Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 101 - 150 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort descending	Keywords
Arsenic In The West-African Water Reserves: Investigation Into Sources Of The Contaminant Through Case Studies In The Region	Andre	van Coller	Western Africa	2013	Contaminant, investigations, Groundwater reserve
Abstract The mineral-rich basin of the West African region has vast reserves of gold, diamond as well as iron ore deposits. Throughout the regional geological setting characterised by structural variations and intrusive belts with metamorphic mineral-rich sequences covered by saprolite soils, one common chemical constituent remains a constant in the water reserves. Arsenic is in high concentrations throughout the region with chemical ranges commonly above the various country guidelines as well as international IFC and WHO standards. The aqueous chemical species is associated with arsenopyrite-rich mineralogy of the regional greenstone belts and highly weathered soils. This conference presentation investigates the natural source of the arsenic through baseline data, as well as the effect of mining on the already high concentrations of arsenic in both the groundwater and surface water. Natural levels of various chemical species in the regional area are already high at baseline level. One of the main research questions is thus whether mining and other anthropogenic activities will have an impact on the environment or will the changes to concentrations be so insignificant to allow the ecosystems and water users to continue in their current ways without any effect. Various case studies in Burkina Faso, Liberia, Sierra Leone and other countries have been combined to investigate the arsenic-rich resources of the West African region through groundwater specialist investigative methods with emphasis on geochemical modelling of the fluid–rock and fluid–fluid interactions leading to the aqueous chemical conditions in the region.
Effects Of Dolerite Intrusions On The Geohydrology Of Upper Karoo Sediments In The Elundini Area, South Africa	Jakobus	Prinsloo	The Elundini Area, South Africa	2013	Geohydrology
Abstract The Karoo Supergroup has a hydrogeological regime which is largely controlled by Jurassic dolerite dyke and sill complexes. The study area is located in the north-eastern interior of the Eastern Cape Province, close to the Lesotho border. The sedimentary rocks of the upper Karoo constitute fractured and intergranular aquifers, due to relatively hydro-conductive lithologies. The main groundwater production targets within the upper-Karoo are related to dolerite intrusions that have a number of characteristics that influence groundwater storage and dynamics. Magnetic, electromagnetic and electrical resistivity geophysical techniques are used to determine the different physical characteristics of the dolerite intrusions, such as size, orientation and the level of weathering. Trends in the data collected from a large-scale development programme can provide evidence that intrusion characteristics also play a role in determining the hydrogeological characteristics of the area. Interpreted geophysical borehole drilling, aquifer testing and water chemistry data can be used to indicate hydrogeological differences between dolerite intrusion types. Observed trends could be used for more accurate future well-field target areas and development.
Delineation Of Zones At Risk From Groundwater Inflows At An Underground Platinum Mine In South Africa	A	Stoll	National	2013	groundwater inflow
Abstract The subject mine has a policy of avoiding groundwater inflow into the underground workings due to the impact on the mine operations. It has already implemented a significant mitigation measure by excluding shallow mining and a large pillar under the river that is present in the mining area. To assess the potential for groundwater inflows into the underground mine workings as a result of a planned expansion project, Environmental Resources Management (ERM) undertook numerical groundwater modelling based on a detailed geological investigation to define the proposed mining area into high, medium and low mining risk areas with respect to potential groundwater inflow. The conceptual definitions of the mining risk areas are: High Risk – general groundwater seepage and inflow expected in the face and roof of the mining unit from numerous joints and fractures which is regarded as serious enough to permanently halt mining operations. Medium Risk – possibility of limited point source groundwater inflow in the face and roof of the mining unit from sporadic selective joints and fractures. Not expected to halt mining operations. Low Risk – no significant groundwater risk to mining operations expected. The areas identified as being potentially at risk from groundwater inflow were determined using a combination of geological mapping, ground geophysics and percussion drilling that was incorporated into a numerical hydrogeological model. The study undertaken by ERM enabled the mine to incorporate the identified mining risk zones into the early stages of the mine planning, and allowed for a significant reduction in the size of the safety pillar under the river.
Flowing Fluid Electrical Conductivity Profiling – An Inventive And Cost-Effective Alternative To Conventional Downhole Hydraulic Profiling Techniques	Samuel D	Möhr	National	2013	Electrical conductivity, Hydraulic profiling
Abstract Flowing fluid electrical conductivity (FFEC) profiling provides a simple and inexpensive way to characterise a borehole with regards to the vertical location of transmissive zones, the hydraulic properties of the various transmissive zones and the intra-well flow conditions which may be present in the well under ambient conditions. The method essentially involves analysing the time evolution of fluid electrical conductivities in a borehole under pumped and ambient conditions using a down-hole conductivity/temperature data logger. The premise of the method is that the borehole column of water has its electrical conductivity altered by adding saline water into the borehole. This results in a contrast in electrical conductivity (EC) between the water in the borehole and the water in the adjacent formation. At depths where transmissive zones are present, decreases in EC values in the FFEC profile will be observed where formation water with a lower EC (relative to the borehole water column) enters into the well, whilst pumping at low abstraction rates (between 500 ml and 1 liter per minute). By altering the EC of the well-borewater and maintaining a constant pumping rate, the sequence of FFEC profiles depicts the dynamic flow and transport response which is dependent upon the hydraulic properties of the formation. In this paper the authors present several examples where FFEC profiling has been used to identify transmissive zones in boreholes where no information existed with regards to the vertical distribution of transmissive zones. Furthermore, the authors present case studies where FFEC profiling has been employed as an alternative technology to more conventional hydraulic profiling techniques. This includes a comparative technology case study where down-hole impeller flow meter technology was employed in addition to FFEC profiling and a multi-rate FFEC profile test which was used to determine discrete fracture transmissivity values in a borehole where packer testing equipment could not be installed. Within the context of groundwater contamination investigations, the method holds several attractions as it generates minimal waste water to be managed and disposed of, is inexpensive and can be completed within a relatively short time period.
Arsenic In The West-African Water Reserves: Investigation Into Sources Of The Contaminant Through Case Studies In The Region	André	van Coller	West African region	2013	Contaminant, case study
Abstract The mineral-rich basin of the West African region has vast reserves of gold, diamond as well as iron ore deposits. Throughout the regional geological setting characterised by structural variations and intrusive belts with metamorphic mineral-rich sequences covered by saprolite soils, one common chemical constituent remains a constant in the water reserves. Arsenic is in high concentrations throughout the region with chemical ranges commonly above the various country guidelines as well as international IFC and WHO standards. The aqueous chemical species is associated with arsenopyrite-rich mineralogy of the regional greenstone belts and highly weathered soils. This conference presentation investigates the natural source of the arsenic through baseline data, as well as the effect of mining on the already high concentrations of arsenic in both the groundwater and surface water. Natural levels of various chemical species in the regional area are already high at baseline level. One of the main research questions is thus whether mining and other anthropogenic activities will have an impact on the environment or will the changes to concentrations be so insignificant to allow the ecosystems and water users to continue in their current ways without any effect. Various case studies in Burkina Faso, Liberia, Sierra Leone and other countries have been combined to investigate the arsenic-rich resources of the West African region through groundwater specialist investigative methods with emphasis on geochemical modelling of the fluid–rock and fluid–fluid interactions leading to the aqueous chemical conditions in the region.
A Methodology To Assess The Movement Of Hydrocarbons And Associated Remediation Thereof	Sascha	Roopa	National	2013	Methodology, Hydrocarbon, remediation, contamination
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.
Numerical modelling of mine dewatering and flooding in the Evander Gold Basin, South Africa	Kai T	Witthueser	Witwatersrand	2013	gold mining, mine water rebound
Abstract The assessment and prediction of mine water rebound has become increasingly important for the gold mining industry in the Witwatersrand basin, South Africa. The cessation of dewatering lead to large volumes of contaminated surface discharges in the western parts of the basin. Towards the eastern extremity of the Witwatersrand basin the detached Evander Goldfield basin has been mined since the early 1950s at depths between 400 and 2000 metres below ground, while overlain by shallower coal mining operations. The hydrogeology of the Evander basin can be categorised by a shallow weathered-fractured rock aquifer comprising of the glacial and deltaic sediments of the Karoo Supergroup, while the deeper historically confined fractured bedrock aquifer consist predominantly of quartzite with subordinate lava, shale and conglomerate of the Witwatersrand Supergroup. The deep Witwatersrand aquifer has been actively been dewatered for the last 60 years with a peak rate of 60 Ml per day in the mid late 1960s. Modelling the impacts of mine dewatering and flooding on a regional scale as for the Evander basin entails challenges like the appropriate discretisation of mine voids and the accurate modelling of layered aquifer systems with different free groundwater surfaces on a regional scale. To predict the environmental impacts of both the historic and future deep mining operations, the detailed conceptual model of the aquifers systems and a 3-dimensional model of the mine voids were incorporated into a numerical groundwater model to simulate the dewatering and post-closure rebound of the water tables for the basin. The presented model could serve as an example for the successful modelling of mine dewatering and flooding scenarios for other parts of the Witwatersrand basin.
Hydrogeochemical Footprint As A Result Of Mining Activities In The Johannesburg Area	Tamiru	Abiye	Johannesburg	2013	hydrochemical
Abstract The water quality in the crystalline rocks of the Johannesburg and its environs has been severely altered by the mining activity. Due to freshwater scarcity and dependency of the people on the groundwater, it is important to understand the extent of hydrogeochemical footprint in the area. The water quality characteristic has been thoroughly assessed in the crystalline aquifers based on the input from hydrogeochemical characteristics and environmental isotopes. The results show that the calculated dilution factor for acid-mine decant is in the range of 68% as a result of interaction with surrounding fresh water. The SO4/Cl ratio has a wide range of values that falls between 0 and 306.37, while that of Fe/Ca ratio falls between 0 and 5.59. High SO4/Cl values potentially indicate the interference of acid-mine decant with the groundwater system traced through sulphate concentration. Similarly, a high Fe/Ca ratio also indicates the impact of acid-mine decant on the groundwater system where iron is traced with respect to calcium concentration. In this regard the ratios above 0,25 (with the assumption of 1 to 4 natural abundance for Fe:Ca in water in the area) could potentially represent acid-mine decant source.The results confirm that most of the water- supply wells have heterogeneous chemistry with distinctive hydrogeochemical footprint represented by abnormally high Fe, SO4 and Si as a result of acid-mine decant.
Effects Of Dolerite Intrusions On The Geohydrology Of Upper Karoo Sediments In The Elundini Area, South Africa	J	Prinsloo	The Elundini Area, South Africa	2013	Dolerite Intrusions, Geohydrology, Groundwater
Abstract The Karoo Supergroup has a hydrogeological regime which is largely controlled by Jurassic dolerite dyke and sill complexes. The study area is located in the north-eastern interior of the Eastern Cape Province, close to the Lesotho border. The sedimentary rocks of the upper Karoo constitute fractured and intergranular aquifers, due to relatively hydro-conductive lithologies. The main groundwater production targets within the upper-Karoo are related to dolerite intrusions that have a number of characteristics that influence groundwater storage and dynamics. Magnetic, electromagnetic and electrical resistivity geophysical techniques are used to determine the different physical characteristics of the dolerite intrusions, such as size, orientation and the level of weathering. Trends in the data collected from a large-scale development programme can provide evidence that intrusion characteristics also play a role in determining the hydrogeological characteristics of the area. Interpreted geophysical borehole drilling, aquifer testing and water chemistry data can be used to indicate hydrogeological differences between dolerite intrusion types. Observed trends could be used for more accurate future well-field target areas and development.
Recent Developments in The Understanding Of Karoo Aquifers And The Deeper Underlying Formations	Peter	Rosewarne	Karoo	2013	Shale gas, Karoo Groundwater Atlas
Abstract The possibility of large reserves of shale gas underlying the Karoo and their exploitation has focused attention on the groundwater resources and aquifers of this region. Much is known about the relatively shallow aquifers (<300 m) which supply many local municipalities and farmers with water for domestic, stock and irrigation use (mostly from boreholes <150 m in depth). Conversely, little is known about the deeper formations (>500 m) and associated groundwater occurrences and their possible interconnection to the shallow aquifer systems. This paper covers a desk study of the southern Karoo, mostly above the Great Escarpment, carried out by a group of hydrogeologists/geochemists with a cumulative experience of about 250 years. The main consideration at this stage has been the collation and analysis of existing information, using GIS, conceptualisations, and identification of knowledge gaps. A Karoo Groundwater Atlas was published in 2012 and Volume 2 has been released at this conference, which present a summary of the main analyses. Borehole yield, recharge and quality in the shallow aquifer tend to improve, and water levels become shallower, from west to east, associated with higher rainfall and increased percentage of dolerite and sandstone. Aquifer yield, quality, lithology and presence of dolerites constitute 60% of a groundwater attributes ratings classification; 54% of the study area has a high rating. Twenty four percent of the study area has a high vulnerability rating. Knowledge of the characteristics of groundwater associated with the deeper formations is restricted to a few thermal springs and sparse data from some deep hydrocarbon exploration wells. Weak artesian flows were recorded from two such wells in the Dwyka Group below the Great Escarpment, with Total Dissolved Solids of up to 10 000 mg/L and temperatures of up to 77 oC, from depths of 2 347 to 3 100 m. Further work and cooperation with other researchers/institutions is on-going and planned to fill in knowledge gaps and assess the risks to groundwater of shale gas exploration.
Estimating groundwater availability at catchment scale using streamflow recession and instream flow requirements of rivers	Girma Yimer	Ebrahim		2015	streamflow, RDM
Abstract Groundwater is an important resource for multiple uses in South Africa. Hence, setting limits to its sustainable abstraction while assuring basic human needs is required. Due to prevalent data scarcity related to groundwater replenishment, which is the traditional basis for estimating groundwater availability, the present article presents a novel method for determining allocatable groundwater in quaternary catchments through information on streamflow. Using established methodologies for assessing baseflow, recession flow, and instream ecological flow requirement, the methodology develops a combined stepwise methodology to determine annual groundwater storage volume using linear reservoir theory, essentially linking low flows proportionally to upstream groundwater storages. The approach was trialled for twenty-one perennial and relatively undisturbed quaternary catchments with longterm and reliable streamflow records. Using the Desktop Reserve Model, maintenance low instream flow requirements necessary to meet present ecological state of the streams were determined, and baseflows in excess of these flows were converted into allocatable groundwater storages on an annual basis. Results show that groundwater development potential exists in nineteen of the catchments, with upper limits to allocatable groundwater volumes (including present uses) ranging from 0.02 to 2.60 Mm3/a over the catchments. With a secured availability of these volumes 75% of the years, variability between years is assumed to be manageable. A significant (R2 = 0.86) correlation between baseflow index and the drainage time scale for the catchments underscores the physical basis of the methodology and also enables the reduction of the procedure by one step, omitting recession flow analysis. The method serves as an important complementary tool for the assessment of the groundwater part of the Reserve and the Groundwater Resource Directed Measures in South Africa.
Integrated Modelling: A Tool For Urban Groundwater Management On The Cape Flats, Cape Town	Benjamin	Mauck		2015
Abstract There is growing concern that South Africa's urban centres are becoming increasingly vulnerable to water scarcity due to stressed surface water resources, rapid urbanisation, climate change and increasing demand for water. Given South Africa's water scarcity, global trends for sustainable development, and awareness around the issues of environmental degradation and climate change, there is a need to consider alternative water management strategies. Water Sensitive Urban Design (WSUD) is an approach to sustainable urban water management that attempts to achieve the goal of a 'Water Sensitive City'. The concept of a Water Sensitive City seeks to ensure the sustainable management of water using a range of approaches such as the reuse of water (stormwater and wastewater), exploiting alternative available sources of supply, sustainable stormwater management and improving the resource value of urban water through aesthetic and recreational appeal. Therefore, WSUD attempts to assign a resource value to all forms of water in the urban context, viz. stormwater, wastewater, potable water and groundwater. However, groundwater is often the least considered because it is a hidden resource, often overlooked as a form a water supply (potable and non-potable) and it is often poorly protected. The management of urban groundwater and understanding the impacts of WSUD on groundwater in South African cities is challenging, due to complex geology, ambiguous groundwater regulations and management, data limitations, and lack of capacity. Thus, there is a need for an approach to assess the feasibility of management strategies such as WSUD, so that the potential opportunities and impacts can be quantified and used to inform the decision making process. An integrated modelling approach, incorporating both surface and subsurface hydrological processes, allows various urban water management strategies to be tested due to the complete representation of the hydrological cycle. This integration is important as WSUD is used to manage surface water, but WSUD known to utilise groundwater as a means of treatment and storage. This paper assesses the application, calibration and testing of the integrated model, MIKE SHE, and examines the complexities and value of establishing an integrated groundwater and surface water model for urban applications in South Africa. The paper serves to demonstrate the value of the application of MIKE SHE and integrated modelling for urban applications in a South African context and to test the models performance in Cape Town's unique conditions, accounting for a semi-arid climate, complex land use, variable topography and data limitations. Furthermore, this paper illustrates the value of integrated modelling as a management tool for assessing the implementation of WSUD strategies on the Cape Flats, helping identifying potential impacts of WSUD interventions on groundwater and the potential opportunities for groundwater to contribute towards ensuring to Cape Town's water security into the future.
Governance and Management of Water Resource in the SA Context - A Review	Kornelius	Riemann		2015
Abstract Water management is a difficult and complex business requiring appropriate institutional arrangements as well as guidance and support from government, which is often unable to act effectively to address day-to-day water resource management (WRM) issues. Theoretically, water as a 'common pool resource' is best managed by users self-organised at a local level and within a basin framework. Water users and other stakeholders have detailed and up-to-date local knowledge as well as an interest in ensuring effective management to share water equitably between different users and to control pollution. This approach is supported by South Africa's National Water Act (NWA), which provides for the establishment of Catchment Management Agencies (CMAs) to perform a range of WRM activities within the framework of a National Water Resource Strategy (NWRS). Hence, water resource management in general and conjunctive use in particular requires cross sector and cross level cooperative governance. Relevant institutions include the DWA at national and regional level, the CMA, if established, provincial departments that might impact on the water resources, water user associations, water services authorities, water services providers, water boards, and individual water users. These institutions are responsible for various activities and often require some level of inter- and intra-institutional cooperation. Ideally, multiple organisations, policies, legislation, plans, strategies and perspectives should be involved in water-related decision-making, which in turns creates complex leadership challenges. Globally, the lack of sustainable groundwater management can be ascribed to poor governance provisions. These include, but are not limited to, institutional arrangements and political will, including fragmented and overlapping jurisdictions and responsibilities, competing priorities, traditional approaches, rights and water pricing systems, diverging opinions, incomplete knowledge, data as well as uncoordinated information systems. Adding the poor operational and maintenance issues, decision-makers often view groundwater as an unreliable resource and are hesitant to make significant investments in groundwater infrastructure and capacity. The recent Worldbank and WRC report on groundwater governance in South Africa revealed that the technical, legal, institutional and operational governance provisions were found to be reasonable at the national level but weak concerning cross-sector policy coordination. At the local level, basic technical provisions such as hydrogeological maps and aquifer delineation with classified typology are in place but other governance provisions such as institutional capacity, provisions to control groundwater abstraction and pollution, cross-sector policy coordination and the existence and implementation of groundwater management action plans are weak or non-existent. It appears from this review that the major hindrances for sustainable groundwater governance and more so for integrated water resource management and conjunctive use scenarios are the discrepancy between groundwater and surface water provisions in the relevant legislation, associated guidelines and their implementation at regional and local, and the lack of skills and clear responsibilities for implementing water resource management actions at municipal level. This is demonstrated with several case studies.
Refinement of a 3D Finite Element Mesh Model, Bela-Bela, South Africa	Tshegofatso	Mophatlane	North West	2015
Abstract This paper follows on current research taking place in the Springbok Flats Basin focusing on Carbon Dioxide Geological Sequestration within coal seams. The research, commissioned by ESKOM, began in 2012 and has a primary aim of producing a hydrogeological risk assessment for carbon dioxide geological sequestration operations scheduled for national pilot testing within the basin. One of the fundamental tools used in the assessment has been finite element mesh modeling. A 3D finite element mesh model of the study area, that has 11307 nodes, has been generated using FEFLOW algorithms. Portions in the study area without linear and point physical features have been modeled with the Advancing Front Algorithm, while the Grid Builder Algorithm has been used to model portions with linear and point features. This paper has investigated the node angle accuracy and precision of the mesh model by generating a map of the maximum interior angle of triangles. Approximately 70 % of the triangles have equilateral angles, while the remainder triangles have obtuse angles. The majority of the equilateral triangles occur within the portions modeled with the Advancing Front Algorithm. Half of the obtuse triangles have been refined to equilateral triangles with the FEFLOW refinement tools while the other half has been refined manually with the node digitizing features. FEM models perform better with dense triangle matrices with equilateral angles, as they influence the accuracy of the FEM.
Estimating Recharge in the Ermelo Region of Mpumalanga by Comparing Different Water Balance Methods	Morne	van Wyk	Mpumalanga	2015
Abstract South Africa is classified as a semi-arid region where the evapotranspiration sometimes exceeds the annual recharge through rainfall which leads to more drought periods. Combine the before mentioned issue with the water shortages and the impact of mining on water in South Africa, the focus therefore then needs to be placed on the proper estimation of recharge from rainfall and subsequent water management of these water sources. The Ermelo region in Mpumalanga was chosen for the investigation into calculating recharge from rainfall, using water balance methods as the basis on which recharge is calculated. The Ground Water Balance, Saturated Volume Fluctuation, Ground water level fluctuation and Cumulative Rainfall Departure methods was used to calculated recharge and then compare the different methods and their values with each other to compile an accurate estimation of recharge in the area. The data was analysed for each of the methods and then plotted and compared on a simple x-y chart. A new equation was formulated whereby any recharge from the previously mentioned methods can be normalized against the new formula for a more accurate recharge value. As a secondary objective a recharge intensity map was compiled for the area showing the areas of potentially high recharge. Keywords: South Africa, Ermelo, Recharge Estimation, Water balance methods, Ground Water Balance, Saturated Volume Fluctuation, Ground water level fluctuation, Cumulative Rainfall Departure, Intensity maps.
High Resolution Site Characterisation (HRSC) In South Africa: Challenges, Successes And Lessons Learned	Samuel D	Mohr		2015
Abstract Inadequate characterization of contaminated sites often leads to the development of poorly constructed conceptual site models and consequently, the design and implementation of inappropriate risk management strategies. As a result, the required remedial objectives are not achieved or are inefficient in addressing the identified risks. Unfortunately, it is all too common to find remedial intervention strategies that run for lengthy periods of time at great cost while generating little environmental benefit due to inadequate characterization of site conditions. High resolution site characterization (HRSC) can provide the necessary level of information to allow for development of rigorous conceptual site models, which can be used to develop and implement appropriate risk management solutions for environmental problems. At the outset, the HRSC approach generally has comparatively higher costs than traditional state-of-the-practice assessment methods. However, the project lifecycle costs can be substantially reduced due to development of optimal risk management strategies. In developing countries where there is a lack of legislation relating to soil and groundwater contamination or, a lack of enforcement of legislation which is present, the long-term liabilities related to contaminated sites are often not immediately apparent to the parties responsible for the sites. This often creates a reticence to employ HRSC techniques due to their increased cost, especially when much of the technology must be imported on a project specific basis from either Europe or the United States. The Authors provide information from several case studies conducted in South Africa where HRSC techniques have been employed to gain a greater understanding of subsurface conditions. Techniques employed have included surface-based geophysical techniques such as electrical resistivity tomography (ERT) and multi-channel analysis of seismic waves (MASW), passive soil gas surveys, deployment of Flexible Underground Technologies (FLUTe?) liners, diamond core drilling, fluid electrical conductivity profiling, downhole geophysical logging tools, the Waterloo Advanced Profiling System (APS), and the use of field laboratories. Several of the techniques required importing equipment and personnel from Europe or the US, and in several case studies, were a first to be employed in South Africa, or the continent of Africa for that matter. The Authors present data obtained using the HRSC techniques from the case studies and elaborate on how the information obtained was used to drive effective decision making in terms of managing long term environmental risks at the various sites, which has been positively embraced by local clients. The authors also highlight key challenges in conducting HRSC investigations in an emerging market context.
Blast curtain optimized with a numerical model for TSF seepage control	Robel	Gebrekristos		2015
Abstract Preventing the spread of seepage from tailings storage facilities (TSF's) in groundwater is necessary as it often contains toxic contaminants. Experience has shown that seepage from TSFs is inevitable and that zero seepage remains difficult even with complex liner systems. Multiple seepage control methods are often required to minimise seepage to ensure that environmental regulations are met. Control methods can be grouped into either barrier or collection systems. Barrier systems are used to hinder seepage whereas collection systems are used to intercept seepage. A blast curtain, which is the focus of this article, is a type of collection system that is still at a conceptual level but has seen little or no application worldwide. It works in principle, similarly to a curtain drain, but is typically extended to greater depths depending on the aquifer vulnerability. Numerical modeling has shown that this mitigation measure could add another line of defence for seepage control. The depth and effectiveness of the curtain can be optimized with a numerical model to ensure optimal interception of contaminated seepage around the TSF. Depths of up to 30 m in fractured aquifers have been simulated in this study. A blast curtain is constructed by drilling a set of boreholes around a TSF in close proximity to one another and then fracturing the rock using either explosives or fracking methods to create a more permeable zone. This is then combined with a series of scavenger wells or natural seepage to abstract the contaminated water. Numerical simulation has shown that blast curtains are effective especially if groundwater flow is horizontal. The effectiveness decreases if the vertical flow component is significant. A blast curtain can result in the lowering of the water table, however, local depression is a less of a concern than potential groundwater contamination. {List only- not presented}
Possible recharge areas for two of the Lower Berg aquifers units, Western Cape	Nicolette	Vermaak	Western Cape	2015	groundwater recharge
Abstract The question about the natural recharge areas for two of the Lower Berg river aquifers units, Elandsfontein Aquifer unit and Langebaan Road aquifer unit, has been keeping geohydrologists working in the area without a definite answer. Tredoux and Engelbrecht have postulated that it must be from the higher grounds around Hopefield, while Woodford hinted that an offshoot fault from the Coleso fault system could also cause the systems to be recharged from the Darling hills. Isotope studies had been done for the proposed Hopefield recharge area, but none has so far been done for the possible Darling recharge system. This paper will look at the studies done up to date and evaluate the data available for the boreholes drilled in the area in an attempt to get a clearer understanding of the two possibilities. It will also identify possible gaps in our knowledge of the area and the steps that would make it possible to fill in the gaps.
Characterization of Groundwater Potential in the northern parts of the Limpopo Province, South Africa: Results from Integrated G	Peter	Nyabeze	Limpopo	2015
Abstract Characterization of Groundwater Potential in the northern parts of the Limpopo Province, South Africa: Results from Integrated Geophysical Studies across the Sagole and Tshipise Hot Springs. The Sagole and Tshipise hot springs are located in the northern Limpopo Province of South Africa. The geology of the area consists of dykes, dolerite sills, quartzite and undifferentiated meta-sediments. Regional-scale airborne magnetic data and satellite images were used for mapping structures and lithological boundaries in order to identify permeable zones that are associated with thermal groundwater aquifers. Various filtering techniques were used to enhance the magnetic signatures that correspond to structural features. Modeling of airborne magnetic data indicated that the heat source depth was an anticlinal structure at a depth range of 3 km to 5 km. Based on results of interpretation of the magnetic and satellite images, ground follow-up targets were identified. Detailed ground geophysical surveys were carried out across the identified targets using the frequency-domain electromagnetic (EM), electrical resistivity tomography (ERT) and magnetic methods. {List only- not presented} The result of interpretation of magnetic data was combined with two-dimensional modeling EM and (ERT). Modeling of the electrical conductivity of the subsurface layers was constrained using existing borehole data. Interpretation of the airborne magnetic data revealed the presence of number of NE-SW striking lineaments that transect the metasedimentary rocks of the Soutpansberg Supergroup. In addition, these structures are manifested by a number of hotsprings that are aligned along major lineaments. The interpretation of 2D modeling of ERT data revealed a highly conductive layer with a depth ranging from surface to 40 m that may be attributed to elevated moisture content. Two-Dimensional modeling of frequency-domain electromagnetic data was carried out to delineate lateral and vertical variation of electrical conductivity. Electrical conductivity values in the range 50 mS/m to 100 mS/m were obtained, indicating the presence of water bearing zones or fractures. Results of the study have shown that hot water rises to the surface along near vertical faults or fractures. Keywords: Aquifer, geophysics, groundwater, thermal spring
Numerical modelling of groundwater contributions to wetlands	Kai T	Witthueser	Witbank	2015	groundwater flow model
Abstract In order to meet the increasing national and international demand for coal, substantial expansion plans for existing as well as new coal mines were put forward in recent years. The mine developments are often proposed in environmentally sensitive areas and require an appropriate assessment of potential environmental impacts, including impacts on groundwater dependent ecosystems. This paper describes the development of a conceptual and numerical groundwater model as part of a wetland reserve determination in the Witbank coalfields. The model was used to assess potential mining related impacts on the shallow groundwater flow, including surface seepages and spring discharges feeding hill slope and valley bottom wetlands as well as pans. A number of shallow monitoring boreholes were sited, drilled and tested in the focus area around a pan to characterise the shallow perched and weathered aquifers. While these aquifers were generally found to be very low to low yielding, higher yields were encountered in a coarser grit layer intersected by two of the eight boreholes. The grit layer represents a potential preferential groundwater flow path towards the pan and was subsequently further delineated based on the exploration drilling logs from the mine. The different aquifers, the target coal seam, and over 60 mapped hill slope and valley bottom wetlands as well as pans, were incorporated into a numerical groundwater flow model. A free seepage boundary was assigned to the entire surface area to evaluate if the model is able to represent the observed seepages and spring discharges. The simulation of unsaturated flow processes (Richard's equation) was found to be crucial for the representation of discharges from perched aquifers. Following a satisfactory calibration of the model, different open cast mine layouts were then incorporated into the model to assess their impacts on the groundwater contribution to wetlands. The presented quantitative simulation of groundwater contributions towards wetlands and pans based on site specific groundwater investigations and data is considered a best practice example in assessing the groundwater component for a wetland reserve determination.
Hydrogeochemical Evolution of an Opencast Colliery After Decommissioning - Static vs. Dynamic Prediction	Altus	Huisamen	Mpumalanga	2015
Abstract Static indicator tests, such as acid-base accounting, are commonly used to provide an indication of ARD potential of backfill material in opencast coal mines. This potential for acidity is then commonly incorporated into numerical models, wrongfully, as a constant contamination source with the maximum possible sulphate being released from the pit, ad infinitum, which is, obviously, not the case. Dynamic tests on the other hand, are considered superior, but are expensive and time consuming. The proposed alternative approach is geochemical modelling, illustrated by a case study in the Mpumalanga coal fields. A decommissioned colliery near Carolina, Mpumalanga, was recently confronted with the prediction of the impacts that its backfilled opencasts might have on groundwater in the long term with regards to acid and contaminant generation, demanding a more realistic and well-defined conceptual and numerical approach than the simple minimum screening method. This study utilised the integration of a well-defined conceptual model, mineralogical data, acid-base accounting data, leaching test data, literature and groundwater monitoring data to address the long term hydrogeochemical evolution of groundwater at the colliery, using transiently calibrated geochemical and numerical flow models. Using the mineralogical data available from samples collected, as well as the sulphur content identified by ABA, a standard error was calculated for the abundances of all mineral phases present along with mean weight percentages, defining the likely boundaries of mineral abundances. Using these values along with reactive surface areas calculated from average grain sizes, using a collapsing core model, as well as rate constants from literature, the fluid rock interaction in the leaching tests was simulated and calibrated against leaching test results in the geochemical model, by varying mineral abundances, reactive surface areas and rate constants within the statistically acceptable boundaries. Once a calibrated mineral assemblage was identified using this method, the assemblage was geochemically modelled in the natural environment, after calculation of fluid to rock ratios, which in this case was purely potential backfill porosity vs. recharge due to the natural groundwater level being below the pit base, as well as potential oxygen fugacity. The calculated concentrations of constituents were then introduced into a transiently calibrated numerical flow and transport model via recharge concentrations, to also chemically calibrate this model. The chemical calibration was successful within a 20 mg/L range, illustrating the reliability of the conceptual and geochemical models, but also the reliability of predicted numerical modelling results. Based on the available data and modelling results, the colliery would not have a future impact on groundwater with regards to ARD and metals. However, elevated major cation and anion concentrations are expected, calculated within order of magnitude accuracy, and can be managed according to dynamic and realistic models, instead of a static worst case scenario.
Platinum mines will leave behind a sustainable legacy which will form a vital building block to meet future water demands	Fanie	Botha		2015	aeration and aerobic storage facilities, Nitrate
Abstract Slightly more out of the box idea is the use of anthropogenic aquifers as storage and chemical conditioners. This concept was first introduce by Eland Platinum Mine(EPM) and reported on in previous papers. At EPM water is used through a serious of natural aeration and aerobic storage facilities to reduce nitrate levels. In 2013 another group introduced pilot studies by virtue of abstraction in support of the water conservation and demand management strategy; which has proven that it could enable the operations to overcome water shortage periods and reduce pressure on Rand Water (RW). The pilot sites would deliver water into the dirty water circuit, but within five to ten years it may further be used to overcome months with zero potable water supply. . In platinum mines the more the aquifers are used the cleaner the water becomes, simply because introduced pollutants are not constant sources and country rock is mostly inert. In the future these aquifers have the potential to become larger storage facilities protected from floods and limited evaporation losses. It is foreseen that some of the mines in the western belt may have more water stored in primary aquifers than water stored within major water dams. Yields from these aquifers for individual aquifers may be up to 450 m3/hour and storage of 18 Mm3. . Why then this paper if we are already using it? The issue is that the true value of these aquifers an only be unlocked when they are used as recharging aquifers and thereby actively storing dirty water within a dirty water aquifer. Once we are able to undertake this the positive environmental gains such of environmental overflows, condition dirty water, reduction of pollution and significant reduction of the use of potable water from RW. {List only- not presented}
Aquifer Vulnerability Assessment Of The Federal Capital City, Abuja - Nigeria	Omogbemi O	Yaya	Nigeria	2015
Abstract Based on a modified DRASTIC model and GIS techniques, shallow groundwater vulnerability assessment was carried out in the Federal Capital City of Abuja, Nigeria. The results indicate that the studied area can be divided into three zones, namely: low groundwater vulnerability zone (vulnerability index <100) which covers about 60% of the City; moderate vulnerability zone (vulnerability indexes 100-140) which covers 35% of the City and high vulnerability zone (vulnerability index >140) which covers only 5% of the City. The highest groundwater vulnerability zone mainly locates in the central solid waste disposal site area in the outskirt of the City. The findings correlate well with the results of the physicochemical and microbiological investigation. The general low contamination vulnerability signature of the City may be attributed to absence of industries, limited agricultural activities, and preponderance of clayey top soil which effectively forms the first defence against contamination of the underlying aquifers as well as the presence of central sewage collection facility that covers about 25% of the City.
Stampriet Transboundary Aquifer System	Joyce T	Leshomo	SADC	2015	IAH, Unesco-IHP, transboundary aquifers
Abstract The International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial, sustainable aquifer development and management. The Stampriet Transboundary Aquifer System was selected as one of the three case studies funded by UNESCO. The Stampriet Aquifer System is located in the arid part of the countries (Botswana, Namibia and South Africa) where groundwater is a sole provider for water resource. The area is characterised by the Kalahari (local unconfined aquifer) and Nossob confined aquifer
#GWD: The use of social media for science communication	Tercia	Strydom		2015
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.
Hydrogeology of the Cedarville Flats primary aquifer, Upper Umzimvubu River Basin, South Africa	Molla	Demlie	Eastern Cape	2015	Cedarville Flats alluvial aquifer, Environmental Isotopes, highland recharge, residence time
Abstract The Cedarville Flats aquifer located in the Upper Umzimvubu River Basin, Eastern Cape Province is a source of water supply for an important agricultural region in South Africa. The hydrogeology of this important aquifer is investigated to understand the occurrence, circulation, recharge and quality of groundwater. To this end, local and regional geology, borehole lithological logs, borehole yields, aquifer hydraulic characteristics (including aquifer thickness, water level, hydraulic conductivity, transmissivity and storage coefficient), hydrometeorological, hydrochemicaland environmental isotope data were collected and interpreted. The results show that the alluvial aquifer is made up of sand, gravel, boulders and clay and its thickness reaches 51 meters in places. Median hydraulic properties indicate that the Cedarville Flats primary aquifer is the most productive aquifer compared to the underlying Molteno and Burgersdorp Formations. It has an estimated median borehole yield in the order of 6 l/s as compared to 2 l/s for the Burgersdorp and 1.5 liters for the Molteno Formations. The aquifers in the area receive an estimated 7% of rainfall recharge. The groundwaters of the area are characterized by low ionic concentration with EC and TDS ranging from 235 to 285 ?S/cm and from 65 to 151 mg/l, respectively. The hydrochemical data further indicate a groundwater hydrochemical facies of either Ca-Na-Mg-HCO3 or Na-Ca-Mg-HCO3 highlighting a typically less evolved recharge area groundwater having short residence time and hence less water-rock interaction. Springs and artesian wells show a relatively depleted stable isotope and very low to dead tritium signals indicating high altitude recharge and longer circulation path and residence times compared to wells tapping the water table aquifer which indicate young water with recharge coming from the immediate surrounding area. Similarity in hydrochemical and stable isotope signatures between the streams that drain across the alluvial flats and the shallow groundwaters mean that there is a close interconnection between surface water and groundwater in the area.
Monitored Natural Attenuation on-sites with different geological setting	Bongani	Masombuka		2015
Abstract When considering how to reduce contamination of petroleum hydrocarbons in shallow aquifers, it is important to recognize the considerable capacity of natural processes continuously at work within the secondary sources of contamination. This natural processes are technically referred to as Monitored Natural Attenuation (MNA), a process whereby petroleum hydrocarbons are deteriorated naturally by microbes. This approach of petroleum hydrocarbon degradation relies on microbes which utilise oxygen under aerobic processes and progressively utilises other constituents (sulphates, nitrates, iron and manganese) under anaerobic processes. MNA process is mostly evident when light non-aqueous phase liquids (LNAPLs) has been removed while the dissolved phase hydrocarbon compounds are prominent in the saturated zone. The case studies aim at determining feasibility and sustainability of Monitored Natural Attenuation process at different sites with varying geological setting.
Groundwater chemical evolution at an underground coal gasification pilot plant in Majuba	Lehlohonolo	Mokhahlane	KwaZulu-Natal	2015
Abstract Underground coal gasification (UCG) is technology that aspires to exploit coal reserves using in-situ gasification. This mining method gasifies coal seams while extracting a syngas that can be used for electricity generation. Since the bulk of this process occurs in the subsurface, there is a possibility of impacting on regional groundwater quality. This paper seeks to assess this impact on groundwater across different aquifers while taking into account the chemical evolution of these aquifers. Three aquifer systems were identified namely the shallow, intermediate and the deep aquifer which comprises of the coal seam. The water chemistry was reviewed over a two year period during which the gasifier was still active. Alkaline conditions were prevalent across the three aquifers with minor seasonal changes. High levels of dissolved solids were observed especially in the deep aquifer but the quality of water was poor even in background samples. The impact of gasification does have small variation in already unusable water in the deep aquifer which was also characterized by low hydraulic conductivity. Higher hydraulic conductivity values were established in the shallow aquifer. No significant groundwater chemistry change was detected in this aquifer as a result of gasification process.
Governing Groundwater Wisely To Provide For Current And Future Generations.	Zine	Matshakeni		2015
Abstract POSTER About 97% of the earth's freshwater fraction is groundwater, excluding the amount locked in ice caps (Turton et al 2007) and is often the only source of water in arid and semi-arid regions and plays a critical role in agriculture, this dependency results in over-exploitation, depletion and pollution (Turton et al 2007). Groundwater governance helps prevent these issues. CSIR defines governance as the process of informed decision making that enables trade between competing users of a given resource, as to balance protection and use in such a way as to mitigate conflicts, enhance security, ensure sustainability and hold government officials accountable for their actions (Turton et al 2007). Realising the issues of groundwater governance is a requirement for developing policy recommendations for both national and trans-boundary groundwater governance. Groundwater level decline has led to depletion in storage in both confined and unconfined aquifer systems (Theesfeld 2010). There are about six institutional aspects, namely voluntary compliance, traditional and mental models, administrative responsibility and bureaucratic inertia, conflict resolution mechanisms, political economy and information deficits (Theesfeld 2010). Each of these aspects represents institutional challenges for national and international policy implementation. Traditional local practices should not be disregarded when new management schemes or technological innovations are implemented. The types of policies that impact governance include regulatory instruments, economic instruments and voluntary/advisory instruments. Regulatory or command and control policy instruments such as ownership and property right assignments and regulations for water use are compulsory. Economic policy instruments make use of financial reasons such as groundwater pricing, trading water right or pollution permits, subsidies and taxes. Voluntary /advisory policy instruments are those that influence voluntary actions or behavioural change without agreement or direct financial incentives. These are ideal types though no policy option ever relies purely on one type of instrument. The aim of these policies is to have an impact on governance structures (Theesfeld 2010). The national water act (1998) of the Republic of South Africa is not widely recognized as the most comprehensive water law in the world even though it is the highlight of socio-political events; socially it is still recent in most sites although the law was implemented 15 years ago (Schreiner and Koppen 2002). Regulations for use include quantity limitations, drilling permits and licensing, use licenses, special zone of conservation and reporting and registering requirement. In general when drilling and well construction are done commercially they increasingly fall under the scope of regulatory legislation. This paper will focus mostly on traditional and mental models; procedures that a certain community is dependent on should be taken into account before replacing with technological advanced tools. Consultation of the public can cause conflicts which lead to poor groundwater management. Keywords: Groundwater governance, policy, policy instruments.
Groundwater governance: where science, economics and politics meet	Nicolette	Vermaak		2015	groundwater governance
Abstract POSTER Researching a subject on the internet the slogan "Water flows upstream to money" popped up. The context was drought, and the meaning clear. If politics come into play as well, it would seem that science is relegated to a distant third place. The proclamation of the National Water Act, of 1998 (Act 36 of 1998), recognized the importance of groundwater and its role in the hydrological cycle and water supply issues. Groundwater governance has grown since then and is becoming increasingly important. One of the most important tenets on which groundwater based is the concept of sustainability. Various definitions of sustainability is used with the best know being "?development which meets the needs and aspirations of the present generation without compromising the ability of future generations to meet their own needs." Even though the basic understanding of sustainability may have been around for much longer than the term, it is the application of the theory in our current context that present us with challenges. Concepts like the precautionary principle, corporate governance and other buzz words that is being used does not always ensure good groundwater governance. One of the greatest problems is often the lack of scientific understanding and knowledge. Groundwater systems tend to be more complex and thus more difficult to manage than surface water. Understanding how groundwater and surface water interact, and that it is actually a linked water resource adds to the complexity. Add to this its importance in the functioning of groundwater dependent ecosystems that is still poorly understood. This article will look at principles for good groundwater governance and the tools that are needed to achieve it. It will finally look at real case studies where scientific considerations fall by the wayside for the requirements of the economy and political goals.
Groundwater and Surface Water Interaction Study for the Ingula Wetland	Christie	Terrell		2015
Abstract The Bedford Dam is the upper storage dam for the Ingula Pumped Storage Scheme and is situated in the Ingula/Bedford Wetland. This wetland has a high structural diversity which supports a unique assemblage of plants and invertebrates. The flow regulation and water purification value is of particular importance as the wetland falls within the Greater Vaal River catchment. Concern was raised with respect to the potential negative impact of the newly constructed dam on the dynamic water balance within the wetland. An assessment of the extent to which groundwater drives / sustains the wetland systems and the water requirements needed to sustain the wetland processes was determined. This includes establishing the impact of the Bedford Dam on the groundwater and wetland systems as well as providing recommendations on management and monitoring requirements. The hydropedological interpretations of the soils within the study area indicate that baseflow to the wetland is maintained through perennial groundwater, mainly recharged from infiltration on the plateau, and was confirmed through isotope sampling and hydrometric measurements. It is apparent that the surface flows in the main wetland are fed by recent sources, while the subsurface layers in the wetland are sustained by the slower moving near-surface and bedrock groundwater. The movement of groundwater towards the wetland is hindered by the numerous dykes creating a barrier to flow. Nevertheless, there seems to be a good connection between the groundwater sources in the upland and the surface drainage features that conduct this water to the contributing hillslopes adjacent to the main wetland. The surface flows of the main wetland are sustained by contributions from tributary fingers. The discharge out of the wetland is highly seasonal
Packer Testing and Analytical Modelling For Groundwater Inflow Estimation for Proposed Shafts	Robel	Gebrekristos		2015
Abstract Two ventilation shafts were proposed to be excavated to depths of 100 and 350 m to intersect an underground mine, in the Bushveld Complex. The area is made up of fractured aquifers and the assignment was to identify the exact positions of the permeable zones within the shafts profiles as well as estimate the groundwater inflow rates at every 5 m interval along the shafts profiles. The project was budget and time constrained and therefore the preferred hydrogeological characterisation techniques, particularly the percussion drilling, aquifer testing and numerical modelling could not be conducted. The study was completed by conducting packer tests in HQ sized holes drilled at the exact positions of the proposed shafts. The packer test data was then interpreted using Thiem equation, a modification of Darcy Equation for radial flow, to estimate the steady state inflow rates into the shafts. Transient state flow is more challenging to calculate analytically, as it is time and aquifer storage dependent. However, transient state flow in shafts exists for the first 10 - 15 days only and is short lived. Thereafter, a steady state flow occurs where the rate is nearly fixed for the rest of the life of mine, unless new external stresses, such as mine dewatering, takes place within the radius of influence. Six months later the shafts were excavated and the permeable zones were encountered at the exact positions as predicted using the packer testing. In addition, the inflow rates calculated using analytical modelling was successful in estimating the inflow rates recorded after the shafts were excavated. The packer testing and analytical modelling was therefore effective in assisting the mine to plan the necessary pumps and management plans within the allocated budget and timeframe.
Interannual variability in rainfall isotope composition as a tracer of spring water flow.	Roger E	Diamond	Western Cape	2015	Table Mountain Group, springs, rainfall isotopes
Abstract Table Mountain reaches 1086m elevation, the upper half of which comprises Table Mountain Group (TMG) quartzite with extensive fracture porosity. The lower half of the mountain comprises a mixture of Cape Granite intruded into Malmesbury Group metapelites, both of which are poor aquifers, but are in places overlain by scree slopes predominantly composed of TMG quartzite boulders. The region experiences a Mediterranean climate with warm, dry summers and cold, wet winters, with rainfall ranging from 600-1600mm/a depending largely on proximity to the mountain. Several springs issue from the slopes of the mountain, ranging in elevation from 15-410masl and in flow from non-perennial to 30L/s. Water chemistry reveals very little about spring water flow, as the waters have very low dissolved solids. Samples of 10 of these springs were taken twice per year for 3 years while rainwater was sampled at 120masl at the University of Cape Town (UCT) and at 1074masl at the Upper Cableway Station. These samples were analysed for oxygen and hydrogen stable isotope composition, mostly by mass spectrometer, but also by laser spectroscopy. The isotope results reveal an altitude gradient between the two rainfall stations of -0.075?/100m for ?D and -0.48?/100m for ?18O. Employing this isotope gradient, the average recharge altitude for the springs is 304masl, compared to an average discharge altitude of 156masl. Using this difference in altitude and the average slope of the terrain, a typical flow path of 1km from recharge to discharge point can be derived. Additionally, there are shifts in the weighted annual mean isotope composition of rainfall at UCT. For the years 2010-2012, the shifts are paralleled by similar shifts in the mean isotope composition at the springs for each of those years. This suggests rainfall discharges in the same winter season it has been recharged. In combination with the evidence for long term reliability of some of the springs over the dry season and during droughts, this suggests a layered flow of groundwater in the scree aquifer, allowing both long term steady discharge of deeper groundwater, as well as short term discharge of recently recharged rain. In combination with the flow path derived above, hydraulic conductivities in the realm of 10-20m/d can be calculated for the scree aquifers.
Water Use Registration: A reflection of Groundwater Governance of the Verlorenvlei Catchment in the Sandveld	Imelda	Haines	Sandveld	2015	patato, RAMSAR, good governance
Abstract Introduction: Verlorenvlei catchment in the renowned potato Sandveld area is shared by three main towns where agriculture is a primary economic activity. This semi-arid catchment, receives low winter rainfall, but has a dynamic groundwater system providing almost all water services in the catchment and sustaining the acclaimed Verlorenvlei RAMSAR site. There have been recurring concerns of land use as a potential threat to water resources and the sustainability of Verlorenvlei RAMSAR site. The Minister of Water and Sanitation as custodian of water resources requires that surface water use less than 18 250 m3 and ground water use less than 3 650 m3/a to be granted under general authorization. All water use above such general authorization volumes is to be registered (Government Gazette No. 20526 of 1999). Water use registration, is identified as a tool used to achieve the effective management and governance of water resources. Water use above general authorization, is associated with larger scale land use activity, which may have an impact on water resources and the environmental at large. The following study, seeks to examine and compare catchment water use for land uses, to catchment water availability using water use registration data. Comparing water allocation and catchment capacity, this study further seeks to explore the effectiveness of water use registration in achieving good governance of water resources. Purpose: The purpose of this study was to determine effectiveness of water use registration in promoting good governance in the Verlorenvlei catchment Results: Of 124 registered water users identified in the Verlorenvlei catchment, only two of these water users are within the legislative limit outlined by Government Gazette No. 20526 of 1999. Overall, permissible water use is 447 547 259.5 m3/a, over 10 times the catchment capacity of 40 000 000 m3/a. Conclusion: Overall, excessive water use for land use activity is observed within the catchment, despite provision of legislature guiding against excessive water use. Increased water use registration, does however correlate with improved land use practices for agricultural production (Potato SA, 2014) suggesting probability of good governance. Lastly, there is a need for monitoring; improved water and land use efficiency, Integrated Water Resources Management and good governance in the catchment.
The use of Hydrogeochemical Analysis Model to assess groundwater quality for drinking and agricultural use in Heuningnes Catchment	Portia Leah	Mokoena	Western Cape	2015
Abstract POSTER The study aims at using hydrogeochemical model to establish groundwater quality in shallow and deep aquifers in Heuningnes Catchment which is located within Bredasdorp in the Western Cape Province. The catchment is positioned at latitude of 34o42'50"S and longitude 20o07'13"E. The area is about 1400km2 has vleis, lakes and pans and its predominant formation is sedimentary rocks of Table Mountain and Bokkeveld Groups sitting on a crystalline basement of the Malmesbury granites. Comprehensive characterisation of the hydrogeochemical evolution is lacking and the current study argues that the use of hydrogeochemical Analysis Model (HAM) has potential to establish water-type, water source, water mixing/rock-water interactions, salinity, saturated adsorption ratio and hardness-softness of that predominant hydrochemical facies in the study area in addition to assessing the compliance of such water to WHO and South Africa water quality guidelines for drinking and agricultural use. Groundwater samples will be collected in 45 different locations (wellpoints/shallow wells, boreholes and wetland as end member) using in-situ sampling techniques to measure pH, electrical conductivity, total dissolved solids and temperature. Turbidity, total hardness, calcium, chloride and bicarbonate will be analysed using analytical chemistry methods including titrimetric method. Magnesium, potassium, sodium, nitrate and phosphate analysed by Atomic Absorption Spectrophotometer whilst sulfate will be analysed using spectrophotometer. Graphical methods such as piper diagram will be used to present the results to determine water-type, water freshness/hardness, water source, water mixing/rock-water interactions, salinity, saturated adsorption ratio and hydrogeochemical processes. The results from the present study are envisaged to inform formulation of science-based interventions strategies that will lead to sustainable utilization and management of the water resources in the area to improve the livelihoods of people and environmental integrity. Key words: Groundwater quality, Heuningnes Catchment, hydrogeochemical Analysis Model, Piper diagrams, Hydrogeochemistry
Investigation of the probable infiltration from the wastewater ponds and its impact on the water quality of Pleistocene aquifer	EL-Said	Ahmed AL-Sayed Ragab	El Sadat	2015	Electrical Resistivity Tomography
Abstract 2-D Electrical Resistivity Tomography (ERT) and hydrochemical study have been conducted at El Sadat industrial city. The study aims at investigating the area around the waste water ponds to determine the possibility of water percolation from the wastewater (oxidation) ponds to the Pleistocene aquifer and to inspect the effect of this seepage on the groundwater chemistry. Pleistocene aquifer is the main groundwater reservoir in this area, where El Sadat city and its vicinities depend totally on this aquifer for water supplies needed for drinking, agricultural and industrial activities. In this concern, 7 ERT profiles were measured around the wastewater ponds. Besides, 10 water samples were collected from the ponds and the nearby groundwater wells. The water samples have been chemically analyzed for major cations (Ca+2, Na+, K+, Mg+2), major anions (Cl-, CO3-2, HCO3-, SO4-2), nutrients (NO2-, NO3-, PO4-3) and heavy elements (Cd, V, Cr, Zn, Ni, Cu, Fe, Mn, Pb). Also, the physical parameters (pH, Alkalinity, EC, TDS) of the water samples were measured. Inspection of the ERT sections shows that they exhibit lower resistivity values towards the water ponds and higher values in opposite sides. Also, the water table was detected at shallower depths at the same sides of lower resistivity. This could indicate a wastewater infiltration to the groundwater aquifer near the oxidation ponds. Correlation of the physical parameters and ionic concentrations of the wastewater (ponds) samples with those of the groundwater samples indicates that; the ionic levels are randomly varying and no specific trend could be obtained. Also, the wastewater samples shows some ionic levels lower than those detected in other groundwater samples. Besides, the nitrate level is higher in samples taken from the cultivated land than the wastewater samples due to the over using of nitrogen fertilizers. Then, we can say that the infiltrated water from wastewater ponds are NOT the main controller of the groundwater chemistry in this area, but rather the variable ionic concentrations could be attributed to local, natural and anthropogenic processes.
Numerical Modelling of Groundwater Flow Between a Complex Underground Mine and an Operational Opencast Mine	Altus	Huisamen	Mpumalanga	2015
Abstract The management of groundwater inflows into an opencast colliery in Mpumalanga is normally fairly easily achievable due to low inflow volumes and high evaporation rates. But, when flooded underground mine workings are encountered, groundwater inflow complexity increases dramatically. Understanding, predicting and managing groundwater inflow under these conditions can be challenging and highly complex. While normal opencast inflows are easily modelled these connected mines are pushing numerical models to their limits. This case study aims to illustrate an approach based on a finite difference model that has been used successfully in a South African coal mine. Based on a study at a colliery near Ermelo, Mpumalanga, the understanding and conceptualisation of the aquifer geometry, geological structures, hydrogeology, defunct underground mine geometry and interconnection between opencasts and the underground, proved to be vital, not only in calibration of the model, but also in the construction of the various layers and calculation of flow volumes between the various sources and sinks. This also aided greatly in constant source contaminant transport modelling to trace which mining areas may have a contamination effect on each other or the surrounding aquifer. In constructing the numerical flow model, the underground mine geometry was found to intersect various layers in the MODFLOW based model and pinching out in some areas. Due to the requirement of MODFLOW that layers should be continuous with no pinchouts to the model boundaries, this presented a notable challenge in the model construction. Therefore, mine geometry was divided into various slices, fitting within the hydrogeological layers, but still retaining the original geometry. The layers were then further divided laterally using different materials to represent the mine hydraulic properties and aquifer properties respectively, ensuring that the lateral distribution of materials also represents the underground mine geometry accurately. Using this model construction, the calculated mean residual head for the simulation of the current situation was found to be less than 3m while the simulation of the current mining situation with no underground mine present, yielded a mean residual head of approximately 10m. Additionally, inflows measured in the opencast penetrating the underground were measured at approximately 1000m3/d while the calibrated model calculated inflows of 1160m3/d, while simulating the current mining situation including the defunct underground. The current decant from the defunct underground, to the southeast of the site, was calculated as 1.9 L/s by the model while the measured rate was just over 1 L/s. Also, as expected, the dewatering of the opencast penetrating the flooded, defunct underground mine, was calculated to predominantly impact an underground mine compartment, isolated by underground seals, as opposed to the aquifer, which has a much lower hydraulic conductivity. {List only- not presented}
A framework for conjunctive use at local government level	Kornelius	Riemann		2015	Conjunctive use, IWRM, framework
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.
Hydraulic fracturing and Water Resources: Separating fact from fiction	Lizanne	Bredenkamp	Karoo	2015	Shale gas, Dolerite Intrusions
Abstract Shale gas in South Africa can be a game changer for the Karoo and South Africa economy but it may have a devastating effect on the environment. The Karoo communities is highly reliable on groundwater for their stock, irrigation and also for domestic use. Knowing the process and the potential impacts of gas-well drilling and fracturing on shallow groundwater systems beforehand different appropriate studies can be done before any hydraulic fracturing can took place in South Africa. The biggest concerns with hydraulic fracturing is that the fracturing fluids will flow and discharge into shallow aquifers due to the high pressure used or the produced water mixed with deep saline water may discharge into the environment. This paper presents a baseline dataset that will be a reference point against which any future changes in groundwater concentrations can be measured. The Karoo basin with its numerous dolerite intrusions make it unique and different from other countries. These dolerite intrusions are associated with high yielding boreholes because of the fractured contact. The Karoo Basin may be under artesian conditions, which imply that any pollutant might migrate upwards in the Karoo. The understanding of key attributes for characterising groundwater of Karoo Aquifers is most importantly the depth to water level, the yield, and groundwater quality.. The understanding of these characteristics will help to close possible legislative loopholes regarding fracturing. This paper establish an interactive database to obtain full understanding of the hydrogeology of the Karoo to be able to quantify how much water is available in the Karoo and who is the users. Not only the quantity of the water in the Karoo, but also quality and age/origin by making use of different isotopes in conjunction with basic macro chemistry. This will allow for a broader picture before any unconventional gas mining in the Karoo takes place and it can be used to identify any future changes in groundwater quality and quantity of the Karoo aquifers.
Investigating the influence of fine ash leaching in a tailings dam on the underlying aquifers	Paul JH	Lourens		2015	primary aquifers
Abstract Groundwater in South Africa is the most important source of potable water for rural communities, farms and towns. Supplying sufficient water to communities in South Africa becomes a difficult task. This is especially true in the semi-arid and arid central regions of South Africa where surface water resources are limited or absent and the communities are only depended on groundwater resources. Due to a growing population, surface water resources are almost entirely being exploited to their limits. These factors, therefore, increases the demand for groundwater resources and a more efficient management plan for water usage. For these reasons, the relation between the geology and geohydrology of South Africa becomes an important tool in locating groundwater resources that can provide sustainable quantities of water for South Africans. It was therefore decided to compile a document that provides valuable geohydrological information on the geological formations of the whole of South Africa. The information was gathered by means of interviews with experienced South African geohydrologists and reviewing of reports and articles of geohydrological studies. After gathering the relevant information, each major geological unit of South Africa together with its geohydrological characteristics was discussed separately. These characteristics include rock/aquifer parameters and behaviour, aquifer types (primary of secondary), groundwater quality, borehole yields and expected striking depths, and geological target features and the geophysical method used to locate these targets. Due to the fact that 90 % of South Africa's aquifers are classified as secondary aquifer systems, groundwater occurrence within the rocks of South Africa is mainly controlled by secondary fractures systems; therefore, understanding the geology and geological processes (faulting, folding, intrusive dyke/sills & weathering) responsible for their development and how they relate is important. However, the primary aquifers of South Africa (Coastal Cenozoic Deposits) should not be neglected as these aquifers can produce significant amounts of groundwater, such as the aquifer units of the Sandveld Group, Western Cape Province. Drilling success rates and possibility of striking higher yielding boreholes can be improved dramatically when an evaluation of the structural geology and geohydrological conditions of an area together with a suitable geophysical method is applied. The ability to locate groundwater has been originally considered (even today) a heavenly gift and can be dated back to the Biblical story of Moses striking the rock to get water: "behold, I will stand there before thee there upon the rocks thou shalt smite the rock and there shall come water out of it" (Exodus 17:6).
Parameter estimation for artesian aquifer in Table Mountain Group Aquifer by analytical and numerical simulation methods	Xiaobin	Sun	Western Cape	2015
Abstract Accurate parameter estimation for fractured-rock aquifer is very challenging, due to the complexity of fracture connectivity, particular when it comes to artesian flow systems where the potentiometric is above the ground level, such as semi-confined, partially confined and weak confined aquifers in Table Mountain Group (TMG) Aquifer. The parameter estimates of these types of aquifers are largely made through constant-head and recovery test method. However, such a test is seldom carried out in Table Mountain Group Aquifer in South Africa due to a lack of proper testing unit made available for data capturing and appropriate method for data interpretation. An artesian borehole of BH 1 drilled in TMG Peninsula Formation on the Gevonden farm in Western Cape Province was chosen as a case study. The potentiometric surface is above the ground level in rainy season, while it drops to/below ground level during the dry season. A special testing unit was designed and implemented in BH 1 to measure and record the flow rate during the free-flowing period, and the pressure changes during the recovery period. All the data were captured at a function of time for data interpretation at later stage. Curve-fitting software developed with VBA was adopted for parameter estimation based on the constant-head and recovery tests theories. The results indicate that a negative skin zone exists in the immediate vicinity of the artesian borehole, and the hydraulic parameters estimates of transmissivity (T) ranging from 6.9 to 14.7 m2/d and storativity (S) ranging from 2.110-5 to 2.110-4 appear to be reasonable with measured data collected from early times. However, due to formation losses, the analytical method failed to interpret the data collected at later times. Consequently the analysed results by analytical solution with later stage data are less reliable for this case. The MODFLOW-2000 (Parameter Estimation) package developed by USGS was also adopted to determine these parameters for the same aquifer. It approves that there exist formation losses, which leads to the aquifer response distinctly different at later stage of overflow and recovery tests. The aquifer parameter estimates with early time data of tests by analytical and numerical methods show that there is generally good agreement. However, significant errors could be generated by analytical method applied where there is occurrence of well or formation losses, while these restrictions could be overcome by applying a numerical method.
An Acid Base Accounting study of the coal-bearing formations in the Waterberg coalfield	Lore-Mari	Deysel	Karoo	2015	coal mine, sulphur, acid base accounting
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.
Use Of Environmental Isotopes To Determine Hydraulic Connectivity Across The Surrounding Aquifers At Majuba UCG	Gundo	Mathoho		2015
Abstract Environmental isotope techniques have been successfully applied in the field of hydrogeology over the last couple of decades and have proved useful for understanding groundwater systems. This paper describes a study of the environmental isotopes for Oxygen (18O) and Hydrogen (1H, 2H-Deutrium, 3H-Tritium) obtained from various points in and around the underground coal gasification (UCG) site in Majuba, South Africa. UCG is an alternative mining method, targeting deep coal seams that are regarded as uneconomical to mine. The process extracts the energy by gasifying the coal in-situ to produce a synthetic gas that can be used for various applications. The site consists of shallow, intermediate and deep aquifer systems at a depth of 70m, 180 and 300m respectively. The intermediate aquifer is further divided into the upper and lower aquifer systems. Samples were taken from each aquifer system together with supplementary samples from the Witbankspruit and an on-site water storage dam. A total of 15 samples were submitted for isotope analyses. By investigating the various isotopic signatures from all the samples taken, it will be possible to determine if there are similar or contrasting isotopic compositions by deducing possible water source for each sample due to isotopic fractionation caused by physical, chemical and biological processes. This will also be supported by deducing the mean residence time (MRT) for each water source sampled based on the Tritium data as well as the chemistry data already available for different sources. The chemistry data established linkages between the upper and lower intermediate aquifers.{List only- not presented} Key words: Environmental isotopes, UCG, Water source, Isotope fractionation
Application of GIS Mapping Techniques to Classify Karoo Aquifers	Mildred	Goes		2015
Abstract POSTER As the National Water Act has evolved to provide for more effective and sustainable management of our water resources, there has been a shift in focus to more strategic management practices. With this shift come new difficulties relating to the presentation of sensitivity issues within a spatial context. To this end it is necessary to integrate existing significant spatial layers into one map that retains the context, enables simple interpretation and interrogation and facilitates decision making. This project shows the steps taken to map and identify key groundwater characteristics in the Karoo using Geographic Information Systems (GIS) techniques. Two types of GIS-based groundwater maps have been produced to assist with interpretation of existing data on Karoo Aquifer Systems in turn informing the management of groundwater risks within Shell's applications for shale gas exploration. Aquifer Attribute and Vulnerability maps were produced to assist in the decision making process. The former is an aquifer classification methodology developed by the project team, while the latter uses the well-known DRASTIC methodology. The overlay analysis tool of ESRI's ArcGIS 10.1 software was used, enabling the assessment and spatial integration of extensive volumes of data, without losing the original detail, and combining them into a single output. This process allows for optimal site selection of suitable exploration target areas. Weightings were applied to differentiate the relative importance of the input criteria. For the Attributes maps ten key attributes were agreed by the project team to be the most significant in contributing to groundwater/aquifer characteristics in the Karoo. This work culminated in the production of a series of GIS-based groundwater attributes maps to form the Karoo Groundwater Atlas which can be used to guide groundwater risk management for a number of purposes. The DRASTIC model uses seven key hydrogeological parameters to characterise the hydrogeological setting and evaluate aquifer vulnerability, defined as the tendency or likelihood for general contaminants to reach the watertable after introduction at ground surface.
Validating Hydrological Models In A Data Scarce Country- Getting The Right Results For The Right Reasons.	Jane L	Tanner		2015
Abstract This study explores some of the principle issues associated with quantifying surface and groundwater interactions and the practical application of models in a data scarce region such as South Africa. The linkages between the various interdependent components of the water cycle are not well understood, especially in those regions that suffer problems of data scarcity and there remain urgent requirements for regional water resource assessments. Hydrology (both surface and groundwater hydrology) is a difficult science; it aims to represent highly variable and non-stationary processes which occur in catchment systems, many of which are unable to be measured at the scales of interest (Beven, 2012). The conceptual representations of these processes are translated into mathematical form in a model. Different process interpretations together with different mathematical representations results in the development of diverse model structures. These structural uncertainties are difficult to resolve due to the lack of relevant data. Further uncertainty is introduced when parameterising a model, as the more complex the model, the greater the possibility that many different parameter sets within the model structure might give equally acceptable results when compared with observations. Incomplete and often flawed input data are then used to drive the models and generate quantitative information. Approximate implementations (model structures and parameter sets), driven by approximate input data will necessarily produce approximate results. Most model developers aim to represent reality as far as possible, and as our understanding of hydrological processes has improved, models have tended to become more complex. Beven (2002) highlighted the need for a better philosophy toward modelling than just a more explicit representation of reality and argues that the true level of uncertainty in model predictions is not widely appreciated. Model testing has limited power as it is difficult to differentiate between the uncertainties within different model structures, different sets of alternative parameter values and in the input data used to run a model. A number of South African case studies are used to examine the types of data typically available and explore the extent to which a model is able to be validated considering the difficulty in differentiating between the various sources of uncertainty. While it is difficult to separate input data, parameter and structural uncertainty, the study found that it should be possible to at least partly identify the uncertainty by a careful examination of the evidence for specific processes compared with the conceptual structure of a specific model. While the lack of appropriate data means there will always be considerable uncertainty surrounding model validation, it can be argued that improved process understanding in an environment can be used to validate model outcomes to a degree, by assessing whether a model is getting the right results for the right reasons.
A Study Of Interaction Between Groundwater And Surface Water Using Environmental Isotopes, Hydrochemistry And Feacal Coliform BA	Bongizenzo	Nyawo		2015
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.
The Complexity of Baseline Monitoring in Unconventional Gas Projects	Richard	O'Brien	Karoo	2015
Abstract The subsurface has been likened to a maze due to the intricate and often disconnected pathways contained even in unconsolidated and relatively homogeneous aquifer systems. The weathered fractured aquifers in the Karoo offer unique challenges to those planning monitoring campaigns and provide opportunities for the research community to identify innovative solutions. Careful thought needs to be given to the objectives of monitoring as these can change the requirements of the work. Other important considerations are the location and design of monitoring wells which often needs to be tailored to site specific conditions while the selection of determinands to be analysed introduces yet another layer of complexity. These include questions around the relevant detection limits, representative sampling methods and a host of other aspects. Following prescribed approaches designed for managing traditional industrial processes may not be relevant even though these approaches are based on decades of research and learning from past experience, both good and bad. Careful consideration of the technical detail in advance of beginning any monitoring in the field is essential and even then, as in any hydrogeological assessment, a level of uncertainty will always remain. This presentation will cover the status of planning work on Karoo aquifer characterisation and geochemical assessment of the ambient or baseline conditions. Significant effort continues to be made to tailor fieldwork to site specific conditions and be ready to collect a representative data set when conditions allow. {List only- not presented}
Investigating the influence of fine ash leaching in a tailings dam on the underlying aquifers	Josepha	Zielke		2015
Abstract Fine ash is a by-product generated during coal combustion and gasification. It is often disposed of as slurry and stored on tailings dams over long periods of time, where it is exposed to weathering. Weathering causes soluble ions to go into solution and to be transported along preferred pathways through the tailings dam. This study was conducted to assess the leaching behaviour of fresh and weathered fine ash and to evaluate the impact on the underlying aquifers. A kinetic test was conducted over 21 weeks to analyse the leachate composition of progressively-aged fine ash and to calculate the release rates for major ions and trace metals of environmental concern. The leachate composition was compared to the groundwater composition of the underlying aquifers to assess the environmental impact of long term ash leaching. The study showed that the release rate of Ca decreased with increasing depth and age of the fine ash. The release rate of Mg, Na, K, Mo, V, Ba, Cr and Mo increased slightly between 22 m and 28 m in the tailings dam. Aluminium had a decreasing release rate from 28 m depth onwards. It was concluded that fine ash leaching influenced the water composition of the underlying aquifers because similarities were observed in the water type trend. The shallow aquifer south of the tailings dam contained Ca/Mg/SO4/Cl/NO3 water with a significant increase in Ca, Mg, Na, Cl and SO4 over time. These ions were expected to be found in the pollution plume due to their high release rate observed in the fine ash. The deeper aquifer northeast and south of the tailings dam showed a reverse trend of decreasing Ca, Mg and NO3 with time. This is possibly due to decreasing release rates in the aging fine ash and due to the cation exchange capacity (CEC) of the aquifer retarding the movement of Ca and Mg in the pollution plume. The shallower aquifer northwest of the tailings dam showed a decrease in Ca and Mg but an increase in K, while the water composition of the deeper aquifer increased in Ca, Mg, Na, K and Cl. This indicates that the pollution plume moved from the shallower to the deeper aquifer and that most of the Ca and Mg content in the fine ash has been leached from the tailings dam after more than 30 years of storage. The study confirmed that leaching of elements from the fine ash tailings dam had a negative influence on the underlying aquifers and that the clay lining was not sufficient in retaining the leachate.
Characterise and quantify contamination within the Crocodile (West) and Marico Water Management Areas, South Africa	Chazanne	Allison	Hartebeespoort Dam	2015	Heavy metal, chemical fingerprint, geochemistry
Abstract Define chemical signatures from river waters collected in the Crocodile (West) and Marico Water Management Areas, South Africa. Samples were analysed for anion complexes using Ion Chromatography (IC) and major and trace element chemistry using quadrupole Inductively Coupled Plasma-Mass Spectrometry (q-ICP-MS). Results are used to define the various chemical signatures resulting from activities within the study area which include mining, agriculture, industry, residential and domestic, and recreational usage and to differentiate the 'background' that arises from the natural geological heterogeneity. The aim of this characterisation is to fingerprint the chemical signatures of various anthropogenic activities irrespective of background. Results from this investigation have been mapped using GIS to visualise the data across the study area. Based on the results, the contamination sources within the area can be identified and ranked in terms of their contribution to the total effective contamination received at Hartebeespoort Dam. {List only- not presented}
'Best Practice' Approach To Undertaking Detailed Groundwater Impact Assessment Studies For Proposed Solar Energy Plants	Sheila	Imrie	Jacobsdal, Free State	2015	Solar energy, EIA, best practice, groundwater management
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.