaturated  zone  of the coal ash medium for a period of approximately 10 year intervals. Field experiments were carried out to determine the model input parameters and the initial conditions, through the determination of average moisture content, average bulk density and the saturated hydraulic conductivity of the medium. A two-dimensional finite-element mesh of 100 m × 45 m model was used to represent cross  section  of  the  ash  dump.  Two-dimensional  time  lapse  models  showing  the  migration  of moisture fluxes and salt plumes were produced for the coal ash medium. An explanation on the variation of moisture content and cumulative fluxes in the ash dump was done with reference to pre-existing ash dump data, as well as the soil physical characteristics of the ash medium.

Abstract

Conservation is most Academic Editor likely linked to the behaviour of the user to use less water and to use the water more efficiently. The actions will include fixing the leaking taps, toilets and pipes; the implementation of best practices; and awareness programs. All these activities are after the water is taken from the water resource. However, the question remains: "Can water be conserved while still in the resource?" Moreover, then further "What is Groundwater Conservation?" Conservation of groundwater is related to the use of groundwater at the right time and adopts a management style that suits the aquifer characteristics. By knowing when, where, and how much to pump an aquifer can enhance the performance and life of an aquifer. By understanding the different operating rules levels and how the rules influence each other, the optimal yield can be determined. Climate variability and change is having a significant impact on our groundwater resource and the way we are managing our aquifers. Cost to pump and treat the groundwater can be cut with benefits not just to the municipality but also to the community and environment. The paper will go into practical examples to understand the concept of groundwater conservation; to implement groundwater conservation at the local level and the benefits.

Abstract

POSTER A quick analysis of spring water quality was conducted in four neighbouring villages, namely Vondo, Matondoni, Maranzhe and Murangoni in Thohoyandou town under the Thulamela Local Municipality (TLM) of the Vhembe District Municipality (VDM). For the purposes of this study these villages will be termed VMMM villages. A study on the spring water quality of VMMM villages was conducted by the CSIR to determine whether the natural quality state of the spring water used by the surrounding communities was suitable for drinking purposes without pre-treatment. From the four springs that were identified in the VMMM villages, namely Tshali (S1), Ramufhufhi (S2), Tshinwela (S3) and Tshivhase (S4), water samples were taken for the quality analyses in the laboratory. The results indicated that S2 and S4 had a high coliform count of 35 and 600 per 100 ml, respectively), that is above  10  counts  per  100 ml.  In  springs  S2  and  S4  the  total  coliform  count  also  displayed  the presence of E.coli (6 and 310 per millilitre, respectively)  – E.coli should not be detected at all according to SANS standard limits (2011). While all other parameters were within standard limits (SANS 241, 2011), it was also interesting to note that both S3 and S4 had a problem of high turbidity (1, 6 and 105 NTU, respectively) compared to 1 NTU which is the standard limit (SANS 241, 2011). These results showed that although these communities relied on groundwater in the form of springs for drinking purposes, unmonitored use of these resources may be a health hazard that has a potential to  result  in disease outbreak  and  unprecedented  deaths. While  groundwater through springs is considered natural, increased activity around the source due to human activity and interference by domestic animals, these sources may be rendered unsafe for drinking purposes without prior treatment. Therefore, there is need for local authorities to put measures in place to monitor water resources considered indigenous and traditional to the communities, especially in areas where these resources have become the main source of water supply for drinking purposes.

Abstract

The Table Mountain Group (TMG) Formation in the Uitenhage region, in the Eastern Province of South Africa, has many groundwater users, which could result in the over-exploitation of the underlying aquifer. Consequently, several investigations have been conducted to help in the planning and management of groundwater resources within the region. Traditionally, these investigations have considered groundwater and surface water as separate entities, and have been investigated separately. Environmental isotopes, hydrochemistry and feacal colifom bacteria techniques have proved to be useful in the formulation of interrelationships and for the understanding of groundwater and surface water interaction. The field survey and sampling of the springs, Swartkops River and the surrounding boreholes in the Uitenhage area have been conducted. After full analysis of the study, it is anticipated that the data from the spring, Swartkops River and the surrounding boreholes show interannual variation in the isotope values, indicating large variation in the degree of mixing, as well as to determine the origin and circulation time of different water bodies. ?D and ?18O value for the spring ranges from ?18.9? to ?7.4?, and 5.25? to 4.82?, respectively, while ?D values for borehole samples range from ?23.5? to ?20.0? and ?18O values range from ?5.67? to ?5.06?. In the river sample, ?D values ranges from ?12.1? to ?4.2?, ?18O from ?3.7? to ?1.13?, respectively. The entrobacter aerogen and E.Coli bacteria were detected in the samples. E. coli population for spring and the artesian boreholes indicated low value while the shallow boreholes had higher values are relatively closer to those of the middle ridges of the Swartkops River. The EC values for the spring samples averages at 14 mS/m, borehole samples ranges from 21 mS/m to 1402 mS/m, and surface water ranges from 19 mS/m to 195 mS/m. Swartkops River is an ephemeral, therefore it is expected that diffuse recharge occurs into the shallow aquifer.

Abstract

The deterioration of wetlands due to human activity has been a problem for many years. Under the old Water Act 36 of 1956 no provision of water was made for managing the environment. This idea was only introduced in the 1970s and focussed mainly on maintaining the floodplains and estuaries in the Kruger National Park, with small amounts being allocated to drinking water for wildlife. This was followed by the Conservation of Agricultural Resources Act, 43 of 1983, the first legislation under which wetlands could be protected, and which today still provides an important legal platform for the protection of wetlands, through integrated conservation of the soil, water resource and vegetation. South Africa became a signatory to the Ramsar Convention in 1975, but until the late 1990s not much was done to enforce wetland conservation. With the introduction of the National Water Act, 36 of 1998, and the National Environmental Management Act, 107 of 1998, South African legislatiobecame  the  first  to  balance  human,  environmental  aneconomic  interests,  for  the purpose of sustainable development. As part of this review I refer to case studies in Gauteng and discuss some of the challenges we still face.

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.

Abstract

Faced with a burgeoning population and property growth, and in preparation for a future drier climate regime; the coastal town of Hermanus in the Western Cape has set up two wellfields to abstract groundwater from the underlying aquifer in order to augment the constrained surface water supply from the De Bos Dam.
Water Use Licences (WUL) were issued to the Overstrand Municipality in June 2011 and December 2013. The licences authorise a maximum annual abstraction of 1 600 Ml of water from the Gateway wellfield and 800 Ml of water from the Volmoed and Camphill wellfield via several boreholes. The water abstracted from the Gateway wellfield is pumped via a booster pump station to the Preekstoel Treatment Plant. The Volmoed and Camphill wellfield are situated at a higher altitude allowing for a gravity feed pipeline.
Earth Science Company, Umvoto Africa, has the responsibility to ensure Resource Quality Objectives are met which include balancing the need to protect the resource on the one hand; and the to develop sustainable utilisation of the Hermanus groundwater resources and compliance with the WUL on the other. The consultancy provides hydrogeological support, wellfield management and technical advice in operating the boreholes, pumps, boosters and related infrastructures.
Running the operations of the wellfield relies on a high-tech, semi-automated system, incorporating a remotely controlled, telemetry based structure. Vital parameters are monitored by electronic sensors, feeding data to processors which alters pump performance to maintain specified boundary levels. Data is simultaneously communicated via telemetry to a central control which uses data acquisition software to portray information to the operators. Warning alarms both alert operators via SMS and in certain instances auto-shut down the system.
To ensure ecological sustainability of the ground water resource, the wellfield also requires hydrogeological monitoring at far field locations within the recharge areas. Some of these locations are in remote areas making data download costly. The high-tech telemetry approach is used with positive results.
Any automated telemetry system is prone to malfunction and environmental hazards. The challenge lies in managing this and providing sufficient back up and duplication of systems.
The paper gives an overview of the components and flow of data based on the experiences gained during the evolution and development over 12 years of operation. Automation produces vast data bases which are often not sufficiently analysed, the premise that "once collected, the task is done". However data is only as good as the people who drive the systems and this paper provides a critical analysis of human intervention in an automated system and the decisive role of quality-checks. Finally the paper seeks to provide a pragmatic guideline for water users to comply with the WUL and institutional regulations.

Abstract

The western part of South Africa is experiencing a prolonged drought. In many cases, the effects of drought have been noticed since 2011, putting the western part of the Northern Cape under severe stress to provide water to the communities. In the past 10 years, rainfall has also decreased, and in most cases, the catchments did not receive rain to help with the recharge of groundwater. Various lessons were learned from the change in the climate and environment. But a lot can be done to minimise the impact of these changes on the water supply to communities. This paper addresses what we are noticing in the environment that impacts the way we think groundwater behaves. The changes include the change in rainfall: patterns, lines, and type of rainfall. The collapsing of boreholes with water strikes closing when being over-pumped occurs more often in the last 3 years. Pump test recommendation changes with water level change – deployment output. A combination of the factors mentioned puts more stress on groundwater resources, and a mindset change is needed to give assurance of future supply to the communities.

Abstract

Conjunctive use of surface water and groundwater resources offers huge advantages to municipalities. It can significantly increase the resilience of the municipal water supply to drought situations. Optimal use and integration of different sources would result in a yield of the total system that is higher than the combined yield of each source separately. However, integrated water resource management (IWRM) in general and planned conjunctive use of both groundwater and surface water resources in particular have not been successfully implemented yet in South Africa. Six selected case studies of municipalities across South Africa, which utilize both surface water and groundwater for the water supply to specific towns, have undergone a review of their current water governance provisions wrt groundwater, surface water and conjunctive use. The review has been based on a questionnaire for direct interaction with the local government officials, supported by other readily available documents such as municipal Integrated Development Plan (IDP) and Water Services Development Plan (WSDP), municipal websites, Blue Drop and Green Drop Assessment Reports, Municipal Strategic Self-Assessment (MuSSA) and the All Towns Reconciliation Strategy reports. These case studies reveal the different institutional arrangements for water resource management and water supply services that exist in municipalities. The advantages and disadvantages of the institutional arrangements for each case study have been determined. Problem areas identified include split of responsibilities for surface water and groundwater resources between different institutions, lack of financial and HR support within the government spheres, lack of formal and structured stakeholder engagement, insufficient monitoring for both sources, inter alia. Based on this comparative study of different municipalities, a draft framework of optimal institutional arrangements and governance provisions at local government level is developed to support the integration and optimisation of surface water and groundwater supply. The proposed framework is based on three pillars; viz. leadership and clear structures within the responsible local government institution, formal engagement with all relevant internal and external stakeholders and a sufficient monitoring network that supports the stakeholder engagement and decision making.

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.

Abstract

The colliery is situated in the Mpumalanga Coalfield, north of Trichardt in the Republic of South Africa. The opencast is already rehabilitated but still acts as an entrance to the underground sections of the mine. The Life of Mine indicates active mining until 2035. We were tasked to develop a mine closure plan. Two surface drainage systems are present, namely the Trichardt Spruit and the Steenkool Spruit. Both these systems have been diverted locally around the opencast with the necessary permission, to maximize coal extraction and protect the environment. Several passive treatment options were tabled to minimise the post closure environmental contamination. After careful consideration it was decided to develop a mine flooding plan to exclude oxygen from the mine thereby minimising the sulphate generation inside the opencast and underground sections. To start flooding as early as possible, sections of the underground mine were identified as natural or artificial compartments to store water. The rehabilitated opencast is flooded using recharge water from rainfall. The capacity of the rehabilitated open pit is enlarged to evaporate all the excess water in the pit making the need for a treatment plant unnecessary.

Abstract

An understanding of the movement of moisture fluxes in the unsaturated zone of waste disposal sites play a critical role in terms of potential groundwater contamination. Increasing attention is being given to the unsaturated or vadose zone where much of the subsurface contamination originates, passes through, or can be eliminated before it contaminates surface and subsurface water resources. As the transport of contaminants is closely linked with the water ?ux in through the unsaturated zone, any quantitative analysis of contaminant transport must ?rst evaluate water ?uxes into and through the this region. Mathematical models have often been used as critical tools for the optimal quantification of site-speci?c subsurface water ?ow and solute transport processes so as to enable the implementation of management practices that minimize both surface and groundwater pollution. For instance, numerical models have been used in the simulation of water and solute movement in the subsurface for a variety of applications, including the characterization of unsaturated zone solute transport in waste disposal sites and landfills. In this study, HYDRUS 2D numerical simulation was used to simulate water and salt movement in the unsaturated zone at a dry coal ash disposal site in Mpumalanga, South Africa. The main objective of this work was to determine the flux dynamics within the unsaturated zone of the coal ash medium, so as to develop a conceptual model that explains solute transport through the unsaturated zone of the coal ash medium for a period of approximately 10 year intervals. Field experiments were carried out to determine the model input parameters and the initial conditions, through the determination of average moisture content, average bulk density and the saturated hydraulic conductivity of the medium. A two dimensional finite-element mesh of 100m x 45m model was used to represent cross section of the ash dump. Two dimensional time lapse models showing the migration of moisture fluxes and salt plumes were produced for the coal ash medium. An explanation on the variation of moisture content and cumulative fluxes in the ash dump was done with reference to preexisting ash dump data as well as the soil physical characteristics of the ash medium.
{List only- not presented}

Abstract

Underground coal gasification (UCG) is considered a cleaner energy source as its known effect on the environment is minimal; it is cheaper and a lesser contributor to greenhouse gas emissions when compared to conventional coal mining. It has various potential impacts but the subsidence of the surface as well as the potential groundwater contamination is the biggest concerns. Subsidence caused by UCG processes will impact on the groundwater flow and levels due to potential artificial groundwater recharge. The geochemistry of the gasifier is strongly depended upon site specific conditions such as coal composition/type and groundwater chemistry. Independent of the coal rank, the most characteristic organic components of the condensates is phenols, naphthalene and benzene. In the selection of inorganic constituents, ammonia, sulphates and selected metals and metalloids such as mercury, arsenic, and selenium, are identified as the dominant environmental phases. The constituents of concern are generated during the pyrolysis and after gasification as dispersion and penetration of the pyrolysis take place, emission and dispersion of gas products, migration by leaching and penetration of groundwater. A laboratory-based predictive study was conducted using a high pressure thermimetric gasification analyser (HPTGA) to simulate UCG processes where syngas is produced. The HPTGA allows for simulation of the actual operational gasifier pressure on the coal seam and the use of the groundwater sample consumed during gasification. A gasification residue was produced by gasifying the coal sample at 800 °C temperature and by using air as the input gas. The gasification residue was leached using the high temperature experimental leaching procedure to identify the soluble phases of the gasified sample. The leachate analysis is used to determine the proportion of constituents present after gasification which will be removed by leaching as it is exposed to external forces and how it will affect the environment. The loading to groundwater for the whole gasifier is then determined by applying the leachate chemistry and rock-water ratio to the gasifier mine plan and volumes of coal consumed. 

Abstract

Sternophysingids are a group of stygobitic amphipods that inhabit groundwater networks characterised by large fractures, cracks and voids, as well as smaller pores, fissures, cavernous openings and interstitial spaces. Two species occurring in Gauteng, South Africa, Sternophysinx filaris and Sternophysinx calceola, were studied using morphological descriptions and molecular analyses to elucidate the distribution, evolutionary history, phylogeny and population structure. The population structure and distribution of stygobitic amphipods is a reflection of the physical structure of groundwater networks, and their evolutionary history can be used to understand the formation of groundwater bodies. S.filaris is a small and common inhabitant of aquifers in the northern regions of the country, while S. calceola occurs in many of the same locations but is much larger and rarer. No morphological differences were observed between individuals of different populations of S. filaris or S. calceola and detailed illustrations have been provided for each. This finding is not believed to be indicative of a high degree of connectivity within the subterranean groundwater network, lending to high rates of gene flow, instead, these morphological similarities are a symptom of cryptic speciation. Sternophysingids are likely to arise from an very ancient and widespread ancestor inhabiting much of Gondwanaland prior to its breakup. Using the COI gene, S. calceola collected from the type locality in Matlapitse Cave was successfully PCR-amplified and sequenced. Phylogenies were constructed using a limited variety of crangonyctoid sequences and the sternophysingids were confirmed to belong to the Crangonyctoidea superfamily, being most closely allied with the Western Australian paramelitids. The relationship between these groups is still distant and ancient; it is expected that the South African paramelitids would be more closely related, as well as other African, Madagascan and Indian crangonyctoids.

Abstract

The intangible nature of groundwater provides challenges when trying to understand and quantify the role of groundwater in the hydrology of lakes and wetlands. This task is made even more difficult by the frequent absence of data. However, by adopting a scientific approach, it is possible to assess the hydrogeological contribution

Abstract

Delineation of groundwater resources of a given area is importance for management of groundwater resources. This is often done manually by combining various geo-scientific datasets in Geographic Information System (GIS) environment, which is time consuming and is prone to subjective bias and also suffers from other human induced uncertainties and difficult to cope with increasing volumes of data. The explosive growth of data leading to ‘rich data, but poor knowledge’ dilemma yet we have challenges to be solved. Artificial Intelligence (AI) has been successfully used in fields such as robotics, process automation in engineering, industry, medical and domestic households. Artificial Intelligence tool have the able to bridge this gap by augmenting the human capabilities in understand science far better than before. Incorporating AI into groundwater potential mapping greatly improves computation speed, reduces the subjectivity nature of manual mapping and lessens human induced uncertainties. The software platform includes artificial intelligence algorithms such as artificial neural networks, support vector machines, random forest, index-overlay and fuzzy logic.

The software platform is semi-automatic to allow the user to control some of the processes yet automating the other processes. The possible inputs to the AI for training includes; aquifer types, topographic slope, lineament and drainage density, land-use / land-cover (LULC), distance to lineaments, distance to streams and soil clay content. Yield values of selected boreholes are used as training outputs.

The software was tested using data gathered for the area surrounding Maluti-a-Phong in the Free State Province of South Africa. The area was chosen because of recent drought which has hit the country and local municipalities are searching for groundwater resources for building wellfields to supply local communities with fresh water. The groundwater potential map of the area was validated using borehole yield values of boreholes which were not used for modelling. Good correlation values as high as 0.85 was obtained between model values and borehole yield. The final groundwater potential map was divided into four zones; very good, good, poor and very poor. Based on this study, it is concluded that the high groundwater potential zones can be target areas for further hydrogeological studies.

The usage of the software proved to be efficient in minimising the time, labour and money needed to map large areas. The results of which can be used by local authorities and water policy makers as a preliminary reference to narrowed down zones to which local scale groundwater exploration can be done. AI should be viewed as augmented intelligence as it aid the decision-making process rather than replacing it. Data-driven approaches should also be knowledge-guided for efficient results.

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.

Abstract

South Africa currently ranks number nine in the world of the proved coal reserves that has been estimated to last for over 200 years. Coal constitutes about 77% of the primary energy needs in the country, with the Waterberg Coalfield estimated to host about 40% of the remaining South African coal resources. Coal deposits in the study area largely consist of shales, mudstones, siltstones and sandstones which host coal-containing clay minerals; quartz, carbonates, sulphides and the most abundant sulphide mineral is pyrite. Once mining begins, the sulphide minerals are exposed to surface which allows contact with atmospheric oxygen and water causes oxidation to take place, therefore causing acid-mine drainage (AMD). Acid-base accounting (ABA) was used to determine the balance between the acid-producing potential (AP) and acid-neutralising potential (NP). From the analysis the Net Neutralising Potential (NP-AP) was determined, which is one of the measurements used to classify a sample as potentially acid or non-acid-producing. Mineralogical analyses will be done by x-ray defraction (XRD) to define and quantify the mineralogy of the geological samples which can help in the management plan to minimise generation of acid. AMD does not only result in thgeneration of acid, but as well as in decreased pH values and increased values of specific conductance, metals, acidity, sulphate, and dissolved and suspended solids. Inductively coupled plasma analysis was done to determine the release of the heavy metals which can be detrimental to the environment. Sample analysis was done on the interburden, overburden as well as the coal samples. From results obtained, over 35% to 50% of the samples have an excess of acid potential which classifies the samples as having a higher risk for acid generation. About 30% to 40% of the samples have a higher neutralising potential; the rest of the samples have a medium acid risk generation. The water demand will increase as developments continue in the  area, with inter- catchment transfers identified as the answer to fill the gap of water scarcity. Acid mine drainage poses a big threat on water resources, both groundwater and surface water nationally, which might be less of a problem in the Waterberg because of the cycle of low rainfall in the area, but the potential of AMD cannot be neglected.

Abstract

Frequently hydrogeologists are required to site boreholes in areas that are not the optimal for groundwater supply and are given budgets that don't allow rigorous science. This paper presents case studies from Windhoek (Namibia), Matatiele (Eastern Cape Province) and the greater Port Elizabeth area where high success rates and yields were achieved by adopting a no-compromise approach to budgets and target areas. In Windhoek, the aim was to locate and intercept faults at depths up to ~500 m. Following geological mapping and geophysics, angled boreholes were drilled to establish fault dips prior to successfully drilling deep production boreholes. In the Matatiele area, an extensive area was flown with airborne geophysics prior to surface geophysical surveys. In Port Elizabeth the electricity supply to a large area was temporarily cut in order to get undisturbed geophysical data. In Jeffreys Bay, the main entrance road was virtually blocked to cater for geophysical surveys. Hankey town is located in a poor groundwater area, so drilling on private land about 20 km out of town had to be negotiated in order to target an aquifer suitable for the town's supply. These are some of the examples that will be presented in the paper. In most areas drilling yields in excess of 50 L/s were achieved, and the success can be attributed to not compromising on doing rigorous science in the right areas.

Abstract

The key towards modern groundwater management lies in a profound strategy from monitoring data collection over data processing and information management to clear reporting on the development of groundwater resources. Only thus planners are enabled to take informed decisions towards sustainable use and well-keeping of available groundwater. A core in this strategy is the digital database in which all relevant data and information is stored, handled and displayed. It is thus that the Namibian Ministry of Agriculture, Water and Forestry (MAWF) decided to replace within the activities of the Namibian–German cooperation project “Groundwater for the north of Namibia”, the existing national groundwater database GROWAS with the completely new development of the GROWAS II  version.  Through  the  experience  of  the  project  partner  BGR  (Federal  Institute  for Geosciences and Natural Resources) the focus was put on the critical issue of data quality control. As the analysis of the old system indicated unclear data operation procedures as a major source of errors, improved user-friendliness was high on the agenda for the new database. Developed closely to  the  needs  of  Namibian  Water  Authorities,  GROWAS II  features  a  GIS-based  graphical  user interface (GUI) with a vast range of query functions, a modular system including time series tools, hydrochemistry, licenses for abstraction application and groundwater status reporting functions, among others. Quality control is secured through different measures like the “fosterage” option which allows the input of data into a temporary status with restricted access until released by senior experts, the quick and direct interaction with Google Earth to verify locations and the extensive use of look-up tables and descriptive keys in alignment with other regional geo-databases. Furthermore, data entries can be marked according to their estimated reliability with traffic light coding. These measures should ensure that only good quality data will be added in the future. Upcoming development steps are the practical tests of the single modules in day-to-day use, the integration into or exchange with other information systems and the improvement of older existing data as far as possible. Namibia will thus be better prepared for future groundwater challenges.

Abstract

Water is integral to our economy, the health of our environment, and our survival as a species. Much of this water is accessed from surface sources, mostly rivers, which are now under increased threat due to over use and the resulting hydro-political forces. Yet, groundwater exists as a viable option in many countries facing these mounting challenges. Knowledge of our deeper groundwater systems, although increasing, is still quite limited due to our propensity to focus efforts in the lower cost, lower risk, near- surface environment. However, accessibility to shallower groundwater is tightening due to increasing use, changing regulatory requirements, and climate change.

The use of classical geophysics to explore for groundwater resources, such as seismic, gravity, magnetics, and resistivity, has been the industry standard for many decades. These technologies have proven quite effective both in the shallow and medium depth environments. However, newer remote sensing and ground-based technologies are now emerging with the ability to significantly reduce costs and time, and increase success for groundwater exploration and development programs. Quantum Direct Matter Indicator (QDMI) technologies, or applied methods of Quantum Geoelectrophysics (QGEP), are poised to enhance the hydrogeophysical industry, much like electro-magnetic (EM) and electrical resistivity tomography (ERT) did years ago. QDMI utilizes resonant frequency remote and direct sensing technologies that detect perturbations in the earth’s natural electric, magnetic and electromagnetic fields. Controlled source electromagnetic pulse methods with electromagnetic spectrum spectroscopy are used to identify aquifers, including thickness, water quality (fresh or saline) and temperature, to depths of 1000 m or more accurately. With multiple successes around the world, the deployment of this inventive and effective approach to groundwater exploration is poised to advance exploration geophysics globally.

Abstract

A geoscientific research project is underway in the Western Karoo Basin near Beaufort West, South Africa. This area has been earmarked for possible gas exploration. The aim of the project is to improve the understanding of the deeper aquifer systems of the Karoo Basin to better predict potential impacts of geo-resource exploration activities on the deep groundwater systems. This paper reports on the airborne and ground geophysical surveys that were conducted in the study area to gain insight into the deep structural geology and its possible association with aquifer systems. Geophysical methods that were used in the investigations include: 1) the airborne magnetic method was employed to detect and delineate non-outcropping dolerite sills and dykes, as well as to map geological structures of regional extent, and 2) the deep-probing magnetotelluric (MT) technique was used to map conductivity contrasts at large depths that could be associated with prominent geological structures. The results of the geophysical surveys showed that the airborne magnetic method was very effective in mapping intrusive magmatic bodies and other major geological structures. The magnetotelluric results indicated the presence of very resistive layers that appear to be associated with dolerite intrusives. Furthermore, the vertical displacement of a conductive zone indicated the possible presence of large-scale faulting. Based on the results of the airborne geophysical investigations, two investigative boreholes were drilled at selected positions to depths of 516 m and 1 402 m to obtain information on the subsurface geological and geohydrological conditions, and to constrain the interpretation of the airborne geophysical data. Downhole geophysical surveys were conducted on these boreholes to obtain in situ geotechnical and structural information. The results of this project show that the combined use of airborne and deeper probing geophysical methods can greatly contribute to the understanding of the deep geological and geohydrological conditions in the Karoo Basin. The approach can be further utilised for similar investigations of other Karoo satellite basins in South Africa and neighbouring countries

Abstract

Three dimensional numerical flow modelling has become one of the best tools to optimise and management wellfields across the world. This paper presents a case study of simulating an existing wellfield in an alluvial aquifer directly recharged by a major perennial river with fluctuating head stages. The wellfield was originally commissioned in 2010 to provide a supply of water to a nearby Mine. Ten large diameter boreholes capable of abstracting ±2 000 m3 /hour were initially installed in the wellfield. The numerical groundwater flow model was used to evaluate if an additional 500 m3 /hour could be sustainably abstract from the alluvial aquifer system. A probabilistic river flow assessment and surface water balance model was used to quantify low and average flow volumes for the river and used to determine water availability in the alluvial aquifer over time. Output generated indicated that the wellfield demand only exceeded the lowest 2% (98th percentile) of measured monthly river flow over a 59 year period, thereby proving sufficient water availability. Conceptual characterisation of the alluvial aquifer was based on previous feasibility studies and monitoring data from the existing hydrogeological system. Aquifer parameters was translated into the model discretisation grid based on the conceptual site model while the MODFLOW River package was used to represent the river. Actual river stage data was used in the calibration process in addition to water levels of monitoring boreholes and pump tests results. The input of fluctuating river water levels proved essential in obtaining a low model error (RMSE of 0.3). Scenario modelling was used to assess the assurance of supply of the alluvial aquifer for average and drought conditions with a high confidence and provided input into further engineering designs. Wellfield performance and cumulative drawdown were also assessed for the scenario with the projected additional yield demand. Scenario modelling was furthermore used to optimise the placement of new boreholes in the available wellfield concession area.

Abstract

Coal constitutes 77% of the primary energy needs in the country, with the Waterberg Coalfield estimated to host about 40% of the remaining South African coal resources. The Karoo coals were deposited in a reduced environment that have the potential to produce sulphides within the sediments they are hosted. The sulphur content within the coal can range from 0.1 wt.% to as high as 10 wt.%. Mining generates a disturbance in the natural groundwater levels and affects the surrounding water chemistry when sulphate is produced as a result of pyrite oxidation. Acid base accounting (ABA) was used to determine the balance between the acid producing potential (AP) and acid neutralizing potential (NP). From the analysis the Net Neutralising Potential (NNP) classified samples as either acid or non-acid producing. ARD does not only result in the generation of acid but is accompanied by decreased pH and increased values of specific conductance, dissolved metals and sulphate. The ABA results showed that interburden and coal samples have higher risks of producing acid upon oxidation than overburden samples. Higher concentrations of neutralising minerals are present in overburden samples. ABA indicated that the material 60m below ground surface had a higher acid producing potential than the material above. The analysis from kinetic tests showed the long-term behaviour of different samples, with the electrical conductivity (EC) and pH changing over time. Samples with lower pH continued to produce more sulphate, while calcium continued to increase until it was depleted from the samples. Inductively coupled plasma analysis determined the release of the heavy metals which can be detrimental to the environment, such as As, Co, Ni and Pb. The water demand will increase as mining continues in the area, with inter-catchment transfers identified to overcome local water scarcity issues. ARD poses a big threat to both groundwater and surface water resources.

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.

Abstract

The mitigation of groundwater impacts related to gold mining tailings disposal within the Orkney-Klerksdorp region was assessed and presented as a case study. The most pressing concern for the facility owners is the potential for pollution of water resources in the vicinity of the mines, especially after mine closure. The key focus of this paper is to describe how methods were applied to characterise the aquifer and keeping the source-pathway-receptor principles in mind. Characterisation also involves lessons learn by comparing pre-tailings deposition and post-tailings deposition aquifer bahviour. Ultimately the process followed in this paper has led to the development of a logical approach to estimate groundwater liability costs in a typical tailings environment. The link between hydrogeology, geotechnical engineering and civil engineering was identified as a critical foundation for the development of a successful groundwater management strategy

Abstract

The effluent at the eMalahleni water reclamation plant is being processed through reverse osmosis which improves the quality of the mine water to potable standards. Brine ponds are generally used for inland brine disposal and this option has been selected for the eMalahleni plant. Limited capacity to store the brines requires enhanced evaporation rates and increased efficiency of the ponds. This study aims to establish the physical behaviour of the brine from the eMalahleni plant in an artificial evaporation environment. This includes the actual brine and synthetic salts based on the major components.

An experimental unit was designed to accommodate and manipulate the parameters that affect the evaporation rate of brines and distilled water under certain scenarios. Two containers, the one filled with 0.5M of NaCl and the other with distilled water were subjected to the same environmental conditions in each experimental cycle. Each container had an area of a 0.25 m² and was fitted with identical sensors and datalogger to record the parameter changes. The energy input was provided by infra-red lights and wind-aided electrical fans. This equipment used in these experiments was to simulate actual physical environmental conditions. 

The rate of evaporation was expected to be a function of humidity, wind, radiation, salinity and temperature. The experiments showed the type of salt and thermo-stratification of the pond to be significant contributors to the evaporation rate. The results also showed that the NaCl solution absorbed more heat than the water system. The difference in evaporation observed was ascribed to a difference in the heat transfer rate, which resulted in a higher temperature overall in the brine container than in the water container under similar applied conditions. This effect remained despite the introduction of 2 m/s wind flow over the tanks as an additional parameter. The wind factor seemed to delay evaporation due to its chilling effect upon the upper layers of the ponds, initially hindering the effective transfer of radiative heat into the ponds.

 

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.

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}

Abstract

The Two-Streams catchment located in the KwaZulu-Natal Midlands, South Africa has been used as an experimental catchment over the past decade to investigate the impacts of Acacia mearnsii stands on hydrological processes. As part of the ongoing study, the hydrogeology of the catchment was investigated and characterized to understand the impacts of Acacia Mearnsii plantations on groundwater. The hydrological, hydrogeological, hydrochemical and environmental isotope methods were employed in characterizing the hydrogeology of the catchment. The study area is underlain by three geological units: top weathering profile, mainly of clay, which is underlain by weathered shale. Shale is in turn underlain by granite rock. Two hydrostratigraphic units were identified: an unconfined aquifer occurring along the weathered shale and the underlying regional semi-confined aquifer. The regional aquifer is characterised by transmissivity range of 0.15 to 0.48 m2/day, hydraulic conductivity of 0.04 m/day and annual recharge of 31.9 mm. The catchment receives a mean annual rainfall of 778 mm, mean annual evapotranspiration of 802 mm and mean annual stream discharge of 20387 m3. The groundwater and stream samples are characterised by mean specific electrical conductivity of 28.5 mS/m and Ca-HCO3 and Ca-Cl dominant hydrochemical facies. Isotopic values indicate recharge from rainfall with insignificant evaporation during or prior to recharge. Seasonal stream isotope data analysis indicates groundwater as the main contributor of streamflow during dry season. Furthermore, the impacts of Acacia mearnsii trees on groundwater were investigated. Results show that direct groundwater uptake by tree roots from the saturated zone at Two-Streams would not be possible due to limiting root depth. Thus, in instances where the regional groundwater table is not available for direct abstraction by tree roots, trees can have large impact on groundwater by extracting water from the unsaturated zone, reducing recharge to aquifers and baseflow, without having direct access to groundwater

Abstract

Groundwater in the West Coast has been utilised for many years as there are not many surface water resources in the area, and is therefore extremely important. Despite studies being conducted on the aquifer systems since 1976, they are still poorly understood especially with regards to their recharge and discharge processes. This means that the amount of water entering and leaving these systems are unknown, which may lead to over abstraction. It is therefore important to investigate these systems to prevent overexploitation of the groundwater as it will have adverse effects for both humans and ecosystems dependent on it. As part of a managed aquifer recharge (MAR) project for the Saldanha Bay Municipality, this study aims at providing better insight and understanding on the natural resource volumes. The study focusses on groundwater recharge, flow paths and discharge processes and aims at quantifying the volume of water related to each. The study will be conducted by identifying aquifer characteristics through Frequency Domain Electromagnetic and Electrical resistivity geophysical methods. Groundwater flow paths through the unsaturated zone, into the groundwater and towards the discharge area will be determined using Chloride Mass Balance calculations and water isotope analyses. The mass balance equations along with isotope analyses will then aid in the identification of natural recharge and discharge areas of the West Coast aquifer systems, as well as quantifying the volume of water moving through each aquifer. Temperature profiles will also be generated to identify specific layers of the aquifer systems and to determine their groundwater-surface water interactions. The aquifer characteristics will be used in numerical models to test the conceptual understanding of recharge and flow through the systems as well as assessing the volumes of water available to the users of the system.

Abstract

POSTER Electrical Resistivity Tomography (ERT) surveys were conducted in the Kruger National park (KNP) as part of a recent Water Research Commission project (titled: Surface water, groundwater and vadose zone interactions in selected pristine catchments in the Kruger National Park). The surveys were carried out in a pristine ephemeral third-order supersite catchment, namely the southern granite (Stevenson Hamilton). This supersite is representative of the southern granite region of KNP as it covers part of the dominant geology, rainfall gradient and dominant land system.

Electrical   resistivity   profiling   provided   valuable   data   on   the   subsurface  geological   material distribution and results depended on soil/rock properties, water content and salinity. The purpose of electrical surveys was to characterise the hydrogeological components of weathering and depth to water level using the subsurface resistivity distribution. The ground resistivity is related to various geological parameters such as the mineral and fluid content, porosity and degree of water saturation in the rock.

Based on the initial ERT survey interpretations, boreholes were drilled providing actual subsurface results in the form of borehole drilling logs, water levels, hydraulic data and in situ groundwater quality  parameters.  Integrating  the  ERT  survey  data  with  the  results  from  the  intrusive  survey enabled an updated conceptualisation of groundwater flow characteristics and distribution across the southern granite supersite.

Abstract

Studies showed that the primary origin of salinity in river flows of the Sandspruit in the Berg Catchment located in the Western Cape Province of South Africa was mainly due to the weathering of the shales, while atmospheric deposition contributed a third of the total salinity. The salts are transported to rivers through surface runoff and subsurface flow (i.e. throughflow and groundwater flow). The purpose of this study was to determine the relative contributions of subsurface flow and surface flows to total flows in the Sandspruit River, Berg Catchment. Three rain events were studied. Water samples for two rain events were analyzed for environmental tracers ?18O, Silica (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component hydrograph separation were ?18O and SiO2. These tracers were selected as Ca2+ and Mg2+ provided inconsistent contributions of both subsurface flow and surface flow. Two component hydrograph separations indicated that groundwater is the dominant contributor to flow, while surface runoff mainly contributes at the onset of the storm event. Groundwater response to precipitation input indicated that boreholes near the river have a greater response than boreholes further away from the rivers, which have minor response to the input of precipitation.
Keywords:
Stable Isotopes, Sandspruit River, Tracers, Hydrograph separation, Salinity