Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 301 - 350 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort descending	Keywords
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.
Connecting the dots: Groundwater / surface water interaction along the Letaba River, Limpopo	Tercia	Strydom	Limpopo	2015
Abstract The National Water Act (NWA) 36 of 1998 is regarded as providing a platform for an innovative way of managing the country's water resources. However, demands on the nation's water resources are intensifying as more and more catchments are coming under increasing stress. This may be attributed to significant changes in land-use and poor water resource governance which negatively affects the Environmental Water Requirement (EWR) flows of rivers in many catchments in South Africa. EWR refers to the flow needed by a river to sustain a healthy ecosystem. It is vital that the determined EWR flows are met and to ensure that all water-users receive their allocated water supplies. To ensure effective water management and water provision, it is critical to understand transmission losses considering that it is a key component of the water balance or hydrological budget. Quantitative investigations of transmission losses are necessary in order to calculate flows in a river and appropriately allocate water for different users. The Groot Letaba River situated in the north-eastern region of South Africa is a prime example of a river system where uncertainties in channel losses and gains are complicating effective water management. The Groot Letaba River is a model river where Strategic Adaptive Management (SAM) is currently being implemented to ensure adaptive and sustainable water resource management. This unique approach is facilitated by the institutional interaction between dam operators (from the upstream Tzaneen Dam) and stakeholders including Kruger National Park. However, there are huge uncertainties surrounding natural water losses (e.g. evapotranspiration) or gains (e.g. groundwater discharge) in the real-time model currently being used by dam operators. This study aims at attempting to narrow down the uncertainty by understanding and quantifying the natural hydrological processes between the two dominant land-uses along this river, i.e. agriculture and protected areas. In particular, the project will investigate the hydrological connectivity between groundwater and surface water along the Letaba River. This project will contribute significantly to management strategies by using a precise hydrological approach which will aid in improving estimates of water supply in the Groot Letaba River. Furthermore, this project could contribute to the development of appropriate water management strategies not only in the Letaba catchment but other similar Lowveld catchments as well.
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.
Evaluating Potential Impact Of Climate Change On Hydro-Meteorological Variables In Upper Blue Nile Basin (A Case Study FINCHAA )	Mekonnen	Daba	Ethiopia	2015
Abstract Throughout the world, climate change impact is the main concern for sustainability of water management and water use activities like agricultural production. Climate changes alter regional hydrologic conditions and results in a variety of impacts on water resource systems. Such hydrologic changes will affect almost every aspect of human well-being. The goal of this thesis is to assess the impact of climate change on the hydro climatology of Fincha Sub-basin located in upper Blue Nile Basin of Ethiopia. The GCM derived scenarios (HadCM3 A2a & B2a SRES emission scenarios) experiments were used for the climate projection. The statistical Downscaling Model (SDSM) was used to generate future possible local meteorological variables in the study area. The down-scaled data were then used as input to the Soil and Water Assessment Tool (SWAT) model to simulate the corresponding future stream flow in of Fincha Sub-basin located in upper Blue Nile Basin. A semi distributed hydrological model, SWAT was used to simulate future stream flow. Three benchmark periods simulated for this study were 2020s, 2050s and 2080s. The time series generated by GCM of HadCM3 A2a and B2a and Statistical Downscaling Model (SDSM) indicate a significant increasing trend in maximum and minimum temperature values and a slight decreasing trend in precipitation for both A2a and B2a emission scenarios in both Shambu and Neshe stations for all three bench mark periods. The hydrologic impact analysis made with the downscaled temperature and precipitation time series as input to the SWAT model suggested an overall decreasing trend in annual and monthly stream flow in the study area, in three benchmark periods in the future. This should be considered by policymakers of water resources planning and management. The hydrologic impact analysis made with the downscaled temperature and precipitation time series as input to the hydrological model SWAT suggested for both A2a and B2a emission scenarios. As a result, at the out let of the watershed the projected on average annual flow decrease by 5.59%,9.03%,11% and 2.16%,4.15 and 3.46% for the 2020s,2050s and 2080s for both A2a and B2a emissions scenarios. Potential evapotranspiration in the watershed also will increase annually on average 3 - 16% for the 2020s and 4-19% for the 2050s and 2080s for both A2a and B2a emissions scenarios. {List only- not presented}
Hydraulic tests of strong artesian boreholes; wellhead construction and test design	Kornelius	Riemann		2015
Abstract Artesian boreholes are a common feature worldwide in confined aquifers, but the hydraulic testing of these boreholes, and estimation of aquifer properties from such tests, still poses a challenge for hydrogeologists. Common hydraulic tests, such as step-drawdown or constant-discharge rate tests require a static water level at the start of the test, and the measurement of drawdown (increasing over time) and abstraction rate (fixed for a period of time). Usually, when undertaking a pumping test in an artesian borehole, the drawdown is measured from ground level, and the drop in hydraulic head between static pressure and ground level is often ignored. This procedure also implies that the starting time of the test is not at the static water level. A constant-head test, set at ground level, is the other option. However, the decrease in flow rate is not only dependent on the hydraulic properties of the aquifer, but also masked by pipe hydraulic effects within the well. This kind of test would also limit the available drawdown to be utilized for the test. Hence, it was required to develop a method for undertaking hydraulic tests in strong artesian boreholes, allowing for the drawdown to fluctuate between levels both above and below ground and avoiding the pitfalls described above. The solution is a specially designed and constructed wellhead for the installation of the pump and monitoring equipment prior to the hydraulic test. The standard tests are slightly modified and are only undertaken after sealing the wellhead and reaching static hydraulic pressure. The recommended wellhead construction and subsequent hydraulic tests were implemented at a strong artesian borehole in the Blossoms Wellfield, south of Oudtshoorn in the Western Cape province of South Africa.
Post Mining Aquifer Testing At A South African Coal Mine	Marnus	du Toit		2017	coal mine, dewatering, geochemistry, pumping test, analytical mocels
Abstract Mining site remnants are everlasting and impact the groundwater regime on a long term scale. An integrated approach to geoscience is necessary due to the complexity of nature and the unknown relationships that must be discovered to further the understanding of impacts on the natural environment. Furthermore, groundwater resources are negatively impacted by mining activities affecting the groundwater quality and quantity. Underground coal mining can be accompanied by roof failure events. This may change the matrix which subsequently alters the flow regime; leads to variations within the water chemistry, provided there is inter- aquifer connectivity; and alters the recharge rate. Dewatered mine voids are in direct contact with oxygen initiating oxidation reactions, depending on the geology of the specific site. A change in water chemistry was analyzed, and this coincides with a roof failure event as interpreted from water level measurements. Concentrations of Mg, Ca, and alkalinity indicate anomalous changes that are still in effect, five to six years after the majority of water levels had stabilized. The changes in the system coincides with and correlates to events of roof failure and different parameters. The latter changes are applied as extra tools when interpreting different site specific anthropogenic induced impacts on the system. Also within this study, constant rate pumping tests were conducted for the interest of the hydraulic properties, using three farming boreholes. The results put forward a range of 0.21 – 0.44L/s and 6.5 – 11.5m2 /d, for sustainable yield and transmissivity, respectively. Furthermore, it is recommended that a better understanding can be gained on system behaviors if chemistry correlations can be gathered through certain events causing specific systems to be in disequilibrium. It is also recommended that additional pumping tests will allow more insightful interpretation and delineation between the abovementioned chemical and water level changes. Finally, the combination of parameters during events can aid in deciding the most appropriate analytical models used for further analysis.
Testing Potential Reservoir Connectivity Using Isotopes	S	Dlakavu	Karoo	2017	Shale gas, hydraulic connectivity, geochemical, Isotopes, contamination
Abstract Anticipated Shale Gas Development could intensify possible natural hydraulic connectivity between deep groundwater reservoirs and shallow aquifers in the Karoo. This project attempts to test geochemical evidence of natural mixing between old groundwater from deep aquifers and young groundwater from shallow aquifers using selected isotopic signatures in conjunction with borehole yields. Borehole yields were determined using slug tests. All isotopes (δ18O, δ2H, δ13C, 3H and 14C) were analysed in the laboratory of Environmental Isotope Group of iThemba Laboratories in Gauteng. To date, results from four water samples collected in Jansenville reveal these average isotope signatures: δ18O = -3.02 ‰, δ 2H = -21.17 ‰, δ 13C = 12.46 ‰ 3H = 0.45 TU and 14C = 65.38 pMC. The δ18O-δ 2H relationship for the groundwater has a gradient of 4.48. This demonstrates that the groundwater has experienced evaporation before or during recharge. The unevaporated isotopic signature of the water is -5.86 ‰ and -33.89 ‰ for δ18O and δ2H, respectively. The enriched δ13CDIC signature suggests that methanogenesis has influenced the groundwater. The unstable isotopes (3H and 14C) suggest that there is groundwater mixing in Jansenville between younger water from shallow aquifers and older water likely from deeper aquifers. Borehole yields increase with decreasing radioactive isotope concentrations. This suggests that high yielding boreholes are areas of potential contamination because they are associated with mixed groundwater.
Investigating Methods to Identify Groundwater Dependent Ecosystems and Assess Potential Impacts of Shale Gas Developments in the South Western Karoo, South Africa	Louelle Chelsea	Philander	Western Karoo, South Africa	2017	Dependent Ecosystems, Shale Gas Developments
Abstract The need to diversify energy resources for South Africa has brought developing shale gas to the forefront. Consequently, the semi-desert Karoo basin in South Africa is being explored as a potential source for shale gas resources. South Africa’s limited water resources have caused concern because groundwater resources are the main source of water for irrigation, drinking and for sustaining groundwater dependent ecosystems. Groundwater dependent ecosystems are found across the South African landscape, affecting the environment and ecological processes where groundwater flow to and discharge from aquifers. The current study assesses potential impacts of shale gas developments on groundwater dependent ecosystems in the Karoo area. Groundwater dependent ecosystems were identified and categorized based on a combination of hydrogeological and morphological type setting. Direct methods based on terrestrial setting and indirect methods based on hydrogeochemistry for determining interaction between groundwater and the groundwater dependent ecosystem were assessed. Preliminary results lean towards potential risks to groundwater dependent ecosystems and shallow aquifer systems from surface processes during shale gas developments instead of subsurface processes. Therefore, it is suggested to ecologically assess groundwater dependent ecosystems and further study the influence of shale gas development on groundwater dependent ecosystems at regional scale perspective in South Africa to inform a level of protection and risk management.
Development of an Artificial Neural Network for the Prediction of Mine Dewatering	S.	Ngoie	Democratic Republic of the Congo.	2017	neural network, mine dewatering
Abstract Open pit mines often experience problems related to groundwater inflows. To perform mineral extractionin safe conditions with high productivity, it is essential to have dry working conditions. For this reason, the groundwater table is often lowered below the elevation of the floors of the pits by using various dewatering schemes. Numerical groundwater models are powerful tools that can be used to simulate the behaviour of aquifers during dewatering operations. However, these models typically require a lot of geohydrological data which are often expensive and time-consuming to collect. When geohydrological input data are limited, artificial neural networks (ANNs) provide an alternative approach of predicting the behaviour of the groundwater system during dewatering. This study investigated the possibility of predicting the impacts of pit dewatering on the aquifer system in the vicinity of open pit mines where geohydrological inputs are limited, using ANNs. First, the performance of the ANNs in predicting hydraulic head responses was evaluated by using synthetic data sets generated by a numerical groundwater model developed for a fictional mine. The synthetic data sets were then used to both train and evaluate the performance of the ANNs. The ANN found to give the best predictions of the hydraulic heads had an architecture of 2-6-1 (input-hidden-output layers) and was based on the hyperbolic tangent transfer function. This network was selected to predict the hydraulic heads at a number of piezometers installed at two open pit mines in the Democratic Republic of the Congo. The only input to the ANN was the recorded hydraulics heads and the time of recording. A portion of the real data set was used to train the ANN, while the remaining portion was used to evaluate the performance of the ANN in predicting the hydraulic heads. The results of the performance analyses indicated that the ANN successfully predicted the general behaviour of the aquifer system under dewatering conditions, using only limited input data. The results of this investigation therefore illustrate the great potential of using ANNs to predict aquifer responses during dewatering operations in the absence of comprehensive geohydrological data sets. Since these networks recognise patterns in the training data sets without considering the underlying physical principles that govern the processes, the responses of complex systems that are dependent on numerous parameters may be predicted.
Alluvial Wellfield Optimisation And Management Using Numerical Flow Modelling And Seasonal River Stages	Brendon	Bredenkamp		2017	Alluvial aquifer, wellfield management, numerical modelling, river stages
Abstract Three dimensional numerical flow modelling has become one of the best tools to optimise and management wellfields across the world. This paper presents a case study of simulating an existing wellfield in an alluvial aquifer directly recharged by a major perennial river with fluctuating head stages. The wellfield was originally commissioned in 2010 to provide a supply of water to a nearby Mine. Ten large diameter boreholes capable of abstracting ±2 000 m3 /hour were initially installed in the wellfield. The numerical groundwater flow model was used to evaluate if an additional 500 m3 /hour could be sustainably abstract from the alluvial aquifer system. A probabilistic river flow assessment and surface water balance model was used to quantify low and average flow volumes for the river and used to determine water availability in the alluvial aquifer over time. Output generated indicated that the wellfield demand only exceeded the lowest 2% (98th percentile) of measured monthly river flow over a 59 year period, thereby proving sufficient water availability. Conceptual characterisation of the alluvial aquifer was based on previous feasibility studies and monitoring data from the existing hydrogeological system. Aquifer parameters was translated into the model discretisation grid based on the conceptual site model while the MODFLOW River package was used to represent the river. Actual river stage data was used in the calibration process in addition to water levels of monitoring boreholes and pump tests results. The input of fluctuating river water levels proved essential in obtaining a low model error (RMSE of 0.3). Scenario modelling was used to assess the assurance of supply of the alluvial aquifer for average and drought conditions with a high confidence and provided input into further engineering designs. Wellfield performance and cumulative drawdown were also assessed for the scenario with the projected additional yield demand. Scenario modelling was furthermore used to optimise the placement of new boreholes in the available wellfield concession area.
Geochemical Simulation of Drain Water Quality in Gold Tailings	Terry R	Harck		2017	geochemistry, modelling
Abstract This paper presents data obtained from sampling and geochemical analysis of gold tailings and associated pool and drain water. Inverse geochemical modelling using PHREEQC indicated geochemical processes operating in the tailings between the pool and drains. These included pyrite oxidation and dissolution of various minerals identified in the tailings. The processes were incorporated into an ensemble geochemical model to calculate post-closure sulphate concentration in tailings seepage. The ensemble model included a spreadsheet model to calculate oxygen flux at various depths in the tailings column, and a one-dimensional transport model in PHREEQC. The calculated oxygen flux was applied to each cell in the tailings column to determine the amount of sulphide oxidation and the release of acidity into the tailings pore water. The rate of vertical transport of pore water in the column was determined from physical characterisation of the tailings particle size and saturated hydraulic conductivity. The model results indicate elevated sulphate concentrations and acidity moving as a front from the top of the column downwards. The modelled sulphate concentration of 1 500 to 1 900 mg/L 8-16 years after closure compared well with measurements of drain water quality at a tailings dam decommissioned approximately 16 years ago. This provided some credibility to the modelled result of 2 300 mg/L sulphate up to 50 years post-closure. However, the tailings moisture content, infiltration rate, and pyrite oxidation rate in the model were based on literature values, rather than site-specific measurements.
Identifying And Modelling Sustainable Groundwater Inflows Into The Verlorenvlei Coastal Estuarine System In South Africa	Jodie	Miller	West Coast, Western Cape	2017	estuarine system, agriculture, hydrochemical, baseflow
Abstract The Verlorenvlei estuarine lake is one of only two freshwater estuarine systems in South Africa. Whilst being important ecologically it is also a critical agricultural region, supporting a significant proportion of South African potato crops as well as a number of other diverse crops. The vlei itself is fed by the Verloren River which is thought to be fed by surface water inflows and baseflow throughout the year along several tributaries, namely the Krom Antonies, Hol, Berg Vallei and Kruismans. Each of these tributaries has a distinct hydrochemical character defined by cation and anion concentrations, as well as O, H and Sr isotopes. Simulated discharge from each tributary suggests that all tributaries contribute to the chemistry of the Verloren River. The Krom Antonies which has the freshest water has the highest discharge at around 50% of surface water inflows, whilst the Hol with the highest EC values contributes around 35% of surface water inflows. In spite of this, the surface water hydrochemistry in the Verloren River, is remarkedly fresh and very similar in character to the surface water of the Krom Antonies. Sr isotopes in each of the tributaries are distinct and support mixing of different components of each tributary above the confluence. However, below the confluence, they drop significantly which indicates mixing with another unidentified Sr-source. This source was thought to be baseflow from the deeper groundwater system, but the Sr isotope composition of deeper groundwater indicates that it is not the contributing component. Recent years have seen dramatic reductions in precipitation, while increases in pumping for agricultural purposes potentially exceeds the long-term sustainable yield of the aquifer system. Identification of this unknown component has therefore become a priority for groundwater management in the area as it is unclear how vulnerable this component will be to climate change and hence what impact climate change will have on the vlei.
Groundwater Resource Protection: State-Of-The-Art, Challenges and Research Needs	Kornelius	Riemann	National	2017	Resource protection, Water Availability
Abstract Water plays a significant role in the economies of the agricultural, business and industrial sectors. Expanding populations, economies and climate change have put pressure on the quality and availability of water resources in South Africa, therefore water resource protection becomes increasingly important for sustainable water supply management. Hence, a review of the state-of-the-art of water resource protection in South Africa has been undertaken on behalf of the WRC, applying the water resource governance framework. Gaps in scientific understanding and implementation with regards to water resource protection have been identified through literature review and discussions with stakeholders and experts. Aiming to improve the water resource protection in South Africa, a research strategy has been developed to tackle the most relevant of the identified gaps. The legislation in South Africa with respect to water resource protection is state-of-the-art and one of the best in the world. However, there is still space for improvement in that the different acts need to be aligned better to facilitate cooperative governance and improve the implementation of the legislation. Regulations and guidelines are plentiful covering most of the relevant activities and various water resources. The main challenge for implementing the intent of the National Water Act with respect to groundwater resource protection is that the standard methodology for determining Resource Directed Measures (RDM) was developed for surface water resources and is not applicable to groundwater or wetlands. Furthermore, classification and Reserve determination are mostly carried out at a scale that is insufficient for effective groundwater resource protection. The methodology requires update to incorporate potential impacts of climate change, changing land use and changing demographics. The different elements of the RDM methodology need to be aligned. There is also often an insufficient spatial and temporal distribution of monitoring networks to effectively manage groundwater resources. Integrated catchment management can provide a solution to the current state of water resource protection. However, this must be based on a scientific understanding of the complex natural system. The different challenges, research needs and possible solutions are demonstrated on a case study of Stanford Aquifer.
Groundwater Augmentation For Housing Estate Water Supply, Implementation And Legal Use	Greg	Molzen	Western Cape	2017	urban water supply, Conjunctive use, estate development, mini-wellfield
Abstract With increasing pressure on Cape Town’s potable water supply, the responsibility of diversifying supply for small, medium and large volume water users has fallen to the user to ensure sustainable use of potable water, and utilising all feasible non-potable sources where available. With estate and sectional title living becoming more common in South Africa, it is possible to develop holistic groundwater development models and strategies for the implementation of mini wellfields within these, in general, more densified living areas. This is well aligned with the Water Conservation and Water Demand Management Strategy of the City of Cape Town, where conjunctive use of groundwater for non- potable uses such as irrigation is implemented, as well as aligning itself with the current water restrictions within the Cape Metropole. Unlike standard residential neighbourhoods, estate development allows for the implementation of well- managed abstraction and monitoring of groundwater levels, as well as the possibility of shared groundwater usage in situations where legislation allows. The installation of fewer higher yielding boreholes (versus individual wellpoints on each residential section) to supply water to all communal areas and private gardens, allows for targeted data collection, interpretation and reporting. Implementation of shared water use from a single water use licence (likely issued to the legal entity of the body corporate) within sectional title property has its own complications, where licensed water use would generally be restricted to communal areas. The multi-phase assessment, implementation and licensing of groundwater supply for a life-rights retirement estate is presented as a case study. This enabled the investigation into shared water usage for irrigation of communal areas, as well as gardens of individual dwellings, eliminating the installation of dozens of wellpoints on estate properties thus ensuring sustainable usage and continued monitoring of the groundwater. Concurrent development of the groundwater infrastructure during the housing estates development brings its own challenges, and requires special consideration during early phases of the project, where infrastructure damage is commonplace on large construction sites. Holistic water conservation strategies were implemented, such as the construction of permeable pavements to increase the amount of recharge to the underlying aquifer storage below the estate instead of trying to store rainwater in the limited surface space. Utilising installed borehole equipment, an Aquifer Stress Test (AST) was undertaken to determine the aquifer parameters, sustainable yield of the individual boreholes and the wellfield as a whole, as well as inter borehole interactions. An AST allows for real world scenario aquifer testing to prove sufficient groundwater availability.
Advances In The Realm Of Hydrogeophysics: The Emerging Role Of Quantum Geoelectrophysics (Qgep) In Deeper Aquifer Exploration	R	Hatala		2017	Deep aquifers, Geophysics, QDMI, QGEP, Electromagnetics, ERT
Abstract Water is integral to our economy, the health of our environment, and our survival as a species. Much of this water is accessed from surface sources, mostly rivers, which are now under increased threat due to over use and the resulting hydro-political forces. Yet, groundwater exists as a viable option in many countries facing these mounting challenges. Knowledge of our deeper groundwater systems, although increasing, is still quite limited due to our propensity to focus efforts in the lower cost, lower risk, near- surface environment. However, accessibility to shallower groundwater is tightening due to increasing use, changing regulatory requirements, and climate change. The use of classical geophysics to explore for groundwater resources, such as seismic, gravity, magnetics, and resistivity, has been the industry standard for many decades. These technologies have proven quite effective both in the shallow and medium depth environments. However, newer remote sensing and ground-based technologies are now emerging with the ability to significantly reduce costs and time, and increase success for groundwater exploration and development programs. Quantum Direct Matter Indicator (QDMI) technologies, or applied methods of Quantum Geoelectrophysics (QGEP), are poised to enhance the hydrogeophysical industry, much like electro-magnetic (EM) and electrical resistivity tomography (ERT) did years ago. QDMI utilizes resonant frequency remote and direct sensing technologies that detect perturbations in the earth’s natural electric, magnetic and electromagnetic fields. Controlled source electromagnetic pulse methods with electromagnetic spectrum spectroscopy are used to identify aquifers, including thickness, water quality (fresh or saline) and temperature, to depths of 1000 m or more accurately. With multiple successes around the world, the deployment of this inventive and effective approach to groundwater exploration is poised to advance exploration geophysics globally.
Numerical Modelling Of a Coal Mine to Improve the Understanding of Mine Water Decant: A 1000-Piece Puzzle	Amy	Allwright		2017	coal ash, dolomites, Mining , numerical modelling
Abstract A coal mine in South Africa had reached decant levels after mine flooding, where suspected mine water was discharging on the ground surface. Initial investigations had indicted a low-risk of decant, but when ash-backfilling was performed in the defunct underground mine, decant occurred. Ash-backfilling was immediately suspended as it was thought to have over-pressurised the system and caused decant. Contrariwise, a number of years later decant was still occurring even though ash-backfilling had been terminated. An investigation was launched to determine whether it was the ash-backfilling which had solely caused decant, or if additional contributing factors existed. Understanding the mine water decant is further complicated by the presence of underlying dolomites which when intersected during mining produced significant inflows into the underground mine workings. Furthermore, substantial subsidence has taken place over the underground mine area. These factors combined with the inherent difficulty of understanding unseen groundwater, produced a proverbial 1000-piece puzzle. Numerical groundwater modelling was a natural choice for evaluating the complex system of inter-related processes. A pre-mining model simulated the water table at the ground surface near the currently decanting area, suggesting this area was naturally susceptible for seepage conditions. The formation of a pathway from the mine to the ground surface combined with the natural susceptibility of the system may have resulted in the mine water decant. This hypothesis advocates that mine water was going to decant in this area, regardless of ash backfilling. The numerical groundwater flow model builds a case for this hypothesis from 1) the simulated upward flow in the pre-mining model and 2) the groundwater level is simulated above the surface near the currently decanting area. A mining model was then utilised to run four scenarios, investigating the flux from the dolomites, subsidence, ash-backfilling and a fault within the opencast mine. The ash-backfilling scenario model results led to the formation of the hypothesis that completing the ash-backfilling could potentially reduce the current decant volumes, which is seemingly counterintuitive. The numerical model suggested that the current ash-backfill areas reduce the groundwater velocity and could potentially reduce the decant volumes; in spite of its initial contribution to the mine water decant which is attributed to incorrect water abstraction methods. In conclusion, the application of numerical models to improve the understanding of complex systems is essential, because the result of interactions within a complex system are not intuitive and in many cases require mathematical simulation to be fully understood.
Developing And Optimising Conditions For Bioflocculation Of Bacillus Sp.Isolated From The Estuary On The Umlalazi Catchment At Mtunzini, KZN Province	TM	Kubhayi	KwaZulu-Natal	2017	Bioflocculant, flocculating activity
Abstract Synthetic flocculants are widely used in water treatment for their efficiency when it comes to flocculation but pose a risk to the environment and human health. The need for an alternative flocculant was investigated in this study. Bioflocculants which are produced by microorganisms have the potential to flocculate fine suspended particles. The bioflocculant production by Bacillus sp. isolated from Umlalazi Estuary in Mtunzini, KwaZulu-Natal Province was evaluated. Optimum flocculation conditions were obtained with an inoculum size of 1% v/v (89%), carbon source which was glucose with a flocculating activity of 88%, a multiple nitrogen source with a flocculating activity of 88%, an optimum temperature of 400C with 95% flocculating activity, shaking speed of 120 rpm with 95% flocculating activity, K+ for the cations was optimum at 95% flocculating activity and the pH of 7 had the flocculating activity of 94%. In the time course assay optimum conditions were reached after 84 hours with the flocculating activity of 92% at pH 5.29 using 0.4% (w/v) kaolin suspension. After extraction and purification, a bioflocculant yield of 2.1g/L was recovered from a 1L fermentation broth. Water treatment without the risk to human health is now a reality.
Sustainability Of Shallow Groundwater Irrigation On Emerging Farms In The Limpopo Province: Case Study In The Molototsi Catchment	Nebo	Jovanovic	Limpopo	2017	Shallow groundwater, modelling, MODFLOW, Irrigation
Abstract A cycle of research is under way to investigate sustainable farming practices and business development on emerging farms in the lowveld of the Limpopo Province of South Africa. One of the main limiting factors for intensive agricultural production in this region is water availability. The objectives of this study were: i) to determine the spatial extent of occurrence of shallow groundwater (<20 m deep), in particular along dry river beds; and ii) to determine the sustainability of shallow groundwater abstraction for irrigation on emerging farms. A case study was investigated in the Molototsi River catchment, a torrential tributary of the Letaba River. The geology consists of well-developed, medium-textured alluvial/colluvial soils overlying predominantly Goudplaats gneiss. Geophysical surveying and mapping was carried out with a Model G5 proton memory magnetometer and an EM-34 electrical resistivity meter. Groundwater level data were collected from the GRIP database (Groundwater Resource Information Project - Department of Water and Sanitation) and selected boreholes were monitored with Solinst water level loggers. Groundwater abstraction data, borehole logs and digital elevation models were also collected. A methodology was developed to map the extent of shallow groundwater using measured groundwater levels, a National Land Cover map (NLC 2013/14), the wetland map of the National Freshwater Ecosystem Priority Areas (NFEPA), satellite remote sensing (MOD16 evapotranspiration data) and ground-truthing. Groundwater level monitoring indicated that the water bearing features may not be directly connected to the alluvium and sand river bed (alluvial aquifer), resulting in limited baseflow estimated to be ~15 m3 a -1 for a river reach of 100 m. Episodic recharge of the alluvial aquifer occurs predominantly via surface runoff. The hydraulic conductivity of the river sand aquifer was estimated to be >20 m d-1 , and one order of magnitude smaller in the fractured rock aquifers. Groundwater modelling with MODFLOW was done at farms abstracting groundwater from fractured bedrock aquifers and directly from the sand bed of the Molototsi River to investigate how much water can be abstracted for sustainable irrigation. Both modelling and monitoring results indicated that there is limited scope for large scale expansion of irrigation, given the competition for water in the area, in particular for drinking water supply. However, the volume of water stored in the dry river bed could represent a useful reserve during periods of severe drought, with recharge from occasional flood events being essential. Given the porosity of the river bed aquifer of about 40%, it was estimated that a 100 m reach of the Molototsi River would retain about 7,200 m3 of water that could be abstracted if numerous wells are established and recovery periods are allowed. A water volume of 7,200 m3 is sufficient to irrigate 1.8 ha of vegetables for one season. This volume could be augmented to a certain extent by establishing river bed sand dams.
The National Groundwater Strategy for South Africa	Fanus	Fourie	National	2017	strategy, IWRM, Governance, risk-based approach
Abstract The paper provides an outline of the recently published National Groundwater Strategy and of the approach to its implementation. According to the National Water Resource Strategy, development of groundwater resources will be crucial for sustaining water security in the light of increasing water scarcity in South Africa. Already groundwater’s role in South Africa has undergone a major change during the water sector transformation post-1994, from an undervalued resource and a ‘private water legal status’ to a source of domestic water and general livelihood to more than 60% of communities in thousands of villages and small towns country-wide. However, there are major concerns that local groundwater resources are very poorly managed and that major aquifers are under pressure in many locations through over- abstraction, declining water levels and water quality degradation. In the light of these general challenges, there has been a recognition, world-wide, that, with increasing level of groundwater development, there has to be an incremental institutional path, moving from technical development of the resource to groundwater management and ultimately to groundwater governance as part of IWRM. This is the path South Africa is intending to follow in the development of a national groundwater strategy initiated in 2015. At the heart is an agreed strategic framework of groundwater governance and a stakeholder-driven process to roll out the framework over the next 10-20 years. Appropriate governance is particularly important for groundwater, because of its ubiquitous nature and relative ease of local access. Focus on local stakeholder involvement will be essential. Thus major issues that will have to be addressed from the beginning to encourage stakeholders to be more willing to contribute to the management efforts include proper valuation of groundwater, scientific understanding and accessible data and information and broad-based education to build social support for management. The strategy framework will address three essential levels, namely the local action level, the national/regional regulatory, planning and institutional development level and an enabling policy level. A major challenge at the enabling level is the present lack of a well-capacitated national groundwater champion to guide and coordinate the overall roll-out process. Different ways for a much greater involvement of the groundwater sector as a whole are suggested. A risk-based approach is proposed to achieve increased focus and levels of management for more stressed aquifers on a priority basis. This must be seen as a major paradigm shift from national management to facilitated local level participative management of groundwater resources within the overall IWRM framework.
Protection, Management And Governance Of Groundwater Resources In Transboundary Aquifers – Stampriet Transboundary Aquifer System (STAS) Case Study	Kwazikwakhe	Majola	Central America, Central Asia, Botswana, Namibia, South Africa	2017	transboundary aquifers, Water security, transboundary cooperation, resource management
Abstract The UNESCO-IHP initiated a project on “Governance of Groundwater Resources in Transboundary Aquifers” in 2013. Three aquifers were selected for case studies: Trifinio (Central America), Pretashkent (Central Asia), and the Stampriet Transboundary Aquifer System (STAS) in southern Africa shared between Botswana, Namibia and South Africa. The project aimed to conduct a detailed assessment of the characteristics, current state and management of transboundary aquifers and to lay the foundations for a multi-country consultation body. It is expected that this will lead to enhanced water security, transboundary cooperation in groundwater management, and improved environmental sustainability in the aquifer region. Phase 1 of the project focused on desktop activities to acquire existing data and information with respect to three components: Hydrogeological, Socio-economic & Environmental, and Legal & Institutional. The integrated assessment determined that the recharge is taking place in Namibia during heavy rain periods, and that is where the resource is mostly used - Namibia (91.2%), Botswana (8.6%), South Africa (0.2%). Lack of time-series data made it difficult to determine aquifer properties. Groundwater quality is mainly impacted by agricultural activities and geological properties. The STAS area depends mainly on groundwater since the rivers are ephemeral. The Information Management System was developed in order to encourage information sharing among countries and to store interpreted and processed data from the assessment of the groundwater resources for use as a tool to support decision makers and relevant stakeholders’ actions. Water Diplomacy training offered involves hydro-politics of water to support cooperative agreements and increasing institutional capacity of sharing countries to reduce conflict and enhance cooperation over shared resources. This formed basis for the development of a Multi-Country Consultation Mechanism, a body that will provide the vision and direction towards governance and sustainable management of the STAS. The project is on-going with Phase 2 expected outcomes including numerical model, among other outcomes, using FREEWAT which is openly available. It is anticipated that ultimately, a joint governance model shall have been drawn amongst the three countries to ensure a mutually sustainable resource management.
Application of Environmental Tracers for Differentiation of Fresh and Re-Circulated Submarine Groundwater Discharge (Sgd) Into Knysna Estuary, South Africa	E.	Petermann	Knysna Estuary, South Africa	2017	Environmental tracers, Submarine Groundwater Discharge
Abstract In coastal areas worldwide terrestrial groundwater resources and the coastal sea are generally hydraulically connected thus allowing continuous groundwater/seawater interaction. This major form of land-ocean interplay is associated with two potential pathways of dissolved matter transport, namely (1) flux from the marine to the terrestrial environment in form of seawater intrusion into terrestrial aquifers and (2) flux of terrestrial groundwater into the coastal ocean manifested as submarine groundwater discharge (“SGD”). The sea-to-land pathway is of relevance due to the risk of irreversible salinization of coastal groundwater resources and is in most cases a manmade (and hence manageable) phenomenon set off by excessive groundwater exploitation that is not balanced by groundwater recharge. The land-to-sea pathway (i.e. SGD), on the other hand, occurs naturally everywhere an aquifer with a positive hydraulic head is connected to the ocean. It is of interest due to two potential threats, namely (i) the loss of freshwater to the ocean, an issue that is particularly relevant in climate zones characterized by water scarcity, and (ii) the detrimental impact of nutrient- or contaminant-laden groundwater discharge on the coastal water quality, an aspect that is of relevance along urbanized coastlines worldwide. The latter implies that SGD localization and quantification is of major relevance with regard to (i) the evaluation of the vulnerability of the coastal sea to groundwater pollution and for (ii) understanding the associated matter cycles including nutrients, organic compounds or inorganic contaminants. We present results of an environmental tracer based approach that aimed at evaluating short-term SGD dynamics into the Knysna estuary, South Africa. Both natural components of SGD, terrestrial freshwater (FSGD) and recirculated seawater (RSGD), were estimated individually. We conducted an end-member mixing analysis for time series of radon (222Rn) and salinity over two tidal cycles in order to determine four water fractions within the estuary: seawater, river water, FSGD and RSGD. The results were backed by stable isotope data (18OH2O and 2HH2O). End-member mixing ratio analyses revealed the mixing ratios that fit best to the observations at every time-step of the 24 h time series, which was carried out near the estuary mouth. Results indicated highest FSGD and RSGD fractions in the estuary water during low tide amounting to 0.2 % and 0.8 % for FSGD and RSGD, respectively. A radon mass balance for the whole estuary revealed a radon flux via SGD of 41 ± 7 Bq m^-2 d^-1, which equals a total FSGD of 4.6 10⁴ m³ d^-1 and RSGD of 1.5 10⁵ m³d^-1 . The results do imply that the majority of nutrient fluxes (DIN) into the estuary are SGD-derived.
Estimating Groundwater Recharge In Commercial Plantation Forests: A Case Study From George (Western Cape)	Richard DH	Bugan	George, Western Cape	2017	Forestry, afforestation, recharge mechanisms, Simulations, HYDRUS-2D
Abstract The benefits of the commercial plantation forestry sector (income generation, job provision, etc.) come at considerable environmental costs, particularly the impact of the industry on water resources. Plantation forests exhibit higher evapotranspiration rates when compared to that observed in indigenous forests/grasslands. A reduction of the water yield in a catchment is one of the most frequently reported impacts of afforestation. Afforestation also significantly impacts groundwater, which is becoming an increasingly important resource for water supply in South Africa. Very few studies have however quantified in detail the impact of different commercial forests grown in South Africa on groundwater and the interactions with surface water. This study seeks to contribute to addressing this important knowledge gap. The main objective was to comprehending groundwater recharge dynamics in commercial plantation forests, i.e. an environment where evapotranspiration losses is a major component of the water balance. The HYDRUS-2D model was used to simulate the hillslope hydrological dynamics in a commercial plantation forest (Pinus radiata) during the period 8 July 2016 to 12 June 2017. The model was used to simulate the interaction between the vegetation, unsaturated zone and the saturated zone in order to better understand the groundwater recharge dynamics evident in the area. As a precursor to model application a detailed conceptual model of the recharge processes occurring in the study areas was developed. The model considered the prevailing geomorphological and hydrogeological conditions. HYDRUS-2D was able to adequately simulate the soil hydraulic properties characterising the study area. The hydrological dynamics of the simulation results also conform to the conceptual understanding of groundwater recharge processes evident in the study area. Over the entire simulation period (340 days), the model quantified potential groundwater recharge to be 31.5 mm. This primarily occurred during a 60 day period (20 September 2016 - 19 November 2016) in response to significant rainfall events of 76.96 mm (DOS 56 – 58) and 45.98 mm (DOS 71 – 72). This groundwater recharge dynamic conforms to the notion that groundwater recharge is driven by single or multiple events and not by annual averages. The results of the investigation are promising and provide motivation for the application of HYDRUS-2D to estimate groundwater recharge in environments which are deemed to be suitable for model application. The model provides the ability to study the dynamics of groundwater recharge at short time scales, as opposed to annual average responses which are derived from commonly applied techniques.
Estimation of Groundwater Recharge Response from Rainfall Events in a Semi-Arid Fractured Aquifer: Case Study of Quaternary Catchment A91h, Limpopo Province, South Africa	Phathutshedzo	Nemaxwi	Limpopo	2017	groundwater recharge
Abstract This study was focused on estimating groundwater recharge response from rainfall events in a semi-arid fractured aquifer. Determination of response of the groundwater recharge from rainfall is important as it directly affects the available groundwater in an aquifer. Groundwater level data was used to evaluate the response of groundwater recharge from rainfall events using Extended model for Aquifer Recharge and soil moisture Transport through unsaturated Hard rock (EARTH) model. Chloride Mass Balance (CMB) method was also used to estimate groundwater recharge in quaternary catchment A91H. Chloride concentration from groundwater and precipitation in the catchment were collected and analysed. Calculated local recharge using CMB method was interpolated in ARCGIS to generate groundwater recharge distribution maps of the quaternary catchment. The estimated local recharge rates using CMB method ranged from 0.24-8.75 mm/a (0.04-1.3% MAP) using rainfall chloride concentrations of 0.1 mg/L. Regional recharge of 30.1 mm/a (4.6% MAP) were calculated using groundwater chloride concentration of 0.1 mg/L. The estimated recharge rates from EARTH model ranged from 3 to 10.3% of mean annual precipitation(MAP). The average estimated recharge rate was calculated as 6.12% of the MAP which is equivalent to 40.1 mm/a. Both EARTH model and CMB method yielded comparable results and were found to be similar to those obtained from other studies. High recharge was estimated in high elevation area while low recharge was estimated in low elevation area. The results obtained from this study have confirmed and expanded existing knowledge on the nature of groundwater recharge response from rainfall in fractured aquifers in semi-arid areas and the applicability of EARTH model and CMB method in recharge estimation in the same environment.
A Geochemical Investigation On Two Soekor Wells Located In The Northern Cape, South Africa	Danita	Hohne	Northern Cape	2017	hydraulic fracturing, geochemical investigation, Isotopes
Abstract The past few years hydraulic fracturing has been a hotly researched topic. Currently, most published documents are just speculation of what can happen if hydraulic fracturing is to take place in South Africa. There is very little work done to firstly establish a baseline on the current groundwater quality and secondly look at the current state of the groundwater around the Soekor wells. For these reasons a geochemical investigation was launched looking at the Soekor wells and the surrounding boreholes to determine a valid baseline. Looking at the two Soekor wells; geochemical analyses was conducted on water, soil and rocks. The drill core of the wells; soils from the waste ponds and water at or nearby the wells were sampled and analysed. By making use of XRF; XRD, Stable Isotopes and water chemistry analyses, a better picture of these wells and groundwater can be developed to give better guidelines to what should happen during the monitoring of hydraulic fracturing wells.
GIS and Groundwater Monitoring	Freda	Jonck	Western Cape	2017	monitoring network, resource assessment
Abstract The Department of Water Affairs and Sanitation is the custodian of the Water Resources in South Africa. The Western Cape Provincial Office, Geotechnical Services (Geohydrology) Sub Directorate, is responsible for management of groundwater resources in two Water Management Areas (WMA), Berg Olifants and Breede- Gouritz. Thirty-eight monitoring routes comprising 700 sites in total are monitored across the Western Cape Province. The purpose of this paper is to show the use of GIS as a management tool for groundwater monitoring in the Western Cape. This is to assist and support the scientists, technicians, managers, external stakeholders and/or general public. The main question that needs to be answered is: “What is the current groundwater monitoring and data management situation in the Provincial office” With GIS as platform, geographical information was generated from existing data bases to answer questions such as, what is being monitored, where is it being monitored, who is monitoring it, why is it being monitored, when is it being monitored, are instruments installed, what instruments are installed, what equipment is involved and what energy source is used? These questions are applicable to the Region, Water Management Areas, the relevant monitoring route and geosites. Generated geographical information showed the gaps, hot spots and what is still needed for all the facets of groundwater management (from data acquisition to information dissemination) processes. The result showed the status of data bases, need for data in areas of possible neglect, training gaps, inadequate structure and capacity, instrumentation challenges, need for improvement of commitment and discipline, as well as many other issues. The information generated proves to be an easy tool for Scientists, Technicians and Data Administrators to assist them to be on top of the groundwater resource management in their area of responsibility. The expansion of the use of GIS as a groundwater management tool is highly recommended. This will ensure better understanding of the “The Hidden Treasure” resource.
Rigorous Methodology For Sustainable Yield Estimation Using Groundwater Numerical Modelling Validation To Detailed Long Term Pumping Test Data	Shuaib	Dustay	Port Alfred	2017	numerical modelling, WUL, large-scale abstraction, Monitoring
Abstract Groundwater numerical models are commonly used to determine the impact that groundwater abstraction has on the ability of surrounding areas to supply water, and thus to inform Water Use Licence (WUL) Applications. However, data available is often limited to that generated by relatively short-term geohydrological studies and pumping tests. In most cases this data and the degree of defined uncertainty in the model results are sufficient. However, for large scale abstractions (such as municipal abstraction) and in sensitive or complex geological areas, a more rigorous approach to calculating the impact from pumping is recommendable. The study area is located on a syncline consisting of two sandstone aquifers. However, there was a lack of data to quantify the connectivity between the two aquifers. SRK Consulting (South Africa) (Pty) Ltd undertook a rigorous, long-term approach, which included a 3- year monitoring plan of the area, input from stakeholders, extending the hydrocensus to the entire catchment and monitoring of pumping in the area. Using this comprehensive data set, the existing numerical groundwater model was updated, re-calibrated and validated such that predictive scenarios could be run to assess the long-term potential impact of the municipal wellfield. These results were submitted for the final allocation of the WUL. Along with mitigation measures, recommendations could also be made on where to focus monitoring and future testing. This rigorous methodology and the use of long- term comprehensive monitoring data is recommended for future use in similarly complex environments to decrease uncertainty on the expected impacted area from large-scale abstractions.
In-Situ Iron Removal Treatment In A Primary Aquifer, The Atlantis Example	L.	Nhleko	Western Cape	2017	Iron Removal, Atlantis Aquifer
Abstract In a town where 98% of the population relies on groundwater-dominated resources, Atlantis is also plagued by varied abstraction rates that promoted iron and manganese borehole clogging. Conventional treatment methods, such as pump-and-treat technology, can be costly and inefficient. In-Situ Iron Removal (ISIR) technologies addresses issues such crucial skilled operators, handling and storage of chemicals, expert management, and the disposal of generated sludge. ISIR has been successfully practised worldwide especially in Europe, for well over a 100 years. In South Africa however this methodology has not filtered through, although our groundwater systems have clogging problems related to iron and manganese precipitation. Atlantis in the Western Cape has benefitted from a pilot study that looked into ISIR and the unique idea of utilizing ozonation. The pilot project was successful, although applied on a small scale. This called for a further study that is now looking into extending the range of treatment, applying the principles of the Vyredox method, and lengthening the treatment period to 3 months of continuous injection. The study also aims to develop the engineering design criteria for full scale application. The success of this project and the technology to be developed goes a long way towards achieving Sustainable Development Goal 6 and improving South Africa’s groundwater systems.
Characterisation and Protection of Deep Aquifers in South Africa: Potential Resources	Amy	Allwright	South Africa	2017	Deep aquifers, aquifer protection
Abstract The importance of groundwater in South Africa has become evident over the past decades, especially as pressure on surface water resources intensifies in response to increasing water supply demands. Research has significantly progressed on the shallow groundwater resources conventionally used for water supply, and leading on from this deeper groundwater resources have become a focus point as a future water source. This focus on deep aquifers is driven by new developments, such as shale gas development, injection of brines into deep aquifers, carbon sequestration and geothermal energy. The understanding of deep groundwater in South Africa is often limited due to insufficient data at these depths. To develop a body of knowledge on deep geohydrology in South Africa, an investigation on the currently available information was launched to assess potential deep groundwater resources. The investigation formed part of the larger WRC Project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). The geology of South Africa was reviewed from a deep groundwater perspective to provide an initial analysis of potential deep groundwater aquifers. The main potential deep aquifers were identified for further investigation using a ranking system, where Rank 1 shows a positive indication, Rank 2 shows some indication, Rank 3 shows a neutral indication, and Rank 4 shows a negative indication for deep groundwater systems. The Rank 1 geological groups include (in no particular order): the Limpopo Belt, Witwatersrand Supergroup, Transvaal Supergroup, Waterberg and Soutpansberg Groups, Natal Group, Cape Supergroup, Karoo Supergroup. In a number of the identified potential deep aquifers, the indicator for deep groundwater flow systems was the presence of thermal springs. Additionally, deep groundwater occurs below the traditionally exploited weathered zone, and the importance of fractured aquifers becomes paramount in the investigation of potential deep aquifers. In conclusion, three main components were considered for the investigation of potential deep aquifers systems, 1) geological groups; 2) thermal springs and 3) depth of fractures. These three components should be used holistically going forward to best characterise the potential deep aquifers of South Africa.
Characterisation And Protection Of Deep Aquifers In South Africa: Characterisation	Francois D	Fourie		2017	Deep aquifers, Aquifer characterization, groundwater flow, Groundwater Quality
Abstract This paper describes the characteristics of the deep aquifer systems in South Africa as derived from the available data. The study formed part of the larger WRC project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). A review of the available literature relevant to potential deep aquifers in South Africa was done to allow characterisation of these aquifer systems. In addition, data obtained from the geological logs of the SOEKOR and KARIN boreholes were considered. This paper focuses on deep aquifers in 1) the Karoo Supergroup, 2) the basement and crystalline bedrock aquifers, 3) the Table Mountain Group, 4) the Bushveld Igneous Complex and 5) the dolomites of the Transvaal Supergroup. From the available data the deep aquifer systems are described in terms of the following characteristics: lithology, occurrence, physical dimensions, aquifer type, saturation level, heterogeneity and degree of isotropy, formation properties, hydraulic parameters, pressurisation, yield, groundwater quality, and aquifer vulnerability. The results of the study show that the deep aquifer systems of South Africa are generally fractured hard-rock aquifers in which secondary porosity was developed through processes such as fracturing and dissolution. The primary porosity of most of the rocks forming the aquifers is very low. Apart from the dolomite aquifers, most of the water storage occurs in the rock matrices. Groundwater flow predominantly takes place along the fractures and dissolution cavities which act as preferential pathways for groundwater migration. The aquifers are generally highly heterogeneous and anisotropic. The deep aquifers are generally confined and associated with positive hydraulic pressures. The groundwater quality generally decreases with depth as the salinity increases. However, deep dolomite aquifers may contain groundwater of good quality. Due to the large depths of occurrence, the deep aquifer systems are generally not vulnerable to contamination from activities at surface or in the shallow subsurface. The deep dolomite aquifers are a notable exception since they may be hydraulically linked to the shallower systems through complex networks of dissolution cavities. The deep aquifers are, however, very vulnerable to over-exploitation since low recharge rates are expected.
Groundwater Modelling as a Water Management Tool	M Eva	Masemola	Free State	2017	dolomites, conceptual site modelling, hydrostratigraphy
Abstract New Vaal Colliery (NVC) is an opencast mine in the northern Free State, located within a meander of the Vaal river and underlain by the Transvaal Supergroup dolomitic aquifer. Dewatering of the pits results in high-sulphate water that needs to be stored in the Maccauvlei dam, the main unlined pollution control dam. In 2011 the mine was issued a water use license containing challenging conditions, one of which was the requirement for all water pollution dams on site to be lined. The conditions were viewed as impractical and unnecessary as the mine impacted water did not pose a risk to the surrounding environment, in particular to the underlying dolomitic aquifer. In order to motivate for the amendment of the license conditions, a hydrogeological conceptual site modelling (CSM) process was initiated in order to identify and quantify the groundwater balance and assess the extent of interaction between the dolomite aquifer and the mine. The CSM formed the basis for the development of a detailed and robust numerical model and triggered the re-evaluation of the mine’s land rehabilitation plan. The results were to be used to ensure the risks associated with water management on site were addressed and for submission of a water use license amendment application. This paper summarises the CSM development. A history of hydrogeological studies provided the initial understanding of the hydrostratigraphy which is characterised by three main units, namely the shallow weathered and mine aquifers, the Karoo aquifers and aquiclude as well as the pre-Karoo aquifer and aquiclude. The available site data indicated that while the Maccauvlei dam may have a hydraulic connection to the shallow artificial mine aquifer, it was unlikely that water from the dam impacted on the dolomitic aquifer. This was supported by water levels measured in boreholes targeting the dolomite aquifer, which generally recorded an elevation above that of the Vaal River, confirming the confined or semi-confined nature of the aquifer. The pressure heads suggested that water flow is from the dolomitic aquifer to the mine and not the other way around. Of significance to the mine’s water management were the findings that 1) a geological graben forming the boundary between NVC and the defunct Cornelia mine could provide substantial groundwater flow into the mine and 2) that the flooded old underground mine working still to be mined are likely to exceed the site’s infrastructure capacity for water storage and limit coal production. The CMS was sufficient to illustrate that it is not likely that the mine water has an impact on the dolomitic aquifer water quality, a finding later supported by the numerical model. The modelling process provided the necessary platform to negotiate a progressive implementation of license conditions that are specific to the mine and cost effective over the life of mine, despite the gaps identified.
Conceptual Model Based Numerical Groundwater Flow Modelling of the Simbithi Eco-Estate, Kwazulu-Natal, South Africa	Jacqueline	Roux	Simbithi Eco-State, Kwazulu-Natal, South a	2017	hydrogeological conceptual model, MODFLOW, numerical groundwater flow model, saltwater intrusion, Simbithi Eco-Estate, Monitoring
Abstract Water stress is frequently experienced in many parts of South Africa. To ensure the longevity of the country’s water resources, particularly groundwater, accurate quantification of the resource and prediction of the responses of each water resource unit to natural and anthropogenic stresses are necessary. To this endeavour, Simbithi Eco-Estate, located at Shaka’s Rock, KwaZulu-Natal requires the implementation of a Water Management Plan that includes a hydrogeological investigation. A hydrogeological conceptual model was developed for the eco-estate, based on which a numerical groundwater flow model was calibrated to simulate the impacts of different rates of groundwater abstraction within the estate. Hydrometeorological information, subsurface geology, hydraulic head, hydraulic characteristics of the aquifer units and hydrochemical data were analysed to develop a two-layer hydrogeological conceptual model. The conceptual model was used as the main input to the numerical groundwater flow model. The calibrated steady-state numerical model, developed using the finite-difference groundwater modelling code, MODFLOW, was used to determine the sustainability of groundwater abstraction within the eco-estate. During calibration, the hydraulic conductivities of the hydrostratigraphic units, and recharge were varied. The Model calibrated recharge was 5.5 % of the mean annual precipitation (MAP). The five abstraction scenarios considered were: Scenario 1, which is the sustainable abstraction rate determined from the analysis of pumping test data, and Scenario 2 to 5 which are assigned progressively increasing abstraction rates of Scenario 1, by a factor of 20%, 50%, 100%, and 1000%, respectively. The numerical model simulations indicate that Scenario 1 is most sustainable in terms of groundwater level drawdown and saltwater intrusion. The simulated groundwater drawdown progressively increased throughout the succeeding four scenarios. The simulation results of the 5th scenario indicate that part of the model domain within the vicinity of the northern boreholes becomes dry and subsequent application of forward particle tracking on the simulation results predicts saltwater intrusion from the Indian Ocean towards the south eastern boreholes. It is accordingly recommended that groundwater resource development should be limited to below the abstraction rates of Scenario 4. Additionally, continuous monitoring of all boreholes within the eco-estate is recommended to generate time-series groundwater level information, which would be used to improve the predictive capabilities of the current steady-state model through a transient numerical groundwater flow model. To that end, an immediate establishment of a groundwater level and specific electrical conductivity (EC) monitoring network, equipped with data loggers, is recommended.
To Be, Or Not To Be – A Career In Hydrogeology: Some Anecdotes And Advice From Adventure And Exploration Over The Past 30 Years	R	Morris	South Africa	2017	Experience, career, profession
Abstract A hydrogeologist studies the ways that groundwater (hydro) exists within and moves through the soil and rock of the earth (geology). How we use this knowledge for the good of the environment and society will lead to our success as hydrogeologists and environmental game-changers. Within the broad field of hydrogeology there exist several specialist domains. One may be more of a specialist in groundwater supply, resource management and monitoring issues. Or one may concentrate on subsurface contamination issues. Or be more slightly removed in areas such as geophysics and specialised modelling. Field experience as a young hydrogeologist is essential to establish a foundation for good science. Early specialisation is however occurring to the detriment of first understanding the essentials of basic hydrogeology. Data collection, collation, interrogation and interpretation all contribute to the report. It is the presentation of the findings in a manner that can be understood by the layman, general public and authority groups that is important. For the field of hydrogeology to obtain the recognition it deserves in South Africa, the hydrogeological fraternity will need to become more ‘heard’ and ‘active players’ in managing the country’s scarce water resources. It is one thing to develop a groundwater supply scheme, but the role of the hydrogeologist must continue with the long term monitoring and management of that supply scheme to ensure its success. This presentation draws on the more than 30 years of experience that the author has had as a practising hydrogeologist in South Africa. The oral presentation of this paper has as its intention to excite passion for the profession of hydrogeology. Reminisces made will show the pleasure of experiences gained and provide guidance to young entrants to the profession. Being a hydrogeologist provides one with the opportunity to be a ‘player in the field’ and contribute to sustainable life and societal well-being. Being a player is more exciting than being a spectator, so engage in how you can enjoy your game.
Characterising Groundwater Recharge In Crystalline Aquifer Johannesburg, South Africa	Khahliso	Leketa	Gauteng	2017	Crystalline aquifer, groundwater recharge, recharge estimation methods, stable isotopes
Abstract Groundwater recharge assessment was undertaken in the crystalline aquifer of the Upper Crocodile River Basin, Johannesburg South Africa. The basin is characterised by the complex hydrogeological setting represented by weathered and fractured granitic gneisses overlain by quartzite, shale and dolostone. A number of recharge estimation methods including the Stable Isotope Enrichment Shift method, were tested. The measurement of δ 18O and δD in springsrevealed the presence of high elevation recharge or cold weather recharge that occurs prior to extreme evaporation, undergoing deep circulation and discharging at the contact between the Witwatersrand quartzite and the underlying shale. In the dolostones, recharge occurs after evaporation at higher elevation undergoing deeper circulation through the dissolution cavities. The Water Table Fluctuation method in the dolostone resulted in the mean annual recharge of 99 mm/year, representing 14% of mean annual precipitation. The Reservoir Water Balance method revealed that the Pretoria Group shale aquifer contributes 16% of dam water outflow per year (groundwater discharge) which equates to 3 429 662 m3 on average, while 7% of dam inflow is lost to groundwater constituting groundwater recharge of average 2 084 131 m3 per annum. Baseflow Separation method applied gave an average recharge value of 9.4% for the entire catchment. The estimated average recharge for the entire catchment was found to be 13% corresponding to 91 mm, which equates to 374 Mm3 . The Stable Isotope Enrichment Shift Method resulted an average annual recharge of 26.1% in the aquifers composed of quartzites and 3% in the dolostones. The method is found to be promising for application in spring regimen however, a further development is recommended since small shifts exaggerate recharge while large shifts undermine it.
Understanding Natural Groundwater Recharge Systems In The Lower Berg River Catchment, West Coast, Western Cape	Clinton W	Andries	West Coast, Western Cape	2017	MAR, geochemical, Lower Berg River Catchment, conceptual model
Abstract The CSIR has embarked on a study to investigate the potential for additional water in the West Coast, Western Cape through the application of Managed Aquifer Recharge (MAR). The benefits of MAR is that it may generate additional water supplies from sources that may otherwise be wasted with the recharged water stored in the aquifer to meet water supply in times of high demand. Determining recharge is the most important aspect of hydrological system. However, the accurate estimation of recharge remains one of the biggest challenges for groundwater investigators. Numerous studies have been conducted using geochemical methods to estimate and distinguish sources of recharge in different groundwater units of unconfined and confined aquifers internationally. The application of geochemical methods to produce accurate conceptual model describing natural recharge in aquifer units of Lower Berg River Region has not been widely published. The Lower Berg River catchment, consisting of 4 primary aquifer units (Adamboerskraal, Langebaan Road, Elandsfontein and Grootwater) will be used to demonstrate the applicability of such methods. The aim of the study is to estimate recharge in the lower berg river catchment, and develop a conceptual natural recharge model that will improve understanding of the aquifer system and be an indicator for water availability in the Lower Berg River Catchment. The objectives in developing the conceptual model includes establish groundwater recharge sources, groundwater flow paths, recharge mechanism and potential mixing of groundwater by using environmental isotopes; and obtain a reliable estimation of its recharge amount using the Chloride Mass Balance. As this study is still in progress, this publication will focus on reviewing literature and the outcomes envisioned from the project as to provide a complete understanding of the complex geology. This will lead to a better understanding of the functioning of natural recharge of the aquifer units in the Lower Berg River Catchment.
Assessment Of The Spatial Coverage Of Groundwater Dependent Ecosystems In A Semi-Arid To Arid River Gouritz River Basin	T	Mbandezi	Western Cape	2017	Shallow groundwater, groundwater dependant ecosystems, remote sensing
Abstract The presence of shallow groundwater at locations with limited spatial coverage in drylands have since time immemorial supported plant and animal communities. These locations often have in comparison to the surrounding dry landscapes high biomass production and biodiversity. The presence of groundwater makes these locations attractive for development of groundwater dependent human activities such as irrigated crop production, and livestock production. Groundwater abstractions from locations that are not necessarily close to these plant and animal communities, but tapping into the same aquifer systems have also a potential to affect the availability of water to these ecosystems which is critical for their existence. The importance of these groundwater dependent ecosystems is not well understood due to limited knowledge about their spatial coverage. Some of the groundwater dependent ecosystems occur in areas that are not accessible such as mountain slopes, or in remote areas. The long-term impact of groundwater usage on some of these ecosystems has not been evaluated, with most of the knowledge about these impacts being based on anecdotal information obtained from the respective land owners. Remote sensing offers an opportunity to map the spatial coverage of groundwater dependent ecosystems in drylands. A distinguishing characteristic of these systems is the active plant growth especially during periods when throughout the landscape, there is limited or no water to support plant growth. Monitoring plant growth during the dry season using indices such as the NDVI enables detection of groundwater dependent ecosystems. Knowledge about the rates of actual evapotranspiration at locations with these ecosystems enables an estimation of the amount of water required to support them during the dry season. The MODIS 16 actual evapotranspiration rates (ETA) which are globally available can be used for evaluating water use by groundwater dependent ecosystems. This paper explores the mapping of the spatial coverage of groundwater dependent ecosystems using remote sensing based vegetation indices in parts of the Gourizt River basin in South Africa. The rates of waters use by the identified groundwater dependent ecosystems are estimated using actual evapotranspiration rates based on MODIS 16. The paper also examines possible long-term changes to the spatial coverage of groundwater dependent ecosystems.
Chemical Processes Governing Siloam And Tshipise Geothermal Springs, Limpopo Province, South Africa	Olatunde	Durowoju	Limpopo	2017	geothermal, hydrochemical, Water quality
Abstract Geothermal springs occur throughout the world and South Africa (SA) is endowed with several springs of this nature. Siloam and Tshipise are among the known scalding geothermal springs found in Limpopo Province. The optimal use of a geothermal spring is largely dependent upon its physical and chemical characteristics. Hence, there is need to understand the chemical processes controlling the springs. Hydrochemical characteristics of Siloam and Tshipise geothermal springs were undertaken for a period of six months May – December 2014. Water samples were collected from the springs and stored at low temperatures (+/- 4 °C) for analysis of hydrochemical characteristics. The results show that Siloam and Tshipise geothermal spring water is not suitable for drinking and irrigation due to high pH, high fluoride concentrations, high sodium absorption ratio (SAR), Residual sodium carbonate (RSC) and permeability index (PI) values. The water type found in Siloam and Tshipise were Na-Cl and Na-HCO3, respectively. The variations were probably due to the differences in fundamental changes in water chemistry and the geology. Plot (Ca+Mg) vs (HCO3+SO4) shows the distribution of geothermal water between silicate and carbonate weathering processes. The chloro-alkaline indices (CAI) 1, 2 calculated from the waters of the study area give negative values and this implies the presence of base-exchange reaction. Hence, sources of the geothermal springs were deep and could not significantly be affected by rainfall recharge. Therefore, major processes controlling the water quality are silicate weathering, mineral dissolution, cation exchange and inverse cation exchange.
Understanding and Affecting Water Consumer Behavior Using Technological Interventions at a Primary School in Stellenbosch	C.	Ripunda	Stellenbosch	2017	Water Consumption, Interventions
Abstract This paper studies and reports the water usage behavior of a primary school. Three interventions were implemented to change this behavior to support water conservation. The aim of the study was to quantify the effects of the technological interventions on behavioral change. The school’s water usage pattern was found to be predictive and regular except for daily losses, which were measured and extrapolated from midnight to early morning volumes. The water usage distribution was Gaussian with the mean being centered around break time. The interventions were able to reduce water consumption of the school by 44% when compared to the use of a school across the road where the interventions were not implemented.
Assessing The Influence Of Groundwater Recharge Mechanism In Non-Perennial River Systems, Tankwa Karoo, South Africa	Phumlani	Mqondeki	Karoo	2017	Ephemeral rivers, localized recharge, baseflow, Hydrochemistry, stable isotopes
Abstract In South Africa and neighboring countries such as southern Zimbabwe, Botswana, southern Angola and Namibia, most river systems are non-perennial due to semi-arid/arid climatic characteristics. In such river systems, the interaction between groundwater and surface water is of significance in terms of developing appropriate methods for determining ecological water requirements among others. However, the interaction is not well understood in terms of the influence on the volume and quality of water on the gaining and losing water bodies. In past years, research on non-perennial rivers (NPRs) has not been widely published for various reasons. In certain cases, NPRs experience extended periods of water ponding within their channels. This could possibly be caused by groundwater seepage that is sufficient to maintain pools but insufficient to generate channel flow (gaining stream) and overcome evaporation losses. The opposite can also occur, whereby some reaches of the river channel are recharging the underlying aquifer (losing stream). Abstraction of either groundwater or surface water thus impacts on both water resources. The objectives of the study are to investigate the role of the Tankwa River in recharging the underlying aquifer and the role of the aquifer in recharging the Tankwa River. Preliminary findings through literature review and field observations seem to suggest that the groundwater flow in terms of the regional perspective is driven by recharge in the far upland TMG Mountains. However, on a local scale, field observations seem to suggest that there is some aquifer-river interaction, whereby the aquifer is maintaining the pools in some parts of the channel whereas some parts of the river are dry. These findings suggest that the river contains both losing and gaining reaches thereby providing indication of an exchange of water between the water resources. This has implication on the quantity and quality of water in gaining and losing water bodies in aquifers and rivers. Future work will involve installing piezometers at points where permanent pools are located and along the river riparian zone. Monitoring of groundwater levels and the river will be carried through the different seasons. Samples will be collected from the aquifer, surface water bodies and rain gauges to integrate with the groundwater chemistry. The overall purpose of the present study is to develop a regional hydrogeological conceptual model of recharge for the Karoo in order to improve understanding of the recharge mechanism in non-perennial river systems especially in the semi-arid environment, using the Tankwa River as a case study.
Determination Of Uranium Mobility Through Geochemical Modelling In The Karoo Uranium Province	Joyce T	Leshomo	Karoo	2017	geochemistry, uranium, redox potential
Abstract The availability of freshwater is one of the major development challenges that South Africa faces. South Africa is a water-scarce (semi-arid) country with rainfall distributed unevenly and away from the centres of major developments. The rainfall is tied to seasonal cycles that drive us repeatedly between floods and droughts. This paper serves to study the groundwater chemistry in light of the uranium mining that precedes shale gas fracking in the Karoo Uranium Province. The aim is to have groundwater baseline chemistry assessment before mining commence in order to be able to track mining effect on groundwater in the future. A total of 128 samples are dealt with in this work, 112 collected from groundwater, 9 collected from springs and 7 extracted from a database. The samples were analysed for physical parameters, cations, anions and metals. Redox potential was also determined as it plays a pivotal role because it controls the availability and form of uranium in a solution. Uranium is a radioactive actinide naturally occurring in the area. Therefore, this assessment will be crucial in order to understand how changing redox and pH conditions affect uranium solubility and to estimate the extent of uranium transport by water during and after mining. The effects of the redox potential and pH on uranium mobility have been examined in this work by means of computer modelling by using the Geochemist’s Workbench (GWB) 11.0. The composition of the water used for modelling resembled that of a typical bedrock groundwater of Karoo Uranium Province. The simulations were carried out under different redox potentials at different pH levels in the presence of ferrihydrite, dissolved organic matter and carbonates/bicarbonates to include the effects of uranium adsorption. The results show that the redox potential at which the uranium mineral (uraninite) dissolves varies depending on the pH of the groundwater. Analysis of the simulation results indicated that the dissolution of uraninite takes place at a lower Redox condition with increasing pH (alkaline pH condition). This means higher redox conditions are needed for the dissolution of uraninite at low pH. Moreover, it is further concluded that the adsorption of uranium to ferrihydrite and carbonates is important at pH 6-10 and pH 5-8 respectively, which therefore play an important role in controlling the mobility of uranium in the modelled groundwater.
Characterization of the Co2 Springs Associated With the Bongwana Fault, Its Impact on Fresh Surface Water and Groundwater Quality and Implications on Carbon Capture and Storage (Ccs) In South Africa	M.	Nkwane	KwaZulu-Natal	2017	Bongwana Fault, CO2 springs, Environmental Isotopes, Hydrochemistry, South Africa
Abstract The natural CO2 springs at the Bongwana area emanates from a number of sites along an 80 km long N-S trending fault known as Bongwana fault. CO2 rich groundwater is observed at a shallow depth in a borehole drilled for water supply parallel to the main fault. The geology along the entire fault length is characterized mainly by Dwyka Group sediments. The objectives of this study are to characterize the CO2 springs and assess their impacts on groundwater and surface water quality. To that end, existing literature and data were reviewed followed by the collection of groundwater and surface water samples at both CO2 emission and CO2 free streams, springs and boreholes around the length of the Fault zone. Major ions, trace elements and environmental isotopes analyses were carried out on the samples collected. EC, TDS, pH, Temperature, DO, Eh, ORP, total alkalinity, CO3 2- , HCO3 - ) were measured onsite. Acidic pH conditions, elevated TDS, EC and trace metals concentration were detected in all CO2 emission sites compared to CO2 free streams, springs and boreholes. These results clearly show the impacts of CO2 on groundwater and surface water quality within the vicinity of emission points. All the travertine cone springs located near Umtamvuna River are characterized by Na-Ca-Mg-HCO3 water types, while boreholes from shallow groundwater and river samples show Ca-Na-Mg-HCO3 types. The correlation among the deep CO2 rich groundwater parameters indicates that the major geochemical processes that could be responsible for the observed chemical composition are the precipitation of calcite and dolomite where their saturation indices (SI) range from 0.74 to 0.82 and from 0.24 to 1.35, respectively and the weathering of feldspars. Stable isotope (δ18O and δ2H) composition of the travertine cone springs shows a major negative shift from the meteoric water lines with δ18O and δ2H values ranging from -7.78 to -6.52 ‰ and -21.5 to -17.9 ‰, respectively. The stable isotopic composition of shallow groundwater reflects local and modern meteoric recharge. These observations indicate that the reservoir and source of recharge for the deep circulating groundwater are different from the shallow groundwater. It appears that natural CO2 emission along the Bongwana fault have impacted the ambient groundwater and surface water quality at the emission sites rendering it unfit for human consumption due to elevated concentration of dissolved constituents above safe drinking standards. The implication of this to CCS in South Africa is the fact that any unintended CO2 leakage into fresh groundwater and surface water resources from subsurface storage site can impact this already scarce resource. Therefore, strict scientific site selection protocols and CO2 leakage detections through properly designed monitoring systems are required to minimise the risk.
Hydrochemical Analysis Of Groundwater In The Danakil Depression, Northern Ethiopia	David C	McGibbon	Ethiopia	2017	hydrostratigraphy, hydrochemical, hydrothermal influx
Abstract An investigation of surface and groundwater chemistry was undertaken as part of a resource assessment of water-supply for potash solution-mining in the Danakil Depression of the Afar Rift, situated in northern Ethiopia on the N/S-trending Ethiopia-Eritrean arm of the East African Rift System. Four hydrostratigraphic units are recognised in the area: 1) Basement Tsaliet Group rocks, low yielding and with poor water quality; 2) Adigrat Formation and Antalo Group fractured sandstones and karstic limestones, high yielding with good water quality; 3) Danakil Group and Zariga Formation fine-grained sediments, forming a good regional aquifer; 4) Dogua Formation alluvial fans, forming a major, regional, primary aquifer with high yields and poor water quality (yields of >50 l/s but 3 times the salinity of sea water). In the mining concession area the only available target for groundwater exploration is the Dogua alluvial-fan system that extends off the Dogua Mountain range to the west. During 2015 and 2016, 5 production and 5 exploration/monitoring boreholes were drilled into the fans, thereafter test pumped and sampled for hydrochemical and isotope analysis. The aquifer stress test proved that there is sufficient groundwater available for the life of mining, but that the water quality is poor. The hydrochemical analysis found that in general, water quality is poor (brine with TDS values >100 000 mg/l and a density >1.05 g/cm3 ) and with temperatures of ~50°C. Water quality degrades from south to north, possibly due to recharge of fresh water from the Antalo limestones in the south and lesser quality water from the Tsaliet basement in the north. The high salinity and temperature found throughout the fans is due to hydrothermal influx along rift-boundary faults that extend downwards into the thermally active, volcanic rift zone. Prolonged pumping results in the degradation of the water quality in the southern boreholes and improvement of quality in the northern boreholes; this is likely as the groundwater heads towards equilibrium, with a similar hydrochemical signature to that of the dominant hydrothermal influx. Stable and radiogenic isotope sampling and analysis was undertaken to determine the source of the recharge, the results showing that it is likely a combination of evaporation from fresh water, lateral recharge of ancient sea water along faults from the Red Sea, and hydrothermal recharge from the sub-surface leaching of young Afar and Red Sea Basalts in the active rift zone.
Drought in the Northern Cape Karoo: Lessons Learned and Options for Future Use	Danita	Hohne	Karoo	2017	Drought
Abstract Most of the Northern Cape has been hit with a drought for the past 4-7years. The western part of the Northern Cape have been dry for at least 7 years now with no rainfall or very little rainfall, while the more central part have been dry for the past 4 years with very little rainfall. It is only the past 2 years that this has been seen as a problem, but for the past 7years the Department with local municipalities have tried their utmost to manage the problem of water scarcity. During the past 7years the DWS has learned many lessons on how to manage the groundwater in these areas to ensure sustainable future use but must also look at new initiatives to deal with this problem as drought is going to be the new norm in the western parts of South Africa.
Change, Challenge And Opportunity – Some Reflections On Hydrogeology Education, The Sustainable Development Goals And Global Change	B	Misstear		2017	education, training, IAH, Strategic Overview papers, SDGs
Abstract This keynote paper addresses several issues central to the conference theme of “Change, Challenge and Opportunity”. For hydrogeologists to exert greater influence on groundwater management globally, proper education and training is essential. Universities play a key role in educating hydrogeologists in the fundamental principles of groundwater science through taught Masters and other degree programmes. Scientific associations such as the International Association of Hydrogeologists (IAH) also have an important part to play in education and training through short courses, conferences and mentoring schemes, and in enhancing groundwater science through journal and book publications and scientific commissions. IAH’s mission is to promote the wise use and protection of groundwater and, in this respect, a series of Strategic Overview papers have been prepared to inform professionals in other sectors of the interactions between groundwater and these sectors. Two of the Strategic Overview papers focus on the SDGs and global change, and some of the groundwater challenges in these areas are described. Whilst these challenges will provide hydrogeologists with opportunities to influence global water issues in the 21st century, hydrogeologists will need to be able to communicate effectively with all of the stakeholders, using traditional and more modern forms of communication, including social media.
Can Danish Groundwater Assessment Be Used In South Africa?	MS	Linneberg	South Africa, Denmark	2017	Vulnerability mapping, Strategic Water Sector Cooperation Program
Abstract Denmark is a small country in the northern part of Europe. The water supply in Denmark is solely reliant on groundwater. In the past 40 years Danish groundwater management has undergone a major development. A key aspect of this, which could be of relevance in South Africa, is The Danish Groundwater Vulnerability Mapping. During a 15 year period, Denmark has spent 2.7 billion DKK (App. 385 million USD) on mapping 40 % of Denmark, in order to conduct a thorough vulnerability mapping and proper delineation of catchment areas and groundwater protection zones. The mapping has been developed intensively through the years. The approach includes development of key components as practice oriented guidance documents on all the professional areas of groundwater mapping, geophysical methods, groundwater modelling etc. As an example the airborne geophysical method of Sky-TEM which is a spin-off from the mapping can be mentioned. Other key tools in the groundwater mapping is geological modelling in GeoScene3D and groundwater modelling in GMS/MODFLOW and MIKE SHE. The foundation for Danish Groundwater Mapping is access to data. In Denmark almost all subsurface data is made available in publicly accessible databases. There are dedicated databases for; boreholes (JUPITER), geophysical data (GERDA), geological and groundwater models (Model database) and groundwater reports (Report database). In recent years Denmark has increased its focus on sharing this knowledge with other countries, including South Africa, China and the United States. Through the Strategic Water Sector Cooperation Program (SSC) on Water between the South African Department of Water and Sanitation and the Danish Ministry for Environment and Food, the Danish method of Groundwater Mapping is being tested on two case studies, in South Africa. One is of an alluvial aquifer in Western Cape, which has similarities to the Danish geological setting. The other is in a fractured rock setting which is widespread in South Africa, but seldom seen in Denmark.
Using Citizen Science Approach to Design Implementation of Science-Policy Interaction Plan for Optimal Use and Protection of Groundwater Resources at Quaternary Scale, South Africa	Stanley	Nzama	South Africa	2017	Citizen-science, ecological model, adaptive management, groundwater resource directed measures, resource directed measures, science-policy interaction
Abstract Using citizen science approach to influence implementation of science-policy interface concept leads to optimal use and protection of groundwater resources that ensures sustained research for practical policy dialogue. Mere determination of water resource classes, the reserve and resource quality objectives within the resource directed measures (RDM) concept for protection of groundwater water resources without considering implementation aspects, propels for defiance in policy implementation at local scale. Although water resource classes and resource quality objectives have not yet been implemented at any catchment at this stage, however findings indicate that in some areas challenges have been experienced with preliminary Reserve implementation at local level, especially in water use license applications. There is a need for an orthodox link between RDM and Source Directed Controls (SDC) to complement current methods used and processes followed in GRDM projects for uncontested RDM implementation to ensure sustainable groundwater resource protection especially at local site where the resource reside. The argument in this paper is that a feasible implementation for GRDM at local level provides science-policy interface platform for the sustained operation of the science-citizen approach. The objective of study was to design a field-tested conceptual model of science-policy interaction that monitors and evaluates GRDM intervention. How policy implementation and evaluation utilizes scientific research outputs at local level were examined using ecological model. Key findings indicated that (i) systems analysis approach was lacking at local level (ii) practical assessments of GRDM at local specific quaternary catchment scale was not adequate (iii) optimal reserve determination methodology for uncontested water utilisation was not clear to provide proper guidance for water use license application (iv) Reflective operational plan (GRDM monitoring) to enhance science-policy interaction was not available at quaternary catchment scale (v) Best practices of adaptive management principle to sustain groundwater resource protection were limited at local level. From these results, it can be said that the up scaling of the current approach for RDM especially GRDM requires refinement for practical uptake of scientific results. The study recommended that a feasible implementation plan for GRDM at local level that provides science-policy interface platform for the sustained operation of the science-citizen approach need to be designed, implemented, monitored and evaluated with citizens to inform reflective policy implementation. Although, the results of this study are not conclusive, the insights as a starting point for proactive buy in approach is provided to ensure that science-policy interaction remain practical and relevant to scientists and policy makers as well as society.
Characterisation And Protection Of Deep Aquifers In South Africa: Consolidation Of Data Sources	Francois D	Fourie		2017	Deep aquifers, data sources
Abstract This paper describes the results of study aimed at consolidating the available data sources on deep aquifers and deep groundwater conditions in South Africa. The study formed part of the larger WRC Project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). Since very little is known about the aquifer conditions below depths of 300 m, all groundwater information from depths greater than 300 m was considered to represent the deep aquifer systems. Various confirmed and potential sources of data on deep aquifers and groundwater conditions were identified and interrogated during this study, namely: 1. Boreholes of the International Heat Flow Commission (IHFC). The IHFC database indicates the location of 39 deep boreholes ranging in depth from 300 to 800 m, with an average depth of 535 m. 2. The Pangea database of the International Council for Science (ICSU). The Pangea database has information on 119 boreholes in South Africa, of which 116 are deeper than 300 m. 3. A database on deep boreholes at the Council for Geoscience (CGS). This database contains information on 5 221 boreholes with depths exceeding 300 m. 4. Information on the deep SOEKOR boreholes drilled during the 1960s and 1970s (at least 38 boreholes). 5. Information on deep boreholes from the database of the Petroleum Agency SA. 6. The National Groundwater Archive (NGA) of the Department of Water and Sanitation (DWS). 7. Information derived from the thermal springs in South Africa. 8. Boreholes drilled as part of the Karoo Research Initiative (KARIN). 9. Information on the locations and depths of underground mines in South Africa. Information on the occurrence of deep groundwater could potentially be obtained from these mines. The study shows that, although information on a vast number of deep groundwater sites is listed in the various databases, the data relevant to the geohydrological conditions are scant at most sites. This paucity of geohydrological data implies that the deep aquifers of South Africa are currently poorly understood.
Nutrient Retention In Stream Sized Rivers, Related To Riparian Land Development And Climatic Change	Reuben	Lazarus	Western Cape	2017	Seasonal cycles, Pollution, physicochemical environment
Abstract The Western Cape of South Africa is rich in small stream sized rivers forming part of its water resources. The Lourens river and Eerste river, both situated in this region are the base for this study. Rivers are affected by their surrounding environments and the continuous development around these rivers could affect their health adversely. Diverse land-use patterns contribute to a wide range of pollutants with different characteristics. Indeed, some of the pollution levels in the Eerste and Lourens rivers were linked directly to specific land-use practices surrounding the rivers. However, the large change in weather during a seasonal cycle causes a significant difference in pollution levels too, because the transport of pollutants from the source to the rivers is primarily based on surface run-off, which in turn is predominantly dependent on the precipitation of the region. A six months long monitoring in 2016 showed that processes like surface run- off, together with first flush events and dilution control the pollution concentrations in the Lourens river and Eerste river. Physicochemical parameters, major agricultural nutrients and industrially produced heavy metals all reacted differently to these processes, thus, providing an insight into the effects continuous development and climate change have on surface water as a national resource. Interestingly, both rivers included sections with substantial retention and/or reduction of pollutants. The natural riparian vegetation, hyporheic zone and microbial community present in these rivers are proposed to be the main drivers behind both rivers’ ability to reduce or retain pollutants. These drivers are sensitive to their environment and react differently depending on the weather, available nutrients, and physicochemical environment. With the effects of climate change becoming more apparent, it is important to study the impact of warmer temperatures, longer droughts, and heavier rain events, for instance, on the pollutant retaining capabilities of these streams.
Modelling Of The Steenkoppies Dolomite Compartment – Sustainable To ‘Unsustainable’ Groundwater Use	Martin	Holland	Gauteng	2017	Uncontrolled groundwater abstraction, Irrigation, numerical model
Abstract Seyler, H; Vahrmeijer, JT; Wiegmans FE The Steenkoppies dolomite aquifer/compartment is situated 15 km north-west of Krugersdorp and has received great attention in March 2007 when the naturally discharging spring (known as “Maloney’s Eye”) reached the lowest flow on record, which was an incident that has drawn much attention. This incident caused major concern to the downstream users as the spring forms part of the Magalies River’s flow. At the time of this incident the flow measured at a record low of 1.58 Mm3 /a compared to an average flow rate since 1908 of 13.8 Mm3 /a. Coincidently in March 2016 exactly nine years after this time the record low flow of 1.58 Mm3 /a was again measured at the Eye. Continued drought conditions in 2016 resulted in the lowest flow recorded for five consecutive months. The flow rate of less than 2.2 Mm3 /a is a mere 38 % of the average flows of (5.7 Mm3 /a) recorded for the last 10 years. While the interest in exploiting groundwater from the Steenkoppies compartment dates back to the late 1890s it is only since the 1980s to 1990s when abstraction for irrigation became substantial. The volume of groundwater abstracted for irrigation increased more than 7.5 times since 1980. The crop area increased 2.6 fold since 1997, while the volume of water abstracted increased 1.6 fold. Unfortunately, despite numerous conceptual reports, scientific papers, lawful water use verification studies and crop water use investigations, the Steenkoppies water users are still without a managing body and groundwater management/use plan. The lack of (adaptive) management has led to uncontrolled abstraction and issuing of new Water Use Licenses without the proper knowledge of the impact of additional water use on the system. The failed establishment of a water user association according to the National Water Act in 2013 dampened the hopes for any collaborated groundwater abstraction, -monitoring and -management plan. The groundwater model developed for the Steenkoppies compartment should be seen as a prospective evaluation tool to determine the potential behaviour of the system with time, given a set of changing parameters. Numerical groundwater models are considered the best tools available to quantify/estimate groundwater, and the results can be used in management decisions. Estimated groundwater abstraction per annum from the Steenkoppies compartment amount to between 25 Mm3 and 30 Mm3 , with a likely current rate of 28.5 Mm3 /a. Based on the modelled fluxes with average groundwater recharge (rainfall) conditions and induced recharge from irrigation return flows, it appears that 25 Mm3 is an optimal abstraction rate while maintaining a flow of around 5 Mm3 from the Maloney’s Eye. However, the Maloney’s Eye is sensitive to below average rainfall events leading to below average recharge conditions and resulting in lower volumes available for abstraction. Neglecting this fact for the past 30 years has resulted in the ‘unsustainable’ use of groundwater in the compartment
Possible Wastewater Volumes Associated With Unconventional Oil And Gas Extraction In South Africa And The Management Thereof	RD	Williamson	Karoo	2017	Unconventional gas, Wastewater, Fracking
Abstract Several oil and gas companies have applied for licenses to extract unconventional oil and gas (UOG) resources in South Africa (SA) through a process known as hydraulic fracturing or fracking. The South African government is in the process of drafting regulations and procedures to allow the extraction of these resources. It is surmised, based on evidence from fracking examples around the world, that large volumes of wastewater may, however, potentially be generated during the extraction of these UOG resources. The issues arise when it comes to determining the actual volumes of wastewater that may be generated from this process, should it be used in SA, as well as the management of the wastewater. The volume of wastewater generated is dependent on a number of factors, with well properties, rock formation, basin properties and the number of fracturing stages within the well, being some of the dominant factors. In this project an extensive review of existing literature, reports and fracking databases was used to identify the methods used for determining wastewater volumes, which databases were used as well as the assumptions and challenges each data source faced. The data was analysed and interpreted in order to come up with various ranges and averages of wastewater generated through UOG extraction. The potential volumes of wastewater generated through fracking were then modelled into the hypothetical scenarios outlined in the Strategic Environmental Assessment (SEA) on Shale Gas Development in the Central Karoo. This allowed for the determination of potential volumes of wastewater associated with UOG extraction in SA from which management implications for wastewater in South Africa can be determined.
Assessment of Plume Stability in Monitored Natural Attenuation Assessments Using the Centre of Mass and Total Plume Mass Approach	Samuel D	Mohr	Western Cape	2017	Monitored natural attenuation, petroleum, Hydrocarbon, plumes, monitoring network
Abstract Monitored natural attenuation (MNA) is becoming a commonly employed sustainable site remediation strategy for sites with petroleum hydrocarbon groundwater impacts. Natural attenuation is essentially the reduction in contaminant concentration, mass or mobility due to naturally occurring processes within the environment. Aromatic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX) are common compounds of concern in the context of petroleum hydrocarbon related investigations because of their relative mobility and toxicity characteristics. Despite this, these compounds have historically displayed a strong affinity towards attenuating temporally and spatially away from the source areas. Evaluating plume stability is an important element of evaluating the overall attenuation of groundwater plumes and numerous methods have been developed in order to assess plume stability including graphical and statistical methods. It is often the case however that these analyses focus on single wells in isolation and do not take an integrated approach to evaluate the attenuation of contaminant mass over the entire plume. The authors present a case study where historical trends in plume characteristics have been used to assess overall plume stability. Trends in parameters such as average plume concentration, total plume contaminant mass, plume area and plume centre of mass were statistically assessed to determine whether the groundwater plume was expanding, stable, or shrinking. The methods employed in the plume stability analysis were found to be effective tools in demonstrating the occurrence of natural attenuation of contaminant plumes. It is important to note that a good quality dataset is required, in terms of a spatially representative monitoring well network and adequate time series data, in order to conduct analyses that will yield meaningful conclusions.