Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 751 - 795 of 795 results

Title	Presenter Name	Presenter Surname	Area Sort descending	Conference year	Keywords
Comparison of Topographical and Seasonal Variation of Geochemical Parameters in the Kuils River and Steenbras River	G.D.	Rezelman	Western Cape	2017	geochemical parameters, Topographical Variation
Abstract Water resources are a great concern in South Africa, more specifically the Western Cape. Therefore, a need has developed to understand the processes that may affect these precious resources. In the Western Cape large proportions of these resources are in the form of streams originating in untouched mountainous areas. However, as these streams continue towards the ocean they are faced by many threats. Alien vegetation, the destruction of river beds and abstraction from streams and boreholes threaten to dry up these resources. Additionally, pollution from fertilizers, sewage treatment plants as well as urban and industrial run-off contaminate these resources. The influx of pollutants, such as fertilizers, usually varies between seasons as it is only applied at certain times of the year. However, pollutant concentrations are not only linked to riparian land-use but are largely affected by climate changes as well. Processes such as surface run-off, along with first flush events and dilution control the nutrient concentrations in the streams. Although water is a renewable resource, it is not replaceable. This project will look at the streams’ self-purification potential. This refers to the processes within the rivers that lead to an in situ reduction of contaminants and pollutants. For example, contaminants and pollutants in rivers can be reduced by particle settling, plant and microbial uptake as well as chemical processes such as redox reactions and complex formation. For this project, pollution will be categorized into two different groups: nutrients and major ions from both point sources and non-point sources. The relevant nutrients analysed in this study are: nitrate, ammonium, phosphate and sulphate; and the major ions analysed are: Calcium (Ca), Sodium (Na), Potassium (K), Aluminium (Al), Iron (Fe) and Manganese (Mn). These will be analysed in conjunction with several physico-chemical parameters: temperature, pH, conductivity, total dissolved solids (TDS), salinity, oxidation reduction potential (ORP) and alkalinity. Analysing these parameters will allow us to measure the effects these processes have on pollution concentrations in the rivers and how climate changes facilitate these processes. For this study, the polluted Kuils River will be analysed and compared to the Steenbras River, which lacks major direct contaminants. This stream will this mainly serve as a ‘control’. Since this study will only be completed at the end of 2017, full conclusions have not been drawn yet. Therefore, this paper will highlight the findings thus far.
In-Situ Iron Removal Treatment In A Primary Aquifer, The Atlantis Example	L.	Nhleko	Western Cape	2017	Iron Removal, Atlantis Aquifer
Abstract In a town where 98% of the population relies on groundwater-dominated resources, Atlantis is also plagued by varied abstraction rates that promoted iron and manganese borehole clogging. Conventional treatment methods, such as pump-and-treat technology, can be costly and inefficient. In-Situ Iron Removal (ISIR) technologies addresses issues such crucial skilled operators, handling and storage of chemicals, expert management, and the disposal of generated sludge. ISIR has been successfully practised worldwide especially in Europe, for well over a 100 years. In South Africa however this methodology has not filtered through, although our groundwater systems have clogging problems related to iron and manganese precipitation. Atlantis in the Western Cape has benefitted from a pilot study that looked into ISIR and the unique idea of utilizing ozonation. The pilot project was successful, although applied on a small scale. This called for a further study that is now looking into extending the range of treatment, applying the principles of the Vyredox method, and lengthening the treatment period to 3 months of continuous injection. The study also aims to develop the engineering design criteria for full scale application. The success of this project and the technology to be developed goes a long way towards achieving Sustainable Development Goal 6 and improving South Africa’s groundwater systems.
Nutrient Retention In Stream Sized Rivers, Related To Riparian Land Development And Climatic Change	Reuben	Lazarus	Western Cape	2017	Seasonal cycles, Pollution, physicochemical environment
Abstract The Western Cape of South Africa is rich in small stream sized rivers forming part of its water resources. The Lourens river and Eerste river, both situated in this region are the base for this study. Rivers are affected by their surrounding environments and the continuous development around these rivers could affect their health adversely. Diverse land-use patterns contribute to a wide range of pollutants with different characteristics. Indeed, some of the pollution levels in the Eerste and Lourens rivers were linked directly to specific land-use practices surrounding the rivers. However, the large change in weather during a seasonal cycle causes a significant difference in pollution levels too, because the transport of pollutants from the source to the rivers is primarily based on surface run-off, which in turn is predominantly dependent on the precipitation of the region. A six months long monitoring in 2016 showed that processes like surface run- off, together with first flush events and dilution control the pollution concentrations in the Lourens river and Eerste river. Physicochemical parameters, major agricultural nutrients and industrially produced heavy metals all reacted differently to these processes, thus, providing an insight into the effects continuous development and climate change have on surface water as a national resource. Interestingly, both rivers included sections with substantial retention and/or reduction of pollutants. The natural riparian vegetation, hyporheic zone and microbial community present in these rivers are proposed to be the main drivers behind both rivers’ ability to reduce or retain pollutants. These drivers are sensitive to their environment and react differently depending on the weather, available nutrients, and physicochemical environment. With the effects of climate change becoming more apparent, it is important to study the impact of warmer temperatures, longer droughts, and heavier rain events, for instance, on the pollutant retaining capabilities of these streams.
Test Pumping: Comparing the Farmer Test, Constant Head Test and SANS 10299-4:2003 methodologies with regards to estimating groundwater abstraction. Data, analyses and recommendations.	Kes	Murray	Western Cape	2021	test-pumping, Irrigation, training, Water security
Abstract Estimating pumping rates for the purpose of equipping boreholes with suitable pumps that will not over abstract either the boreholes or the aquifer(s) that are intersected is often assessed through test pumping of the boreholes prior to pump selection. While the South African National Standard has guidelines on the methodologies and durations of these tests (SANS 10299-4:2003), many production boreholes in the agricultural and industrial sectors are still equipped based upon so called Farmer Tests or Pump Inlet Tests (PIT), often of a short (6-24 hour) duration. These tests are also frequently and incorrectly confused with a Constant Head Test (CHT), both of which are different in methodology to SANS 10299-4:2003 testing, which relies to a high degree on data collected during a Constant Discharge/Rate Test (CDT or CRT) and recovery thereafter. The study will assess differences in test pumping methodology, data collection, analysis methodology and final recommendations made between Farmer Tests and SANS 10299-4:2003 methodology tests for 20 boreholes in which both tests were performed. The selected sites cover a variety of geological and hydrogeological settings in the Western Cape. Test comparisons include boreholes drilled into the Malmesbury Group, Table Mountain Group and Quaternary alluvial deposits, with tested yields ranging from 0.5 – 25 L/s.
Sharing water resources and the complexities around it: Three Case Studies from the Western Cape	Christel	Van Staden	Western Cape	2021	Water resource, De Doorns, Worcester, Drilling, Water level, Drawdown, abstraction, Irrigation, Quartzite bedding
Abstract With increasing population growth and a subsequently increased demand for food production, the agricultural sector has had to grow and develop continuously despite drought-stricken water resources in recent years. The expansion in this sector requires increasingly efficient water use management and increases in water supplies, which are often met through groundwater utilization. In the past several years the use of groundwater in the Western Cape has increased exponentially and thus has forced the sharing of resources. The question pertains to how an invisible water resource that is difficult to measure and quantify, can be shared. Issues of varying complexities can arise when submitting a water use licence application (WULA), such as historical water use debates, interactions between groundwater and surface water, seasonal stresses on resources, etc. In one case study in De Doorns, a WULA became side-tracked soon after initiation by a neighbour’s complaint that his production borehole was severely affected by the drilling of the applicant’s boreholes. In the second case study in the Hexriver Valley, a WULA was complicated by a gentleman’s agreement stating that no one in the valley is allowed to abstract groundwater from deeper than 6 m. This gentleman’s agreement stems from past disagreements regarding such practices. The final case study was not a WULA but arose out of concerns for dropping weir levels connected to a new borehole. The borehole was equipped with new casing to case off the alluvium; it was suspected to be the cause of the disturbance. The scientific method was used to evaluate the borehole’s impact on the weir. Case studies such as these will become more prevalent as the demand on water resources will increase. Hydrogeologists needs to more informed of the complexities that can and will arise in the future as a result of shared water resources.
Groundwater and surface water interaction in farming areas in the Rawsonville area of the Western Cape.	Siphumelelo	Mbali	Western Cape	2015
Abstract The understanding of groundwater and surface water interaction is important for the planning of water resources in particular for farming areas. The interactions between groundwater and surface water are complex. To understand the relationship of groundwater and surface water interactions it is important to have a good understanding of the relation of climate, landform, geology, and biotic factors, a sound hydrogeoecological framework. Surface-water and groundwater ecosystems are viewed as linked components of a hydrologic continuum leading to related sustainability issues. In this study the Gevonden farm in Rawsonville will be used as the study site. This study site forms part of the Table Mountain Group (TMG). The methods to establish the relationship of groundwater and surface water interaction are collection of rainfall data monthly, river channel parameters at the farm such as the discharge on a monthly bases, chemistry of the water in the stream and groundwater were also be analyzed and pumping tests will be conducted twice to get the hydraulic parameters of the aquifer. The aquifer parameters will be analyzed using the Theis and Cooper-Jacob methods. The river has lower water levels in the summer months and this is also the case in the water levels in the boreholes on the farm, however in winter the opposite is true. The chemical analyses which are identical indicate that there is groundwater and surface water interaction in the farm. The degree of the interaction differs throughout the year. The results show that the interaction is influenced by the rainfall. The results clearly suggests that the farmers need to construct dams and drill pumping borehole in order to have enough water to water their crops in the summer season as by that time the river is almost dry. {List only- not presented}
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.
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.
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
Groundwater development for Municipal water supply in response to drought of 2015 to 2019.	Dale	Barrow	Western Cape	2019	Drought, TMG
Abstract The geographic positioning of the Western Cape results in a Mediterranean climate - receiving majority of its rainfall during the winter months. A demand on the water supply throughout the year is typically met by storing water from winter rainfall in large dams. The Western Cape experienced a significant drought between 2015 and 2019. As a result, the supply dams have not been filled to capacity and drastic water restrictions had to be implemented. In the search for alternative water sources, groundwater exploration became a priority. Groundwater development projects were implemented rapidly in attempt to alleviate the implications caused by severe water restrictions and ultimately prevent running out of water. As a local groundwater institution, GEOSS got involved in several fast-tracked groundwater development projects for Department of local government, local municipalities, as well as other industrial and agricultural corporations. For obtaining the required water volumes, alternative measures were implemented. Previously under developed aquifers were targeted. In certain instances, in order to target the Table Mountain Group Aquifer (TMG), horizontal exploration drilling was conducted. The results of exploration and drilling yielded valuable learnings in terms of relevant hydrostratigraphy within the study areas. Additionally, there were learnings in terms of managing projects of this nature. In fast-tracked projects, careful management of the contractors, data collation (and storage) and public perception is critical to the success of the project. In this paper on water supply development for Municipalities, the various components of groundwater development are detailed along with relevant learnings from the recent emergency drought response measures.
Assessing groundwater dependence of wetlands and streams within the Table Mountain Group Aquifer: A Case Study from the Kogelberg	Dale	Barrow	Western Cape	2021	Ecosystems, datasets, conceptualisation, Monitoring
Abstract Ewart Smith, J; Snaddon, K; de Beer, J; Murray, K; Harillal, Z; Frenzel, P; Lasher-Scheepers, C Various analysis techniques are available for assessing the groundwater dependence of ecosystems. Hydrogeological monitoring within the Kogelberg and greater Table Mountain Group (TMG) aquifer has provided various datasets from multiple scientific disciplines (hydrological, hydrogeological, geochemical, climatic, ecological and botanical). Using a variety of analysis techniques, and using the Kogelberg as a case study, this paper assesses the groundwater dependence of several ecological sites (wetlands and streams). The starting point is a sound geological and hydrogeological conceptualisation of the site. The approach involves conceptualisation and analysis within each scientific discipline, but also requires bridging between areas of specialisation and analysis of a variety of datasets. This paper presents the data and analyses undertaken and the relevant results as they pertain to several sites within the Kogelberg.
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
Airborne And Ground Geophysical Surveys To Investigate The Deep Geology And Geohydrology In The Beaufort West Area, Western Karoo, South Africa	Matome	Sekiba	Western Cape	2019	Geology, Geohydrology, Airborne, Magnetotelluric
Abstract A geoscientific research project is underway in the Western Karoo Basin near Beaufort West, South Africa. This area has been earmarked for possible gas exploration. The aim of the project is to improve the understanding of the deeper aquifer systems of the Karoo Basin to better predict potential impacts of geo-resource exploration activities on the deep groundwater systems. This paper reports on the airborne and ground geophysical surveys that were conducted in the study area to gain insight into the deep structural geology and its possible association with aquifer systems. Geophysical methods that were used in the investigations include: 1) the airborne magnetic method was employed to detect and delineate non-outcropping dolerite sills and dykes, as well as to map geological structures of regional extent, and 2) the deep-probing magnetotelluric (MT) technique was used to map conductivity contrasts at large depths that could be associated with prominent geological structures. The results of the geophysical surveys showed that the airborne magnetic method was very effective in mapping intrusive magmatic bodies and other major geological structures. The magnetotelluric results indicated the presence of very resistive layers that appear to be associated with dolerite intrusives. Furthermore, the vertical displacement of a conductive zone indicated the possible presence of large-scale faulting. Based on the results of the airborne geophysical investigations, two investigative boreholes were drilled at selected positions to depths of 516 m and 1 402 m to obtain information on the subsurface geological and geohydrological conditions, and to constrain the interpretation of the airborne geophysical data. Downhole geophysical surveys were conducted on these boreholes to obtain in situ geotechnical and structural information. The results of this project show that the combined use of airborne and deeper probing geophysical methods can greatly contribute to the understanding of the deep geological and geohydrological conditions in the Karoo Basin. The approach can be further utilised for similar investigations of other Karoo satellite basins in South Africa and neighbouring countries
Feasibility of iron and manganese removal by in-situ ozonation - Atlantis Aquifer Case Study	Kate	Robey	Western Cape	2015
Abstract The development of groundwater supply schemes is on the increase in South Africa. However, the sustainability of many of these wellfields is threatened due to the presence of iron (Fe2+) and manganese (Mn2+) ions in the groundwater. Their occurrence can manifest in problems with water quality and supply to consumers. The World Health Organisation recommends the removal of iron and manganese to below 0.3 mg/? and 0.1 mg/? respectively, to circumvent water quality risks. However, production borehole clogging is of greatest concern in the operation of wellfields due to the severe cost implications associated with reduced production. Clogging is caused by the precipitation of iron- and manganese-oxides at the borehole screen initiated by biogeochemical processes. Since Fe2+ and Mn2+ ions and the bacterial populations are naturally present in anoxic/anaerobic aquifer systems and the ingress of oxygen through pumping cannot be entirely prevented. The only approach to controlling borehole clogging is through management and rehabilitation procedures. Locally, these procedures have been implemented and in severe clogging cases the Blended Chemical Heat Treatment method has been applied. However, the effectiveness of rehabilitation has been limited. This can be ascribed to factors such as the incorrect production borehole design
Groundwater Augmentation For Housing Estate Water Supply, Implementation And Legal Use	Greg	Molzen	Western Cape	2017	urban water supply, Conjunctive use, estate development, mini-wellfield
Abstract With increasing pressure on Cape Town’s potable water supply, the responsibility of diversifying supply for small, medium and large volume water users has fallen to the user to ensure sustainable use of potable water, and utilising all feasible non-potable sources where available. With estate and sectional title living becoming more common in South Africa, it is possible to develop holistic groundwater development models and strategies for the implementation of mini wellfields within these, in general, more densified living areas. This is well aligned with the Water Conservation and Water Demand Management Strategy of the City of Cape Town, where conjunctive use of groundwater for non- potable uses such as irrigation is implemented, as well as aligning itself with the current water restrictions within the Cape Metropole. Unlike standard residential neighbourhoods, estate development allows for the implementation of well- managed abstraction and monitoring of groundwater levels, as well as the possibility of shared groundwater usage in situations where legislation allows. The installation of fewer higher yielding boreholes (versus individual wellpoints on each residential section) to supply water to all communal areas and private gardens, allows for targeted data collection, interpretation and reporting. Implementation of shared water use from a single water use licence (likely issued to the legal entity of the body corporate) within sectional title property has its own complications, where licensed water use would generally be restricted to communal areas. The multi-phase assessment, implementation and licensing of groundwater supply for a life-rights retirement estate is presented as a case study. This enabled the investigation into shared water usage for irrigation of communal areas, as well as gardens of individual dwellings, eliminating the installation of dozens of wellpoints on estate properties thus ensuring sustainable usage and continued monitoring of the groundwater. Concurrent development of the groundwater infrastructure during the housing estates development brings its own challenges, and requires special consideration during early phases of the project, where infrastructure damage is commonplace on large construction sites. Holistic water conservation strategies were implemented, such as the construction of permeable pavements to increase the amount of recharge to the underlying aquifer storage below the estate instead of trying to store rainwater in the limited surface space. Utilising installed borehole equipment, an Aquifer Stress Test (AST) was undertaken to determine the aquifer parameters, sustainable yield of the individual boreholes and the wellfield as a whole, as well as inter borehole interactions. An AST allows for real world scenario aquifer testing to prove sufficient groundwater availability.
Knowledge comes with trial, error and time: The Langebaan Road story	Nicolette	Vermaak	Western Cape	2015
Abstract When planning an experimental setup in the laboratory, it is very important and possible to control all the variables so that one can manipulate particular variables at a given time. Experimental setups under natural conditions could be a challenging task. The success of an experiment depends to a large extent on the correct understanding of the functioning of a natural system. If the conceptual understanding of the natural system is erroneous, it is likely that unexpected results could be achieved. This was the case with the artificial recharge pilot project that was done in 2008 and 2009 at the Langebaan Road wellfield just outside Hopefield in the Western Cape. Years of research gave scientists a fairly good idea of the way in which the aquifer system functioned, especially since the establishment of the well field. This provided information of the response of the aquifer unit to large scale abstraction. The Langebaan Road aquifer unit is a multilayered system with a lower aquifer composed of Elandsfontyn gravel overlaying a bedrock layer of either granite of the Vredenburg or Darling plutons of the Cape Granite Suite or Malmesbury shale. The bedrock was considered impermeable. The upper aquifer layer was composed of mostly the Varswater Formation with peat and clay of the Elandsfontyn Formation forming the confining layer between the two aquifer layers. The extent of the different layers of the aquifer unit was plotted with a fair amount of accuracy and the clay layer was considered to be continuous between the two aquifer layers. Monitoring data for the area was done since 1974 with a gap in data-set between 1991 and 2001. Despite all the data from geophysical work, boreholes drilled, and the monitoring record, the research done prior and during the artificial recharge pilot project in 2008 and 2009 the aquifer units did not respond quite as anticipated. The Artificial Recharge (AR) pilot project team concluded that the aquifer units responded in a particular manner as opposed to the expected response according to the data and conceptual model at hand. It was thus clear that there are gaps in the conceptual model of the aquifer systems in the bigger Lower Berg River Valley that include the Langebaan Road, Elandsfontein and other aquifers that needed to bridge before another pilot test is attempted. Although the artificial recharge pilot project did not yield the expected results, valuable lessons were learned. This article will look at the conclusions and recommendations of the research done on the pilot project and attempt to evaluate the monitoring data (water levels, chemistry and rainfall) from the period just before the beginning of the AR pilot project. The monitoring data would be manipulated using the following techniques
The use of Hydrogeochemical Analysis Model to assess groundwater quality for drinking and agricultural use in Heuningnes Catchment	Portia Leah	Mokoena	Western Cape	2015
Abstract POSTER The study aims at using hydrogeochemical model to establish groundwater quality in shallow and deep aquifers in Heuningnes Catchment which is located within Bredasdorp in the Western Cape Province. The catchment is positioned at latitude of 34o42'50"S and longitude 20o07'13"E. The area is about 1400km2 has vleis, lakes and pans and its predominant formation is sedimentary rocks of Table Mountain and Bokkeveld Groups sitting on a crystalline basement of the Malmesbury granites. Comprehensive characterisation of the hydrogeochemical evolution is lacking and the current study argues that the use of hydrogeochemical Analysis Model (HAM) has potential to establish water-type, water source, water mixing/rock-water interactions, salinity, saturated adsorption ratio and hardness-softness of that predominant hydrochemical facies in the study area in addition to assessing the compliance of such water to WHO and South Africa water quality guidelines for drinking and agricultural use. Groundwater samples will be collected in 45 different locations (wellpoints/shallow wells, boreholes and wetland as end member) using in-situ sampling techniques to measure pH, electrical conductivity, total dissolved solids and temperature. Turbidity, total hardness, calcium, chloride and bicarbonate will be analysed using analytical chemistry methods including titrimetric method. Magnesium, potassium, sodium, nitrate and phosphate analysed by Atomic Absorption Spectrophotometer whilst sulfate will be analysed using spectrophotometer. Graphical methods such as piper diagram will be used to present the results to determine water-type, water freshness/hardness, water source, water mixing/rock-water interactions, salinity, saturated adsorption ratio and hydrogeochemical processes. The results from the present study are envisaged to inform formulation of science-based interventions strategies that will lead to sustainable utilization and management of the water resources in the area to improve the livelihoods of people and environmental integrity. Key words: Groundwater quality, Heuningnes Catchment, hydrogeochemical Analysis Model, Piper diagrams, Hydrogeochemistry
Geohydrological characterisation of the Citrusdal syncline basin	C.	Peek	Western Cape	2017	Geohydrological
Abstract Agriculture in Citrusdal is dominated by citrus fruit farms with the majority of freely available land been occupied by citrus crops. However, agriculture uses large amounts of water, which is often in short supply. During periods of stress where rainfall is low and surface water sources are not recharged and increase in demand for the citrus crops due to global economy has lead farmers to seek alternative sources of water to augment current sources for irrigation. One source in particular is groundwater. Groundwater has become the primary alternative source of water as building dams is an expensive exercise and has inherent limitations, such as faulty dam walls and inflow streams drying up. The development of groundwater sources is relatively cheaper and can be spatially convenient. The Citrusdal valley is located in the Western Cape province of South Africa, the valley is located between latitudes 18o15’ and 19°10’ and longitudes 32o20’ and 32°52’. It is composed of the Precambrian Table Mountain Group (TMG) consisting of sequences of arenites and subordinate argillites overlain by extensive cover of Tertiary to Quaternary sediments. The Citrusdal valley TMG overlies the basement Malmesbury shales at great depth. The Citrusdal Valley is primarily composed of the Peninsula sandstone, Cedarberg shale Formations and the topmost Nardouw Subgroup sandstone. Groundwater is located within two units within the Citrusdal basin, the Nardouw aquifer and Peninsula aquifer. Groundwater in the basin is constrained by large faults, small-scale fracture networks, lithologies, and topography. This project uses groundwater chemistry, exploration drilling and pumping tests to examine the groundwater system in the region to understand the complex geometric and hydraulic properties of the syncline basin. Understanding the geometric and hydraulic properties plays a significant role in developing agriculture in the region and to help manage the groundwater so that it is sustainable.
Is potato cultivation negatively impacting the groundwater resources of the Sandveld, Western Cape?	Julian E	Conrad	Western Cape	2015	groundwater monitoring
Abstract Groundwater is used extensively in the Sandveld for the irrigation of potatoes. The groundwater resources are plentiful and of good enough quality for the production of potatoes, however there has been a significant increase in potato production especially from the period 1975 to 2008. The area planted has increased from 2 369 Ha to 6 715 Ha in this period. The rate of increase has reduced significantly since 2008 and is now quite consistent at approximately 6 800 ha/a. In the region groundwater is vital for the proper functioning of ecosystems and it is also the sole source of water for five towns in the area and supplies most of the domestic water for the farms in the area. Thus the abstraction of groundwater for agriculture needs to be carefully assessed to ensure impacts on other systems and users do not occur. For this reason Potatoes South Africa has taken the responsible approach of investing in the on-going monitoring of groundwater levels (quantity) and groundwater quality in the Sandveld. PSA appointed the groundwater consultancy, GEOSS to do this monitoring and they have continually committed to this monitoring for the past 10 years. The long term monitoring data has been very valuable in that it shows groundwater trends and the spatial distribution of the measured parameters. Regarding the trends it is clear that certain areas are being over-abstracted and groundwater levels are dropping. In the more critical areas, intervention has occurred - boreholes were closed down and the points of abstraction distributed over a much wider area. This region (Lower Langvlei River) is showing clear signs of recovery both in terms of groundwater levels and quality. The other localized areas where negative trends are evident the land owners have been informed and are aware of the problems. In some critical areas continuous groundwater level loggers have been installed to monitor trends. The long-term groundwater monitoring, has helped significantly in addressing the negative perception about the widespread impact on groundwater resources due to potato cultivation in the Sandveld. It is important the monitoring continues and regular feedback provided to land owners. The monitoring that the local municipality and the Department of Water Affairs do also needs to be integrated into a single database. It is evident that the initial abstraction of groundwater in the pioneer days of potato cultivation did impact groundwater resources and associated ecosystems in the Sandveld, however currently as the rate of expansion has reduced and stabilized, the groundwater resources closely mimic rainfall patterns and the areas that are being impact are localized, well known and being addressed.
Water Supply Boreholes must be Test Pumped	John	Weaver	Western Cape	2017	Drought, sustainable yield
Abstract This past drought (summer of 2016/17) in the Western Cape has resulted in a number of boreholes “failing” and desperate farmers calling for more boreholes to be drilled. A closer look shows that many, if not most, of these boreholes were tested by the long-discredited “Maximum drawdown-yield at end of 48 hours x 60% = yield” method. A prime example was a borehole drilled and tested by the “old” method in 1983. This borehole was the main borehole supplying a stud horse farming operation. The borehole was equipped with a large capacity pump set at depth for paddock irrigation, plus a low capacity pump set above for drinking water supply. Using the existing main pump the author carried out a step-test in 2012. The borehole appeared to be sustainable. When re-tested in the middle of the drought of 2017 it hit pump- suction in 8 hours, i.e. it is not sustainable. Two radical examples of water supply boreholes are examined: a borehole with air-lift yield of 10 to 15 L/sec for which the sustainable yield was determined to be 0.5 L/sec, and a borehole with an air-lift yield of 0.5 to 0.7 L/sec for which the sustainable yield was determined to be 7.5 L/sec. Conclusion: In order to determine the sustainable yield of a borehole, especially in the fractured rock environment of Southern Africa, do not rely on the driller’s report of air- lift yield, and use the proper method of test-pumping a borehole. If not you may be in trouble.
GIS and Groundwater Monitoring	Freda	Jonck	Western Cape	2017	monitoring network, resource assessment
Abstract The Department of Water Affairs and Sanitation is the custodian of the Water Resources in South Africa. The Western Cape Provincial Office, Geotechnical Services (Geohydrology) Sub Directorate, is responsible for management of groundwater resources in two Water Management Areas (WMA), Berg Olifants and Breede- Gouritz. Thirty-eight monitoring routes comprising 700 sites in total are monitored across the Western Cape Province. The purpose of this paper is to show the use of GIS as a management tool for groundwater monitoring in the Western Cape. This is to assist and support the scientists, technicians, managers, external stakeholders and/or general public. The main question that needs to be answered is: “What is the current groundwater monitoring and data management situation in the Provincial office” With GIS as platform, geographical information was generated from existing data bases to answer questions such as, what is being monitored, where is it being monitored, who is monitoring it, why is it being monitored, when is it being monitored, are instruments installed, what instruments are installed, what equipment is involved and what energy source is used? These questions are applicable to the Region, Water Management Areas, the relevant monitoring route and geosites. Generated geographical information showed the gaps, hot spots and what is still needed for all the facets of groundwater management (from data acquisition to information dissemination) processes. The result showed the status of data bases, need for data in areas of possible neglect, training gaps, inadequate structure and capacity, instrumentation challenges, need for improvement of commitment and discipline, as well as many other issues. The information generated proves to be an easy tool for Scientists, Technicians and Data Administrators to assist them to be on top of the groundwater resource management in their area of responsibility. The expansion of the use of GIS as a groundwater management tool is highly recommended. This will ensure better understanding of the “The Hidden Treasure” resource.
The presence and concentration of antiretroviral drugs in different water bodies around the Western Cape	Phumelele	Maphumulo	Western Cape	2021	Antiretroviral, chemical formulas
Abstract This study is based on the presence and concentration of antiretroviral drugs in water bodies around the Western Cape Province in South Africa, these areas include wastewater treatment plants, water treatment plants, stormwater, and landfill boreholes. South Africa has the highest rate of HIV and AIDS in the entire world, statistics from 2018 show that 7.7 million South Africans are infected with HIV/AIDS and 68% of them are on antiretroviral treatment (UNAIDS). South Africa has the largest antiretroviral treatment program (ART) in the world, due to the lack of proper water and sanitation these drugs are deposited in the environment poorly and reach water bodies, therefore, contaminating them. This study involves the collection of samples from areas such as Mitchell’s Plain, Khayelitsha, Athlone, Cape Flats, and Atlantis around the western cape, these samples are analyzed to determine the presence of 5 antiretroviral drugs used in South Africa which are Efavirens, Lopinavir, Nevirapine, Ritonavir, and Tenofovir. Water samples are prepared for analysis by filtering 2.5ml water through a 1µm glass fiber filter, the sample is then placed into sample vials and analyzed on HPLC-QTOF/MS. Mass Hunter software is used to identify the specific ARVs in the water samples analyzed, by searching for the compounds via their chemical formulas. With a match made if their chemical formula, retention time and mass to charge ratio of the compounds correspond. Concentrations range between 0.0855ng/ml Nevapine to 4.3289ng/ml Lopinavir, this analysis has determined that all the mentioned antiretroviral drugs are indeed present in different water bodies around the identified areas within the Western Cape in varying concentrations.
Mountain Catchment Studies and Catchment Management	Nicolette	Vermaak	Western Cape	2015	catchment management
Abstract The mountain catchments of the Western Cape winter rainfall area were identified as areas needing more study in the early 1960s and so the Mountain Catchment studies were born. A number of study areas were suggested for these studies, but it was finally narrowed down to three sites. The studies in Jonkershoek had already started in 1935, with Zachariashoek and Jakkalsrivier added on in the 1960s. The Zachariashoek site was the only one that included groundwater as part of the experimental setup. A number of publications had been written about the work done in Zachariashoek. Most of the publications focused on changes in runoff after deforestation and fires, as well as the recovery patterns of the vegetation. The studies in Zachariashoek were done from 1964 till its termination in 1991 because of a lack of funding. The groundwater component consisted of 14 boreholes, with recorders on the five boreholes near the five weirs. The Zachariashoek area is made up of three catchments, Zachariashoek, Bakkerskloof and Kasteelkloof. It is adjacent to the Wemmershoek catchment. Bakkerskloof was the control catchment, while different burn cycles were part of the experimental setup of the two other catchments. The vegetation of Kasteelkloof was burned every 6 years with a 12 year cycle for Zachariashoek. Monitoring of the 5 weirs, 14 boreholes and the 9 rain gauges was done every week, with recorders on all five weirs, five of the 14 boreholes and at least 4 of the rain gauges. This data was entered into the data bases of the Department of Water and Sanitation, stretching from 1964 to 1986, with a complete record contained in 10 small field books. In this publication, we will look at the experiments done in Zachariashoek to see how this long term monitoring data can assist in managing the water resources within a catchment, taking into account the effects of deforestation and fires on surface water, groundwater and recharge to groundwater, the interaction between groundwater and surface water, as well as climate change.
Developing Groundwater Supplies To Supplement The Water Supply Of Ladismith, Western Cape Province	Roger	Parsons	Western Cape	2015
Abstract Ladismith was established in 1852 at a point where freshwater springs discharge from the Swartberg mountains. Growth of the town required building of the Goewerments Dam in 1920 and the Jan F le Grange Dam in 1978. However, water demand now matches supply, and water shortages are being experienced. Poor management and recent droughts exacerbated the situation. A project was initiated to address problems with the existing water supply and identify additional sources of water. Groundwater is an obvious option, with the regionally extensive Cango-Baviaanskloof fault being located directly north of the town. The west-east trending fault juxtaposes the highly productive Table Mountain Group aquifer with less productive argillaceous rocks of the lower Witteberg Group. This paper presents the results of initial geohydrological exploratory work and examines the role groundwater can play in the future water supply to the town. {List only- not presented} KEYWORDS groundwater, exploration, water supply, Ladismith
Assessment of Plume Stability in Monitored Natural Attenuation Assessments Using the Centre of Mass and Total Plume Mass Approach	Samuel D	Mohr	Western Cape	2017	Monitored natural attenuation, petroleum, Hydrocarbon, plumes, monitoring network
Abstract Monitored natural attenuation (MNA) is becoming a commonly employed sustainable site remediation strategy for sites with petroleum hydrocarbon groundwater impacts. Natural attenuation is essentially the reduction in contaminant concentration, mass or mobility due to naturally occurring processes within the environment. Aromatic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX) are common compounds of concern in the context of petroleum hydrocarbon related investigations because of their relative mobility and toxicity characteristics. Despite this, these compounds have historically displayed a strong affinity towards attenuating temporally and spatially away from the source areas. Evaluating plume stability is an important element of evaluating the overall attenuation of groundwater plumes and numerous methods have been developed in order to assess plume stability including graphical and statistical methods. It is often the case however that these analyses focus on single wells in isolation and do not take an integrated approach to evaluate the attenuation of contaminant mass over the entire plume. The authors present a case study where historical trends in plume characteristics have been used to assess overall plume stability. Trends in parameters such as average plume concentration, total plume contaminant mass, plume area and plume centre of mass were statistically assessed to determine whether the groundwater plume was expanding, stable, or shrinking. The methods employed in the plume stability analysis were found to be effective tools in demonstrating the occurrence of natural attenuation of contaminant plumes. It is important to note that a good quality dataset is required, in terms of a spatially representative monitoring well network and adequate time series data, in order to conduct analyses that will yield meaningful conclusions.
Western Cape Groundwater Status Amid Times Of Severe Drought - Selected Case Studies.	Julian E	Conrad	Western Cape	2019	Drought
Abstract The rainfall situation in the Western Cape became a focal point in 2015; 2016 and 2017. The rainfall in 2015 was half the long term average; in 2016 it was still below the long-term average and in 2017 it was again about half the long-term average. In 2018 the rainfall was better and was about the same as the long term average. These consecutive years of low rainfall were really problematic and with the declaration of the "Day Zero" campaign the media brought the plight of the City of Cape Town into the global headlines. However it was not only the City of Cape Town that was under dire stress but the whole of the Western Cape Province (and beyond). The neighbouring District Municipalities (DM) also embarked on frantic groundwater development and augmentation programmes. GEOSS South Africa (Pty) Ltd was fortunate to be involved in the DMs surrounding the City of Cape Town. This presentation focusses more on the groundwater aspects per se rather than the technical; aspects of boreholes; pumps etc, with specific reference to case studies including the Sandveld; Saldanha Bay Local Municipality and the Stellenbosch Local Municipality (specifically the Franschhoek area). The Sandveld (which is within the Berg River District Municipality) has a significant agricultural sector and 25 years of regional groundwater monitoring indicates that even with significant groundwater abstraction for the agricultural activities within the area, the groundwater volumes are robust enough to support further development of groundwater to meet the increasing water requirements for the town supply of Graafwater and Lamberts Bay. This expansion is currently underway. The West Coast District Municipality (specifically the Saldanha Bay Local Municipality) committed significant resources to groundwater development in the times of the drought. The Langebaan Road Aquifer wellfield was expanded with additional production boreholes and a new wellfield, known as the Hopefield Wellfield was also fully developed and equipped with all infrastructure in place. The wellfields have also set up to implement Managed Aquifer Recharge. Although these schemes are not yet operational, the groundwater levels held up well during the drought, indicating these wellfields should play a major role in times of future drought. Groundwater within the Franschhoek area (Winelands District Municipality) is utilized by many sectors and from detailed and long term monitoring the drought had little impact on the resources supporting the development of groundwater supply schemes for Municipal augmentation. From widespread work in the Western Cape Province it is evident that the drought had little impact on the groundwater levels of the region and it bodes well as a resource to be utilised in times of severe stress, so long as it is properly authorised, monitored and managed.
Using passive sampling to identify trends in aquatic pesticide pollution in the Western Cape, South Africa	Emma	Davies	Western Cape, South Africa	2023	Imidacloprid, passive water sampling, pesticide, South Africa, surface water, Sustainable Development Goal
Abstract South Africa is the leading user of pesticides in Sub-Saharan Africa, but data on pesticide occurrence in (ground)water is limited. Consequently, there is a need to improve knowledge on transport pathways that cause pesticides to enter the aquatic environment. This research monitored pesticide concentrations in three agricultural catchments in the Western Cape, South Africa, including Grabouw (pome fruit), Hex River Valley (table grapes), and Piketberg (wheat). Passive samplers were deployed in rivers from March 2022- March 2023, adding to a 2017-2019 dataset of analytical and pesticide application data. Field and laboratory methods were developed at Stellenbosch University to measure pesticides using Liquid Chromatography-Mass Spectrometry. For quality control, duplicate samples were analyzed at Eawag, Switzerland. 30 compounds were detected, yet two/three comprise most of the total mass, including an analyte not considered in earlier investigations (dimethomorph). Rainfall-flow relationships and agricultural application could only partially explain detection levels, suggesting that other factors, including non-agricultural application or groundwater input, might influence detections. Two compounds exceeded European Environmental Quality Standards (chlorpyrifos and imidacloprid). Imidacloprid is particularly concerning because it exceeded consistently despite few recorded applications. 2017-2022 imidacloprid data indicates a decreasing concentration trend in Hex River Valley and increasing trends in Piketberg and Grabouw. Consistently high detections during wet and dry periods suggest groundwater input. However, such pesticide transport pathways are poorly understood due to a lack of local evidence. Local authorities must establish a long-term monitoring program to understand better the risk pesticides pose to the aquatic environment and human health.
Keep the flow: Applying a HOPE model	Jacqueline	Goldin	Western Cape, South Africa	2023	community engagement, Governance, social justice, transformative
Abstract Top-down governance systems are not well designed to secure the protection, use and management of groundwater at the local level and, on the contrary, perpetuate ‘wicked’ problems of poor groundwater management and protection. Citizen science promises solutions to these ‘wicked’ problems. We present findings from a project in the Hout Catchment, Limpopo, where citizen scientists monitor water in wells in remote rural settings. We redress the bias towards the natural sciences and pay attention to human systems as it is through engaging with people’s ‘ordinary’ citizens that they will protect their environment for better planetary health. To better understand these human systems that impact groundwater, we emphasise diversity and difference and argue for a HOPE model (heralding optimal participatory equity). HOPE has intrinsic and extrinsic value (equity) (addressing a hydrological void and understanding groundwater features). To achieve this, we open up a toolkit providing very practical methods. Using these tools, we propose that citizen science - taking science away from remote institutions, out of libraries and laboratories - and bringing it close to people is emancipatory and addresses new ways of understanding polycentric governance. Citizen science is transformative; citizens move from a passive state of non-engagement with science to acting as scientists. Disempowered people now have a sense of being part of the betterment of their world and improved water resources management. Narrowing the natural and social sciences divide is crucial for improved polycentric governance.
Development of Table Mountain Group aquifer wellfields and monitoring networks for the City of Cape Town (Western Cape, South Africa)	Dylan	Blake	Western Cape, South Africa	2023	Critical Zone, Table Mountain Group aquifers, environmental monitoring, wellfield development, “no-regrets” approach
Abstract The City of Cape Town (CCT) initiated its “New Water Programme” in 2017 (during the major 2015-2018 “Day Zero” drought) to diversify its bulk water supply, thereby improving longterm water security and resilience against future droughts. This includes bulk groundwater abstraction from the major fractured Peninsula and Nardouw Aquifers of the Table Mountain Group (TMG) in the mountain catchments east of the CCT. The TMG aquifers are essential in sustaining groundwater-dependent ecosystems associated with the Cape Floral Kingdom – a global biodiversity (but also extinction) hotspot with exceptional endemic diversity. A strong geoethical, “no-regrets” approach is therefore required to develop TMG wellfield schemes for the CCT (and other towns/cities in the Western/Eastern Cape) to reduce the risk of any negative ecological and environmental impacts while still enhancing the drought resilience of the city, providing water for future urban growth, and meeting Sustainable Development Goals 6 and 11. To this extent, the CCT has developed an extensive regional (and local, in terms of Steenbras Wellfield) environmental monitoring network, incorporating a range of in-situ and remote sensing-based measurements across the Earth’s “Critical Zone” – this includes current groundwater, surface water, ecological, soil and meteorological monitoring stations, and future seismo-geodetic monitoring. An ongoing ambition is to include this CCT TMG monitoring network into the “Greater Cape Town Landscape”, which is currently in development as one of six national South African landscapes under the “Expanded Freshwater and Terrestrial Environmental Observation Network” (EFTEON) platform being hosted by the South African Environmental Observation Network.
Investigating Methods to Identify Groundwater Dependent Ecosystems and Assess Potential Impacts of Shale Gas Developments in the South Western Karoo, South Africa	Louelle Chelsea	Philander	Western Karoo, South Africa	2017	Dependent Ecosystems, Shale Gas Developments
Abstract The need to diversify energy resources for South Africa has brought developing shale gas to the forefront. Consequently, the semi-desert Karoo basin in South Africa is being explored as a potential source for shale gas resources. South Africa’s limited water resources have caused concern because groundwater resources are the main source of water for irrigation, drinking and for sustaining groundwater dependent ecosystems. Groundwater dependent ecosystems are found across the South African landscape, affecting the environment and ecological processes where groundwater flow to and discharge from aquifers. The current study assesses potential impacts of shale gas developments on groundwater dependent ecosystems in the Karoo area. Groundwater dependent ecosystems were identified and categorized based on a combination of hydrogeological and morphological type setting. Direct methods based on terrestrial setting and indirect methods based on hydrogeochemistry for determining interaction between groundwater and the groundwater dependent ecosystem were assessed. Preliminary results lean towards potential risks to groundwater dependent ecosystems and shallow aquifer systems from surface processes during shale gas developments instead of subsurface processes. Therefore, it is suggested to ecologically assess groundwater dependent ecosystems and further study the influence of shale gas development on groundwater dependent ecosystems at regional scale perspective in South Africa to inform a level of protection and risk management.
Baseline concentrations of radionuclides in groundwater of the Namibian Uranium Province, Namib Desert, western Namibia	Ester	Gustavo	Western Namibia		Namib Desert, baseline, Groundwater, radionuclides, uranium province
Abstract The Namibian uranium province, located in the Namib Desert, derives its name from the local presence of almost ten uranium tenements. The mines conduct monitoring of natural radionuclide concentrations of Ra226, Ra228, Pb210, U234, U238, Th232 and Po210 in local aquifers. This data is useful in mine rehabilitation and developing closure criteria, as only radiation doses additional to natural doses are usually considered ‘controllable’ for radiation protection purposes. An accredited laboratory analyzed the baseline data collected through quarterly groundwater sampling with submersible pumps. The uranium deposits are hosted in Damara age granites or as secondary mineralization in Tertiary calcareous paleochannels. The analysis of the long-term baseline data provides the background radionuclide concentrations of three aquifer types in the province, i.e., the Quaternary saturated alluvium of the Khan and Swakop ephemeral Rivers, the Tertiary paleochannel sediments, and Proterozoic basement aquifers. The ephemeral rivers are important because they supply groundwater downstream of the mines for agricultural use. The analysis demonstrated that the alluvial aquifers have the lowest natural radionuclide content, with the U234 concentrations ranging between 0.03 and 3.4 Bq/l, while paleochannel and basement aquifers show intermittent U234 concentrations ranging between 0.25 and 5.1 Bq/l. The groundwater in the immediate ore zones shows the highest U234 concentrations, ranging between 44.8 and 86.3 Bq/l, exceedingly higher than the WHO standards of 1 Bq/l. This study illuminates that radioactivity is a natural phenomenon and that groundwater baseline data is paramount to groundwater protection.
Numerical modelling of groundwater contributions to wetlands	Kai T	Witthueser	Witbank	2015	groundwater flow model
Abstract In order to meet the increasing national and international demand for coal, substantial expansion plans for existing as well as new coal mines were put forward in recent years. The mine developments are often proposed in environmentally sensitive areas and require an appropriate assessment of potential environmental impacts, including impacts on groundwater dependent ecosystems. This paper describes the development of a conceptual and numerical groundwater model as part of a wetland reserve determination in the Witbank coalfields. The model was used to assess potential mining related impacts on the shallow groundwater flow, including surface seepages and spring discharges feeding hill slope and valley bottom wetlands as well as pans. A number of shallow monitoring boreholes were sited, drilled and tested in the focus area around a pan to characterise the shallow perched and weathered aquifers. While these aquifers were generally found to be very low to low yielding, higher yields were encountered in a coarser grit layer intersected by two of the eight boreholes. The grit layer represents a potential preferential groundwater flow path towards the pan and was subsequently further delineated based on the exploration drilling logs from the mine. The different aquifers, the target coal seam, and over 60 mapped hill slope and valley bottom wetlands as well as pans, were incorporated into a numerical groundwater flow model. A free seepage boundary was assigned to the entire surface area to evaluate if the model is able to represent the observed seepages and spring discharges. The simulation of unsaturated flow processes (Richard's equation) was found to be crucial for the representation of discharges from perched aquifers. Following a satisfactory calibration of the model, different open cast mine layouts were then incorporated into the model to assess their impacts on the groundwater contribution to wetlands. The presented quantitative simulation of groundwater contributions towards wetlands and pans based on site specific groundwater investigations and data is considered a best practice example in assessing the groundwater component for a wetland reserve determination.
Witwatersrand Mine Voids – Their Hydrochemistry And Hydrodynamic Characteristics	Eddie	van Wyk	Witwatersrand	2013	Hydrochemistry, hydrodynamics
Abstract Gold mining on the Witwatersrand has started in the late nineteenth century as sporadic open cast mining and ceased in the late twentieth century, leaving a complex network of haulages, tunnels and ultra-deep vertical shafts/sub-vertical shafts. At least three ore bodies (conglomeritic horizons) were mined down to a depth in excess of 3 000 m from surface. Three large mining basins resulted from the mining methodology applied, namely the Western, Central and Eastern (Rand) Basins. In the early days of mining on the Witwatersrand reefs, gold mine companies realised that dewatering of their mine workings is required to secure mining operations at deeper levels and decades of pumping and treatment of pumped mine water followed. As the majority of deep gold mines on the Witwatersrand ceased operations since 1970, the deeper portions of the mine voids became flooded and led to a new era in the mining history in the Witwatersrand. Rewatering of the mine voids is a combination between excessive surface water ingress generated by surface runoff, and to lesser degree recharge from an overlying fractured and weathered aquifer system (where developed). The flow regime in the mine voids from a scattering of ingress/direct recharge points and single discharge points are complex and is driven by shallow (<100 m) and probably deep (>1 000 m) man-made preferential pathways. The high concentrations of iron sulphide minerals (pyrite. for example FeS2) content, three percent (by weight), of the mined reefs/backfilled stopes and surrounding waste rock piles/tailings dams mobilised significant levels of sulphates (SO4) and ferrous iron (Fe2+) producing an acidic mine-void water (<3 pH). Monitoring of the rewatering mine void hydrological regime became necessary following the first acid-mine water decant from a borehole in the West Rand Basin, and the Department initiated a mine-void water table elevation trend and water quality monitoring programme. Results from this monitoring programme will be illustrated and discussed in this paper with some views on the future water quality and discharge scenarios.
Geochemical reaction modelling as a tool to quantify gold mining impacts on shallow groundwater resources in the East Rand Basin	Robert	Hansen	Witwatersrand	2015
Abstract In recent years acid mine drainage (AMD) has become the focus on many mine sites throughout the world. The Witwatersrand gold mines have been the main focus of AMD in South Africa due to their extensive impact on especially groundwater resources. The Witwatersrand Basin is a regional geological feature containing the world-famous auriferous conglomerate horizons. It is divided into sub-basins and the East Rand Basin is one of them. Due to the regional scale of the East Rand Basin AMD issues, a systems approach is required to provide a useful tool to understand the pollution source term and fate and transport dynamics and to aid in environmental decision making and to evaluate the geochemical impact of mitigation measures and evaluate future scenarios. The numeric geochemical models, using a systems perspective, show that the mine waste facilities, specifically the tailings dams are significant contamination point sources in the East Rand Basin, specifically for acidity (low pH), SO4, Fe, Mn, U, Ni, Co, Al and Zn. When the AMD solution enters the soil beneath the tailings, ferrous and SO4 concentrations remain elevated, while Mn, U, Ni and Co and perhaps other metals are adsorbed. After ~50 years the pollution plume starts to break through the base of the soil profile and the concentration of the adsorbed metals increase in the discharging solution as the adsorption capacity of the soil becomes saturated. The pollution pulse then starts to migrate to the shallow groundwater where contamination of this resource occurs. Toe seepage from the tailings either first reacts with carbonate, where acidity is neutralised to a degree and some metals precipitated from solution, where after it reaches the surface water drainage, such as the Blesbokspruit, where it is diluted. Some evaporation can occur, but evaporation only leads to concentration of acidity and dissolved constituents, thereby effectively worsening the AMD solution quality. The mixing models have shown that the dilution factor is sufficient to mitigate much of the AMD, although seasonal variability in precipitation and evapotranspiration is expected to have some influence on the mixing ratio and some variability in the initial solution will also be reflected in variation in surface water and groundwater quality. {List only- not presented}
Numerical modelling of mine dewatering and flooding in the Evander Gold Basin, South Africa	Kai T	Witthueser	Witwatersrand	2013	gold mining, mine water rebound
Abstract The assessment and prediction of mine water rebound has become increasingly important for the gold mining industry in the Witwatersrand basin, South Africa. The cessation of dewatering lead to large volumes of contaminated surface discharges in the western parts of the basin. Towards the eastern extremity of the Witwatersrand basin the detached Evander Goldfield basin has been mined since the early 1950s at depths between 400 and 2000 metres below ground, while overlain by shallower coal mining operations. The hydrogeology of the Evander basin can be categorised by a shallow weathered-fractured rock aquifer comprising of the glacial and deltaic sediments of the Karoo Supergroup, while the deeper historically confined fractured bedrock aquifer consist predominantly of quartzite with subordinate lava, shale and conglomerate of the Witwatersrand Supergroup. The deep Witwatersrand aquifer has been actively been dewatered for the last 60 years with a peak rate of 60 Ml per day in the mid late 1960s. Modelling the impacts of mine dewatering and flooding on a regional scale as for the Evander basin entails challenges like the appropriate discretisation of mine voids and the accurate modelling of layered aquifer systems with different free groundwater surfaces on a regional scale. To predict the environmental impacts of both the historic and future deep mining operations, the detailed conceptual model of the aquifers systems and a 3-dimensional model of the mine voids were incorporated into a numerical groundwater model to simulate the dewatering and post-closure rebound of the water tables for the basin. The presented model could serve as an example for the successful modelling of mine dewatering and flooding scenarios for other parts of the Witwatersrand basin.
Acid mine drainage in the Witwatersrand: Unanswered questions	Henk	Coetzee	Witwatersrand	2015
Abstract Since the first decant of acid mine drainage in the West Rand in 2002, a great deal of effort has gone into researching the challenges which it poses there and in the adjacent Central Rand and East Rand Gold Fields. Short-term interventions have been implemented to maintain water at conservatively-determined safe levels and remove the worst contaminants from the water pumped from the mined. A feasibility study, looking at the long-term options has proposed treatment of water to a much higher standard, identifying a number of potential end-users of the treated water and highlighted the extremely high costs involved in responsible management. During the second half of 2010, a team of experts was convened to assess problems related to acid mine drainage in the Witwatersrand and propose solutions. A number of recommendations were made and the most urgent - the need for a short-term intervention to bring things under control and the the feasibility study for long-term management of the problems were undertaken. Nevertheless, despite the intense focus on the problem, a number of questions have remained unanswered. Throughout the period of min flooding, no detailed systematic monitoring of surface water flow has been undertaken, preventing the detailed apportionment of pollution between underground and surface sources. Ingress control measures have been proposed, but funding mechanisms, regulatory hurdles and challenges relating to long-term management have not all been comprehensively addressed. On a more positive note, the installation and operation of pumps to control the water level in the Western and Central Basins will start to provide valuable data regarding the response of the flooded mine workings to pumping, assisting in the characterisation of the hydraulic properties and behaviour of the large voids. This will facilitate the optimisation of pumping strategies and the refinement of environmental critical levels and assist in the development of more sustainable management options.
Vulnerability of South African water resources to emerging organic contaminants: a case study of the Witwatersrand Goldfields, Eastern Basin	L	Ligavha-Mbelengwa1	Witwatersrand Goldfields, Eastern Basin	2023	bisphenol A, caffeine, emerging organic contaminants, estrone, Groundwater
Abstract The occurrence of emerging organic contaminants (EOCs) in the aquatic environment is of no surprise since these are applied for various purposes daily. This study investigated the changes in EOCs concentrations in the water between 2019 and 2020. During rainy seasons, samples were collected from dams and surrounding boreholes in the Eastern Basin of the Witwatersrand Goldfields. During the first and second laboratory analyses, 24 and 11 analytes were screened in the water samples. The findings indicated that in 2020, compounds such as caffeine, sulfamethoxazole, atrazine and metolachlor displayed detection frequency exceeding 2019. This indicates that the occurrence of these compounds in the aquatic system has increased within a year. Whilst carbamazepine was still traced in 12 sites as previously observed in 2019, compounds estradiol, estrone, bisphenol A and ibuprofen were traced in fewer sites than they were detected in 2019. Compounds 4-nonylphenol, methylparaben, caffeine and atrazine were detected in all the samples analysed for 2019 and 2020, respectively. Antiretrovirals (ARVs) were analysed once and were detected in most sites, with efavirenz registering the highest (12/18) detection frequency. Assessing the occurrence of EOCs in boreholes according to the depth indicated that bisphenol A and estrone were traced in greater concentrations in deep than shallow aquifers, whilst the opposite was observed for atrazine. This study showed groundwater susceptibility to contamination by EOCs, with concentrations of most compounds increasing with time due to their high usage and improper sewer systems in the area.
Isotopic Study Of Water Resources In Wonderfonteinspruit Valley, North-Western, South Africa	Naziha	Mokadem	Wonderfonteinspruit Valley, North-West	2019	Water resources Groundwater, Wonderfonteinspruit Valley, South Africa
Abstract Stable Hydrogen and Oxygen isotopic technique were used in studying the water resources interaction in Wonderfonteinspruit Valley, North-western South Africa. The objective of this study is to refine the understanding of recharge processes in typical watersheds representative for karstic semiarid areas. This study investigated the isotopic composition of 35 boreholes, 5 surface water, 4 Dams, 4 springs, 1 canal, 2 pipelines, 1 cave and 4 rain stations for two periods October and Mars. Oxygen-18 (?18O?SMOW) and deuterium (?D?SMOW) isotopic data of the karst aquifer reflects the identification of different sources of recharge controlled mainly by the rainfall for the majority of samples and by bank filtration of the main rivers (Wonderfonteinspruit, Middelvieinspruit, Renfonteinspruit) for some samples. Stable isotopes,
Correlation Between Rainfall, Streamflow And Groundwater Levels For The Zachariashoek Sub‐Catchment Near Wemmershoek, Western Cape	Nicolette	Vermaak	Zachariashoek, Western Cape	2013	Rainfall, streamflow, Groundwater levels, Geohydrological
Abstract Zachariashoek catchment was one of the study areas looking into the hydrological characteristics of winter rainfall catchments in the Western Cape. Nearly thirty years of historical data are available for the Zachariashoek area. This data include rainfall, gauge plate readings for the weirs, and water levels for the boreholes in the area. Numerous articles and reports had been written about the research done in the area, concentrating mostly on the effects of fire on streamflow and vegetation. This article will look at patterns that can be observed from the data record and correlate the different data sets for the Zachariashoek sub‐catchment. It will use the data from the two weirs, three rain gauges and at least three of the boreholes that was drilled in this sub‐catchment. The information gained from this comparison can then be used to evaluate possible future hydrological patterns and the interaction between the various components of the hydrological system.
Regional-scale identification of recharge or discharge using remote sensing and GIS: Implications towards groundwater-surface water interactions	Kawawa	Banda	Zambia	2023	Barotse Floodplain, Groundwater-Surface water, Zambezi River, Zambia, Ecosystems
Abstract Identifying groundwater recharge and discharge areas across catchments is critical for implementing effective strategies for salinity mitigation, surface water and groundwater resource management, and ecosystem protection. This study seeks to identify potential GW-SW discharge and recharge areas around the Barotse Floodplain. The results of remote sensing analysis using the Normalised Difference Vegetation Index (NDVI) show that the vegetation is sensitive to the dynamics of groundwater level, with shallower levels (< 10 m) in the lower reaches compared to deeper levels (>10 m) in the upper catchment). These zones are further investigated and likely represent geological variability, aquifer confinement and the degree of GW-SW interactions. GW-SW interactions likely are influenced by an interplay of factors such as water levels in the groundwater and surface level and hydrogeological conditions. Based on the findings, the wetland hosts riparian vegetation species responsive to the groundwater dynamic. NDVI can thus be used as a proxy to infer groundwater in the catchment. Therefore, effective water resources management of the floodplain should be implemented through conjunctive management of groundwater and surface water.
Characterisation And Development Of A Carbonate Rock Aquifer For Large Scale Irrigation In Zambia (A Case Study)	Kobus	Troskie	Zambia	2013	aquifer, case study, Groundwater
Abstract Limestones and dolomites form an important aquifer system in Zambia. The municipal water supplies for Lusaka and several population centres on the Copperbelt all depend on the carbonates for a substantial proportion of their water supply. Currently 155,912 ha of land are irrigated in Zambia, which is about 30 percent of the economical irrigation potential. Development of large scale irrigation schemes from carbonate rock aquifers proves to be a viable groundwater resource in Zambia. The Katanga carbonate rock aquifers are considered to have good groundwater potential, with high yielding anomalies of up to 60l/s common in certain areas of the country. A phased approach was adopted to characterise the Katanga Carbonates by means of quantifying the volume of groundwater available for abstraction within the geological boundaries. The first phases included geophysical surveys (mainly electrical resistivity and magnetic methods), exploration drilling and aquifer testing. Later phases included the drilling of production boreholes and wellfield development. Lessons learned during the exploration included the identification of high yielding drilling targets and the role of anomaly frequency in target selection. Further development of the Katanga aquifers for production provided challenges regarding production borehole construction and design. The feasibility of the optimum design of production boreholes versus the initial capital cost of the development of these carbonates proved to be an important consideration in this regard.
Complementary use of electromagnetic frequency domain and electroseimic survey methods in groundwater exploration in Zimbabwe.	Joseph M	Zulu	Zimbabwe	2015
Abstract Complementary use of electromagnetic frequency domain and electrosiesmic geophysical exploration methods in groundwater exploration in Zimbabwe. Joseph M Zulu, Josrum Enterprises No. 129 A Fort Street, Albion Flats, 2nd Floor, Office Suite 5 Room 3, Bulawayo, Zimbabwe. Email Address: [email protected]. Abstract Geophysical survey methods and divining are commonly used in groundwater exploration. In view of the current costs of drilling boreholes and fear of drilling a dry borehole, most people prefer the use of geophysical survey methods to have their boreholes sited. Some prefer the use of diving methods for initial siting and then confirmation of the identified site using geophysical survey methods. The key principle being complementarity of the methods to confirm the presence of water at the identified site. Electrical resistivity method and electromagnetic frequency domain methods are popular in ground water exploration in Zimbabwe, with electrical resistivity being the method of choice by many investigators. A new approach in groundwater exploration is proposed where complementarity of geophysical methods is exploited. A complementary approach of using geophysical methods in conjunction with geology, where two methods are used in investigating a site is proposed. In the study the latest technology in groundwater exploration, electrosiesmic survey method was used to complement the electromagnetic frequency domain method in various geological environments. Electromagnetic profiles were carried out on the target areas. Inversion was done on the collected and results presented as a pseudo section. Anomalies identified were further investigated using electrosiesmic sounding. The results of the sounding were presented in the form of a sounding curve. The subsurface layer thicknesses were calculated using forward modelling assuming the typical seismic velocity values of waves generated when passing through geological formations in the areas under investigation. The geology of areas studied include granite, greenstone, Kalahari sands, sandstones, mudstones and basalt of the Karoo stratigraphy. The approach produced impressive results. High yielding borehole sites were identified and successfully drilled in areas where it had been accepted that it was difficult to get water or in areas where it had been accepted there was no groundwater. Comparison of driller's log with models generated from geophysical survey results was also done. Key words: electromagnetic, electroseismic, geology, complementarity, groundwater. I acknowledge that this work has not been published elsewhere.
Integration of geophysical and well monitoring techniques in the evaluation of the groundwater potential for the Urban Bulawayo	Innocent	Muchingami	Zimbabwe	2015
Abstract POSTER Most developing urban areas in semi-arid regions of Sub Saharan Africa are often forced to utilise groundwater as an alternate source of domestic water supplies. As such groundwater evaluations strategies often face dual challenges in terms of resource quantification and their quality evaluation. However, groundwater potential assessment and aquifer yield evaluations often present a challenge when the system is of crystalline basement nature where groundwater potential is highly spatially variable and cases of dry holes and seasonal wells have been reported. This study demonstrate the integrated combination of geophysical techniques, (namely, vertical electrical sounding, electrical resistivity tomography, magnetic mapping, and seismic refraction tomography) with both borehole monitoring and infiltration techniques in the groundwater prospecting and spatial yield analysis of the Urban Bulawayo crystalline basement aquifer. The Bulawayo Metropolitan Province of Zimbabwe is located in the semi-arid region of Zimbabwe with an average annual rainfall of below 500 mm and has had a prolonged dry spell has resulted in the dwindling of the existing surface water resources. The aquifer system consists of syenite granite and fractured basaltic greenstone crystalline basement complexes. Provisional geophysical results have shown that the thickness of the fractured zone sharply varies in terms of spatial distribution and often some sections are characterized by shallow surface fractured zone that may only be 20-30 m thick and some sections have a reported regolith of up to 60m in thickness. Borehole yield assessments and chemical analysis techniques will be done on drilled wells in order to come out with detailed spatial variation in the borehole yield and water quality variations across the aquifer system. All the technical evaluations are then integrated to produce a detailed hydro-geophysical map of the system that can be used in the technical groundwater management of the urban Bulawayo aquifer.
Can Groundwater Sustain The Future Development Of Rural Zimbabwe?	Jeffery	Davies	Zimbabwe	2013	Groundwater, development, Rural development
Abstract Zimbabwe occupies a tectonically stable plateau underlain by ancient Precambrian crystalline basement rocks. These form a central craton bounded by east-west trending mobile belts; the Zambezi mobile belt to the north and the Limpopo mobile belt to the south. Zimbabwe receives generally low and variable quantities of seasonal rainfall within a semi-arid to savannah type climate characterised by moderate to high temperatures. Evaporation commonly exceeds rainfall so that recharge to the thin near surface aquifers is generally low and in some years non-existent. The groundwater resources of the weathered and fractured basement aquifers that underlie more than 60% of the country are of limited potential, typically sufficient to supply the needs of small villages and cattle ranches. However, within the central plateau area of the African to Post-African erosion surfaces, the weathered and fractured basement may exceed 60 m in thickness. The thickness of this zone diminishes towards the main valley systems where subsequent cycles of erosion have stripped the weathered zone away, leaving only a shallow surface fractured zone that may only be 20-30 m thick. Groundwater resources have been developed extensively in Zimbabwe since the 1920s. During 1991/92 drought abstraction from urban boreholes within the southern Harare area caused yield decline and ultimate failure of numerous boreholes. It is now time to question the long-term viability of groundwater development within the basement aquifers in Zimbabwe given the uncertainty in groundwater resources, the complexities of the climate–groundwater interactions and the projected demands of a growing rural population.
Per and Polyfluoroalkyl Substances (PFAS) Groundwater Toolkit	Fern	Beetle-Moorcrof	western United States	2023	PFAS, fate and transport, Groundwater, sampling
Abstract Per and Polyfluoroalkyl substances (PFAS) are ubiquitous on our planet and in aquifers. Understanding PFAS transport in aquifers is critical but can be highly uncertain due to unknown or variable source conditions, hydrophobic sorption to solid organic aquifer matter, ionic sorption on mineral surfaces, changing regulatory requirements, and unprecedentedly low drinking water standards. Thus, a PFAS toolkit has been developed to enable decision makers to collect the hydrogeologic data necessary to understand and better predict PFAS transport in aquifers for the purpose of managing water resources. This toolkit has been tested at a significant alluvial aquifer system in the western United States, which provides water for 50,000 people. Here, the toolkit has provided decision makers with the data necessary to optimize water pumping, treatment and distribution systems. The toolkit describes (1) the design and implementation of a sentinel well network to measure and track PFAS concentrations in the alluvial aquifer over time in response to variable pumping conditions, (2) data collection used to empirically derive input parameters for groundwater fate and transport models, which include the collection of paired aquifer matrix and groundwater samples, to measure PFAS distribution coefficients (Kds) and modified borehole dilution tests to measure groundwater flux (Darcy Velocity) and (3) the use of data collection techniques to reduce cross contamination, including PFAS-free, disposable bailers and a triple-rinse decontamination procedure for reusable equipment. The PRAS transport toolkit has the potential to assist decision makers responsible for managing PFAS contaminated aquifers.