Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 1 - 50 of 795 results

Title	Presenter Name	Presenter Surname	Area Sort ascending	Conference year	Keywords
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.
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.
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.
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.
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.
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.
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,
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.
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}
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
The Use Of Derivative Analysis To Choose And Refine Conceptual Models Of Groundwater Flow Systems	Thokozani	Kanyerere	Western Cape	2019	modelling, flow systems
Abstract Groundwater flow system responses have been understood using derivative analysis. The argument is that the use of derivative analysis derived from pumping test data improves the understanding of aquifer types and curve matching in a hydrogeologic setting. The different aquifer systems encountered in Western Cape Government Business Continuity Programme (WCBCP) of South Africa was used as case study where the analysis of the time versus draw-down derivative plots were applied to validate the aquifer characteristics to explaining the groundwater flow systems. Key findings showed that analysis from the time versus draw-down derivative plots can be used to infer conditions within the wellbore, groundwater flow to boreholes and boundary conditions within the aquifer to provide insights. In addition, results confirmed that the archetypal time vs draw-down responses enabled characterizing the aquifer types and such analysis showed unique responses to the pumping. Lastly, long term operation of boreholes for water supply were ascertained when the analysis was interpreted. The analysis was enhanced when the geological information that was collected during drilling operations, were added to the conceptual understanding of groundwater flow studied aquifer system. However, due to costs implications of conducting long-term aquifer hydraulic pumping tests, deviations from the conventional draw-down responses are expected. In this study, it is suggested that due to complexities associated with heterogeneous flow in aquifer types, it is essential to combine derivative analysis with pumping methods to improve interpretation and assessing long term operation of boreholes for water supply
Can Palaeochannels Be Used To Enhance Groundwater Recharge? A Case Study: Langebaan Road Aquifer	Awodwa	Magingi	Western Cape	2017	Palaeochannels, hydraulic parameters, Drought, artificial recharge
Abstract The assumed interconnection between palaeochannels and subsurface water resources is described. This paper (poster) discusses the different methods that can be used to indicate the significance of palaeochannels into groundwater recharge. Hydraulic parameters such as permeability and transmissivity of the layer underlying the palaeochannel act as the main dependents of groundwater recharge on palaeochannels. Considering the drastic drought from which South Africa is recovering or has recovered the importance of artificial recharge through palaeochannels is explained. The Langebaan Road Aquifer with its palaeochannel is used as a practical example and a detailed explanation on how palaeochannels can be used to enhance groundwater recharge is further demonstrated. Enhancement of recharge would ensure groundwater sustainability and augmentation to surface water especially during drought periods.
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.
Identifying Potential Managed Aquifer Recharge Zones In West Coast Aquifers, Western Cape	Ashleigh	Tomlinson	Western Cape	2019	Poster, recharge, MAR
Abstract The overexploitation of water resources has resulted in a global decline in groundwater levels. Managed aquifer recharge (MAR) is a globally acceptable practice to manage the depletion of water in overexploited aquifers in regions with limited water availability. The West Coast of South Africa experiences a semi-arid climate with predominantly dry summers. This study aims to identify potential areas suitable for MAR in the Saldanha Bay area to maximize the water available to these areas during the dry season. This will be done through the delineation of the aquifer(s) units to determine the distribution of suitable aquifers, understanding the aquifer(s) hydraulic and hydrogeological characterises and investigate the water quality. This study focuses on 1) Frequency domain electromagnetic and electrical resistivity geophysical methods to characterise the subsurface; 2) Aquifer testing, to estimate the hydraulic properties of the aquifer(s); 3) Water quality sampling and analysis for water quality investigations. Practical considerations like distance from suitable water sources will also be considered. The expectations for this study, based on the results that should be obtained from these methods, should include the identification of several zones that would allow for MAR practices
Existing Springs in City of Cape Town and Environs: Spring Use Strategy	Louise	Soltau	Western Cape	2015
Abstract Cape Town... Home to over 3 and a half million people, the second most populated city in South Africa was born in the shadow of the Table Mountain. The mountain offered all the elements vital for human settlement... most importantly WATER. The reports of the abundance of fresh water and fertile land at the foot of the mountain and surrounds inspired the VOC to set up a refreshment station at the Cape. By the late-1800s, spring water was solely used for domestic supply to the settlers of Cape Town. Until the 1930s, the Stadsfontein or Main Spring was still being used as a source of drinking water but because of on-going concerns about the safety of the water for human consumption, and sufficient water being available from the new schemes like Steenbras and Wemmershoek, a decision was taken to discontinue using the Stadsfontein for drinking water purposes. Since then most of the water joined the stormwater to the sea, until 2010 when the City recommenced using the water for irrigation at Green Point Stadium and the Commons. City of Cape Town faces a number of water supply challenges. These include managing the ever increasing demands on the current water supply. The City of Cape Town Springs Study was born from this 2001 Water Demand Management study and it aims primarily to examine the possibility of using spring water as an alternative source of water for non-potable supply. Of these, the springs which hold the most potential for use are found in two areas - the CBD area of Oranjezicht, home to the Field of Springs
Evaluating changes in groundwater storage during the 2015-2018 drought in the Western Cape using GRACE data	Ritshidze	Nenweli	Western Cape	2021	Poster, Drought, GRACE, Groundwater storage
Abstract The frequency, intensity, and duration of droughts are increasing globally, putting severe pressure on water supply systems worldwide. The Western Cape Province suffered from a period of severe water shortages that began around January 2015 and lasted until about July 2018. During this recent drought, there was a forced reduction in water use, predominantly from the agricultural sector. Citizens also reduced water use and increasingly tapped into groundwater for their needs irrespective of whether the hydrogeology was considered favourable or not. Unmonitored and unregulated abstraction of groundwater, especially under unstable climatic conditions, poses a significant risk to the future water security of the Western Cape. We hypothesize that groundwater enabled the municipalities, residents, and industries of the Western Cape to survive the recent drought. Our aim is to evaluate the change in groundwater storage during the 2015 to 2018 drought and its subsequent recovery. To achieve this, we must gain a comprehensive understanding of the dynamics of separate components of the water cycle, as well as the overall water balance. While there is data on surface water use during the drought, the impact on groundwater resources has yet to be evaluated. However, the accurate assessment of groundwater use is difficult, especially in data-scarce regions, such as South Africa. In our study, we combine remote sensing from NASA’s Gravity Recovery and Climate Experiment (GRACE), the Global Land Data Assimilation Systems, groundwater level measurements from the National Groundwater Archive, and ancillary datasets from the City of Cape Town’s weekly water dashboard to assess the total change in groundwater storage in the Cape Town Metropolitan area and surrounding cities over an 8-year period, from 2012 to 2020. Preliminary results from GRACE data analysis show a steady decline in aquifer saturated thickness over the drought, indicative of an increase in groundwater use.
Groundwater Quality And Potability	Roger	Parsons	Western Cape	2019	quality
Abstract The quality of groundwater is, in part, controlled by the character of the rock in which it is stored and the water - rock contact time. Rainfall (or recharge) is also a contributing factor as the mineralisation of groundwater increases from east to west across South Africa. It is well established that groundwater is more mineralised than surface water, and with most of South Africa's domestic supplies being sourced from dams, municipal water supplies are generally of low salinity. The exception to this is where water supplies are sourced from groundwater - such as in the Karoo and along the West Coast. The assessment of water potability is based on both the South African National Standard 241 and the Department of Water and Sanitation guidelines, with the former being a legal requirement. Previously, SANS 241 had two classes of water with the lower class only being allowed for a limited period. In 2015, Class II water was done away with and only a single class of water is now specified. While this may have been done to conform to World Health Organisation standards, it disregarded the realities of a resource-strapped South Africa where in large parts the municipal water supplies simply cannot meet the SANS241 standard. This paper examines the implications of the SANS 241 standard on efforts to establish emergency groundwater supplies during the drought impacting the Western Cape Province.
Assessment Of Groundwater Iron Concentration In Aquifers With Focus On Geological, Hydrogeological And Hydrogeochemical Conditions For Its Occurrence, Western Cape, South Africa	Presanta	Bissonram	Western Cape	2019	Poster, hydrochemical, iron
Abstract Due to the recent drought in the Western Cape province of South Africa, surface water can no longer meet our current demand of water and as a result groundwater usage has increased. High iron concentration in groundwater is a problem which results in iron encrustation and iron clogging. This results in decreased borehole yields, decreased water quality and expensive treatments to remove iron encrustation or the drilling of entirely new boreholes. From both international and local literature there are two common factors which stand out which is that high concentration of iron in groundwater is a global issue, the second common factor is that the occurrence and influencing factors of high iron concentrations are site specific. Boreholes drilled for drought relief in health facilities across the Western Cape have reported increased concentrations of iron. Understanding of the geology, hydrogeology and hydrogeochemical conditions that cause the increased iron concentrations in groundwater at these specific locations is required. The objectives of this research project are to: 1) Assess spatial and temporal variations in iron and manganese concentrations; 2) Establish site specific processes that control the concentration of iron in groundwater; and 3) model the geochemical processes that impact iron levels in groundwater. These objectives will be achieved through historical groundwater quality data analysis, geochemical modeling, field work where samples will be collected and laboratory analysis of the samples collected. The information provided from this research project will allow for the effective management decisions to be made in terms of iron removal from groundwater and early preventative measures that can be made to ensure iron clogging and encrustation does not occur. The study is currently ongoing and there are currently no results available at this point however, at the time of the conference there will be information ready to share.
Comparing The Influence Of Aquifer Heterogeneity On Borehole Design, Test Pump Results And Interpretations Between The Primary Cape Flats And Atlantis Aquifers Of The Western Cape, South Africa.	Luke	Towers	Western Cape	2019	Heterogeneity, development, Management
Abstract The recent Western Cape drought initiated large scale development of the Cape Flats Aquifer (CFA) and refurbishment of the Atlantis Water Resource Management Scheme (AWRMS). Both aquifers are comprised of primary sediments of the Sandveld Group. Lithologies and depositional environments of the two aquifers are often directly compared and linked, but recent borehole drilling in these two aquifers is highlighting their inherent differences. The use of conventional mud rotary drilling techniques in these aquifers and changing nomenclature over time, has created uncertainty in their lithological character, leading to complications in borehole design and interpretation of test pumping results. Sonic drilling - Atlantis (20) and CFA (25) - was undertaken and incorporated with approximately 200 mud rotary borehole drill logs and geophysical survey results to investigate aquifer geometry and hydro-lithological characteristics. Results to date indicate the CFA is more heterogenous and has greater lateral variation compared to the Atlantis Aquifer. The CFA is interspersed with clay lenses, organic rich layers, calcrete and thick basal shell units. Whilst the Atlantis Aquifer displays a more homogeneous character with limited clay lenses, minor organic layers, interspersed calcrete and a near non-existent basal shell layer. Results of the sonic drilling have led to increased confidence in boreholes design, test pump analyses and numerical model results. The influence of CFA's heterogeneity on test pumping interpretation is displayed in the results through a variety of unconfined, confined, semi-confined and leaky type curves. Atlantis however, typically displays unconfined Neuman-type curves. Delayed gravity drainage signals, test pump duration, varying hydraulic conductivities of different lithological units and other boundary effects not only have an economic impact on test pump design, but can lead to the misinterpretation of test pump data which greatly influences planning for the aquifers' response to large scale abstraction and Managed Aquifer Recharge (MAR) alike.
Are Farmers Drying Out The Cederberg? Deep Groundwater Flow And Isotopes In The Table Mountain Group.	Roger E	Diamond	Western Cape	2017	TMG, Isotopes
Abstract The Table Mountain Group is a major fractured rock aquifer system throughout the Western Cape, with many interconnected but semi-independent parts, each having its own recharge area, flow paths and discharge area. Groundwater is known to travel long distances and reach great depths, including through the Olifants River syncline, such as at The Baths hot spring near Citrusdal. Stable isotope compositions of rain and groundwater in the Cederberg and Olifants River Mountains were measured over a period of 2-3 years. Rainfall in the Cederberg averaged -22‰ and -4.7‰ for D and  18O respectively, whereas rainfall in the Olifants River Mountains averaged -11‰ and -3.0‰ similarly. Groundwater used by farmers in the Olifants River Mountains averaged -13‰ and -2.9‰ similarly. The similarity between groundwater and rainfall isotope compositions in the Olifants River Mountains suggests local groundwater movement. It was concluded that the source of groundwater abstracted by farmers in the Olifants River Mountains is from the peaks west of the Olifants River with little to no contribution from the Cederberg, east of the Olifants River syncline. Geological evidence (thinning of the Olifants River syncline and increased faulting northwards) supports this conclusion.
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.
Assessment Of The Spatial Coverage Of Groundwater Dependent Ecosystems In A Semi-Arid To Arid River Gouritz River Basin	T	Mbandezi	Western Cape	2017	Shallow groundwater, groundwater dependant ecosystems, remote sensing
Abstract The presence of shallow groundwater at locations with limited spatial coverage in drylands have since time immemorial supported plant and animal communities. These locations often have in comparison to the surrounding dry landscapes high biomass production and biodiversity. The presence of groundwater makes these locations attractive for development of groundwater dependent human activities such as irrigated crop production, and livestock production. Groundwater abstractions from locations that are not necessarily close to these plant and animal communities, but tapping into the same aquifer systems have also a potential to affect the availability of water to these ecosystems which is critical for their existence. The importance of these groundwater dependent ecosystems is not well understood due to limited knowledge about their spatial coverage. Some of the groundwater dependent ecosystems occur in areas that are not accessible such as mountain slopes, or in remote areas. The long-term impact of groundwater usage on some of these ecosystems has not been evaluated, with most of the knowledge about these impacts being based on anecdotal information obtained from the respective land owners. Remote sensing offers an opportunity to map the spatial coverage of groundwater dependent ecosystems in drylands. A distinguishing characteristic of these systems is the active plant growth especially during periods when throughout the landscape, there is limited or no water to support plant growth. Monitoring plant growth during the dry season using indices such as the NDVI enables detection of groundwater dependent ecosystems. Knowledge about the rates of actual evapotranspiration at locations with these ecosystems enables an estimation of the amount of water required to support them during the dry season. The MODIS 16 actual evapotranspiration rates (ETA) which are globally available can be used for evaluating water use by groundwater dependent ecosystems. This paper explores the mapping of the spatial coverage of groundwater dependent ecosystems using remote sensing based vegetation indices in parts of the Gourizt River basin in South Africa. The rates of waters use by the identified groundwater dependent ecosystems are estimated using actual evapotranspiration rates based on MODIS 16. The paper also examines possible long-term changes to the spatial coverage of groundwater dependent ecosystems.
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
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.
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.
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.
Development and testing of a hydrogeological multilevel sampling device and analysis of water chemistry through hydrochemical parameters	Lesedi	Sipuka	Western Cape	2021	Poster, Groundwater Sampling, Hydrochemistry
Abstract This study investigates and elaborates the development and testing of a multilevel sampling device. The primary purpose of this device is to achieve multilevel sampling in a well simultaneously, producing samples that are representative of the in situ groundwater. The device has been designed to have four different depths from which extraction of groundwater samples can be performed. Testing of the device involves a two-part process. A laboratory based testing and field based testing. The laboratory testing was done in a simulated well where three water tests were performed; normal tap water, salt water and hot boiling water. The field based testing was done on existing boreholes in the Rietvlei Wetland Reserve in the Western Cape. In the two processes involved, hydrochemical parameters were used to test for the efficiency of the device in terms of its working performance and to furthermore analyse the water chemistry which enables us to determine the water quality.
Possible recharge areas for two of the Lower Berg aquifers units, Western Cape	Nicolette	Vermaak	Western Cape	2015	groundwater recharge
Abstract The question about the natural recharge areas for two of the Lower Berg river aquifers units, Elandsfontein Aquifer unit and Langebaan Road aquifer unit, has been keeping geohydrologists working in the area without a definite answer. Tredoux and Engelbrecht have postulated that it must be from the higher grounds around Hopefield, while Woodford hinted that an offshoot fault from the Coleso fault system could also cause the systems to be recharged from the Darling hills. Isotope studies had been done for the proposed Hopefield recharge area, but none has so far been done for the possible Darling recharge system. This paper will look at the studies done up to date and evaluate the data available for the boreholes drilled in the area in an attempt to get a clearer understanding of the two possibilities. It will also identify possible gaps in our knowledge of the area and the steps that would make it possible to fill in the gaps.
Parameter estimation for artesian aquifer in Table Mountain Group Aquifer by analytical and numerical simulation methods	Xiaobin	Sun	Western Cape	2015
Abstract Accurate parameter estimation for fractured-rock aquifer is very challenging, due to the complexity of fracture connectivity, particular when it comes to artesian flow systems where the potentiometric is above the ground level, such as semi-confined, partially confined and weak confined aquifers in Table Mountain Group (TMG) Aquifer. The parameter estimates of these types of aquifers are largely made through constant-head and recovery test method. However, such a test is seldom carried out in Table Mountain Group Aquifer in South Africa due to a lack of proper testing unit made available for data capturing and appropriate method for data interpretation. An artesian borehole of BH 1 drilled in TMG Peninsula Formation on the Gevonden farm in Western Cape Province was chosen as a case study. The potentiometric surface is above the ground level in rainy season, while it drops to/below ground level during the dry season. A special testing unit was designed and implemented in BH 1 to measure and record the flow rate during the free-flowing period, and the pressure changes during the recovery period. All the data were captured at a function of time for data interpretation at later stage. Curve-fitting software developed with VBA was adopted for parameter estimation based on the constant-head and recovery tests theories. The results indicate that a negative skin zone exists in the immediate vicinity of the artesian borehole, and the hydraulic parameters estimates of transmissivity (T) ranging from 6.9 to 14.7 m2/d and storativity (S) ranging from 2.110-5 to 2.110-4 appear to be reasonable with measured data collected from early times. However, due to formation losses, the analytical method failed to interpret the data collected at later times. Consequently the analysed results by analytical solution with later stage data are less reliable for this case. The MODFLOW-2000 (Parameter Estimation) package developed by USGS was also adopted to determine these parameters for the same aquifer. It approves that there exist formation losses, which leads to the aquifer response distinctly different at later stage of overflow and recovery tests. The aquifer parameter estimates with early time data of tests by analytical and numerical methods show that there is generally good agreement. However, significant errors could be generated by analytical method applied where there is occurrence of well or formation losses, while these restrictions could be overcome by applying a numerical method.
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.
Suitability of drilling techniques for geological interpretation and borehole design within the Cape Flats Aquifer, Western Cape.	Sasha Dean	Singh	Western Cape	2021	Bulk water supply, MAR, Drilling, facies analysis
Abstract McGibbon, D; Riemann, K The Cape Flats Aquifer Management Scheme (CFAMS) includes both abstraction of groundwater and managed aquifer recharge (MAR) as part of the City of Cape Towns (CoCT) New Water Programme to diversify their bulk water supply and build resilience against future droughts. Since the project was initiated in early 2018, over 250 boreholes have been drilled for exploration, monitoring, abstraction, and MAR. Rotary mud drilling was used for most of the drilling due to its suitability in unconsolidated geological material, typical of the CFA. As effective as rotary mud drilling is for large scale development, it lacks in accuracy for detailed geological interpretation used for borehole siting and design (gravel pack and screen aperture size and screen position). This is due to the mixing of material and the circulation of the drilling mud washing away fine sediment which can skew grain size analysis results and obscure the vertical position and thickness of thin confining clay or organic rich lenses. The clay and organic rich layers can cause surface flooding during injection as they act as confining layers which effects borehole design and more importantly siting of MAR boreholes. To overcome this, two additional drilling techniques were explored, sonic and air core. Air core was disregarded early on due to the air creating a cavity in the underlying unconsolidated sediments. Sonic drilling, however, was successful in retrieving a continuous undisturbed core log through high resonant energy that liquefies the sediments, which are then brought to surface in a core barrel. The undisturbed continuous nature of the log allows for accurate grain size analysis and detailed vertical geological logging which can be used for facies analysis to interpret the paleoenvironment and predict the lateral extent of clay or organic rich layers that influence borehole siting, design, and the hydrochemistry.
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
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
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
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
Assessing Spatial, Temporal Depth Variation Of Groundwater Salinity Variation, Cape Flats Aquifer, South Africa	Danica	Carnow	Western Cape	2017	sampling, Salinity, Irrigation, Water quality, unconfined aquifer, urban
Abstract The use of specific-depth sampling technique to demonstrate groundwater quality variation different groundwater units of unconfined aquifers has not been widely published. To demonstrate the feasibility of such technique, the unconfined Cape Flats Aquifer (CFA) in Cape Town of South Africa was studied. The aquifer underlies an urbanised area which is vulnerable to contamination from industrial and agricultural activities, waste disposal sites, landfill sites, and formal and informal settlements. The study assessed Spatio-temporal and depth variation salinity levels in CFA using electrical conductivity (EC) as an indicator of salinity. Groundwater samples were collected using specific-depth sampling, and analysed using multi-parameters probes and standard laboratory methods for EC, temperature, pH and major ionic concentrations. Statistical analysis was used to compare mean concentrations of selected parameters to guidelines set by Department of Water and Sanitation and Food and Agricultural Organization to establish fitness for irrigation use. The results showed high EC levels (212.26 mS/m) at shallow depths (9m) and low EC levels (78.53 mS/m) at greater depths (39m) proposing anthropogenic influence. Potassium, sodium, chloride, and the Sodium Adsorption Ratio (SAR) exceeded permissible ranges set for irrigation water suggesting that groundwater be used with caution. A conceptual diagram was developed to explain sources and processes contributing to groundwater salinization of the aquifer. The diagram illustrated that irrigation return flow, in residential and agricultural areas, contributed significantly to salinity levels. In conclusion, groundwater in the CFA is suitable for irrigation use but should be used with caution as shallow depths contain groundwater with elevated salinity levels. It is recommended that the specific-depth sampling technique be used to understand how the physical, chemical and microbiological constituents vary with depth in these groundwater units.
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.
Conceptualization Of Groundwater Flow System In Heuningnes Catchment	Vincent	Banda	Western Cape	2017	hydrochemical, groundwater flow
Abstract Records review and field based methods were used to collect and interpret groundwater level and hydro- chemical data to characterise groundwater occurrence and flow system in the Heuningnes catchment, Western Cape Province of South Africa. Our research outcome indicates that the study area has alluvial and fractured rock aquifers. The groundwater system has a rainfall driven recharge mechanisms resulting in freshwater in higher altitudes situated in the northern and western parts of the catchment. Highly saline waters are found in low-lying areas. Few samples showing high salinity water exhibit a signature of seawater although in many instances the groundwater chemistry is by and large governed by the geological formation. Groundwater potentiometric surface map shows that the general groundwater flow direction is southwards. In relation to the surface water bodies, groundwater mainly flows towards the Nuwejaars River especially in the northern and north-west part of the study area resulting in fresh water in this part of the river. As this is an ongoing study, these preliminary findings provide the required insight for further analysis and investigation. Future work will involve carrying out aquifer hydraulic tests and collection of water samples for analysis of major ions and stable isotopes. Further discussion will wait for the validation of these results to inform a meaningful implication of such findings.