Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 151 - 200 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort descending	Keywords
Modelling recharge in an opencast coal mining environment, applying model parameters on a catchment scale.	Freek	van Devnter		2015
Abstract The provision, usage and discharge of water resources are major concerns for coal mines, both underground and opencast. Water resources in a coal mining environment will often account for a significant portion of the daily operational cost. In order to cut costs, the mine will often collect as much runoff as possible to recycle for future use. This on-going recycling of site water and management of the resource demands a complete site water balance model in order to understand the dynamics of the resource within the boundaries of the mine. To improve the understanding of the dynamics of the resource on a much larger scale, and the effect it will have on recharge in an open cast coal mine environment, one must consider alternative modelling approaches which can compensate for such conditions. This amounts to describing recharge as a modelling component in a physically based distributed model. The main goal of this project is to calculate recharge into the main pit at this specific colliery by applying parameters on a quaternary catchment scale. The colliery is located just west of the town of Ogies, Mpumalanga on the peripheral region of the quaternary catchment B20G. The physiography of the quaternary catchment B20F is described as a central Highveld region gently sloping to the north. The geohydrological modeling application MIKE SHE (developed by DHI) was used to develop a fully integrated catchment model. The model was created mainly to simulate the impact of human activities on the hydrological cycle and hence on water resource development and management. Different modules of MIKE SHE that was used during the modelling stage include saturated- and unsaturated flow and a small degree of overland flow. Key words: Mpumalanga, MIKE SHE, recharge
Cadmium contamination of groundwater in South Africa - the potential hazard of phosphate fertilizers	Dylan	Blake	Hermanus	2015	Cadium contamination
Abstract Cadmium is a highly mobile and bioavailable non-essential element that is toxic to plants, and is an animal and human carcinogen (affecting the kidneys and bones in vertebrates). Since the late-1970s the effects of cadmium on the environment have become a global issue of concern, and many countries have conducted evaluations on the exposure of their populations to cadmium in phosphate fertilizer (a major non-point source of anthropogenic cadmium). A scoping project, funded by the Water Research Commission, aimed to review cadmium contamination of South African aquifer groundwater systems (predominantly) via phosphate fertilizer use. Topics reviewed included fertilizer composition and types, metal speciation, metal mobility in soil and groundwater systems, metal bioavailability, health and environmental effects, and local South African contamination case studies. A preliminary study site, namely the greater Hermanus region, was identified for trace metal and groundwater quality studies (which incorporated urban and agricultural areas in various hydrogeological settings). Hermanus was selected due to: 1) the discovery of cadmium concentrations of 20 ?g/l (in comparison to the SANS 241-1:2011 cadmium limit of 3 ?g/l) in a golf estate irrigation borehole, during drilling and test-pumping of the borehole at the end of 2012
Modelling groundwater recharge in the Upper Vaal River Catchment.	Gaelene	Kramers	Gauteng	2015
Abstract At a regional scale, groundwater recharge is often calculated using surface water models. Precipitation and surface water runoff are easier to measure than groundwater recharge, and evapotranspiration can be estimated with relative accuracy using indirect methods. In modelling, surface water measurements can be used for calibration, and groundwater is the residual term in the water balance of the catchment. This can give a good indication of regional trends, but provides limited scope for the accommodation of groundwater system characteristics and recharge processes. Recently, much research has been focused on the interaction of surface and groundwater models. The coupling of physically based surface and ground water models allows for calibration of the model using both surface and groundwater data while providing scope for improved insight into the processes which define the interaction of groundwater with the rest of the water cycle. For example: stream discharge, interflow, preferential flow through the unsaturated zone and interaction with surface water retained in dams and wetlands. One such model is GSflow (United States Geological Survey), which we are applying to the Upper Vaal Catchment. This model integrates the surface water model PRMS (Precipitation-Runoff Modelling System) with MODFLOW (Modular Groundwater Flow model). The model is initially being calibrated at quaternary catchment scale, starting with the surface water components and later adding the groundwater system. The quaternary catchment is subdivided into smaller, topologically defined hydrological response units. This scaling allows for a better understanding of how well the characteristics of the units are represented in the physical processes incorporated into the model, so that ultimately the sensitivity analysis can incorporate these processes. The results will be compared to current work on recharge being carried out using GRACE data and previous work done in the same area. Once the entire model has been calibrated, there will be scope to calculate future scenarios, allowing for climate and land-use changes. A brief overview of existing work as well as methods and initial results and sensitivity analysis will be presented.
Simulation of Underground Mine Flooding with EPANET and MODFLOW	Stephen	Fonkem	Free State	2015	mine shaft, flooding, modelling, MODFLOW
Abstract Underground mine water rebound prediction in its simplest form can be simulated linearly by comparing the volume of the mined ore with long-term average recharge rate to obtain an estimate of the time which will elapse before the workings are full to their decant elevation. This type of linear interpolation of rising water levels can lead to an over estimation or an underestimation of the date when mine voids will flood to the critical levels. This is due to the fact that this method cannot account for the variability and interconnection between different mine voids and also does not consider the change in storage over time which is an important factor. In an abandoned underground water environment, water is stored in flooded mine stopes (tanks) and flows through a network of haulages (pipes). Due to the dip and strike of the ore body, the mined stopes are extensively interconnected on multiple levels and bounded by faults and dykes, so that water rising within any one tank will display a common level throughout that tank. At certain elevations, adjoining tanks may be connected via a discrete "overflow point", which may be a holding or permeable geological features. Water level rise during flooding is a function of head-dependent inflows from adjoining mine aquifers and/or other tanks, and the distribution of storage capacity within the tank. The process of flooding occurs independently in two (or more) adjoining tanks until such time as the water level in one or more of the tanks reaches an overflow point. Inter-tank transfers of water will then occur until the difference in head between the two tanks either side of each overflow point is minimised. To apply the conceptual model stated above, EPANET 2 was used to predict the risk of flooding of a mine shaft, in the Free State Goldfields, if dewatering is discontinued. Considerations on stope volumetric calculations, haulage interconnections, modelling assumptions and predictions, are presented.
Case Study: Thermals springs in the Lower Orange River Valley	Danita	Hohne	Lower Orange River Valley	2015	earthquakes, thermal springs, Monitoring
Abstract POSTER Since June 2010 and still ongoing today, the Lower Orange River Valley has experienced over a 1168 tremors(a) and earthquakes in the vicinity of Augrabies. Of these 1168 tremors, 71 quakes registered above 3 on the Richter scale and on 18 December 2011, the area was struck with an earthquake that registered 5 on the Richter scale. Four thermal springs are also located near this earthquake zone and the temperature of the water have a range of between 38?C -46.6?C, according to Kent LE. (1949/1969). 25?C is the division between thermal and non-thermal waters and the thermal gradient for the Riemvasmaak area(b) is 24?C, clearly indicating that the four springs are thermal when looking at the temperature difference. The Department of Water Affairs has been monitoring these springs monthly since 2011 and has been taking field measurements and chemical analyses. The aim of this study is a) to see if the tremors and earthquakes have an effect on the chemistry of the thermal springs, b) to create a data set for the thermal springs, as these springs was recorded and mentioned in Kent LE. reports of 1949 and 1969 but no samples were collected and analysed, c) to see if the water source for the groundwater in the area and the thermal springs are connected and d) to see if the recent floods may have had an influence on the earthquake zone seeing as the Orange River runs through the zone. The following sources are used to describe the earthquakes and water quality: (a) Earthquake data from the Council of Geosciene (b) ZQM data on NGA temp range between 21-28?C depending on the season with 24?C being the mean.
Using modified hydrogeological conceptual model to assess groundwater flooding in Cape Flat Aquifer, South Africa	Masixole	Langa	Western Cape	2015
Abstract POSTER The poster presents the modified hydrogeologic conceptual model that was used to assess the dynamics of groundwater flooding in Cape Flat Aquifer (CFA). The groundwater flooding remains poorly understood in the context of urban hydrogeology of the developing countries such as South Africa. While engineering intervention are relevant to providing solution to such events, continue estimation of hydrogeologic parameters at local scale alongside field measurements remain paramount to plausible modeling the groundwater flooding scenarios that inform such engineering interventions. However, hydrogeologic conceptual model which informs numerical simulation has not been modified to include local scale variation in the CFA to reflect various groundwater units. The current study argues that modifying hydrogeologic conceptual model improves numerical simulations thereby enhancing certainty for engineering solutions. The current study developed groundwater units, set up site specific models and estimated aquifer parameters using pumping step-drawdown and constant rate pumping tests in order to produce a comprehensive modified hydrogeological conceptual model for CFA to inform groundwater modeling at catchment level for water sensitive cities. Key Words: Aquifer parameters, Groundwater flooding, specific models, hydrogeologic conceptual model, groundwater units, numerical simulations, water sensitive cities, CFA
An assessment of the contribution of surface and subsurface flows to river flows of the Sandspruit in the Berg River Catchment,	Matthew	Damons	Western Cape	2015
Abstract Studies showed that the primary origin of salinity in river flows of the Sandspruit in the Berg Catchment located in the Western Cape Province of South Africa was mainly due to the weathering of the shales, while atmospheric deposition contributed a third of the total salinity. The salts are transported to rivers through surface runoff and subsurface flow (i.e. throughflow and groundwater flow). The purpose of this study was to determine the relative contributions of subsurface flow and surface flows to total flows in the Sandspruit River, Berg Catchment. Three rain events were studied. Water samples for two rain events were analyzed for environmental tracers ?18O, Silica (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component hydrograph separation were ?18O and SiO2. These tracers were selected as Ca2+ and Mg2+ provided inconsistent contributions of both subsurface flow and surface flow. Two component hydrograph separations indicated that groundwater is the dominant contributor to flow, while surface runoff mainly contributes at the onset of the storm event. Groundwater response to precipitation input indicated that boreholes near the river have a greater response than boreholes further away from the rivers, which have minor response to the input of precipitation. Keywords: Stable Isotopes, Sandspruit River, Tracers, Hydrograph separation, Salinity
Cost Effective Drilling Methods For Obtaining Water Supply In Sodwana, Northern Kwazulu Natal	Jean	Simonis	KwaZulu-Natal	2015
Abstract We contend that borehole drilling costs on the Zululand Coastal Plain, South Africa can be much reduced by assisting low cost drillers in drilling 6" diameter boreholes using light weight, maneuverable rigs with trained teams which are more cost-effective and provide optimal value for money invested over the lifespan of the borehole. The improved drilling package will allow local drillers to tap into the deeper more sustainable aquifer identified in the area and provide for better borehole construction. The remoteness of the rural population in the Maputaland area, northern KZN, South Africa, influences the degree of groundwater development. Rural water supply infrastructure is minimal and 40 per cent of the rural community is forced to rely on surface water as well as shallow, low cost drilling for water supply. A number of these low cost drillers were investigated to determine their expertise. Results showed that formal training in drilling technology is unavailable in the area. The inexperience of the drillers results in poor borehole construction. Currently low cost drilling is not cost effective as most of these boreholes collapse after a short time. The correct method of drilling in the area is by Direct Mud Rotary (DMR). Professional DMR drilling and borehole construction costs are in excess of US$ 125/m, unaffordable for poor households. We propose that with limited training and suitable equipment the local drillers can halve existing drilling costs, provide quality work as well as focus on good management practices. This will create jobs as well solve the pending water crisis in the area (and elsewhere in Africa).
Vanwyksvlei: Water provisioning and the Blue Drop system - how effective is this?	Danita	Hohne	Vanwyksvlei	2015	Blue drop standards, water supply challenges
Abstract POSTER Vanwyksvlei had always experienced problems with water supply and quality of drinking water. The town relies on 6 boreholes to supply the town with drinking water. Since 2011 the town was told not to use the water that was supplied from the borehole called Soutgat. This meant that the town could now rely only on the water being supplied from the other 5 boreholes.From 2011 till present the town has experienced a lot of problems regarding water supply, due to the fact that the Soutgat could not be used anymore. Extra stress was put on the other boreholes and these were pumped almost dry. The two aquifers are currently failing and monitoring data since 2009 shows that the water levels of the town are decreasing. Due to low rainfall, recharge to the boreholes are much lower, which exacerbates the problem. This poster will examine the effectiveness of using the Blue Drop system in small towns with limited water supply, at the hand of a case study of Vanwyksvlei. This review will take into account factors such as the point at which water quality is tested in the water supply system, the type of water treatment available for the town and a review the usefulness of certain standards in the Blue Drop system which may indicate failure of supply sources.
Groundwater fingerprinting for identifying potential project risks	Meris	Mills		2015
Abstract Implementation of a mining project in South Africa involved dewatering of a fractured rock aquifer at considerable depth below ground level. Groundwater quality within this aquifer is not suitable for domestic use due to high levels of salinity. Numerous geological investigations in the area indicate that the target aquifer is confined, with a different piezometric head to the shallower aquifers. However, regulators and other interested and affected parties expressed concern regarding the potential mixing of more saline groundwater from the deeper aquifer to be dewatered with groundwater from shallower aquifers, which are extensively used for farming and domestic purposes. A large database of groundwater quality monitoring data collected over 16 years was available to investigate the degree of mixing between the deeper more saline and shallower freshwater aquifers. The groundwater chemistry of selected boreholes with known geological profile, depth and construction was used to develop groundwater fingerprinting criteria for each of the aquifers in the area. These fingerprinting criteria were then applied to private and exploration boreholes in the area in order to identify the main aquifer from which groundwater was being sourced. Once the boreholes were classified in terms of groundwater origin, an attempt was made to identify indicators of mixing with deeper, more saline groundwater from the aquifer being dewatered. Groundwater fingerprinting allowed identification of impacts related to the mining operations. The data showed that there was no upward mixing of water related to dewatering operations, but rather that surface spillages and disposal schemes may have resulted in minor changes in shallow groundwater quality. {List only- not presented}
Remediation of Groundwater at AngloGold Ashanti South Africa	Gawie	van Dyk		2015
Abstract Gold Mining activities the past 60 years at AngloGold Ashanti polluted the groundwater underlain by 4000 ha of land at the Vaal River and West Wits operations in South Africa. Sulphide material in Tailings Storage Facilities, Waste Rock Dumps and extraction plants produce Saline Mine Drainage with Sulphate, minor salts and metals that seep to the groundwater and ultimately into surface water resources. Water regulation requires mines to prevent, minimise/ reduce or eliminate pollution of water resources. The waste philosophy has matured from tolerate and transfer to treat and termination of pollution sources. The impact of the pollution was determined and possible technologies to treat the impact were evaluated. Source controls of proper water management by storm water management, clean dirty water separation, lined water conveyance structures and reduced deposition of water on waste facilities is crucial. The aquifer character determines the possible remediation technology. From the possible technologies phytoremediation, physical interception and re-use of this water was selected. In future possible treatment of the water would be considered. This paper explain the strategy and report on the phased implementation of these plans and the expected results. The establishment of 750 ha of woodlands as phytoremediation, interception trenches of 1250 m, 38 interception boreholes and infrastructure to re-use this water in 10 water management areas is planned. The total volume of 15 Ml/day would be abstracted for re-use from the boreholes and trenches. The woodlands can potentially attenuate and treat 5 ml/day. The established woodlands of 150 ha proof successful to intercept diffused seep over the area of establishment and reduce the water level and base flow. The 2 implemented trenches of 1000 m indicate a local decline in the water level with interception of shallow groundwater within 1-2 m from surface. The 2 production interception well fields abstracting 50 and 30 l/s respectively indicate a water level decline of between 2 to 14 m with regional cones of depression of a few hundred meters to intercept groundwater flow up to 20 meter. Predictions from groundwater modelling indicate that these schemes can minimise pollution during the operational phase and protect downstream water resources. Predictions from modelling indicate that the pollution sources need to be removed to ensure long term clean-up to return the land to save use. The gold and uranium prize is securing the removal of the sources through re-processing of the tailings and waste rock dumps. After removal of the sources of pollution the remediation schemes would have to be operated for 20 years to return the groundwater to an acceptable standard of stock watering and industrial water use. The water quality is observed by a monitoring network of approximately 100 observation boreholes.
Fluoride challenge in groundwater of the Ethiopian Rift Valley and adjacent highlands	Taddesse M	Bollollo	Ethiopia	2015	Fluoride
Abstract The urban and rural communities sources of water for domestic and other uses come from groundwater in most parts of Ethiopia. But the groundwater is not free from challenge. Fluoride is one of those critical problems which are affecting the health of inhabitants of this corridor. There are places where the fluoride contents reach more than 10mg/l. groundwater Treatment plants, changing the water scheme source from surface water and related efforts have been made so far to alleviation such challenges. Fluoride affects bones and teeth by changing its color and easily affected to a number of health complication in the rift valley of Ethiopia. {List only- not presented}
Hydrocarbon plume delineation using a Hydrogeological and Geophysical approach	Albert	Kruger		2015
Abstract Simple and cost-effective techniques are needed for land managers to assess and quantify the environmental impacts of hydrocarbon contamination. During the case study, hydrocarbon plume delineation was carried out using hydrogeological and geophysical techniques at a retail filling station located in Gauteng. Laboratory and controlled spill experiments, using fresh hydrocarbon product, indicate that fresh hydrocarbons generally have a high electrical resistivity, whilst biodegraded hydrocarbons have a lower resistivity. This is attributed to the changes from electrically resistive to conductive behaviour with time due to biodegradation. As such, it should be possible to effectively delineate the subsurface hydrocarbon plume using two-dimensional (2D) Electrical Resistivity Tomography (ERT). As part of the case study, two traverses were conducted using an Electric Resistivity Tomography (ERT) survey with an ABEM SAS1000 Lund imaging system. The resultant 2D tomographs were interpreted based on the resistivity characteristics and subsurface material properties to delineate the plume. Localised resistivity highs were measured in both models and are representative of fresh hydrocarbons whereas areas of low resistivity represented areas of biodegraded hydrocarbons. More conventional plume delineation techniques in the form of intrusive soil vapour and groundwater vapour surveys as well as hydrochemical anlayses of the on-site monitoring wells were used to compare the results and to construct the detailed Conceptual Site Model. During the investigation, four existing monitoring wells located on the site and additional two wells were installed downgradient of the Underground Storage Tanks (USTs) in order to determine the extent of the plume. In conclusion, a comparison was found between the groundwater results and geophysical data obtained during the case study and it was concluded that ERT added a significant contribution to the Conceptual Site Model.
Monitored Natural Attenuation of Inorganic Constituents: A Case Study in a Karoo Aquifer	Vevanya	Naidoo	Karoo	2015
Abstract Natural attenuation describes a set of natural processes which decrease the concentrations and/or mobility of contaminants without human intervention. In order to evaluate and demonstrate the effectiveness of natural attenuation, regular long term monitoring must be implemented. This entire process is called Monitored natural attenuation (MNA). The focus of MNA is generally placed on hydrocarbons and chlorinated solvents but according to the United States Environmental Protection Agency (USEPA) MNA can be used for various metals, radio nuclides and other inorganic contaminants. MNA was deemed the best method to reduce the concentration and mobility of contaminants impacting the groundwater environment, at a fertiliser plant in the Free State. A number of improvements in infrastructure were made in 2013which were assumed to have prevented further release of contaminants into the groundwater system, from the source areas on site. MNA was also considered to be the most effective affordable solution for the site as groundwater in the vicinity is not used for domestic purposes (low risk). Cl, NO3 and NH4 were used to monitor the movement of the contamination off site and the effectiveness of MNA. With regards to the inorganic contaminants emanating from the site, sorption, dispersion, dilution, and volatilization are the main attenuation mechanisms. These mechanisms are considered to be non-destructive attenuation mechanisms. Denitrification, nitrate reduction through microbial processes, may also facilitate in the attenuation of the in organic constituent nitrate. Denitrification is considered a destructive mechanism. Classed posts and temporal graphs of the Cl, NO3 and NH4 concentrations between 2008 and 2014 were utilised to show the movement and change in size and shape of the contamination plumes and subsequently, monitor MNA. The data indicates that the NO3, Cl and NH4 contamination plumes from the various source areas on the site have detached from the site and are currently moving down gradient along the natural drainage. Contaminant concentrations at the site have generally decreased in recent monitoring events while concentrations downstream of the site have remained stable. This indicates that MNA is currently an effective method of remediation for the site and monitoring should be continued to ensure that it remains effective.
High Resolution Site Characterisation Assessment Of A Chlorinated Solvent Plume In A Shallow Unconfined Aquifer	Kate	Naude		2015
Abstract Identifying and characterising the vertical and horizontal extent of chlorinated volatile organic compound (CVOC) plumes can be a complex undertaking and subject to a high degree of uncertainty as dense non-aqueous phase liquid (DNAPL) movement in the subsurface is governed most notably by geologic heterogeneities. These heterogeneities influence hydraulic conductivity allowing for preferential flow in areas of higher conductivity and potential pooling or accumulation in areas of lower conductivity. This coupled with the density-induced sinking behaviour of DNAPL itself and the effects of groundwater recharge in the aquifer result in significant challenges in assessing the distribution and extent of CVOC plumes in the subsurface. It has been recognized that high resolution site characterization (HRSC) can provide the necessary level of information to allow for appropriate solutions to be implemented to mitigate the effects of subsurface contamination. Although the initial cost of HRSC is higher, the long-term costs can be substantially reduced and the remedial benefits far greater by obtaining a better understanding of the plume characteristics upfront. The authors will discuss a case study site in South Africa, where ERM has conducted HRSC of a CVOC plume to characterise the distribution of the source area and plume architecture in order to assess the potential risk to receptors on and off-site. The source of impact resulted from the use of a tetrachloroethene (PCE)-based solvent in an on-site workshop. The following methods of characterization were employed: - Conducting a passive soil gas survey to identify and characterise potential source zones and groundwater impacts; - Vertical characterisation of the hydrostratigraphy, contaminant distribution and speciation in real time using a Waterloo Advanced Profiling System (APS) with a mobile on-site laboratory; - Using the Waterloo APS data to design and install groundwater monitoring wells to delineate the vertical and lateral extent of contamination; and - Conducting a vapour intrusion investigation including sub-slab soil gas, indoor and outdoor air sampling to estimate current risk to on-site employees. In less than a year, the risk at the site is now largely understood and the strategies for mitigating the effects of the contamination can be targeted and optimised based on the information gained during the HRSC assessment.
A fresh look at the National Water Balance	Andries	Wilke		2015
Abstract The national water balance is primarily based on the availability of surface water and the historic allocation thereof. The changes that are required the next 20 years to ensure sustainable development of the nation will be painful, but is unfortunately at present not part of the public discussion, it is essentially ignored in favour of more "popular water topics".This paper intends to look at a few core aspects, they include the current water allocation in the national water balance, the relative value of the utilisation, the position of groundwater resources in changing the current relative allocation and the current groundwater utilisation. The paper further intends to be a less formal presentation of these aspects with the required data, references and conclusions available for distribution afterwards.
Groundwater Resource Development targeting major fault zones In Banded Iron Formations (BIF) for Augmentation of the Vaal Gamaga	Frans	Wiegmans	Northern Cape	2015
Abstract The mineral rich Northern Cape Province produces 84% of South Africa's iron ore, while the Kalahari basin holds 92% of the world's high grade manganese deposits, with diamond and lime mining operations to a lesser degree. Mining expansion programs and new mines planned in the Northern Cape drive the region's economic development and growth strategy. The planned mining expansion depend on water being available for mining water needs and related increased demands for domestic water supplies. Current water supplies consist of local groundwater resources (boreholes and mine dewatering) and bulk water supply from the Vaal Gamagara (VGG) Pipeline Scheme. In 1992 the Kalahari East water supply pipeline was incorporated to supply domestic and stock water to an area of approximately 1.4 million ha. The VGG scheme consists of 370 km pipes, was built in the late sixties and is nearing its useful life expectancy. Increased water supply interruptions are being experienced while operating at capacity. The pipeline has the capacity to convey and import water of approximately 15 million m3/a into the D41J and D41K quaternary catchments. Water demand projections show an increase to 40.1 million m3/a in 2030. Various options were investigated to upgrade the VGG water supply scheme. One option considers groundwater resources to augment the water from the Vaal River from four indentified target areas (SD1 to SD4). Major fault zones in Banded Iron Formations (BIF) are targeted for groundwater resource development in the SD4 area, located east of Hotazel. This area is largely covered by Quaternary age sand and located near the endpoint of the VGG scheme and therefore prioritized as investigation area. The primary objective of the hydrogeological investigation was to identify the existence of exploitable resources for additional source development. Secondary objectives were to assess the contribution groundwater can make to augmenting pipeline water; providing a source to an area and thus diminish reliance on the pipeline; and providing an independent source, which could prevent the need for pipeline extensions. The paper will discuss the use of an airborne magnetic and Time Domain Electromagnetic's (TDEM) survey combined with gravity ground surveys as a key success factor in adding to the geological and structural information of the area. The paper will also present the results of exploration drilling (> 60 boreholes) over a large area and related borehole test pumping with water sampling to identify a sustainable and potable water supply of 2.5 million m3/a.
Aquifer Vulnerability (Recharge, Depth to Groundwater, Soil Type and Slope) to Classify the Vadose Zone of the Limpopo Province.	Olma Tsakani	Makonto	Limpopo	2015
Abstract The aquifer vulnerability of the Molototsi (B81G) and Middle Letaba (B82D) quaternary catchments of the Limpopo Province was assessed to determine the influence of the vadose zone on the groundwater regime. The aquifer vulnerability was assessed by developing a new method, RDSS, which evaluates the vadose zone as a pathway for pollutants by using the following four parameters: Recharge, Depth to water table, Soil type (saturated vertical hydraulic conductivity) and Slope. Recharge was estimated using the Chloride-mass balance method and the depth to the water table was measured in the field using dipmeter. The seepage behavior (soil type) was determined as hydraulic conductivity from in-situ infiltration and percolation testing. (SABS 0252-2:1993 and double ring infiltrometer). The slopes were determined with the digital elevation method using ArcGIS software. The four parameters were overlaid using Weighted Sum, Weighted Overlay and Raster Calculator to produce the vulnerability map. Different weightings were attributed in the methods and the best selected. The results obtained indicated high vulnerability on the lower and upper parts of both catchments. The benefits of the method described are: (a) the easy quantification of the parameters through fairly simple methods and (b) the exclusion of arbitrary index values.
The use Vegetable Oil Substrate's in the treatment of contaminated groundwater	Michelle	Pienaar		2015
Abstract Edible vegetable oil (EVO) substrates have been successfully used to stimulate the in situ anaerobic biodegradation of groundwater contaminated chlorinated solvents as well as numerous other anaerobically biodegradable contaminants like nitrates and perchlorates at a many commercial, industrial and military sites throughout the United States of America and Europe. EVO substrates are classified as a slow release fluid substrate, and comprise of food grade vegetable oil such as canola or soya bean oil. The EVO substrate serves as an easily biodegradable source of carbon (energy) used to create a geochemically favorable environment for the anaerobic microbial communities to degrade specific contaminants of concern. EVO substrate's can either be introduced into the subsurface environment as pure oil, in the form of light non aqueous phase or as an oil/water emulsion. The emulsified vegetable oil substrates holds several benefits over non-emulsified vegetable oil as the fine oil droplet size of the commercially manufactured emulsified oils can more easily penetrate the heterogeneous pore and fracture spaces of the aquifer matrix. The use of this technology to stimulate in situ biodegradation of groundwater contaminants is still relatively unknown in South Africa. This paper will give an overview of the EVO technology and its application, specifically looking at the advantages of using this relatively inexpensive, innocuous substrate based technology to remediate contaminated groundwater within fractured rock environments commonly encountered in South Africa. {List only- not presented}
The Structural Hydrogeology of a Gold Mine	Stephen	Fonkem	South Africa	2015	gold mining, fractures, hydrogeological models
Abstract Gold mineralization in study area is structurally controlled. The geomorphology of the local drainage system is highly controlled by the fault architecture. Surface water flowed through, and eroded open fractures in exposed damaged zones (zone of subsidiary structures surrounding a fault). Previous conceptual hydrogeological models of groundwater system suggested is a two-aquifer system, consisting of a fractured aquifer overlain by a weathered aquifer, where groundwater flow mimics surface topography. Based on recent drilling and reassessment of historic geological and hydrogeological data, the groundwater system cannot only be described in terms of an elevation or stratigraphic units, as traditional aquifers are, but instead in relationship with the folds and faults. The fractured aquifer system around the mine pit is structurally compartmentalized both laterally and vertically, as depicted by the variance in static hydraulic heads and borehole yields over short distances. The un-fractured mass has very low drainable porosity. Virtually all water is contained in fractures. The main fracture zones north and west of the pit typically yield 1.3 to 2 L/s
Unravelling the complex geohydrological structure of the Elandsfontein aquifer unit	Kezia	Smith	Western Cape	2015
Abstract The Elandsfontein aquifer is currently under investigation to assist with the management of the system and to ensure the protection of the associated Langebaan lagoon RAMSAR site. The Elandfontein aquifer unit is situated adjacent to the Langebaan Road aquifer in the Lower Berg River Region and is bounded by the Langebaan Lagoon, possible boundary towards Langebaan Road aquifer, the Groen River bedrock high and the Darling batholith. The study will investigate the boundaries and hydraulic characteristics of the different aquifers and aquitards (Elandsfontein clay layer) in the Elandsfontein unit and their relationship to the Langebaan Lagoon. A literature review and baseline study has been completed to determine groundwater flow patterns and the general distribution of water quality, using historic data to characterize the different aquifers and aquitards of the system. An initial conceptual model has been formulated based on this data. Pumping tests will be used to acquire hydraulic characteristics of the Elandsfontein aquifer where data gaps exist, together with water quality and stable isotope sampling. Future plans are to construct a groundwater numerical flow model of the Elandsfontein system to assist with the management of the complex relationships between the recharge areas, flow paths through the different aquifer layers and aquitards towards the Langebaan Lagoon discharge. Results will be presented using graphical methods such as time series graphs amongst the monitoring boreholes over the years, piper diagrams to show water type characterization (Na-Cl type water) and initial results from the groundwater flow model. The expected results are envisaged to advance knowledge on groundwater availability and quality to inform the decision about water resource protection and utilization. Therefore this study is designed to provide large-scale background information that will improve the knowledge and understanding of the Elandsfontein aquifer unit and provide a basis for potential future studies of a more-detailed nature.
SKA and Groundwater Management	Danita	Hohne	Karoo	2015
Abstract In 2009 it was announced that South Africa and Australia would be in competition for the race of the Square Kilometre Array (SKA). In 2009 the MeerKAT project was started in the Karoo near the core site of the SKA, which set out to demonstrate that South Africa was able to build the infrastructure of the SKA. The SKA required water for the building of roads, the dishes and the foundations of the dishes at the MeerKAT site. This poster explains the groundwater monitoring that is being performed at the MeerKAT site from 2011 till present in order to illustrate how good monitoring and management of groundwater can ensure sustainable groundwater use at sites like these. {List only- not presented}
The value (or not) of measuring redox potential in groundwater: A case study	Meris	Mills		2015
Abstract The redox state of groundwater is an important variable for determining the solubility and mobility of elements which can occur in different redox states at earth surface conditions, such as Fe, Mn, Cr, As, U, N, S, V etc. Eh-pH diagrams are potentially invaluable for understanding and predicting the behaviour of these redox species yet, unlike pH, redox is seldom a routine field parameter due to the difficulties in measurement and interpretation. This paper discusses the potential use and limitations of field measurements of the redox state of groundwater with specific reference to the geochemical behaviour of dissolved iron in the Table Mountain Group (TMG) aquifer. As part of an investigation into iron cycling within the TMG aquifer, the redox state of groundwater was estimated through three different methods, namely direct in-situ measurement of Eh, direct measurement of DO and calculation from iron speciation in groundwater. Comparison of the results from the three methods highlights the potential value of collecting redox data, but also the complexity of controls on redox potential. The redox measurements allowed the determination of the controlling reactions on iron mobility within the TMG, but only by using the iron speciation method to calibrate the in-situ values and thereby identify which redox pair was controlling redox equilibrium. As this requires measurement of redox ion pairs in solution, it is unlikely to become a routine method for redox assessment, unless the specific redox state of an element is critical in understanding its mobility. For the majority of groundwater site investigations, measurement of the dissolved oxygen content of groundwater is probably sufficient as a first pass.
Groundwater Monitoring During An Underground Coal Gasification Process	Johan	van Dyk		2015
Abstract Underground Coal Gasification (UCG) is an emerging, in-situ mining technology that has the advantage to access a low cost energy source that is currently classified as not technically or economically accessible by means of conventional mining methods. As such it offers significant potential to dramatically increase the world's non-recoverable coal resource. Groundwater monitoring in the South African mining industry for conventional coal mining as an example, is well established, with specific SANS, ASTM and ISO Standards dedicated for the specific environment, location and purposes. In South Africa a major impact of the coal mining industry can be a reduction in the groundwater quantity and quality. South-Africa's groundwater is a critical resource that provides environmental benefits and contributes to the well-being of the citizens and the economic growth. Groundwater supplies the drinking water needs of a large portion of the population; in some rural areas it represents the only source of water for domestic use. Utilization and implementation of groundwater monitoring programs are thus non-negotiable. The groundwater quality management mission, according to the Department of Water and Sanitation in South-Africa, is set in the context of the water resources mission and is as follows: "To manage groundwater quality in an integrated and sustainable manner within the context of the National Water Resource Strategy and thereby to provide an adequate level of protection to groundwater resources and secure the supply of water of acceptable quality." The scope of this paper is to propose an implemention strategy and a fit-for-purpose groundwater monitoring program for any Underground Coal Gasification commercial operation. It is thus important to pro-actively prevent or minimise potential impacts on groundwater through long-term protection and monitoring plans. A successful monitoring program is one that consists of (1) an adequate number of wells, located at planned and strategic points; (2) sufficient groundwater sampling schedules; and (3) a dedicated monitoring program and quality control standard. In order to have an efficient monitoring program and to prevent unnecessary analysis and costs, it is also critical to determine upfront what parameters have to be monitored for the specific process and site conditions.
Selling the invisible: Communicating the Groundwater Message	Elanda P	Botes		2015	stakeholder communication, strategy, policy implementation
Abstract As we look at the legislation set out in the driving policies and its guiding frameworks, the need for able institutions to implement strategies that promise and deliver social growth and development, are highlighted. It is only possible to define an 'able institution' through its ability to fulfil its function and enable stakeholders to be part of the decision-making process. (Goldin, 2013) It is this relationship with the collection of stakeholders, in particular strategic water resource stakeholders, their linkages as well as the identification of specific stakeholder issues, that are critically reviewed. The recent Groundwater Strategy (2010) identified key strategic issues/themes. Each chapter listed a number of well thought out recommended actions that address specific challenges in each theme. It is the need for strategic direction (to put these strategies in place "plans into action") and to articulate the specific vision in the right context to the different stakeholders, (internal as well as external) that requires thinking. It is also the uptake of this information by publics (social action and intervention) and the impact of new learning that will need to be measured. This paper will present on a study where the groundwater sector and all its stakeholders are strategically examined to understand the process of communal thinking in the current environmental conditions. It would draw from current communication practices, style, strengths, sector experiences and trends and also reference specific and unique experiences as with the recent WRC Hydrogeological Heritage Overview: Pretoria project. {List only- not presented}
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.
Water Monitoring in the Mining Industry: An Overview	Callie	Pickering		2015
Abstract Water monitoring is a key aspect in the mining industry, in terms of gathering baseline data during the pre-construction stage, identifying potential areas of concern and mitigating source pollutants during the operational stage. A proper water monitoring program assists in the monitoring of plume development and water level rebound during the closure phase. The data made available through consistent long term monitoring should not be underestimated. Monitoring the effect that coal mine operations have on the water quality and quantity of surface and groundwater resources is a complex and multidisciplinary task. Numerous methodologies exist for monitoring of this kind. This paper will supply an overview of the water- rock chemistry associated with coal mine environments and the key indicator elements that should be focused on for water monitoring as well a review of the Best Practice Guidelines requirements in terms of water monitoring. Two case studies of coal mines in KwaZulu Natal will be reviewed, the key challenges outlined and mitigation measures implemented. The impact of requirements such as those set out by the Department of Water and Sanitation in terms of strict water quality limits for water containment and waste facilities as specified by Water Use Licences has also created unrealistic non-compliance conditions. The initial approach to creating a water monitoring programme should involve first identifying gaps in previous datasets and delineating potential sources of contamination. The sampling frequency will depend primarily on the water resource being monitored and the water quality analysis will depend on the type of facility. The facilities required for a specific situation will depend on the type and amount of waste generated, potential for leachate formation, vulnerability of groundwater resources and potential for water usage or resource sensitivity.
Reliability of laboratory testing of groundwater samples	Venetia	Mitchell		2015
Abstract Resources required for groundwater sampling includes but not limited to pumping equipment, trained manpower and technical resources specific to the sampling function. Bearing these expenses in mind, choosing a laboratory for testing the water samples collected should be a carefully considered purchase. Choosing a testing facility that cannot deliver an efficient, reliable and technically sound service could render the sampling futile. Water samples submitted to a laboratory for testing are received from third party sources more than ninety percent (90%) of the time and sampling techniques and sample integrity cannot be verified by the laboratory. However, the validity, reliability and integrity of the laboratory testing are within the control of the testing facility. These aspects of a laboratory are usually controlled within a quality management system where established policies and procedures form the basis of such a system. This system maintains a foundation for technical competence and customer service at the laboratory. There are numerous testing facilities available to Consultants requiring chemical and microbiological groundwater testing, each with varying levels of integrity and technical ability. It is imperative to maintain confidence in the validity of results of analyses from a laboratory and this assurance can be understood through an examination of a facility's management system. An established quality management system would comprise a policy statement, associated technical methods and technical and administrative procedures. This system would be formally documented and audited as part of the on-going laboratory's management system. In some instances, laboratories formalise this into an accreditation of the laboratory to an international standard, such as ISO 17025:2005. The assurance that the results of analyses from any laboratory are of sound technical integrity would depend on factors such as - personnel training, - accommodation and environmental conditions under which the tests are carried out, - validation of the methodology applied (including the uncertainty of measurement), - the calibration and maintenance of the equipment used, - understanding the traceability of and measurement undertaken, - handling and preservation of the sample on receipt and while in the laboratory. Each of these factors plays a critical role in the integrity of results of analyses and should be interrogated when trying to understand the reliability and competence of the laboratory of choice.{List only- not presented}
Modelling Mine Water Rebound With MODFLOW	Stephen	Fonkem		2015
Abstract A review from international literature discredits the capability of MODFLOW to simulate mine water rebound, due to the nonstandard hydrogeology of underground mine systems. The conceptual understanding is that, after cessation of dewatering, mine water inflow rates and hydraulic heads are related to the void-volume, the differences in head between the water in the mine void and head dependent source, plus natural recharge to the mine voids. The flooded mine voids in the study area are partially underlain by a dolomitic aquifer. The other head dependent source of inflow into the mine voids are the surrounding and overlying Karoo aquifers. Head independent inflow rates into the mine voids, using the long term decant rates, was estimated to be 0.2% of rainfall. During mining, dewatering occurred at approximately 3 to 6 Ml/d. The objective of the model was therefore to simulate the changes head-dependent inflow rates during the rebound period. Analysis of the water level recovery data depicted that once the mine filled up with water, the hydraulic head of the mine rose with the elastic storage coefficient value of the mine void and not the specific retention as conditions changed from unconfined to confined. A three layer model was setup, to represent the two seams mined, separated by a deep Karoo aquifer. The presence of the dolomite on the mine floor was incorporated using the general head boundary package. Head dependent influx from overlying shallow and intermediate Karoo aquifers were simulated using the river package. All model layers were simulated as confined, initially to avoid model convergence issues. The confined setup proved to be the core in simulating mine water rebound with MODFLOW. The modelling exercise showed that storage during rebound is a boundary condition. This simply means that the complexity of mine water rebound can only be achieved in MODFLOW by proper time stepping and dividing the model into different stress periods to represent the changes in storage. Rebound in the study area, modelled with 21 stress periods produced a perfect water level recovery data for the different mine compartments. This was achieved by applying storage capacities of between 0.3 to 0.006 to simulate rebound during unconfined conditions, and values of between 10-4 and 10-5 when the mine void is flooded. The results showed that the inflow from the dolomitic aquifer steadily decreased from 4121 m3/d to 0 m3/d as the mine hydraulic head increased and rose over the head in the dolomitic aquifer. During the same period, inflow from the surrounding Karoo aquifers decreased from 2422 m3/d to less than 10 m3/d. The results of the model were very important in determining the volumes of water to be abstracted from the mine voids for ash-backfilling. {List only- not presented}
Qualitative interpretation of groundwater flow distribution within the southern granite supersite of the Kruger National Park	Ashton	Van Niekerk	Mpumalanga	2015
Abstract Understanding the hydrogeology of fractured or crystalline rocks could be complicated because of its complex structure and a porosity that is almost exclusively secondary. These types of geologies are known to exhibit strong heterogeneities and irregularities contrasted in hydraulic properties, spacing and flow distribution within fractured rock aquifers. Therefore it is important to develop a conceptual model based on site specific data such as the hydraulic roles between groundwater and nearby hillslope/surface water bodies in order to understand its movement within the environment. Therefore this study intends to develop a hydrogeological conceptual model to qualitatively interpret the dominant groundwater flow processes at a 3rd order scale within southern granite supersite of the Kruger National Park (KNP). Key findings based on actual subsurface results in the form of Electrical Resistivity Tomography (ERT) surveys, borehole drilling logs, water levels and hydraulic data suggest that two aquifer types exist on the southern granite supersite namely, a weathered low resistivity of 3-75 ?m (average depth ranging 383-328 mamsl) and hard rock high resistivity of 1875-5484 ?m (average depth ranging 364-299 mamsl) granite/gneiss aquifer. The weathered aquifer flow system responds to localized processes such as piston recharge, indirect surface water recharge and groundwater water discharge via interflow. This was due to the relatively rapid response time of 2-3 weeks in groundwater levels to the major sequence of rainfall events over the hydrological year. The hard rock aquifer is part of a regional groundwater flow system. This is owed to the lengthy response time lags of 2-3 months in groundwater levels to the major sequences of rainfall events over the hydrological year. Due to the generally low transmissivity (ranging 9.50E-08 to 11.2 m2/day) values obtained during the borehole pump and slug tests and inclining trend of groundwater levels after the wet season, suggest these ephemeral hillslope landscapes are likely to act as hydraulic boundary areas. In that they contribute during the dry season to the regional hydraulic head generating baseflow to perennial streams. Therefore from a management perspective certain reaches within these ephemeral streams contribute to recharge which in turn should receive attention as many of the ephemeral stream sand are used for grading tourist gravel roads. Furthermore these granite ephemeral landscapes are characteristic of generally low transmissive aquifer properties and therefore should be given careful consideration before including it in a water supply scheme scenario.
Understanding Site Hydrology of the Northern Kwa Zulu Natal Anthracite Coal fields	Hendrik	Botha	KwaZulu-Natal	2015	coal mining, AMD, mine closure
Abstract POSTER Investigations have shown that receiving water bodies, which mainly include rivers, streams and the more complicated geohydrological system, are part of the primary end receivers of harmful contaminants from identified coal mining waste bodies. Some of these potential dangers include acid mine drainage (AMD) and sulphur mine drainage (SMD) which have dire effects on the surroundings. The need for a cost effective methodology to assess site hydrology and geohydrology, to understand the associated legal responsibility of contaminated streams and aquifers, is recognised. In the compilation of this paper the unique nature of South African legislation and policies are implemented in the development of a logical approach towards mine closure specifically in the field of groundwater assessments. Furthermore, this paper explores co-disposal of discard and slurry material and the environmental impact of co-disposed wastes is assessed. The unique geological attributes of the KZN coal fields and the geochemical research results found indicates that on its own discard has great potential to produce long term SMD and that slurry has lower SMD potential. Co-disposed results are promising and buffering against long term chemical changes are noted. The final product of this approach constantly considered site hydrogeology, related impacts, risks and liabilities. This gave more clarity on aspects related to the principles followed to identify objectives for sustainable mine closure and to adopted a philosophy of mine closure as a hydrogeological concept. Overview of methods that could be used for mitigation of polluted aquifers and a brief site specific application is discussed with the aim to achieve the key deliverable which focuses on methods to scientifically assess sources, pathways and receivers. Ultimately this process has led to the development of a logical approach towards mine closure for groundwater assessment and remediation in the typical anthracite mine environment.
Groundwater Exploration And Monitoring At Selected Western Cape Schools	Candice	Lasher	Western Cape	2015
Abstract POSTER The Department of Transport and Public Works has been involved with the building and upgrading of schools in the Western Cape, as well as providing green areas for sports fields. Due to the excessive costs of using municipal water the option of using groundwater for irrigation was investigated by SRK Consulting. A number of successful boreholes have been scientifically sited, drilled and tested since 2011. The boreholes have been equipped with pumps and data loggers have been installed in several. These data loggers measure time-series water levels and temperature while the flow meters measure the discharge rate and the quantity of groundwater used. Currently groundwater is being abstracted to irrigate the sports fields. Initially some problems were encountered. Boreholes were not operating optimally due to incorrect pump sizes resulting in water levels to be at pump inlet depths and pumps were not being switched off for recovery. However, due to continuous monitoring, the pumping rates and times were adjusted accordingly. It is imperative that all boreholes are equipped with loggers and continuously monitored to ensure that the boreholes are being optimally and sustainably used. Monitoring groundwater abstraction and aquifer water levels provides critical information for proper groundwater resource management. It is envisaged that schools will become proactive and participate in the groundwater monitoring. The latter will assist with groundwater awareness and assist in the use of alternative water sources and ease the burden on already stretched conventional sources.
Estimation of Groundwater Recharge Response from Rainfall Events in a Semi-Arid Fractured Aquifer: Case study	Phathutshedzo	Nemaxwi		2015
Abstract Estimating groundwater recharge response from rainfall remains a major challenge especially in arid and semi-arid areas where recharge is difficult to quantify because of uncertainties of hydraulic parameters and lack of historical data. In this study, Chloride Mass Balance (CMB) method and Extended model for Aquifer Recharge and soil moisture Transport through unsaturated Hardrock (EARTH) model were used to estimate groundwater recharge rates. Groundwater chemistry data was acquired from the Department of Water and Sanitation (DWS) and Global Project Management consultants, while groundwater samples were collected to fill-in the identified gaps. These were sent to Council for Geoscience laboratory for geochemical analysis. Rainfall samples were also collected and sent for geochemical analysis. An average value of rainfall chloride concentration, average groundwater chloride concentration and mean annual precipitation (MAP) were used to estimate recharge rate at a regional scale. Local scale recharge was also calculated using chloride concentration at each borehole. The results were integrated in ArcGIS software to develop a recharge distribution map of the entire area. For EARTH model, long term rainfall and groundwater levels data were acquired from the South Africa Weather Services and DWS, respectively. Soil samples were collected at selected sites and analysed. These were used to determine representative values of specific yield to use on EARTH model. 60% of the groundwater levels data for 5 boreholes was used for model calibration while the remaining 40% was used for model validation. The model performance was evaluated using coefficient of determination (R2), correlation coefficient (R), Root Mean Square Error (RMSE) and Mean square error (MSE). Regional recharge rates of 12.1 mm/a (equivalent to 1.84% of 656 mm/a MAP) and 30.1 mm/a (equivalent to 4.6% MAP) were calculated using rainfall chloride concentrations of 0.36 and 0.9 mg/L, respectively. The estimated local recharge rates ranged from 0.9-30.2 mm/a (0.14 - 4.6%) and 2 - 75 mm/a (0.3 - 11.4%) using chloride concentration of 0.9 and 0.36 mg/L, respectively. The average recharge rate estimated using EARTH model is 6.12% of the MAP (40.1 mm/a). CMB results were found to fall within the same range with those obtained in other studies within the vicinity of the study area. The results of EARTH model and CMB method were comparable. The computed R2, R, RMSE and MSE ranged from 0.47-0.87, 0.68-0.94, 0.04-0.34, 0.16-3.16, and 0.50-0.79, 0.68-0.89, 0.07-0.68, 0.15-8.78 for calibration and validation, respectively. This showed reasonable and acceptable model performance. The study found that there is poor response of groundwater levels during rainy season which is likely to be due to lack of preferential flows between surface water and groundwater systems. This has resulted in poor relationship between estimated and observed groundwater levels during rainfall season. Key words: ArcGIS, CMB, EARTH, Groundwater recharge, rainfall
Decision making with web-based geo-spatial databases coupled to groundwater models	John	Wise		2015
Abstract Model calibration and scenario evaluations of 2D and 3D groundwater simulations are often computationally expensive due to dense meshes and the high number of iterations required before finding acceptable results. Furthermore, due to the diversity of modelling scenarios, a standardised presentation of modelling results to a general audience is complicated by different levels of technical expertise. Reducing computational time In this presentation we look briefly at the use of Reduced Order Models (ROM's), which is one of the recent developments in groundwater modelling. The method allows significant speed-up times in model calibration and scenario evaluation studies. In saturated flow for example, these approaches show speed-up times of >1000 when compared to full models created with Finite Element of Finite Difference methods. These methods are demonstrated to a case study in the Table Mountain Group, in which we show a simplified parameter calibration and scenario evaluation study. Standardising presentation In order to present the results to as wide an audience as possible, the use of a web-browser as a GUI is proposed, where the web-page is coupled to a geo-spatial database and data is presented in a spatial and numeric format. The use of the spatial database manager PostgreSQL with PostGIS is proposed. Through a browser interface, users can run modelling scenarios using the ROM, which is evaluated in near real-time. Following the evaluation of the model, we show how PostGIS can spatially present data on a base-map such as google maps. In keeping with the current trends in online map customisation, viewers can interactively choose to overlay the base-map with a data-type (such as pressure or hydraulic head contours or flow direction) that is most intuitive for their level of familiarity with the data. Conclusion In using advanced modelling techniques and a simplified browser based presentation of results, high-level decisions in water resource management can be significantly accelerated with the use of interactive scenario evaluations. Furthermore, by reaching a broader audience, public participation will be significantly enhanced.
Using electrical resistivity method for subsurface mapping of shallow aquifers in Heuningnes Catchment, South Africa	Kinsley	Manyama		2015
Abstract The current study investigated the subsurface of aquifers in Heuningnes Catchment focusing on aquifer characteristics for groundwater resource assessments. Surface geophysical resistivity method was adapted for mapping the shallow subsurface layers and hydrogeologic units at selected sites within the catchment. The aim was to provide a preliminary overview of the subsurface nature of aquifers within the study area, by establishing features such as geological layers, position of weathered zones, faults and water bearing layers. The multi-electrode ABEM SAS 1000 resistivity meter system, using the Wenner array, was used to obtain 2D resistivity data of the subsurface. The acquired data was processed and interpreted using Res2DINV software to produce the 2D resistivity models. The analysis of the resistivity models of the subsurface reveals maximum of four layers; sandstone, shale, poor clayed and brackish water saturated layer. On comparing the model results with the surficial geological formation of the catchment geological map, the identified layers were found to correspond with the geology of the area. The findings i) provide insights on sites that can be drilled for groundwater exploration, ii) show possible water-type variations in the subsurface. Although the results are not conclusive but they provide basis for further research work on quality and flow dynamics of groundwater. {List only- not presented} Key words: aquifer properties, hydrogeologic units, geo-electric model, electrical-resistivity method
Physico-Chemical Assessment of Groundwater in the Orange Water Management Area	Olma Tsakani	Makonto		2015
Abstract The groundwater quality of the Orange Water Management Area (OWMA) was assessed to determine the current groundwater status. Groundwater is of major importance in the Orange Basin and constitutes the only source of water over large areas. Groundwater in the OWMA is mainly used for domestic supply, stock watering, irrigation, and mining activities. Increase in mining and agricultural activities place a demand for the assessment of groundwater quality. The groundwater quality was assessed by collecting groundwater samples from farm boreholes, household boreholes, and mine boreholes. Physical parameters such as pH, temperature and Electrical Conductivity (EC) were measured in-situ using an Aquameter instrument. The groundwater chemistry of samples were analysed using Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography, and Spectrophotometer for cations, anions and alkalinity respectively. The analyses were done at Council for Geoscience laboratory. The results obtained indicated high concentration of Nitrate (NO3), EC, sulphate (SO4), Iron (Fe), and dissolved metals (Chromium, Nickel, Copper, Zinc, and Lead). The concentrations were higher than the South African National Standards (SANS) 241 (2006) drinking water required guideline. The OWMA is characterised by the rocks of the Karoo Supergroup, Ventersdorp Supergroup, Transvaal Supergroup, Namaqua and Natal Metamorphic Province, Gariep Supergroup, and Kalahari Group. Groundwater is found in the sandstones of the Beaufort Group. Salt Mining occurs in the Namaqua Group, hence the high concentration of EC observed. High EC was also found in the Dwyka Group. The salt obtained from the pans underlain by the Dwyka Group rocks has relatively high sodium sulphate content, this probably results from oxidation of iron sulphate to sulphate. Therefore, high concentration of SO4 is due to the geology of the area. High concentration of NO3 is due to agricultural activities, whereas high concentration of EC, Fe, SO4 and dissolved metals is due to mining activities.
Contaminated soil and groundwater: Vacuum Enhanced Recovery as an alternative method	Ernest	Rambau	South Africa	2015	Vacuum Enhanced Recovery, hybrocarcon contamination
Abstract Vacuum Enhanced Recovery (VER) has widely been applied in many hydrocarbon contaminated site to recover liquid hydrocarbon from the subsurface Hydrocarbon contamination to groundwater and soil is usually as results of leak or release. Different technologies and method exist to treat contaminated groundwater and soil through hydrocarbon. This paper focuses on the efficiency of VER as alternative method to the site where over 6 000 litres of petrol leaked to the subsurface over a period of time. The application of VER involves creating a capture zone in a particular monitoring well by increasing the hydraulic gradient towards that particular well or set of wells affected by hydrocarbon.
A Baseline Study of Scarce Groundwater Resources in Anticipation of Fracking in the Karoo	Divan	Stroebel	Eastern Cape, Karoo	2015	Shale gas, Fracking, sampling
Abstract The anticipated exploration and exploitation of Shale Gas in the Eastern Cape Karoo through hydraulic fracturing has raised considerable debate regarding the benefits and risks associated with this process for both the Karoo, and the country as a whole. Major concerns include the potential impact of hydraulic fracturing on ecological, environmental and especially scarce water resources. The Eastern Cape Karoo region is a water stressed area and with further climate change it will become increasingly so. Thus, effective and reliable groundwater management is crucial for sustainable development in this region. This research aims to hydrochemically characterise both the shallow groundwater (<500m) and deeper saline groundwater in the vicinity of the Shale Gas bearing formations, based on major and trace elements, as well as gas isotope analyses. Sampling will include water sampling and gas measurements from shallow boreholes (<300m), SOEKOR drillholes (oil exploration holes drilled in the 60's and 70's up to 4km deep) and thermal springs (source of water >500m). To-date, a desktop study includes the collation of information determining the areas with the highest potential for Shale Gas Exploration throughout the Eastern Cape Karoo, from which the research area has been determined. This includes the identification of the respective oil companies' exploration precincts. A Hydrocensus has been initiated across this area, which includes slug testing and electrical conductivity profiling of open, unequipped boreholes. Further borehole selection will be finalised from this acquired information. The boreholes will be sampled and analysed a minimum of three times per year, which will occur after summer (April/May) and winter (October/November), after which the hydrochemistry will be analysed. The sampling will be preceded by purging of all inactive boreholes. The possible hydraulic connectivity between the shallow and deep aquifers will be tested, particularly in those areas where dolerite intrusions as well as fault systems may enhance preferential flow of water, using the chemical forensics complemented with passive seismic profiling/imaging and deep penetrating Magneto-Telluric (MT) imaging. The data collected will form a record against which the impact of fracking can be accurately determined. The research is a critical first step towards the successful governance of groundwater in light of the proposed Shale Gas development. In its absence, effective regulation of the sector will not be possible.
Urbanization effects on the channel morphological changes in the Kuils River, Western Cape	Naeem	Davids	Western Cape	2015
Abstract POSTER The human interferences in river catchments includes impoundment construction, sediment mining, bank revetment and artificial cutoff, which eventually leads to changes in the hydrology system and channel transportation ability, and may reduce channel stability. In past 10 years the Kuils River had been upgraded between Van Riebeeck Road and the Stellenbosch Arterial route to reduce flood levels. The stretch of the river between the R300 and Van Riebeeck Road was also upgraded: reducing any possibility of flooding, by concrete-lining of some areas of the river that are within the Kuilsrivier Municipal Area. Producing a cross-section of a river channel is of great importance in river studies. To determine the discharge one should survey the profile of a feature such as a meander or riffle, it is necessary to produce a cross-section of the river. In order to focus on restoration requirements of a river, a map of the river is needed. This provides an indication of what exactly the river currently is. Habitat mapping is intended to access the stream. Woody debris, substrate, aquatic vegetation is measured continuously throughout a river, to be able to identify conservation and restoration needs. The cross section 1.3 of site 1 indicates that the channel width from January 2002 is almost similar in width of September 2012. The depth of the channel is about 0.5m deeper when compared to January 2002. The Kuils River banks are covered in grassy vegetation, with some trees with deep and large roots that provide protection against undercutting along rivers. The banks of Site 1 are covered long weeds and annual grasses with shallow root systems, which don't provide stability when the banks were saturated after high rainfall. The Kuils River area is used for various types of land uses and this also impacts the channels eg. Urban, Industrial and Agricultural use. Because of canalization occurring upstream one can see evidently the changes within the channel.
Ground Water Management in South Africa: Challenges and Constraints	Courage	Mlambo		2015
Abstract Water scarcity is a growing issue in South Africa. The consumption of water is rising and as such, water is becoming a scarce and valuable resource. Given the circumstances that South Africa is facing, improving the use of ground water could help tackle water scarcity in South Africa. Groundwater has been an important source of water and it can bring socio-economic benefits if properly used. Studies have proved that groundwater resources play a fundamental role in the security and sustainability of livelihoods and regional economies throughout the world. However, in South Africa, groundwater still remains a poorly managed resource and this hinders socio-economic development. This paper examines the current state of ground water management in South Africa. The paper also examines how ground water in South Africa is currently allocated and used, and explores some of the consequences of current water management arrangements. {List only- not presented}
Water balance calculations in a rehabilitated environment	Jean	van Niekerk	Mpumalanga	2015
Abstract A groundwater study at Middelburg Colliery was completed with the emphasis on the investigations into water balances on a rehabilitated coal mining environment. Water balance calculations and water scheduling for collieries in Mpumalanga have become important facets of mine planning over the past years. Opencast mining involves the blasting and removal of rocks overlying the coal layer, which is removed completely. The overburden is then replaced (backfilled) and covered with soil and the terrain is rehabilitated. Rainwater penetrating through the soil into the backfill may become acidic by pyrite and sulphides in the backfill material and ultimately decants on the surface. Decanting generally commences a decade or more after mining ceases. Opencast mining impacts the natural groundwater regime and radically alters the nature of groundwater-surface water interactions. The Department of Water Affairs and Forestry in South Africa requires that mines minimise the release of their polluted water. A groundwater balance is the numerical accounting of the annual recharge to a groundwater resource. It can further be described as a quantitative assessment of the total water resources of a basin over a specific period of time. In a groundwater development program, such a budget is necessary to efficiently manage and utilize the resource. Many of the parameters that determine recharge to an aquifer are measured directly and some are computed from hydraulic characteristics and measured field data. The Middelburg Mine Services has been experiencing excess water problems in past years. Because of the lack of space and the concerns of decanting of mine water out of the rehabilitated pit, it was suggested that mine water treatment should be considered. Geohydrological models were created to determine the decant positions and water volumes for the rehabilitated area. The size of the water treatment plant can then be determined using the calculated decant volumes and positions.
Integration of water simulation modelling for water conservation and demand management in the mining sector (a case study)	Fanie	Botha	South Africa	2015	legislative challenges, integrated modelling, WUL
Abstract This paper outlines and presents out-of-the-box theories as examples to highlight some of the challenging restraints within the current legislative environment preventing scientists, engineers and other operational personnel to take theory into action and implementation. Key to this is the very static nature of the water use license (WUL)and associated process. The first example shows how integrated dynamic water modelling can be utilized to create an integrated water and waste management plan within the mining sector. The models developed using principles from Government Notice 704, the Best Practice Guidelines (BPGs) and the principles of water conservation and demand management. Ultimately it keeps clean and dirty water flows separate and optimises the use of dirty water in order to reduce raw/potable water off-takes through this process. The objective of these models are to optimise the water use and develop strategies to ultimately enable mines to optimize it's internal non-potable water resources therefor relieving pressure on the limited potable systems, as well as aiding surrounding communities, in which they operate, with potable water. Results from the model provides for 1 or 20 years simulation data that differs year-on-year based on numerous factors, i.e. rainfall, run of mine (ROM) feed and growing/declining surface run-off areas. The variability of the results makes it almost impossible to utilize within application documentation as it is too complex and it does not align with the application figures as required in the WUL process. This resulting in a fairly simplistic and sometimes unrealistic static model that is submitted as part of the application.
A case study review of a high tech approach towards wellfield and aquifer management.	Paul	Lee		2015
Abstract Faced with a burgeoning population and property growth, and in preparation for a future drier climate regime; the coastal town of Hermanus in the Western Cape has set up two wellfields to abstract groundwater from the underlying aquifer in order to augment the constrained surface water supply from the De Bos Dam. Water Use Licences (WUL) were issued to the Overstrand Municipality in June 2011 and December 2013. The licences authorise a maximum annual abstraction of 1 600 Ml of water from the Gateway wellfield and 800 Ml of water from the Volmoed and Camphill wellfield via several boreholes. The water abstracted from the Gateway wellfield is pumped via a booster pump station to the Preekstoel Treatment Plant. The Volmoed and Camphill wellfield are situated at a higher altitude allowing for a gravity feed pipeline. Earth Science Company, Umvoto Africa, has the responsibility to ensure Resource Quality Objectives are met which include balancing the need to protect the resource on the one hand; and the to develop sustainable utilisation of the Hermanus groundwater resources and compliance with the WUL on the other. The consultancy provides hydrogeological support, wellfield management and technical advice in operating the boreholes, pumps, boosters and related infrastructures. Running the operations of the wellfield relies on a high-tech, semi-automated system, incorporating a remotely controlled, telemetry based structure. Vital parameters are monitored by electronic sensors, feeding data to processors which alters pump performance to maintain specified boundary levels. Data is simultaneously communicated via telemetry to a central control which uses data acquisition software to portray information to the operators. Warning alarms both alert operators via SMS and in certain instances auto-shut down the system. To ensure ecological sustainability of the ground water resource, the wellfield also requires hydrogeological monitoring at far field locations within the recharge areas. Some of these locations are in remote areas making data download costly. The high-tech telemetry approach is used with positive results. Any automated telemetry system is prone to malfunction and environmental hazards. The challenge lies in managing this and providing sufficient back up and duplication of systems. The paper gives an overview of the components and flow of data based on the experiences gained during the evolution and development over 12 years of operation. Automation produces vast data bases which are often not sufficiently analysed, the premise that "once collected, the task is done". However data is only as good as the people who drive the systems and this paper provides a critical analysis of human intervention in an automated system and the decisive role of quality-checks. Finally the paper seeks to provide a pragmatic guideline for water users to comply with the WUL and institutional regulations.
Characterising surface water-groundwater interactions in the Vo?lvlei (Agulhas Plain), using a multi-disciplinary approach	Nabuweya	Noordien		2015
Abstract Coastal wetlands are complex hydrogeological systems in which groundwater have a significant influence on both its water balance and hydrochemistry. Differences in groundwater flow and groundwater chemistry associated with complex hydrogeologic settings have been shown to affect the diversity and composition of plant communities in wetland systems. A number of wetlands can be found across the flat terrain of the Agulhas Plain, of which the most notable is the Soetendalsvlei and the Vo?lvlei. Despite the ecological and social importance of the Vo?lvlei, the extent to which local, intermediate and regional groundwater flow systems influences the Vo?lvlei is poorly understood. The aim of this work is to characterize the spatial and temporal variations in surface water and groundwater interactions in order to demonstrate the influence of groundwater flow systems on the hydrology of the Vo?lvlei. The specific objectives of the study are; 1) to establish a geological framework of the lake sub-surface, 2) to determine the physical hydrological characteristics of the Vo?lvlei and 3) to determine the physical-chemical and isotopic characteristics of groundwater and surface water. Data collection will be done over the period of a year. Methods to be used will include the use of geophysical (electrical resistivity) to determine high water bearing areas surrounding the wetland, a drilling investigation (the installation of piezometers at 5-10m depths and boreholes at 30m depth, sediment analysis (grain size analysis, colour and texture), hydraulic (slug testing to determine hydraulic properties; hydraulic conductivity and transmissivity), hydrological (to estimate groundwater discharge; Darcy flux and hydraulic head difference between groundwater level and lake level), physical-chemical (electrical conductivity, temperature and pH) and stable environmental isotopic (oxygen and hydrogen) analysis of surface water and groundwater, to determine flow paths and identify processes. Thus far, results obtained for the geophysical survey has revealed that the sub-surface of this wetland system is highly variable. Three traverses were done on the South-Western, South-Eastern and Northern side of the wetland (See Figure 1). In VOEL1 (South west), the upper couple of meters show areas of very low resistivity, which is associated with clays, poor water quality and water which has high dissolved salts. The changing of medium to high resistivity values on the North-eastern side is usually indicative of weathered sandstone (Table Mountain Group). VOEL2 (South eastern), indicates that the subsurface is of low resistivity. These low values are the result of noticeable salt grains in the sand. VOEL3 (Northern), indicated upper layers of low resistivity, while the lower depth indicate areas of high resistivity. It is expected that the results of this study will provide a conceptual understanding of surface water-groundwater interactions and the processes which control these interactions, in order to facilitate the effective management and conservation of this unique lacustrine wetland.
Estimation of representative transmissivities in heterogeneous aquifers	Fanie	de Lange		2015
Abstract The so-called apparent increase of transmisivity (T) or hydraulic conductivity (K) with scale is an artifact and does not exist in the field. The reason for the apparent increasing of T with scale is due to the use of the "not applicable" random log Gaussian stochastic models that are used by geohydrologists. In the petroleum field, which uses deterministic methods, the apparent increase of T with aquifer volume does not occur. Groundwater practitioners have to change their view and use models that do not show this effect. By using intuitive inspection of geological, fracture and connectivity data as well as real pumping test data, this paper shows that up-scaling must be performed with an exponential decaying function, where T always decreases with scale . Two types of heterogeneities exists namely a.) horizontal and b.) vertical. Connectivity between fractures is extremely important in both cases, but it is only in semi-confined and watertable aquifers that the vertical heterogeneities are really important (typical case of fracture dewatering) {List only- not presented}
Using gravity anomalies from GRACE to estimate changes in groundwater storage in the Vaal River Basin	Khuliso	Masindi		2015
Abstract The Gravity Recovery and Climate Experiment (GRACE) satellites detect minute temporal variation in the earth's gravitational field at an extraordinary accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores (snow, groundwater, surface water and soil moisture) due to increases or decreases in storage. The GRACE monthly TWS data are being used to estimate changes in groundwater storage in the Vaal River Basin for a period (2002 to 2014). The Vaal River Basin has been selected, because it is one of the most water stressed catchments in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands, it is critical to monitor and calculate changes in groundwater storages as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin were mostly localised focusing mainly on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, but many of these models do not take into account the groundwater component. Thus, there is a significant gap in the understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks are often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is a good approach to estimate changes in hydrological storages as it covers large areas and generates real time data. It does not require information on soil moisture, which is often difficult to measure. The accuracy of calculating change in groundwater storage lies in the processing of GRACE data and smoothing radii. For this study, smoothing radii of 1500, 900, 500, 300, 150 and 1 km are used. Currently the associated error with different smoothing radii is unknown. The preliminary results indicate that the study area experienced a loss in TWS of -31.58 mm equivalent water height over a period of 144 months in TWS at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamics, which will improve water management practices.
An Analysis Of The Challenges For Groundwater Governance During Unconventional Gas Development In South Africa	Kevin C	Pietersen	National	2015	groundwater governance, Unconventional gas
Abstract The groundwater governance arrangements for the development of groundwater resources were analysed. The analysis highlighted gaps and barriers to overcome before unconventional gas (shale gas and coal bed methane) development can take place at an industrial scale. The following governance challenges were identified (i) setting baseline measurements to detect groundwater pollution and to determine resource status; (ii) review of licenses and setting conditions for the development of unconventional resources; (iii) compliance monitoring and enforcement systems in place (iv) dealing punitively with non-compliant operators (v) mitigation options in place to prevent groundwater pollution; (vi) goal-based regulatory framework in place rather than a prescriptive regulatory framework; (vii) disclosure of hydraulic injection fluid; (viii) coordination with other government departments and regulatory bodies; (ix) a framework for subsidiarity and support to local water management; and (x) an incentive framework that support good groundwater management. To overcome the challenges requires a decentralized, polycentric, bottom-up approach, involving multiple institutions to deal with unconventional gas development. This provides better conditions both for cooperation to thrive and for ensuring the maintenance of such institutions.
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.
Characterisation of a large LNAPL plume in Limpopo Province, South Africa	Mahlogonolo	Phahlamohlaka	Limpopo	2015
Abstract Work is being conducted in Limpopo province following a large volume spill of petroleum hydrocarbons that took place from a leaking underground pipeline, resulting in significant volume of groundwater contamination. This is by far the largest spillage to date in South Africa.10 million litres of jet fuel leaked for a 15 year period from an underground pipeline until its detection 13 years ago. The leak has since been repaired and bailing was the first method proposed and applied to the recovery of the free product, but due to its ineffectiveness the "quicker"pump-and-treat method replaced it. Due to complications caused by pum-and-treat, the process was stopped in 2007 and is about to be reinstated again in 2013. A village to the north of the spillage depends mostly on groundwater. Immediate remediation actions have to be established before the contaminant reaches their abstraction boreholes. This project aims to model the areal extent of this contaminant and eventually design a life cycle of remediation. This will be based on comparison between existing models dated 2002 and 2012 respectively for background information and to address the influence of ten years' bailing, pumping and natural attenuation. The new model will focus around implementing remedial measures to prevent further migration of the free phase or dissolved plumes in order to protect the water supply to the surrounding villages. The progress will be presented in this paper.
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.