Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 151 - 200 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort descending	Keywords
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
Knowledge comes with trial, error and time: The Langebaan Road story	Nicolette	Vermaak	Western Cape	2015
Abstract When planning an experimental setup in the laboratory, it is very important and possible to control all the variables so that one can manipulate particular variables at a given time. Experimental setups under natural conditions could be a challenging task. The success of an experiment depends to a large extent on the correct understanding of the functioning of a natural system. If the conceptual understanding of the natural system is erroneous, it is likely that unexpected results could be achieved. This was the case with the artificial recharge pilot project that was done in 2008 and 2009 at the Langebaan Road wellfield just outside Hopefield in the Western Cape. Years of research gave scientists a fairly good idea of the way in which the aquifer system functioned, especially since the establishment of the well field. This provided information of the response of the aquifer unit to large scale abstraction. The Langebaan Road aquifer unit is a multilayered system with a lower aquifer composed of Elandsfontyn gravel overlaying a bedrock layer of either granite of the Vredenburg or Darling plutons of the Cape Granite Suite or Malmesbury shale. The bedrock was considered impermeable. The upper aquifer layer was composed of mostly the Varswater Formation with peat and clay of the Elandsfontyn Formation forming the confining layer between the two aquifer layers. The extent of the different layers of the aquifer unit was plotted with a fair amount of accuracy and the clay layer was considered to be continuous between the two aquifer layers. Monitoring data for the area was done since 1974 with a gap in data-set between 1991 and 2001. Despite all the data from geophysical work, boreholes drilled, and the monitoring record, the research done prior and during the artificial recharge pilot project in 2008 and 2009 the aquifer units did not respond quite as anticipated. The Artificial Recharge (AR) pilot project team concluded that the aquifer units responded in a particular manner as opposed to the expected response according to the data and conceptual model at hand. It was thus clear that there are gaps in the conceptual model of the aquifer systems in the bigger Lower Berg River Valley that include the Langebaan Road, Elandsfontein and other aquifers that needed to bridge before another pilot test is attempted. Although the artificial recharge pilot project did not yield the expected results, valuable lessons were learned. This article will look at the conclusions and recommendations of the research done on the pilot project and attempt to evaluate the monitoring data (water levels, chemistry and rainfall) from the period just before the beginning of the AR pilot project. The monitoring data would be manipulated using the following techniques
Cadmium contamination of groundwater in South Africa - the potential hazard of phosphate fertilizers	Dylan	Blake	Hermanus	2015	Cadium contamination
Abstract Cadmium is a highly mobile and bioavailable non-essential element that is toxic to plants, and is an animal and human carcinogen (affecting the kidneys and bones in vertebrates). Since the late-1970s the effects of cadmium on the environment have become a global issue of concern, and many countries have conducted evaluations on the exposure of their populations to cadmium in phosphate fertilizer (a major non-point source of anthropogenic cadmium). A scoping project, funded by the Water Research Commission, aimed to review cadmium contamination of South African aquifer groundwater systems (predominantly) via phosphate fertilizer use. Topics reviewed included fertilizer composition and types, metal speciation, metal mobility in soil and groundwater systems, metal bioavailability, health and environmental effects, and local South African contamination case studies. A preliminary study site, namely the greater Hermanus region, was identified for trace metal and groundwater quality studies (which incorporated urban and agricultural areas in various hydrogeological settings). Hermanus was selected due to: 1) the discovery of cadmium concentrations of 20 ?g/l (in comparison to the SANS 241-1:2011 cadmium limit of 3 ?g/l) in a golf estate irrigation borehole, during drilling and test-pumping of the borehole at the end of 2012
Simulation of Underground Mine Flooding with EPANET and MODFLOW	Stephen	Fonkem	Free State	2015	mine shaft, flooding, modelling, MODFLOW
Abstract Underground mine water rebound prediction in its simplest form can be simulated linearly by comparing the volume of the mined ore with long-term average recharge rate to obtain an estimate of the time which will elapse before the workings are full to their decant elevation. This type of linear interpolation of rising water levels can lead to an over estimation or an underestimation of the date when mine voids will flood to the critical levels. This is due to the fact that this method cannot account for the variability and interconnection between different mine voids and also does not consider the change in storage over time which is an important factor. In an abandoned underground water environment, water is stored in flooded mine stopes (tanks) and flows through a network of haulages (pipes). Due to the dip and strike of the ore body, the mined stopes are extensively interconnected on multiple levels and bounded by faults and dykes, so that water rising within any one tank will display a common level throughout that tank. At certain elevations, adjoining tanks may be connected via a discrete "overflow point", which may be a holding or permeable geological features. Water level rise during flooding is a function of head-dependent inflows from adjoining mine aquifers and/or other tanks, and the distribution of storage capacity within the tank. The process of flooding occurs independently in two (or more) adjoining tanks until such time as the water level in one or more of the tanks reaches an overflow point. Inter-tank transfers of water will then occur until the difference in head between the two tanks either side of each overflow point is minimised. To apply the conceptual model stated above, EPANET 2 was used to predict the risk of flooding of a mine shaft, in the Free State Goldfields, if dewatering is discontinued. Considerations on stope volumetric calculations, haulage interconnections, modelling assumptions and predictions, are presented.
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
Understanding Site Hydrology of the Northern Kwa Zulu Natal Anthracite Coal fields	Hendrik	Botha	KwaZulu-Natal	2015	coal mining, AMD, mine closure
Abstract POSTER Investigations have shown that receiving water bodies, which mainly include rivers, streams and the more complicated geohydrological system, are part of the primary end receivers of harmful contaminants from identified coal mining waste bodies. Some of these potential dangers include acid mine drainage (AMD) and sulphur mine drainage (SMD) which have dire effects on the surroundings. The need for a cost effective methodology to assess site hydrology and geohydrology, to understand the associated legal responsibility of contaminated streams and aquifers, is recognised. In the compilation of this paper the unique nature of South African legislation and policies are implemented in the development of a logical approach towards mine closure specifically in the field of groundwater assessments. Furthermore, this paper explores co-disposal of discard and slurry material and the environmental impact of co-disposed wastes is assessed. The unique geological attributes of the KZN coal fields and the geochemical research results found indicates that on its own discard has great potential to produce long term SMD and that slurry has lower SMD potential. Co-disposed results are promising and buffering against long term chemical changes are noted. The final product of this approach constantly considered site hydrogeology, related impacts, risks and liabilities. This gave more clarity on aspects related to the principles followed to identify objectives for sustainable mine closure and to adopted a philosophy of mine closure as a hydrogeological concept. Overview of methods that could be used for mitigation of polluted aquifers and a brief site specific application is discussed with the aim to achieve the key deliverable which focuses on methods to scientifically assess sources, pathways and receivers. Ultimately this process has led to the development of a logical approach towards mine closure for groundwater assessment and remediation in the typical anthracite mine environment.
An assessment of the contribution of surface and subsurface flows to river flows of the Sandspruit in the Berg River Catchment,	Matthew	Damons	Western Cape	2015
Abstract Studies showed that the primary origin of salinity in river flows of the Sandspruit in the Berg Catchment located in the Western Cape Province of South Africa was mainly due to the weathering of the shales, while atmospheric deposition contributed a third of the total salinity. The salts are transported to rivers through surface runoff and subsurface flow (i.e. throughflow and groundwater flow). The purpose of this study was to determine the relative contributions of subsurface flow and surface flows to total flows in the Sandspruit River, Berg Catchment. Three rain events were studied. Water samples for two rain events were analyzed for environmental tracers ?18O, Silica (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component hydrograph separation were ?18O and SiO2. These tracers were selected as Ca2+ and Mg2+ provided inconsistent contributions of both subsurface flow and surface flow. Two component hydrograph separations indicated that groundwater is the dominant contributor to flow, while surface runoff mainly contributes at the onset of the storm event. Groundwater response to precipitation input indicated that boreholes near the river have a greater response than boreholes further away from the rivers, which have minor response to the input of precipitation. Keywords: Stable Isotopes, Sandspruit River, Tracers, Hydrograph separation, Salinity
Combined Vlf-Electromagnetic And Geoelectric Soundings For Mapping Of Groundwater Bearing Fractured Zone At Ibuso, Sw, Nigeria.	Julius	Fatoba	Nigeria	2015	Electromagnetics
Abstract VLF-Electromagnetic and geoelectric soundings were carried out at Ibuso-Gboro area via Ibadan, Oyo state. The objective was to delineate the groundwater potentials of the area. VLF-Electromagnetic method was adopted for reconnaissance survey with a view to locating bearing fractured zones in the basement bedrock. Sixteen (16) VLF-Electromagnetic profiles whose length ranges from 90-290 m were occupied with station interval of 10 m. The VLF-Electromagnetic results were presented as profiles. Linear features, suspected to be fractured zones, which were from the anomaly curves of the VLF-Electromagnetic were delineated in seven localities along the profiles. These localities were further confirmed by Vertical Electrical Soundings (VES). The seven Schlumberger Vertical Electrical Soundings (VES) were occupied with the electrode spacing (AB/2) varying from 1 m to 100 m with the total spread length of 200 m. The VES data were presented as sounding curves and interpreted by partial curve matching and computer assisted 1-D forward modeling. The results were presented as geoelectric sections, which showed the subsurface geoelectric images. Two out of the seven delineated linear features were test drilled and the fractured zones were met at depth range of between 25.0 m and 38.2 m beneath borehole (1) and 43.0 m and 52.1 m beneath borehole (2) for confined fractured. The pumping test analysis revealed borehole yield varied from 4.8 m3/hr and 5.2 m3/hr, where three (3) abortive boreholes had earlier been drilled. {List only- not presented} Key Words: VLF-Electromagnetic, Linear features, Geoelectric Soundings and Pumping test.
The effects of land use change on surface water/groundwater interactions in the coastal lakes and wetlands of KwaZulu Natal	Jane	Tanner	KwaZulu-Natal	2015
Abstract The eastern coastal plain of South Africa has one of the outstanding natural wetland and coastal sites of Africa. The estuaries are complex and dynamic systems sustained by both groundwater and surface water. These systems are driven primarily by changing sea level and fluctuating climatic conditions, especially river runoff and sedimentation rates, which have been heavily affected by land use change. The largest lake, St Lucia, lies at the bottom end of several rivers, some of which have major afforestation within their catchments. Given that there is a strong connection between surface water and groundwater, a significant driver of the reduced river runoff constitutes reduced groundwater baseflows due to the lowering of groundwater levels in the upstream reaches of the lake's catchments. The remaining large lakes (Lake Sibaya and the Kosi Bay Lake system) are largely groundwater driven and are also affected by increasing impacts on the groundwater sustaining the lakes. There is an urgent need to quantify the impact of land use change, particularly increasing plantation forestry, on these coastal estuarine systems. While previous work has been undertaken to better understand the complex environment, this study examines the coastal environment (Lake St Lucia, Lake Sibaya and the Kosi Bay lakes) in an integrated manner and considers the impacts of various land use activities on the system, both in the 'buffer zone' surrounding the lakes and within the upstream reaches of the river catchments. The study builds on previous investigations and utilises results from existing models as well as available field data. The integrated Pitman Model is used to model the groundwater/surface water dynamics and will be validated using existing numerical model results, observed stream flow, groundwater levels and lake level information. While the model has been established at a quaternary catchment scale for the upstream reaches of the rivers, the downstream reaches have been modelled at smaller spatial scales dictated by groundwater flow directions. A wetland sub-model has been established to represent the numerous and varied wetlands while a specific sub-model has been developed to represent the hydrodynamics of Lake St Lucia and its complex connections to the sea. The currently ongoing study aims to quantify the current and future land use change impacts on the groundwater and surface water resources sustaining the lakes.
Vanwyksvlei: Water provisioning and the Blue Drop system - how effective is this?	Danita	Hohne	Vanwyksvlei	2015	Blue drop standards, water supply challenges
Abstract POSTER Vanwyksvlei had always experienced problems with water supply and quality of drinking water. The town relies on 6 boreholes to supply the town with drinking water. Since 2011 the town was told not to use the water that was supplied from the borehole called Soutgat. This meant that the town could now rely only on the water being supplied from the other 5 boreholes.From 2011 till present the town has experienced a lot of problems regarding water supply, due to the fact that the Soutgat could not be used anymore. Extra stress was put on the other boreholes and these were pumped almost dry. The two aquifers are currently failing and monitoring data since 2009 shows that the water levels of the town are decreasing. Due to low rainfall, recharge to the boreholes are much lower, which exacerbates the problem. This poster will examine the effectiveness of using the Blue Drop system in small towns with limited water supply, at the hand of a case study of Vanwyksvlei. This review will take into account factors such as the point at which water quality is tested in the water supply system, the type of water treatment available for the town and a review the usefulness of certain standards in the Blue Drop system which may indicate failure of supply sources.
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.
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.
Fluoride challenge in groundwater of the Ethiopian Rift Valley and adjacent highlands	Taddesse M	Bollollo	Ethiopia	2015	Fluoride
Abstract The urban and rural communities sources of water for domestic and other uses come from groundwater in most parts of Ethiopia. But the groundwater is not free from challenge. Fluoride is one of those critical problems which are affecting the health of inhabitants of this corridor. There are places where the fluoride contents reach more than 10mg/l. groundwater Treatment plants, changing the water scheme source from surface water and related efforts have been made so far to alleviation such challenges. Fluoride affects bones and teeth by changing its color and easily affected to a number of health complication in the rift valley of Ethiopia. {List only- not presented}
Selling the invisible: Communicating the Groundwater Message	Elanda P	Botes		2015	stakeholder communication, strategy, policy implementation
Abstract As we look at the legislation set out in the driving policies and its guiding frameworks, the need for able institutions to implement strategies that promise and deliver social growth and development, are highlighted. It is only possible to define an 'able institution' through its ability to fulfil its function and enable stakeholders to be part of the decision-making process. (Goldin, 2013) It is this relationship with the collection of stakeholders, in particular strategic water resource stakeholders, their linkages as well as the identification of specific stakeholder issues, that are critically reviewed. The recent Groundwater Strategy (2010) identified key strategic issues/themes. Each chapter listed a number of well thought out recommended actions that address specific challenges in each theme. It is the need for strategic direction (to put these strategies in place "plans into action") and to articulate the specific vision in the right context to the different stakeholders, (internal as well as external) that requires thinking. It is also the uptake of this information by publics (social action and intervention) and the impact of new learning that will need to be measured. This paper will present on a study where the groundwater sector and all its stakeholders are strategically examined to understand the process of communal thinking in the current environmental conditions. It would draw from current communication practices, style, strengths, sector experiences and trends and also reference specific and unique experiences as with the recent WRC Hydrogeological Heritage Overview: Pretoria project. {List only- not presented}
Using modified hydrogeological conceptual model to assess groundwater flooding in Cape Flat Aquifer, South Africa	Masixole	Langa	Western Cape	2015
Abstract POSTER The poster presents the modified hydrogeologic conceptual model that was used to assess the dynamics of groundwater flooding in Cape Flat Aquifer (CFA). The groundwater flooding remains poorly understood in the context of urban hydrogeology of the developing countries such as South Africa. While engineering intervention are relevant to providing solution to such events, continue estimation of hydrogeologic parameters at local scale alongside field measurements remain paramount to plausible modeling the groundwater flooding scenarios that inform such engineering interventions. However, hydrogeologic conceptual model which informs numerical simulation has not been modified to include local scale variation in the CFA to reflect various groundwater units. The current study argues that modifying hydrogeologic conceptual model improves numerical simulations thereby enhancing certainty for engineering solutions. The current study developed groundwater units, set up site specific models and estimated aquifer parameters using pumping step-drawdown and constant rate pumping tests in order to produce a comprehensive modified hydrogeological conceptual model for CFA to inform groundwater modeling at catchment level for water sensitive cities. Key Words: Aquifer parameters, Groundwater flooding, specific models, hydrogeologic conceptual model, groundwater units, numerical simulations, water sensitive cities, CFA
Groundwater Vulnerability Assessment Of A Sedimentary Basin In South Western Nigeria	Saheed	Oke	Nigeria	2015
Abstract The Dahomey Basin is a transboundary sedimentary basin with its eastern half in south western Nigeria. The vulnerability assessment of the basin was carried out to ascertain the degree of the shallow unconfined aquifers sensitive to groundwater contamination through the investigations of the intrinsic properties of lithology over the unconfined aquifer systems. The basin is a multi-layered aquifer system hosting large population densities particularly in Lagos where nearly half of the population rely on the groundwater for domestics and industrial purposes. The vulnerability evaluation involves determining the protective cover and infiltration condition of the unsaturated zone in the basin. This was achieved using the PI vulnerability method of the European vulnerability approach. The PI method specifically measures the protection cover and the degree to which the protective cover is bypassed. Intrinsic parameters assessed were the subsoil, lithology, topsoil, recharge and fracturing for the protective cover. While, the saturated hydraulic conductivity of topsoil, infiltration processes and the lateral surface and subsurface flow were evaluated for the infiltration bypassed. The results were depicted in vulnerability maps. Map of the protective cover ranges from high to very high. This means a very effective cover over the groundwater resources. The I map revealed a low to very low degree of bypass. The final vulnerability map shows that the Dahomey Basin vulnerability ranges from moderate to very low vulnerability areas. Low vulnerability areas were characterised by lithology with massive sandstone and limestone, sub soils of sandy loam texture, high slopes and high depth to water table. The moderate vulnerability areas were characterised by high rainfall and high recharge, low water table, unconsolidated sandstones and alluvium lithology. The vulnerability map was validated with hydrochemical properties of the groundwater. Chloride and TDS concentration of the groundwater reveals high chloride concentration for low groundwater vulnerability areas while low chloride concentrations were observed for moderate vulnerability areas. Low to moderate groundwater vulnerability areas show low TDS concentrations according to the WHO standards except for the coastal areas with relatively higher TDS concentrations. The groundwater vulnerability maps will be a useful tool for planning land use activities which will minimise groundwater contamination and enhance the protection of the Dahomey Basin groundwater resources. {List only- not presented} Keywords: PI method, Dahomey Basin, aquifer vulnerability, protective cover, groundwater resources.
Incorporating participation in groundwater decision support systems for water scarce rural areas: Siloam Village case study	John Ogony	Odiyo	Limpopo	2015
Abstract A groundwater decision support system (DSS) that incorporates stakeholder participation has been developed for Siloam Village in Limpopo Province, South Africa. Residents of Siloam Village are dependent on groundwater to augment inadequate pipe borne water supply. This creates the need for a DSS that ensures efficient and sustainable management and utilization of water. Such a DSS is constituted of both quantitative and qualitative components. The study further proposes framework for implementation of the DSS which incorporates community participation. This will act as a tool for empowering and educating the communities in rural villages so that they can be able to manage their water resources. The developed DSSs will make it possible for Siloam community to operate their water supply systems efficiently taking into account environmental needs and water quality
Aquifer Vulnerability (Recharge, Depth to Groundwater, Soil Type and Slope) to Classify the Vadose Zone of the Limpopo Province.	Olma Tsakani	Makonto	Limpopo	2015
Abstract The aquifer vulnerability of the Molototsi (B81G) and Middle Letaba (B82D) quaternary catchments of the Limpopo Province was assessed to determine the influence of the vadose zone on the groundwater regime. The aquifer vulnerability was assessed by developing a new method, RDSS, which evaluates the vadose zone as a pathway for pollutants by using the following four parameters: Recharge, Depth to water table, Soil type (saturated vertical hydraulic conductivity) and Slope. Recharge was estimated using the Chloride-mass balance method and the depth to the water table was measured in the field using dipmeter. The seepage behavior (soil type) was determined as hydraulic conductivity from in-situ infiltration and percolation testing. (SABS 0252-2:1993 and double ring infiltrometer). The slopes were determined with the digital elevation method using ArcGIS software. The four parameters were overlaid using Weighted Sum, Weighted Overlay and Raster Calculator to produce the vulnerability map. Different weightings were attributed in the methods and the best selected. The results obtained indicated high vulnerability on the lower and upper parts of both catchments. The benefits of the method described are: (a) the easy quantification of the parameters through fairly simple methods and (b) the exclusion of arbitrary index values.
Steytlerville Bulk Water Supply	CJ	Roets	Eastern Cape	2015
Abstract The continuous increase in demand for water from a growing population and associated additional housing projects in the town of Steytlerville in the Eastern Cape Province has resulted in a shortage in water supply from the existing boreholes. In order to supplement the additional demand, a bulk water augmentation scheme using surface water from the Groot Rivier at a point immediately east of the Hadley crossing was implemented. This was done by drilling two large diameter production boreholes vertically into the alluvium and underlying bedrock of the river to a depth of intersecting the entire thickness of the mapped alluvium. Two boreholes were connected to a network of subsurface drains that allowed for recharge from the open channel to flow into the production boreholes. In addition to the sub-surface drain system connecting the sump boreholes, three recharge drains were constructed upstream of the abstraction boreholes. The purpose of these drains were to recharge the underlying paleo-channel to improve the water quality and yield from the paleo-channel. This was achieved by connecting the sub-surface drainage pipe to a vertical screened recharge borehole. The end result of the study was the successful implementation of a alternate borehole yield of 14l/s from the production wells to the Steytlerville town water reticulation supply.
The Structural Hydrogeology of a Gold Mine	Stephen	Fonkem	South Africa	2015	gold mining, fractures, hydrogeological models
Abstract Gold mineralization in study area is structurally controlled. The geomorphology of the local drainage system is highly controlled by the fault architecture. Surface water flowed through, and eroded open fractures in exposed damaged zones (zone of subsidiary structures surrounding a fault). Previous conceptual hydrogeological models of groundwater system suggested is a two-aquifer system, consisting of a fractured aquifer overlain by a weathered aquifer, where groundwater flow mimics surface topography. Based on recent drilling and reassessment of historic geological and hydrogeological data, the groundwater system cannot only be described in terms of an elevation or stratigraphic units, as traditional aquifers are, but instead in relationship with the folds and faults. The fractured aquifer system around the mine pit is structurally compartmentalized both laterally and vertically, as depicted by the variance in static hydraulic heads and borehole yields over short distances. The un-fractured mass has very low drainable porosity. Virtually all water is contained in fractures. The main fracture zones north and west of the pit typically yield 1.3 to 2 L/s
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.
Case Study: Groundwater Exploration in the Basement Granites of the Kraaipan Group using Aeromagnetic Surveys	Marius	Terblanche	North-West	2015
Abstract Aurecon was appointed to conduct groundwater exploration for production well fields in the towns of Setlagole and Madibogo. These towns are located in an arid part of the North West province on the edge of the Kalahari. The landscape is flat and covered by aeolian sand underlain by basement granite of the Kraaipan Group Geology. Historically groundwater exploration consisted of reconnaissance geophysical surveys followed by detail ground surveys. Where no potentially water bearing geological structures are shown on geological maps & aerial photos, the project area would be divided into a grid on which the ground geophysical survey would be done. This type of exploration is time consuming and expensive. In some cases the terrain or cultural noise prohibits the use of conventional geophysical methods, with only more expensive and time consuming methods being left as an option. This is where the high resolution airborne magnetic survey excels. The results obtained from this type of survey are of such nature that only a small amount of ground geophysics is necessary to locate drilling targets. This survey method is also cost effective allowing a larger area to be covered in a short amount of time as compared to conventional ground techniques. This paper will discuss successes achieved using high resolution aeromagnetic surveys as the basis for groundwater exploration in traditionally low-yielding igneous geology.
SKA and Groundwater Management	Danita	Hohne	Karoo	2015
Abstract In 2009 it was announced that South Africa and Australia would be in competition for the race of the Square Kilometre Array (SKA). In 2009 the MeerKAT project was started in the Karoo near the core site of the SKA, which set out to demonstrate that South Africa was able to build the infrastructure of the SKA. The SKA required water for the building of roads, the dishes and the foundations of the dishes at the MeerKAT site. This poster explains the groundwater monitoring that is being performed at the MeerKAT site from 2011 till present in order to illustrate how good monitoring and management of groundwater can ensure sustainable groundwater use at sites like these. {List only- not presented}
Hydrogeochemical processes in the shallow aquifer of the Lubumbashi river basin: multivariate statistical approach	Lumu	Moussa Antoine		2015
Abstract Understanding the hydrogeochemical processes that govern groundwater quality is important for sustainable management of the water resource. A study with the objective of identifying the hydrogeochemical processes and their relation with existing quality of groundwater was carried processes in the shallow aquifer of the Lubumbashi river basin. The multivariate statistical approach includes self organizing maps (SOM'S) of neural networks, hierarchical cluster (HCA) and principal component analysis of the hydrochemical data were used to define the geochemical evaluation of aquifer system based on the ionic constituents, water types, hydrochemical facies and groundwater factors quality control. Water presents a spatial variability of chemical facies (HCO3- - Ca2+ - Mg2+, Cl- - Na+ + K+, Cl- - Ca2+ - Mg2+ , HCO3- - Na+ + K+ ) which is in relation to their interaction with the geological formation of the basin. The results suggests that different natural hydrogeochemical processes like simple dissolution, mixing, weathering of carbonate minerals and of silicate weathering and ion exchange are the key factors. Added to this is the imprint of anthropogenic input (use of fertilizers, septic practice poorly designed and uncontrolled urban discharges). Limited reverse ion exchange has been noticed at few locations of the study.
The importance of rainfall data in water resource planning and risk management	Nicolette	Vermaak		2015	rainfall data
Abstract Water resource management and risk management rely heavily on the availability of data and information. This includes the volumes of water needed, the volumes of water available, where the available water is and where it would be needed, etc. Historical records help to determine past use and gives a way to predict future use in the case of water resource planning while it helps to predict the possibility of floods and droughts when it comes to risk management. Rainfall data can provide valuable data for both water resource planning and risk management, since it is the input to the hydrologicalcycle. It is possible to determine dry and wet cycles using the cumulative deviation from mean that is calculated from the measured rainfall data. This was done for the Gnangara Mound in Australia, with the results giving a fair representation of the dry and wet cycles in the area. Data measured over a period of about 30 years for the Zachariashoek sub-catchment analyzed in the same fashion provided wet-dry cycles of about 8 years. The rainfall measurements had been taken at various settings around the catchment, and varied from place to place and differed from that measured at the WeatherSA stations in the vicinity. This article will draw a comparison between the Zachariashoek data and the WeatherSA data to determine whether the WeatherSA data followed the same patterns for the wet-dry cycles observed in Zachriashoek. It will then analyse the longer data record available for the WeatherSA data from 1920 to 2012. It is expected that the shorter wet-dry cycles seen in Zachariashoek will become part of longer wet-dry cycles that can be used in water resource planning and risk management. Rainfall is also dependent on a number of factors
Feasibility of iron and manganese removal by in-situ ozonation - Atlantis Aquifer Case Study	Kate	Robey	Western Cape	2015
Abstract The development of groundwater supply schemes is on the increase in South Africa. However, the sustainability of many of these wellfields is threatened due to the presence of iron (Fe2+) and manganese (Mn2+) ions in the groundwater. Their occurrence can manifest in problems with water quality and supply to consumers. The World Health Organisation recommends the removal of iron and manganese to below 0.3 mg/? and 0.1 mg/? respectively, to circumvent water quality risks. However, production borehole clogging is of greatest concern in the operation of wellfields due to the severe cost implications associated with reduced production. Clogging is caused by the precipitation of iron- and manganese-oxides at the borehole screen initiated by biogeochemical processes. Since Fe2+ and Mn2+ ions and the bacterial populations are naturally present in anoxic/anaerobic aquifer systems and the ingress of oxygen through pumping cannot be entirely prevented. The only approach to controlling borehole clogging is through management and rehabilitation procedures. Locally, these procedures have been implemented and in severe clogging cases the Blended Chemical Heat Treatment method has been applied. However, the effectiveness of rehabilitation has been limited. This can be ascribed to factors such as the incorrect production borehole design
Investigating The Potential Of Using Groundwater Associated With A Ring-Dyke To Augment The Municipal Water Supply To Bloemfonte	Christinah	Makoae	Free State	2015
Abstract The city of Bloemfontein is currently entirely dependent on remote surface water sources for its potable water supply. The water is purified at great cost, before being pumped over large distances to the reservoirs of the city. However, the surface water resource is unreliable and susceptible to droughts. In addition, large volumes of the purified water are lost before reaching the users. These losses are due to various factors, including leakages in the pipelines transporting the water to Bloemfontein and illegal connections. To reduce the city's dependence on remote surface water sources, this investigation aims to assess the potential for using groundwater resources to augment the municipal water supply. A prominent ring-dyke underlying the city is thought to be associated with strong aquifers. Our geophysical investigations have shown that this dyke yields large and well-defined magnetic and resistivity anomalies that allow easy interpretation of the geometry of the dyke. Future investigations will include the installation of boreholes at positions as determined from an interpretation of the geophysical data. Hydraulic tests will be performed on the aquifers intersected by the boreholes to determine the hydraulic parameters and sustainable yields. The groundwater quality will be assessed to evaluate its suitability for human consumption.
Case Study: Thermals springs in the Lower Orange River Valley	Danita	Hohne	Lower Orange River Valley	2015	earthquakes, thermal springs, Monitoring
Abstract POSTER Since June 2010 and still ongoing today, the Lower Orange River Valley has experienced over a 1168 tremors(a) and earthquakes in the vicinity of Augrabies. Of these 1168 tremors, 71 quakes registered above 3 on the Richter scale and on 18 December 2011, the area was struck with an earthquake that registered 5 on the Richter scale. Four thermal springs are also located near this earthquake zone and the temperature of the water have a range of between 38?C -46.6?C, according to Kent LE. (1949/1969). 25?C is the division between thermal and non-thermal waters and the thermal gradient for the Riemvasmaak area(b) is 24?C, clearly indicating that the four springs are thermal when looking at the temperature difference. The Department of Water Affairs has been monitoring these springs monthly since 2011 and has been taking field measurements and chemical analyses. The aim of this study is a) to see if the tremors and earthquakes have an effect on the chemistry of the thermal springs, b) to create a data set for the thermal springs, as these springs was recorded and mentioned in Kent LE. reports of 1949 and 1969 but no samples were collected and analysed, c) to see if the water source for the groundwater in the area and the thermal springs are connected and d) to see if the recent floods may have had an influence on the earthquake zone seeing as the Orange River runs through the zone. The following sources are used to describe the earthquakes and water quality: (a) Earthquake data from the Council of Geosciene (b) ZQM data on NGA temp range between 21-28?C depending on the season with 24?C being the mean.
Modelling Mine Water Rebound With MODFLOW	Stephen	Fonkem		2015
Abstract A review from international literature discredits the capability of MODFLOW to simulate mine water rebound, due to the nonstandard hydrogeology of underground mine systems. The conceptual understanding is that, after cessation of dewatering, mine water inflow rates and hydraulic heads are related to the void-volume, the differences in head between the water in the mine void and head dependent source, plus natural recharge to the mine voids. The flooded mine voids in the study area are partially underlain by a dolomitic aquifer. The other head dependent source of inflow into the mine voids are the surrounding and overlying Karoo aquifers. Head independent inflow rates into the mine voids, using the long term decant rates, was estimated to be 0.2% of rainfall. During mining, dewatering occurred at approximately 3 to 6 Ml/d. The objective of the model was therefore to simulate the changes head-dependent inflow rates during the rebound period. Analysis of the water level recovery data depicted that once the mine filled up with water, the hydraulic head of the mine rose with the elastic storage coefficient value of the mine void and not the specific retention as conditions changed from unconfined to confined. A three layer model was setup, to represent the two seams mined, separated by a deep Karoo aquifer. The presence of the dolomite on the mine floor was incorporated using the general head boundary package. Head dependent influx from overlying shallow and intermediate Karoo aquifers were simulated using the river package. All model layers were simulated as confined, initially to avoid model convergence issues. The confined setup proved to be the core in simulating mine water rebound with MODFLOW. The modelling exercise showed that storage during rebound is a boundary condition. This simply means that the complexity of mine water rebound can only be achieved in MODFLOW by proper time stepping and dividing the model into different stress periods to represent the changes in storage. Rebound in the study area, modelled with 21 stress periods produced a perfect water level recovery data for the different mine compartments. This was achieved by applying storage capacities of between 0.3 to 0.006 to simulate rebound during unconfined conditions, and values of between 10-4 and 10-5 when the mine void is flooded. The results showed that the inflow from the dolomitic aquifer steadily decreased from 4121 m3/d to 0 m3/d as the mine hydraulic head increased and rose over the head in the dolomitic aquifer. During the same period, inflow from the surrounding Karoo aquifers decreased from 2422 m3/d to less than 10 m3/d. The results of the model were very important in determining the volumes of water to be abstracted from the mine voids for ash-backfilling. {List only- not presented}
Integration of geophysical and well monitoring techniques in the evaluation of the groundwater potential for the Urban Bulawayo	Innocent	Muchingami	Zimbabwe	2015
Abstract POSTER Most developing urban areas in semi-arid regions of Sub Saharan Africa are often forced to utilise groundwater as an alternate source of domestic water supplies. As such groundwater evaluations strategies often face dual challenges in terms of resource quantification and their quality evaluation. However, groundwater potential assessment and aquifer yield evaluations often present a challenge when the system is of crystalline basement nature where groundwater potential is highly spatially variable and cases of dry holes and seasonal wells have been reported. This study demonstrate the integrated combination of geophysical techniques, (namely, vertical electrical sounding, electrical resistivity tomography, magnetic mapping, and seismic refraction tomography) with both borehole monitoring and infiltration techniques in the groundwater prospecting and spatial yield analysis of the Urban Bulawayo crystalline basement aquifer. The Bulawayo Metropolitan Province of Zimbabwe is located in the semi-arid region of Zimbabwe with an average annual rainfall of below 500 mm and has had a prolonged dry spell has resulted in the dwindling of the existing surface water resources. The aquifer system consists of syenite granite and fractured basaltic greenstone crystalline basement complexes. Provisional geophysical results have shown that the thickness of the fractured zone sharply varies in terms of spatial distribution and often some sections are characterized by shallow surface fractured zone that may only be 20-30 m thick and some sections have a reported regolith of up to 60m in thickness. Borehole yield assessments and chemical analysis techniques will be done on drilled wells in order to come out with detailed spatial variation in the borehole yield and water quality variations across the aquifer system. All the technical evaluations are then integrated to produce a detailed hydro-geophysical map of the system that can be used in the technical groundwater management of the urban Bulawayo aquifer.
The most valuable resource	Nicolette	Vermaak	West Coast, Western Cape	2015	resource economics
Abstract Mining is becoming a problem in the Western Cape - different kinds of mining and other resources, different problems than in other parts of the country. The West Coast had been declared a development corridor and a mining priority area. It is an arid to semi-arid area, where surface water is scarce, and rainfall relatively low and decreasing as one moves north. Some areas have significant volumes of good quality groundwater available, with potential impacts by the mining activities. This would play the importance of different resources off against the other. Most see resources as minerals, such as gold, silver, phosphate, and others where the value of these resources is measurable. Resources are also human capital, time, water, air, a healthy environment. It is more difficult to measure the value of the second group, as some of them have more than just a Rand and cent value. The value of resources is mostly done by measuring its monetary value, i.e. how much you will get when you sell the resource to a customer, providing the way the value of most resources is measured, i.e. resource economics. Economics is an area that most scientists are not familiar with as it contains a way thinking, of rules and laws unrelated to the way they have been taught. Supply and demand determines the value of a commodity, with scarce resources normally fetching higher prices. The value of the second group of resources is more difficult to determine. When does a resource become a strategic resource? This would be a resource that has a limited supply, does not get regenerated through natural processes and that is needed for defence, energy supply and others important for the stability of a country. There are also a category of resources we cannot live without such as water, and air - pure, fresh air and water. Without it life on this planet will cease to exist. This could be termed critical resources. What do you do if the occurrence of two very important critical resources overlaps, where the extraction of the one will lead to irreparable damage to the other? This article will look at one site where a strategic resource occurs at the same site as an important water resource. It will compare the potential value of the mineral resource with the value of the water resource in the aquifer measured at the current value of water as available to the public. It will also take into account the value of the water resource from the perspective of a healthy functioning ecosystem and a RAMSAR site. This analysis becomes more valuable when considering the potential effects of climate change in the area and the cost of desalination.
Integration of water simulation modelling for water conservation and demand management in the mining sector (a case study)	Fanie	Botha	South Africa	2015	legislative challenges, integrated modelling, WUL
Abstract This paper outlines and presents out-of-the-box theories as examples to highlight some of the challenging restraints within the current legislative environment preventing scientists, engineers and other operational personnel to take theory into action and implementation. Key to this is the very static nature of the water use license (WUL)and associated process. The first example shows how integrated dynamic water modelling can be utilized to create an integrated water and waste management plan within the mining sector. The models developed using principles from Government Notice 704, the Best Practice Guidelines (BPGs) and the principles of water conservation and demand management. Ultimately it keeps clean and dirty water flows separate and optimises the use of dirty water in order to reduce raw/potable water off-takes through this process. The objective of these models are to optimise the water use and develop strategies to ultimately enable mines to optimize it's internal non-potable water resources therefor relieving pressure on the limited potable systems, as well as aiding surrounding communities, in which they operate, with potable water. Results from the model provides for 1 or 20 years simulation data that differs year-on-year based on numerous factors, i.e. rainfall, run of mine (ROM) feed and growing/declining surface run-off areas. The variability of the results makes it almost impossible to utilize within application documentation as it is too complex and it does not align with the application figures as required in the WUL process. This resulting in a fairly simplistic and sometimes unrealistic static model that is submitted as part of the application.
A case study review of a high tech approach towards wellfield and aquifer management.	Paul	Lee		2015
Abstract Faced with a burgeoning population and property growth, and in preparation for a future drier climate regime; the coastal town of Hermanus in the Western Cape has set up two wellfields to abstract groundwater from the underlying aquifer in order to augment the constrained surface water supply from the De Bos Dam. Water Use Licences (WUL) were issued to the Overstrand Municipality in June 2011 and December 2013. The licences authorise a maximum annual abstraction of 1 600 Ml of water from the Gateway wellfield and 800 Ml of water from the Volmoed and Camphill wellfield via several boreholes. The water abstracted from the Gateway wellfield is pumped via a booster pump station to the Preekstoel Treatment Plant. The Volmoed and Camphill wellfield are situated at a higher altitude allowing for a gravity feed pipeline. Earth Science Company, Umvoto Africa, has the responsibility to ensure Resource Quality Objectives are met which include balancing the need to protect the resource on the one hand; and the to develop sustainable utilisation of the Hermanus groundwater resources and compliance with the WUL on the other. The consultancy provides hydrogeological support, wellfield management and technical advice in operating the boreholes, pumps, boosters and related infrastructures. Running the operations of the wellfield relies on a high-tech, semi-automated system, incorporating a remotely controlled, telemetry based structure. Vital parameters are monitored by electronic sensors, feeding data to processors which alters pump performance to maintain specified boundary levels. Data is simultaneously communicated via telemetry to a central control which uses data acquisition software to portray information to the operators. Warning alarms both alert operators via SMS and in certain instances auto-shut down the system. To ensure ecological sustainability of the ground water resource, the wellfield also requires hydrogeological monitoring at far field locations within the recharge areas. Some of these locations are in remote areas making data download costly. The high-tech telemetry approach is used with positive results. Any automated telemetry system is prone to malfunction and environmental hazards. The challenge lies in managing this and providing sufficient back up and duplication of systems. The paper gives an overview of the components and flow of data based on the experiences gained during the evolution and development over 12 years of operation. Automation produces vast data bases which are often not sufficiently analysed, the premise that "once collected, the task is done". However data is only as good as the people who drive the systems and this paper provides a critical analysis of human intervention in an automated system and the decisive role of quality-checks. Finally the paper seeks to provide a pragmatic guideline for water users to comply with the WUL and institutional regulations.
Variability In Kd And How It Relates To The New Guidelines For Contaminated Land	Michelle	Papenfus		2015
Abstract Globally, a growing concern have been that the heavy metal contents of soil are increasing as the result of industrial, mining, agricultural and domestic activities. While certain heavy metals are essential for plant growth as micronutrients, it may become toxic at higher concentrations. Additionally, as the toxic metals load of the soil increases, the risk of non-localized pollution due to the metals leaching into groundwater increases. The total soil metal content alone is not a good measure of risk, and thus not a very useful tool to determine potential risks to soil and water contamination. The tendency of a contaminant to seep into the groundwater is determined by its solubility and by the ratio between the concentration of the contaminant sorbed by the soil and the concentration remaining in solution. This ratio is commonly known as the soil partitioning or distribution coefficient (Kd). A higher Kd value indicate stronger attraction to the soil solids and lower susceptibility to leaching. Studies indicate that the Kd for a given constituent may vary widely depending on the nature of the soil in which the constituent occurs. The Kd of a soil represents the net effect of several soil sorption processes acting upon the contaminant under a certain set of conditions. Soil properties such as the pH, clay content, organic carbon content and the amount of Mn and Fe oxides, have an immense influence on the Kd value of a soil. Kds for Cu, Pb and V for various typical South African soil horizons were calculated from sorption graphs. In most cases there were contrasting Kd values especially when the cations, Cu and Pb, had high contamination levels, the value for V was low. There is large variation between the Kds stipulated in the Framework for the Management of Contaminated land (as drafted by the Department of Environmental Affairs) and the values obtained experimentally in this study. The results further indicate that a single Kd for an element/metal cannot be used for all soil types/horizons due to the effect of soil properties on the Kd. The results for Cu and Pb indicated that the Kds can range in the order of 10 to 10 000 L/kg for Cu and 10 to 100 000 L/kg for Pb. The variation in V Kd was not as extensive ranging from approximately 10 to 1 000 L/kg. {List only- not presented}
Using electrical resistivity method for subsurface mapping of shallow aquifers in Heuningnes Catchment, South Africa	Kinsley	Manyama		2015
Abstract The current study investigated the subsurface of aquifers in Heuningnes Catchment focusing on aquifer characteristics for groundwater resource assessments. Surface geophysical resistivity method was adapted for mapping the shallow subsurface layers and hydrogeologic units at selected sites within the catchment. The aim was to provide a preliminary overview of the subsurface nature of aquifers within the study area, by establishing features such as geological layers, position of weathered zones, faults and water bearing layers. The multi-electrode ABEM SAS 1000 resistivity meter system, using the Wenner array, was used to obtain 2D resistivity data of the subsurface. The acquired data was processed and interpreted using Res2DINV software to produce the 2D resistivity models. The analysis of the resistivity models of the subsurface reveals maximum of four layers; sandstone, shale, poor clayed and brackish water saturated layer. On comparing the model results with the surficial geological formation of the catchment geological map, the identified layers were found to correspond with the geology of the area. The findings i) provide insights on sites that can be drilled for groundwater exploration, ii) show possible water-type variations in the subsurface. Although the results are not conclusive but they provide basis for further research work on quality and flow dynamics of groundwater. {List only- not presented} Key words: aquifer properties, hydrogeologic units, geo-electric model, electrical-resistivity method
Physico-Chemical Assessment of Groundwater in the Orange Water Management Area	Olma Tsakani	Makonto		2015
Abstract The groundwater quality of the Orange Water Management Area (OWMA) was assessed to determine the current groundwater status. Groundwater is of major importance in the Orange Basin and constitutes the only source of water over large areas. Groundwater in the OWMA is mainly used for domestic supply, stock watering, irrigation, and mining activities. Increase in mining and agricultural activities place a demand for the assessment of groundwater quality. The groundwater quality was assessed by collecting groundwater samples from farm boreholes, household boreholes, and mine boreholes. Physical parameters such as pH, temperature and Electrical Conductivity (EC) were measured in-situ using an Aquameter instrument. The groundwater chemistry of samples were analysed using Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, and Spectrophotometer for cations, anions and alkalinity respectively. The analyses were done at Council for Geoscience laboratory. The results obtained indicated high concentration of Nitrate (NO3), EC, sulphate (SO4), Iron (Fe), and dissolved metals (Chromium, Nickel, Copper, Zinc, and Lead). The concentrations were higher than the South African National Standards (SANS) 241 (2006) drinking water required guideline. The OWMA is characterised by the rocks of the Karoo Supergroup, Ventersdorp Supergroup, Transvaal Supergroup, Namaqua and Natal Metamorphic Province, Gariep Supergroup, and Kalahari Group. Groundwater is found in the sandstones of the Beaufort Group. Salt Mining occurs in the Namaqua Group, hence the high concentration of EC observed. High EC was also found in the Dwyka Group. The salt obtained from the pans underlain by the Dwyka Group rocks has relatively high sodium sulphate content, this probably results from oxidation of iron sulphate to sulphate. Therefore, high concentration of SO4 is due to the geology of the area. High concentration of NO3 is due to agricultural activities, whereas high concentration of EC, Fe, SO4 and dissolved metals is due to mining activities.
Supervised committee artificial neutral network in groundwater exploration in granitic and metamorphic terrains of South Africa	Emmanuel	Sakala	Northern Cape	2015
Abstract POSTER The areas studied in this paper are situated in semi-dry regions of Limpopo and Northern Cape Provinces of South Africa. Groundwater is the only dependable source of water for many local users and farming communities. The growing population is putting immense pressure in the current water resources, hence a need to find new groundwater resources. The areas are most dominated by fractured rock aquifers which accounts to over 90% of South African aquifers. Finding sustainable sources of groundwater in these regions is often a challenge due the complex nature of the fracturing network system of fractured aquifers. This study uses a supervised committee learning with artificial neutral network (SCLANN) model to improve the regional groundwater exploration in granitic basement terrains and valley controlled aquifers in metamorphic terrains of South Africa. The data used in the study was obtained from the national groundwater archive and interpretation of high resolution aeromagnetic data, ground surveys and remote sensing datasets. The artificial neural network (ANN), Fuzzy (F) and Neuro-fuzzy (NF) unsupervised models whose input were groundwater controlling parameters like regolith thickness, lithology, relief, faults, lineament density, lengths of lineaments was used. The results from the ANN, F and NF models were used as inputs to a nonlinear supervised SCLANN framework with the borehole yield as the training and validation outputs. Borehole yield was used as it is one of the measurable parameter that directly related to productivity of groundwater resources. The use of the unsupervised models improved the results significantly as the SCLANN model results as a combined advantage of the individual models to achieve the optimal high performance. The results show that the three models used to build a SCLANN model was able to improve the identification of potential groundwater targets at regional scales. This approach can be incorporated in regional groundwater exploration programs to improving drilling success rate on granitic basement and metamorphic terrains in South Africa. The results show that the SCLANN outperforms individual unsupervised models. However the SCLANN results for granitic basement terrains were far much better than the metamorphic terrains probably showing the limitation of the approach in metamorphic terrains.
Flow Test Analysis And Monitoring Of The Deep Confined Peninsula Aquifer In Blossoms (Oudtshoorn), Western Cape, South Africa	David	McGibbon	Western Cape	2015
Abstract The Oudtshoorn Groundwater Project aims to target deep groundwater as a long-term option to augment the water supply to the greater Oudtshoorn Local Municipality. Located 15 km south of Oudtshoorn towards the Outeniqua Mountain range, the Blossoms Wellfield lies within a potentially high-yielding artesian basin. The Peninsula Formation (of the Table Mountain Group (TMG), hydrostratigraphically known as the Peninsula Aquifer, is exposed in the Outeniqua Mountains (high rainfall recharge area), and is deeply confined northwards by the overlying Bokkeveld Group. The project is currently emerging from an exploration phase, with eight existing boreholes that target the deep confined Peninsula Aquifer, and three boreholes that monitor the shallower Nardouw (Skurweberg) Aquifer. Estimation of the aquifer's productive and sustainable groundwater potential involves determining its hydraulic properties by stressing the aquifer through flow and pumping tests and accurately monitoring flow rates, the potentiometric surface level (PSL) during flow, and PSL recovery thereafter. Free-flow and pumping tests were carried out on four boreholes between the 12th May 2014 and the 29th June 2014. The boreholes were all equipped with data-loggers to record pressure and flow-meters to determine the flow-rate. Recovery of the aquifer after the testing is still being continuously monitored. Results from the month and a half flow-test show that there is no interaction between the deep confined Peninsula Aquifer and the shallower Nardouw Aquifer beneath the southern part of the wellfield. Because the water-use licence stipulates that there can be no negative impact from Peninsula Aquifer abstraction on the Nardouw Aquifer, which is utilised by farmers in the region, this issue is of paramount importance. The hydrochemical signature of the two aquifers is also different. Recovery monitoring emphasised that the northern block is better inter-connected through fracture systems than the southern block, because those boreholes recovered to their original potentiometric surface almost immediately, whereas the southern boreholes took days for recovery. Two boreholes in the south are still recovering eight months later, which is most likely due to their being drilled into the limb of folded rock systems and not the more fractured hinge zone (as with the more connected boreholes). Using the drawdown and recovery curves ('Horner plots'), the transmissivity and storativity of the aquifer is calculated analytically by the Theis equation. The results show a large variation in storativity (1.0E-1 to 1.46E-4) and transmissivity (9-20 m2/day) between the various boreholes, emphasising the heterogeneity of the aquifer. The aquifer properties gained from this testing are essential in better understanding the aquifer system, and developing numerical models for future wellfield testing and model simulation.
Urbanization effects on the channel morphological changes in the Kuils River, Western Cape	Naeem	Davids	Western Cape	2015
Abstract POSTER The human interferences in river catchments includes impoundment construction, sediment mining, bank revetment and artificial cutoff, which eventually leads to changes in the hydrology system and channel transportation ability, and may reduce channel stability. In past 10 years the Kuils River had been upgraded between Van Riebeeck Road and the Stellenbosch Arterial route to reduce flood levels. The stretch of the river between the R300 and Van Riebeeck Road was also upgraded: reducing any possibility of flooding, by concrete-lining of some areas of the river that are within the Kuilsrivier Municipal Area. Producing a cross-section of a river channel is of great importance in river studies. To determine the discharge one should survey the profile of a feature such as a meander or riffle, it is necessary to produce a cross-section of the river. In order to focus on restoration requirements of a river, a map of the river is needed. This provides an indication of what exactly the river currently is. Habitat mapping is intended to access the stream. Woody debris, substrate, aquatic vegetation is measured continuously throughout a river, to be able to identify conservation and restoration needs. The cross section 1.3 of site 1 indicates that the channel width from January 2002 is almost similar in width of September 2012. The depth of the channel is about 0.5m deeper when compared to January 2002. The Kuils River banks are covered in grassy vegetation, with some trees with deep and large roots that provide protection against undercutting along rivers. The banks of Site 1 are covered long weeds and annual grasses with shallow root systems, which don't provide stability when the banks were saturated after high rainfall. The Kuils River area is used for various types of land uses and this also impacts the channels eg. Urban, Industrial and Agricultural use. Because of canalization occurring upstream one can see evidently the changes within the channel.
Multi-data Integration Approach in Groundwater Resource Potential Mapping: A case study from the North West Province, South Afri	Abera	Tessema	North-West	2015
Abstract Multi-data integration approach was used to assess groundwater potential in an area consisting crystalline basement and carbonate rocks that are located in the North West Province of South Africa. The main objective of the study is to evaluate the groundwater resource potential of the region based on a thorough analysis of existing data combined with field observation. Integration of six thematic layers was supplemented by a statistical analysis of the relationship between lineaments density and borehole yield. Prior to data integration, weighting coefficients were computed using principal component analysis. The resulting thematic layer derived from integration of the six layers revealed a number of groundwater potential zones. The most probable groundwater potential zones cover ~14% of the entire study area and located within carbonate rocks consisting limestone and dolomite. The presence of pre-existing structures together with younger and coarse sedimentary rocks deposited atop the carbonate rocks played a significant role in the development of high well fields in the southern part of the area. Moderate-to-high groundwater potential zones within Ventersdorp lava coincide with maximum concentrations of fractures. The results of statistical correlation suggest that 62% of high borehole yield within the Ventersdorp lave can be attributed to fracture density. In general, the present approach is very effective in delineating potential targets and can be used as a sound scientific basis for further detailed groundwater investigation. KEY WORDS:- Multi-data, thematic layers, groundwater, carbonate rocks, structures
A numerical simulation of solute transport in dry coal ash dumps with a case study in South Africa	Innocent	Muchingami		2015
Abstract An understanding of the movement of moisture fluxes in the unsaturated zone of waste disposal sites play a critical role in terms of potential groundwater contamination. Increasing attention is being given to the unsaturated or vadose zone where much of the subsurface contamination originates, passes through, or can be eliminated before it contaminates surface and subsurface water resources. As the transport of contaminants is closely linked with the water ?ux in through the unsaturated zone, any quantitative analysis of contaminant transport must ?rst evaluate water ?uxes into and through the this region. Mathematical models have often been used as critical tools for the optimal quantification of site-speci?c subsurface water ?ow and solute transport processes so as to enable the implementation of management practices that minimize both surface and groundwater pollution. For instance, numerical models have been used in the simulation of water and solute movement in the subsurface for a variety of applications, including the characterization of unsaturated zone solute transport in waste disposal sites and landfills. In this study, HYDRUS 2D numerical simulation was used to simulate water and salt movement in the unsaturated zone at a dry coal ash disposal site in Mpumalanga, South Africa. The main objective of this work was to determine the flux dynamics within the unsaturated zone of the coal ash medium, so as to develop a conceptual model that explains solute transport through the unsaturated zone of the coal ash medium for a period of approximately 10 year intervals. Field experiments were carried out to determine the model input parameters and the initial conditions, through the determination of average moisture content, average bulk density and the saturated hydraulic conductivity of the medium. A two dimensional finite-element mesh of 100m x 45m model was used to represent cross section of the ash dump. Two dimensional time lapse models showing the migration of moisture fluxes and salt plumes were produced for the coal ash medium. An explanation on the variation of moisture content and cumulative fluxes in the ash dump was done with reference to preexisting ash dump data as well as the soil physical characteristics of the ash medium. {List only- not presented}
Mountain Catchment Studies and Catchment Management	Nicolette	Vermaak	Western Cape	2015	catchment management
Abstract The mountain catchments of the Western Cape winter rainfall area were identified as areas needing more study in the early 1960s and so the Mountain Catchment studies were born. A number of study areas were suggested for these studies, but it was finally narrowed down to three sites. The studies in Jonkershoek had already started in 1935, with Zachariashoek and Jakkalsrivier added on in the 1960s. The Zachariashoek site was the only one that included groundwater as part of the experimental setup. A number of publications had been written about the work done in Zachariashoek. Most of the publications focused on changes in runoff after deforestation and fires, as well as the recovery patterns of the vegetation. The studies in Zachariashoek were done from 1964 till its termination in 1991 because of a lack of funding. The groundwater component consisted of 14 boreholes, with recorders on the five boreholes near the five weirs. The Zachariashoek area is made up of three catchments, Zachariashoek, Bakkerskloof and Kasteelkloof. It is adjacent to the Wemmershoek catchment. Bakkerskloof was the control catchment, while different burn cycles were part of the experimental setup of the two other catchments. The vegetation of Kasteelkloof was burned every 6 years with a 12 year cycle for Zachariashoek. Monitoring of the 5 weirs, 14 boreholes and the 9 rain gauges was done every week, with recorders on all five weirs, five of the 14 boreholes and at least 4 of the rain gauges. This data was entered into the data bases of the Department of Water and Sanitation, stretching from 1964 to 1986, with a complete record contained in 10 small field books. In this publication, we will look at the experiments done in Zachariashoek to see how this long term monitoring data can assist in managing the water resources within a catchment, taking into account the effects of deforestation and fires on surface water, groundwater and recharge to groundwater, the interaction between groundwater and surface water, as well as climate change.
A review of groundwater resource protection measures in South Africa	Eberhard	Braune		2015

Managing Transboundary Groundwater Resources: The Case of the Ramotswa Aquifer	Nicole	Lefore	SADC	2015
Abstract What are the key institutions, both formal and informal, that determine actual groundwater use in the Ramotswa aquifer? Are current institutions at regional, national and sub-national levels adequate to collaborate for equitable benefit-sharing for the future? These are the questions that the paper will address based on early findings of a project aimed at determining the role the Ramotswa aquifer can play in addressing multiple-level water insecurity, drought and flood proneness, and livelihood insecurity. Groundwater resources are critical in the SADC region
Developing Groundwater Supplies To Supplement The Water Supply Of Ladismith, Western Cape Province	Roger	Parsons	Western Cape	2015
Abstract Ladismith was established in 1852 at a point where freshwater springs discharge from the Swartberg mountains. Growth of the town required building of the Goewerments Dam in 1920 and the Jan F le Grange Dam in 1978. However, water demand now matches supply, and water shortages are being experienced. Poor management and recent droughts exacerbated the situation. A project was initiated to address problems with the existing water supply and identify additional sources of water. Groundwater is an obvious option, with the regionally extensive Cango-Baviaanskloof fault being located directly north of the town. The west-east trending fault juxtaposes the highly productive Table Mountain Group aquifer with less productive argillaceous rocks of the lower Witteberg Group. This paper presents the results of initial geohydrological exploratory work and examines the role groundwater can play in the future water supply to the town. {List only- not presented} KEYWORDS groundwater, exploration, water supply, Ladismith
Estimation of representative transmissivities in heterogeneous aquifers	Fanie	de Lange		2015
Abstract The so-called apparent increase of transmisivity (T) or hydraulic conductivity (K) with scale is an artifact and does not exist in the field. The reason for the apparent increasing of T with scale is due to the use of the "not applicable" random log Gaussian stochastic models that are used by geohydrologists. In the petroleum field, which uses deterministic methods, the apparent increase of T with aquifer volume does not occur. Groundwater practitioners have to change their view and use models that do not show this effect. By using intuitive inspection of geological, fracture and connectivity data as well as real pumping test data, this paper shows that up-scaling must be performed with an exponential decaying function, where T always decreases with scale . Two types of heterogeneities exists namely a.) horizontal and b.) vertical. Connectivity between fractures is extremely important in both cases, but it is only in semi-confined and watertable aquifers that the vertical heterogeneities are really important (typical case of fracture dewatering) {List only- not presented}
Radon-222 in Thermal Springs of Limpopo Province, South Africa	Humberto	Saeze	Limpopo	2015
Abstract Studies have shown that the use of natural water (drinking and bathing) with high level of 222Rn concentration may contribute to negative health effect in human beings. Thermal springs located in Limpopo province were sampled for the determination of 222Rn concentration by gamma ray spectrometry. The spring water has been used for domestic purposes: drinking and bathing, and for recreation bathing mainly. 19 samples were collected between thermal springs emanation points and swimming facilities (out and in doors). Radon-222 concentration found in these water ranges from 0.2 to 624 Bq/l. These results indicate that 7 thermal springs may represent increasing risk on bathing or inhalation of radon gas, leading to an increased risk of healthy.
Using gravity anomalies from GRACE to estimate changes in groundwater storage in the Vaal River Basin	Khuliso	Masindi		2015
Abstract The Gravity Recovery and Climate Experiment (GRACE) satellites detect minute temporal variation in the earth's gravitational field at an extraordinary accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores (snow, groundwater, surface water and soil moisture) due to increases or decreases in storage. The GRACE monthly TWS data are being used to estimate changes in groundwater storage in the Vaal River Basin for a period (2002 to 2014). The Vaal River Basin has been selected, because it is one of the most water stressed catchments in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands, it is critical to monitor and calculate changes in groundwater storages as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin were mostly localised focusing mainly on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, but many of these models do not take into account the groundwater component. Thus, there is a significant gap in the understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks are often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is a good approach to estimate changes in hydrological storages as it covers large areas and generates real time data. It does not require information on soil moisture, which is often difficult to measure. The accuracy of calculating change in groundwater storage lies in the processing of GRACE data and smoothing radii. For this study, smoothing radii of 1500, 900, 500, 300, 150 and 1 km are used. Currently the associated error with different smoothing radii is unknown. The preliminary results indicate that the study area experienced a loss in TWS of -31.58 mm equivalent water height over a period of 144 months in TWS at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamics, which will improve water management practices.
Is potato cultivation negatively impacting the groundwater resources of the Sandveld, Western Cape?	Julian E	Conrad	Western Cape	2015	groundwater monitoring
Abstract Groundwater is used extensively in the Sandveld for the irrigation of potatoes. The groundwater resources are plentiful and of good enough quality for the production of potatoes, however there has been a significant increase in potato production especially from the period 1975 to 2008. The area planted has increased from 2 369 Ha to 6 715 Ha in this period. The rate of increase has reduced significantly since 2008 and is now quite consistent at approximately 6 800 ha/a. In the region groundwater is vital for the proper functioning of ecosystems and it is also the sole source of water for five towns in the area and supplies most of the domestic water for the farms in the area. Thus the abstraction of groundwater for agriculture needs to be carefully assessed to ensure impacts on other systems and users do not occur. For this reason Potatoes South Africa has taken the responsible approach of investing in the on-going monitoring of groundwater levels (quantity) and groundwater quality in the Sandveld. PSA appointed the groundwater consultancy, GEOSS to do this monitoring and they have continually committed to this monitoring for the past 10 years. The long term monitoring data has been very valuable in that it shows groundwater trends and the spatial distribution of the measured parameters. Regarding the trends it is clear that certain areas are being over-abstracted and groundwater levels are dropping. In the more critical areas, intervention has occurred - boreholes were closed down and the points of abstraction distributed over a much wider area. This region (Lower Langvlei River) is showing clear signs of recovery both in terms of groundwater levels and quality. The other localized areas where negative trends are evident the land owners have been informed and are aware of the problems. In some critical areas continuous groundwater level loggers have been installed to monitor trends. The long-term groundwater monitoring, has helped significantly in addressing the negative perception about the widespread impact on groundwater resources due to potato cultivation in the Sandveld. It is important the monitoring continues and regular feedback provided to land owners. The monitoring that the local municipality and the Department of Water Affairs do also needs to be integrated into a single database. It is evident that the initial abstraction of groundwater in the pioneer days of potato cultivation did impact groundwater resources and associated ecosystems in the Sandveld, however currently as the rate of expansion has reduced and stabilized, the groundwater resources closely mimic rainfall patterns and the areas that are being impact are localized, well known and being addressed.
Development of a water resource early warning monitoring system in the South Western Karoo	Zaheed	Gaffoor	Karoo	2015
Abstract POSTER Shale gas, a form of natural gas, has only recently become an economic source of energy. In the last 20 years techniques such as horizontal drilling coupled with hydraulic fracturing, have made possible the extraction of these unconventional hydrocarbon reservoirs. America has used hydraulic fracturing to produce numerous shale gas deposits in the country. This production has satisfied America's energy needs, and essentially made them a net exporter of petroleum. In light of this success South Africa is interested in developing potential economically profitable reserves of shale gas in the Karoo. However media, as well as recent studies, have identified issues with the hydraulic fracturing. These studies have linked hydraulic fracturing to contamination of groundwater resources in active production regions in America. There are fears among experts that the same could happen in the Karoo. This would be devastating to the local ecosystem and human population, as groundwater is the main water resource in the region. However it may still be necessary to proceed with shale gas development for its economic benefits. To ensure that some of the risks of hydraulic fracturing is mitigated, this paper proposes an early warning monitoring system. This system will essentially protect the local groundwater resources by early detection of any indicators that identify hydraulic fracturing contamination. The early warning system will operate by continues monitoring of groundwater parameters, in real time, and compare this regional baselines, and there by identify any changes in the groundwater properties. If a change is linked to a contamination event, the system will warn authorities, thus allowing for rapid response and ultimately ensure conservation of groundwater resources in the region.