Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 151 - 200 of 795 results

Title	Presenter Name Sort descending	Presenter Surname	Area	Conference year	Keywords
Cape Flats Aquifer Management Scheme – the City of Cape Town’s groundwater abstraction and MAR scheme for a resilient future (South Africa)	D	McGibbon	South Africa	2023	groundwater supply, Managed aquifer recharge, primary aquifer, Resilience, urban
Abstract In response to the Western Cape’s worst drought experienced during 2015-2018, the City of Cape Town implemented various projects to augment its water supply, including desalination, re-use and groundwater. The Cape Flats Aquifer Management Scheme (CFAMS) forms one of the groundwater projects that includes groundwater abstraction and managed aquifer recharge (MAR). The Cape Flats Aquifer (CFA) is a coastal, unconfined, primary aquifer within an urban and peri-urban environment. As such, it is well situated to take advantage of enhanced recharge using high-quality advanced treated effluent but also has challenges related to seawater intrusion (SWI) and risk of contamination. MAR is currently being tested and implemented with a three-fold purpose: (1) to create hydraulic barriers against seawater intrusion and other contamination sources, (2) to protect groundwater-dependent ecosystems harbouring biodiversity, and (3) to increase storage and improve water quality to enhance resilience to effects of drought. As no legislation for MAR exists in South Africa, international guidelines are used to determine water quality requirements related to clogging environmental and health concerns. Further consideration includes aquifer-scale design, the interaction of multiple abstraction and injection wellfields within an area, and the design of individual boreholes to enhance yield and limit clogging. We aim to present progress made to date that includes exploration, wellfield development, monitoring, numerical modelling, aquifer protection, and the lessons learnt.
Hydrogeochemical and temporal nitrate variation in an unconfined urban aquifer in a tropical area in Brazil	D	Lookin	Brazil	2023	Bauru Aquifer System, Hydrogeochemistry, Nitrate, Urban Area
Abstract The Bauru Aquifer System (BAS) is a significant source of water supply in the urban area of Bauru city. Over the last decades, BAS has been widely affected by human activities. This study evaluates the nitrate plume in groundwater from 1999 to 2021 and how it relates to urbanization. The methods used were analysis of the data of 602 wells, survey of the sewer network and urbanization, and reassessment of nitrate concentration data. The seasonal analysis of 267 groundwater samples allowed the identification of concentrations up to 15.1 mg/L N-NO3 - mainly from the area’s central region, where the medium to high-density urban occupation dates back to 1910. Otherwise, the sewage system was installed before 1976. The reactions controlling the nitrogen species are oxidation of dissolved organic carbon, dissolution of carbonates, mineralization, and nitrification. Wells, with a nitrate-increasing trend, occur mainly in the central and northern regions, settled from 1910 to 1980-1990, when no legislation required the installation of the sewage network before urbanization. In turn, wells with stable or decreasing nitrate concentrations occupy the southwestern areas. Over the years, the concentrations of these wells have shown erratic behaviour, possibly caused by the wastewater that leaks from the sewer network. The bivariate statistical analysis confirms a high positive correlation between nitrate, sanitation age, and urban occupation density, which could serve as a basis for the solution of sustainable groundwater use in the region. Project supported by FAPESP (2020/15434-0) and IPA/SEMIL (SIMA.088890/2022-02).
Mitigating climate change with managed aquifer recharge: 5 Case Studies	D	Hohne	South Africa	2023	Climate change; drought; MAR; nature-based solution; case studies
Abstract In the past decade, Southern Africa has experienced periods of extreme drought. This was especially true in the western Karoo in South Africa. Continuous drought and limited rainfall led to declining aquifer water levels that curtailed sustainable water supply for towns and livestock. The western Karoo is almost completely dependent on groundwater. Managed aquifer recharge (MAR) is being used to reduce the effects of droughts and mitigate climate change impacts. A good understanding of the geology and the behaviour of the aquifers is needed for implementing various MAR designs, including nature-based solutions, which are used to recharge aquifers with limited rainfall. This paper discusses 5 active MAR case studies in the Western Karoo. Here, site-specific MAR methods that use small rainfall events deliver reasonable results, whereas the implemented MAR options keep most aquifers functional. Observations at the MAR sites also showed improved water quality and less bacterial clogging. This improves the environment around the managed aquifer recharge sites. The MAR methods and designs discussed in this paper can be used on a larger scale for a town or a smaller scale for a farm. Maintenance costs are low, which makes these options cost-effective for less wealthy areas.
A Systematic Approach To The Interpretation Of Conductivity Anomalies Across Intrusive Dolerite Dykes And Sills In The Karoo	Dakalo	Makhokha	Karoo	2015
Abstract South Africa is a semi-arid country. Its average rainfall of roughly 464 mm/a is much lower than the world average of 860 mm/a. Due to a shortage of surface water, groundwater plays an important role in the water supply to domestic, industrial, agricultural and mining users. Groundwater exploration has become increasingly dependent on the use of geophysical techniques to gain insight into the subsurface conditions to minimise the risk of drilling unsuccessful production boreholes. Dolerite dykes and sills are often targeted during groundwater exploration programmes in Karoo rocks. Due to the high pressures and temperatures that reigned during the emplacement of these structures, the sedimentary host rocks along the margins of the intrusive structures are typically strongly altered. These altered zones are often heavily fractured and, as a result, have increased hydraulic conductivities as compared to the unaltered host rock. The altered zones often act as preferential pathways for groundwater migration, making them preferred targets during groundwater exploration. In conjunction with magnetic methods, electromagnetic (EM) methods are the techniques most often used for groundwater exploration in Karoo rocks. In South Africa, the ground EM system most commonly used is the Geonics EM34-3 frequency-domain system. This system has already been in use for a few decades, yet a great deal of uncertainty still remains regarding the interpretation of anomalies recorded over geological structures associated with lateral changes in electrical conductivity. This uncertainty results from the fact that the Geonics EM34-3 system employs measurements of the out-of-phase components of the secondary magnetic field relative to the primary magnetic field to calculate an apparent conductivity for the subsurface. The apparent conductivity profiles across lateral changes in conductivity often do not make intuitive sense. This project focuses on the development of guidelines for the interpretation of anomalies recorded with the EM34-3 system across intrusive structures of geohydrological significance in Karoo rocks. Geophysical surveys were conducted across known dykes and sills in an attempt to systematically investigate the responses recorded across these structures. Data from magnetic and two-dimensional electrical resistivity tomography surveys, as well as from geological borehole logs in some cases, were used as controls to assist in the interpretation.
Assessing groundwater dependence of wetlands and streams within the Table Mountain Group Aquifer: A Case Study from the Kogelberg	Dale	Barrow	Western Cape	2021	Ecosystems, datasets, conceptualisation, Monitoring
Abstract Ewart Smith, J; Snaddon, K; de Beer, J; Murray, K; Harillal, Z; Frenzel, P; Lasher-Scheepers, C Various analysis techniques are available for assessing the groundwater dependence of ecosystems. Hydrogeological monitoring within the Kogelberg and greater Table Mountain Group (TMG) aquifer has provided various datasets from multiple scientific disciplines (hydrological, hydrogeological, geochemical, climatic, ecological and botanical). Using a variety of analysis techniques, and using the Kogelberg as a case study, this paper assesses the groundwater dependence of several ecological sites (wetlands and streams). The starting point is a sound geological and hydrogeological conceptualisation of the site. The approach involves conceptualisation and analysis within each scientific discipline, but also requires bridging between areas of specialisation and analysis of a variety of datasets. This paper presents the data and analyses undertaken and the relevant results as they pertain to several sites within the Kogelberg.
Groundwater dependency and the plight of Loeriesfontein	Dale	Barrow	Northern Cape	2015	mini-wellfield, mixing model
Abstract The town of Loeriesfontein, situated in the northern Cape, is entirely groundwater dependent, and is currently facing a serious water shortage. Low rainfall and the lack of storm events have resulted in groundwater levels dropping drastically. The current supply boreholes have been over abstracted and cannot meet the required demand. Water levels are close to pump depth for some of the municipal boreholes, and yields are decreasing. The town at one stage was trucking in water in order to supply its residents. Additional supplies are therefore urgently required. A number of measures were implemented to monitor and manage the current demand and the limited supply. Thereafter GEOSS investigated the occurrence of groundwater within a 20 km radius of Loeriesfontein, and found that dolerite represents the primary target formation for groundwater exploration. Groundwater occurrence is found at the lower dolerite contact with the host rock, or in fractures in the dolerite itself. Based on an extensive hydrocensus, geophysical surveys, drilling and yield testing, the Rheeboksfontein area was identified as a suitable water source. Initially water was being trucked into Loeriesfontein from Rheeboksfontein and later an innovative arrangement of solar driven borehole pumps and reservoir pumps resulted in water being transported much closer to Loeriesfontein, reducing the transportation distances and costs. During this first Phase of exploration the projected supply still did not meet the water demand and water quality targets. A number of high yielding boreholes were drilled, however the water quality was such that it would have required treatment and disposal of brine in that area is problematic. The extent of the exploration was then increased to a distance of 40 km from Loeriesfontein. A detailed hydrocensus was completed, followed up with further geophysical surveys, drilling and yield testing. Successful boreholes were drilled and the required demand and water quality standards could just be met. This finding is being verified with numerical modelling. A process is underway to develop a mini-wellfield and then the environmental processes are being followed so that a pipeline can be built delivering water directly into the reservoirs at Loeriesfontein. On-going monitoring and maintenance is crucial to the long-term success of the groundwater supply.
The use of boreholes for the infiltration of treated effluent - Pearly Beach Waste Water Treatment Works - A case study.	Dale	Barrow	Western Cape	2015	monitoring network
Abstract A Waste Water Treatment Works (WWTW) is being constructed at Pearly Beach. A geohydrological assessment was conducted to assess the potential discharge of treated effluent above and below the subsurface calcrete layers. A hydrocensus has been completed of the area to confirm there is no use of groundwater down-gradient of the WWTW and there is no likely impact on ecosystem functioning. Based on existing boreholes, infiltration above the calcrete layer in the vadose zone was found to be more efficient. A geophysical study was conducted to determine the optimal locations of boreholes for disposal of the treated effluent. The geophysics included an extensive electromagnetic (EM) survey. Resistivity data were acquired along a single resistivity profile to use as calibration for the EM data. This information has been correlated with borehole information from the monitoring boreholes that were drilled at the proposed WWTW site. From this information it would seem that the areas with higher conductivity (lower resistivity) can be targeted for drilling boreholes to dispose of the treated effluent. Also, the higher conductivity areas are interpreted as the areas with increased porosity. However, the change in conductivity could result from an increase in salinity or changes in calcrete content in the subsurface. The expected depth of the unconsolidated sand formations is generally less than 10 m based on the interpreted depth of the saturated formation from the resistivity data. Drilling will target the unconsolidated sands, as well as potential higher porosity zones beneath the calcrete. The geophysics data should then be calibrated with the information obtained from drilling the first borehole. The other sites can then be confirmed or reviewed based on the information. The boreholes are to be drilled soon and pump tested. The obvious concern is that the boreholes may clog, however measures will be put in place to minimise this risk. A detailed monitoring network will also be established. On-going monitoring is crucial to ensure the success of the scheme. The full conference paper will include the drilling and pump testing results and infiltration tests. This method of disposal needs to be taken into consideration especially if such schemes can be run successfully so that another option is available for the disposal of treated effluent. {List only- not presented}
Groundwater development for Municipal water supply in response to drought of 2015 to 2019.	Dale	Barrow	Western Cape	2019	Drought, TMG
Abstract The geographic positioning of the Western Cape results in a Mediterranean climate - receiving majority of its rainfall during the winter months. A demand on the water supply throughout the year is typically met by storing water from winter rainfall in large dams. The Western Cape experienced a significant drought between 2015 and 2019. As a result, the supply dams have not been filled to capacity and drastic water restrictions had to be implemented. In the search for alternative water sources, groundwater exploration became a priority. Groundwater development projects were implemented rapidly in attempt to alleviate the implications caused by severe water restrictions and ultimately prevent running out of water. As a local groundwater institution, GEOSS got involved in several fast-tracked groundwater development projects for Department of local government, local municipalities, as well as other industrial and agricultural corporations. For obtaining the required water volumes, alternative measures were implemented. Previously under developed aquifers were targeted. In certain instances, in order to target the Table Mountain Group Aquifer (TMG), horizontal exploration drilling was conducted. The results of exploration and drilling yielded valuable learnings in terms of relevant hydrostratigraphy within the study areas. Additionally, there were learnings in terms of managing projects of this nature. In fast-tracked projects, careful management of the contractors, data collation (and storage) and public perception is critical to the success of the project. In this paper on water supply development for Municipalities, the various components of groundwater development are detailed along with relevant learnings from the recent emergency drought response measures.
Assessing 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.
3-D Electrical Conductivity Image as a Decision-Aiding Tool in the Post-Closure Management of a South African Colliery	Danie	Vermeulen	Free State	2013	Electrical conductivity, closure management
Abstract The colliery is situated in the Vereeniging–Sasolburg Coalfield, immediately southwest of Sasolburg in the Republic of South Africa. The stratigraphy of this coal field is typical of the coal-bearing strata of the Karoo Sequence. The succession consists of pre-Karoo rocks (dolomites of the Chuniespoort Group of the Transvaal Sequence) overlain by the Dwyka Formation, followed by the Ecca Group sediments, of which the Vryheid Formation is the coal-bearing horizon. Mainly the lava of the Ventersdorp and Hekpoort Groups underlie the coal. The Karoo Formation is present over the whole area and consists mainly of sandstone, shale and coal of varying thickness. The underground mine was flooded after mining was ceased at the colliery in 2004. The colliery is in the fortunate position that it has a very complete and concise monitoring programme in place and over 200 boreholes were drilled in and around the mine throughout the life of the mine. To stabilise mine workings located beneath main roads in the area, an ashfilling project was undertaken by the colliery since 1999. A key issue is if the mine will eventually decant, and what the quality of the water will be. This is important for the future planning of the company, as this will determine if a water treatment plant is necessary, and what the specifications for such a plant will be, if needed. Therefore it was decided to do a down-the-hole chemical profile of each available and accessible borehole with a multi- parameter probe with the aim of observing any visible stratification. Ninety-four boreholes were accessible and chemical profiles were created of them. From the data collected a three-dimensional image was created from the electrical conductivity values at different depths to see if any stratification was visible in the shallow aquifer. The ash-filling operations disturbed the normal aquifer conditions, and this created different pressures than normally expected at a deeper underground colliery. From the three-dimensional image created it was observed that no stratification was visible in the shallow aquifer, which lead to the conclusion that in the event that if decant should occur, the water quality of the decanting water will still be of very good quality unless external factors such as ash-filling activities are introduced. It is not often that it is possible to create chemical profiles of such a large number of boreholes for a single colliery and as a result a very complete and informative three-dimensional electrical conductivity image was created. This image is very helpful in aiding the decision-making process in the future management of the colliery and eventually obtaining a closure certificate, and also to determine whether ash-filling is a viable option in discarding the ash.
Developing and testing a Groundwater Mapping methodology to increase drilling success rates for sustainable drinking water boreholes in African Arid and Semi-Arid Lands – the case study of Cunene Province, Angola	Daniela	Benedicto van Dalen	Angola	2023	Analytic Hierarchy Process, WASH program, groundwater mapping, remote sensing
Abstract In recent years, practical applications of vector and raster multi-layers overlay analysis to enhance outcomes of conventional hydrogeological methods for allocation of productive boreholes have been applied in arid and semi-arid lands and is currently being tested in Ethiopia, Kenya, Somalia and Angola in cooperation with UNICEF. Advanced Remote Sensing (RS) and Geographic Information Systems (GIS) techniques combined with traditional geological, hydrogeological and geophysical methods are being used for improved access to sustainable drinking water supply boreholes in the scope of a WASH program. Identifying suitable areas with a good potential for sustainable groundwater resources exploitation mainly depends on a) consistent/reliable aquifer recharge and b) favourable hydrogeological conditions for groundwater abstraction. Multi-layer analyses and attribution of layer scores to the hydrogeological information layers – aquifer recharge, aquifer class, lineaments, slope, land cover, and presence of streams – combine into a qualitative Groundwater Suitability Map, using pairwise comparison (weights) to determine their relative importance with the Analytic Hierarchy Process (AHP). Additionally, traditional field methods enhance the quality of outputs and delineate Target Areas for detailed investigations: validation of hydrogeological conceptual models, hydrogeological assessment, groundwater sampling and finally, geophysical methods. Downscaling the remote sensed information of the groundwater suitability map with field verifications is required to recommend borehole drilling sites. The engagement of stakeholders is vital for the data collection and validation of the weighting criteria analyses (AHP method), as well as for the cooperation on the ground, validation of the Target Areas selection and implementation.
Building evidence through hydrogeological survey and monitoring for the conjunctive development and management of water resources in Kunzila catchment area – Amhara Region, Ethiopia	Daniela	Benedicto van Dalen	Ethiopia	2023	catchment management, Conjunctive use, groundwater monitoring, participatory landscape Approach
Abstract Deploying a participatory approach for surveying the complex geohydrological system and defining the status of the groundwater resources in the Kunzila catchment area has crucial importance towards conjunctive use of its water and land resources for sustainable economic growth, social well-being, and environmental protection. Several initiatives are being undertaken to pilot the ‘Integrated Landscape Management and WASH’ project in this community to implement evidence-based approaches. A comprehensive hydrogeological study has been carried out to understand the hydrogeological system, propose ecosystem restoration measures, identify suitable locations for drilling boreholes and design a groundwater and surface water monitoring network. The first results pointed out the central area of the catchment as holding the best potential for groundwater abstraction, a productive Late Quaternary basalt aquifer. As this area is in use by private floriculture farms, several other borehole locations were sited to meet the domestic and livelihood demand across the watershed. In addition to the drinking water supply goals, the project proposed catchment intervention for soil and water conservation based on the Landscape Approach and 3R measures implementation - Retain, Recharge, Reuse. Such measures include but were not limited to riparian vegetation restoration, terracing and contour bunds, agroforestry, controlled grazing, etc. A telemetric monitoring network has been designed and installed to support the conjunctive management of shallow and deep groundwater water resources, streams and Lake Tana, together with a functional dashboard for data registrations and sharing. The monitoring program gauges the impact of groundwater abstraction and the quality parameters.
A Geochemical Investigation On Two Soekor Wells Located In The Northern Cape, South Africa	Danita	Hohne	Northern Cape	2017	hydraulic fracturing, geochemical investigation, Isotopes
Abstract The past few years hydraulic fracturing has been a hotly researched topic. Currently, most published documents are just speculation of what can happen if hydraulic fracturing is to take place in South Africa. There is very little work done to firstly establish a baseline on the current groundwater quality and secondly look at the current state of the groundwater around the Soekor wells. For these reasons a geochemical investigation was launched looking at the Soekor wells and the surrounding boreholes to determine a valid baseline. Looking at the two Soekor wells; geochemical analyses was conducted on water, soil and rocks. The drill core of the wells; soils from the waste ponds and water at or nearby the wells were sampled and analysed. By making use of XRF; XRD, Stable Isotopes and water chemistry analyses, a better picture of these wells and groundwater can be developed to give better guidelines to what should happen during the monitoring of hydraulic fracturing wells.
Drought in the Northern Cape Karoo: Lessons Learned and Options for Future Use	Danita	Hohne	Karoo	2017	Drought
Abstract Most of the Northern Cape has been hit with a drought for the past 4-7years. The western part of the Northern Cape have been dry for at least 7 years now with no rainfall or very little rainfall, while the more central part have been dry for the past 4 years with very little rainfall. It is only the past 2 years that this has been seen as a problem, but for the past 7years the Department with local municipalities have tried their utmost to manage the problem of water scarcity. During the past 7years the DWS has learned many lessons on how to manage the groundwater in these areas to ensure sustainable future use but must also look at new initiatives to deal with this problem as drought is going to be the new norm in the western parts of South Africa.
Assuring supply during a changing environment focussing on drought	Danita	Hohne	National	2021	Drought, community supply, operating rules
Abstract Fourie, F Communities reacted differently to the drought. In some cases, you would notice a proactive approach and good management of the wellfields. In other cases, communities have been under a misconception that they received good rainfall for a recharge which did not reflect in monitoring data, and lastly, you get the communities that are mismanaging the groundwater. Various lessons were learned from the change in the climate and environment. But a lot can be done to minimise the impact of these changes on the water supply to communities. This paper addresses the changes that we can apply to deal with the changing environment around us to provide a sustainable water supply. The changes can include relooking at operating rules to ensure better management on the aquifer and borehole level. Recharge determined during pump test must be considered periods low to no recharge. Methods to enhance the recharge to the aquifer will ensure recharge occur during low rainfall events By implementing these rules, groundwater can be sustainably managed for future use.
Hydrocarbon groundwater analyses: a Karoo case study	Danita	Hohne	Karoo	2021	Hydrocarbon, Water level, contamination, Artisan borehole, Methane concentration, Natural gas, Dolrites, quality, Fracturing
Abstract The South African government is considering shale gas extraction in the Karoo basin, South Africa. To protect groundwater resources, there is an urgent need to do a groundwater baseline in possible gas extraction areas. Various groundwater samples have therefore been taken at a borehole and 2 soekor wells in the Northern Cape, from 2016 to 2021. The groundwater samples were analysed for dissolved gasses, specifically focussing on methane. As laboratories became more efficient ethane was also included in later analyses. From the analyses we found that drought might influence the dissolved gas concentrations in the groundwater via pressure influences on the groundwater flow and the dissolved gas flow towards the shallow aquifers. Artesian conditions at this site are helping with the flow of dissolved gasses from deep to shallow aquifers via preferential pathways. The possibility of shallow-deep groundwater interconnections and the migration of deep methane to shallow aquifers make it important to establish a groundwater baseline in the Karoo. By focusing on boreholes and wells that are emitting methane, a better understanding of groundwater flow and interaction with geological layers can be determined. If other gasses like propane and butane can be analysed in addition to methane, more information can be gathered to determine the origins of the methane and whether it is thermogenic or biogenic.
Vanwyksvlei: Water provisioning and the Blue Drop system - how effective is this?	Danita	Hohne	Vanwyksvlei	2015	Blue drop standards, water supply challenges
Abstract POSTER Vanwyksvlei had always experienced problems with water supply and quality of drinking water. The town relies on 6 boreholes to supply the town with drinking water. Since 2011 the town was told not to use the water that was supplied from the borehole called Soutgat. This meant that the town could now rely only on the water being supplied from the other 5 boreholes.From 2011 till present the town has experienced a lot of problems regarding water supply, due to the fact that the Soutgat could not be used anymore. Extra stress was put on the other boreholes and these were pumped almost dry. The two aquifers are currently failing and monitoring data since 2009 shows that the water levels of the town are decreasing. Due to low rainfall, recharge to the boreholes are much lower, which exacerbates the problem. This poster will examine the effectiveness of using the Blue Drop system in small towns with limited water supply, at the hand of a case study of Vanwyksvlei. This review will take into account factors such as the point at which water quality is tested in the water supply system, the type of water treatment available for the town and a review the usefulness of certain standards in the Blue Drop system which may indicate failure of supply sources.
SKA and Groundwater Management	Danita	Hohne	Karoo	2015
Abstract In 2009 it was announced that South Africa and Australia would be in competition for the race of the Square Kilometre Array (SKA). In 2009 the MeerKAT project was started in the Karoo near the core site of the SKA, which set out to demonstrate that South Africa was able to build the infrastructure of the SKA. The SKA required water for the building of roads, the dishes and the foundations of the dishes at the MeerKAT site. This poster explains the groundwater monitoring that is being performed at the MeerKAT site from 2011 till present in order to illustrate how good monitoring and management of groundwater can ensure sustainable groundwater use at sites like these. {List only- not presented}
Case Study: Thermals springs in the Lower Orange River Valley	Danita	Hohne	Lower Orange River Valley	2015	earthquakes, thermal springs, Monitoring
Abstract POSTER Since June 2010 and still ongoing today, the Lower Orange River Valley has experienced over a 1168 tremors(a) and earthquakes in the vicinity of Augrabies. Of these 1168 tremors, 71 quakes registered above 3 on the Richter scale and on 18 December 2011, the area was struck with an earthquake that registered 5 on the Richter scale. Four thermal springs are also located near this earthquake zone and the temperature of the water have a range of between 38?C -46.6?C, according to Kent LE. (1949/1969). 25?C is the division between thermal and non-thermal waters and the thermal gradient for the Riemvasmaak area(b) is 24?C, clearly indicating that the four springs are thermal when looking at the temperature difference. The Department of Water Affairs has been monitoring these springs monthly since 2011 and has been taking field measurements and chemical analyses. The aim of this study is a) to see if the tremors and earthquakes have an effect on the chemistry of the thermal springs, b) to create a data set for the thermal springs, as these springs was recorded and mentioned in Kent LE. reports of 1949 and 1969 but no samples were collected and analysed, c) to see if the water source for the groundwater in the area and the thermal springs are connected and d) to see if the recent floods may have had an influence on the earthquake zone seeing as the Orange River runs through the zone. The following sources are used to describe the earthquakes and water quality: (a) Earthquake data from the Council of Geosciene (b) ZQM data on NGA temp range between 21-28?C depending on the season with 24?C being the mean.
A conceptual model for methane occurrences in the Western Karoo as part of a geochemical baseline for shale gas development	Danita	Hohne	Western Cape	2023	Western Karoo, shale gas development, shallow and deep groundwater, thermogenic and biogenic methane; isotopes
Abstract Although methane occurrences have been documented in Karoo groundwater in the past, the advent of possible unconventional oil and gas extraction now made it important to determine the type and origin of this methane to assess the possibility of shallow-deep groundwater interaction. During groundwater surveys from 2016-2021, methane was detected at three sites in the Western Karoo: the Soekor sites KL1/65, QU1/65 and an unidentified shallow groundwater borehole (BHA). The Soekor wells were drilled in the 1960-1970s to depths of between 2500-3500 meters in South Africa’s search for oil. On the other hand, Borehole BHA was drilled in 1998 and only up to a depth of 298m. This study aimed to determine methane’s origin through gas and isotope analyses. To do this, groundwater, rock and soil samples were analysed to determine whether the methane is thermogenic or biogenic and its origin. We determined that methane was both thermogenic and biogenic and probably originated from different layers of the Karoo formations and that mixing occurs between deep and shallow aquifer systems at these Soekor sites. This information was used to develop a final conceptual model of what the Karoo underground system might look like and to make recommendations for establishing a groundwater baseline.
The Economics Of Sustainable Groundwater Ecosystem Services	Darian	Pearce	National	2013	economic value, natural assest values, ecosystem services values
Abstract This paper outlines the core factors related to the economic assessment of groundwater resources. Included in the discussion is a delineation of the factors that determine the economic value of groundwater as well as a thorough description of the range of ecosystem services that are derived from groundwater resources. Several factors affect the economic value of aquifers, but these factors can split into two categories, natural asset values and ecosystem services values. Ecosystem services are the benefits that humans receive from ecosystems, and are officially defined by the Millennium Ecosystems Assessment. Ecosystems produce these ecosystem services on an annual basis, and the value of these services accrue on a country’s national income statement, and should ideally be measured through indicators that relate to Gross Domestic Product (GDP). Aquifer themselves are natural assets. They form part of the ecological infrastructure of a country and the values of these assets theoretically appear on a country’s natural resources balance sheet. The asset value can be determined by calculating the Net Present Value (NPV) of the perpetual stream of aquifer ecosystem services delivered. By understanding the full range of factors that underlie the natural asset values of aquifers, along with their ecosystem service values and the full range of inter-temporal and inter-ecosystem service characteristics, we can begin to adequately assess the economic value of groundwater resources.
Groundwater and mining on the West African shield: application of mineralogical and weathering profiling	David	Love	West Africa	2015
Abstract The Birimian and Tarkwaian rocks of the Paleoproterozoic West African Shield host some of the most important gold reserves in the world, with Ghana the world's 10th largest gold producer and the region collectively producing more gold than all but five countries in the world. The gold was deposited during successive hydrothermal sulphide alteration events, which were channelled by shear zones and thrusts formed during the regional progressive Eburnean tectono-thermal deformation event. The hydrothermal fluids were auriferous and sulphide-rich, resulting in two distinct types of gold and sulphide mineralisation: (1) gold-bearing quartz- and quartz-ankerite veins, occurring in NNE-SSW trending shear zones or thrust folds, usually in Birimian metasediments, with associated sulphides deposited on the fragmented wall rock and (2) disseminated gold-bearing pyrite and arsenopyrite, occurring in halos within the same shear zones or thrust folds as the quartz veins. The sulphidic nature of the gold deposit leads to a high risk of acid rock drainage (ARD). During operations, inflowing groundwater may carry the ARD into underground workings and opencast pits. Post-closure, as the groundwater rebounds, there is a risk of acidic pit lakes forming or acidic decant of underground mines. However, the occurrence of ARD in such systems can be predicted by a combination of weathering profiling, mineralogical profiling and conventional acid base accounting (ABA). The weathering profile can be divided into three zones, readily distinguishable in borehole core: (i) Oxide Zone, from which both the acid-generating sulphide minerals and the acid-neutralising carbonate minerals have been largely leached, (ii) Transitional Zone, from which the carbonate minerals have been largely leached but the sulphide minerals remain, (iii) a Fresh/Primary Zone, where both sulphide and carbonate minerals occur. The Oxide Zone is generally non acid-generating, the Transitional Zone is acid-generating and the Fresh Zone is potentially acid-generating, depending upon the balance of sulphide vs carbonate minerals. Mineralogical profiles can be prepared from the relative abundance of macroscopic sulphide and carbonate minerals in the borehole core, again providing an assessment of ARD risk. Combined logs can then be prepared from these profiles with acid-generation and neutralisation data from ABAs, illustrating in space where the highest ARD risk zones are located. Using this information, groundwater and mine water management options can be developed for operations and closure, such as prioritisation of open pit backfilling or which levels of an underground mine water should be preferentially excluded from.
Linking Geology And Wildlife Water Supply In The Hwange National Park, Kalahari Basin	David	Love	The Hwange National Park, Kalahari Basin, Zimbabwe	2013	Water supply, Geology
Abstract Most of the 14 651 km2 Hwange National Park in Zimbabwe is on monotonous Aeolian sands of the Kalahari Basin, with endorheic drainage. The large game populations of the park are sustained by seasonal accumulations of water in grassy pan depressions and year-round supply of groundwater to pans (except in the northwest where there are rivers and dams). Some of this is from natural seeps, such as at the Shakwanki, Nehimba and Ngweshla Pans, but most are supplied from boreholes. Game animals show clear preferences for some pans over others and it has long been speculated by wildlife managers that there is a nutritional or taste basis for this discrimination. In this preliminary study, the location, host geology and sub-Kalahari lithologies of the pans are compared with the frequency of use by game animals. Results show that the pans that are most frequented by game are hosted in fossil drainage channels, with limestone horizons (calcrete) developed within the Kalahari Sands. Many popular pans are also found on Kalahari Sand overlying the granitic rocks and the meta- sedimentary Malaputese Formation of the Kamativi–Dete Inlier. This can be related to sodium and potassium enrichment.
Flow Test Analysis And Monitoring Of The Deep Confined Peninsula Aquifer In Blossoms (Oudtshoorn), Western Cape, South Africa	David	McGibbon	Western Cape	2015
Abstract The Oudtshoorn Groundwater Project aims to target deep groundwater as a long-term option to augment the water supply to the greater Oudtshoorn Local Municipality. Located 15 km south of Oudtshoorn towards the Outeniqua Mountain range, the Blossoms Wellfield lies within a potentially high-yielding artesian basin. The Peninsula Formation (of the Table Mountain Group (TMG), hydrostratigraphically known as the Peninsula Aquifer, is exposed in the Outeniqua Mountains (high rainfall recharge area), and is deeply confined northwards by the overlying Bokkeveld Group. The project is currently emerging from an exploration phase, with eight existing boreholes that target the deep confined Peninsula Aquifer, and three boreholes that monitor the shallower Nardouw (Skurweberg) Aquifer. Estimation of the aquifer's productive and sustainable groundwater potential involves determining its hydraulic properties by stressing the aquifer through flow and pumping tests and accurately monitoring flow rates, the potentiometric surface level (PSL) during flow, and PSL recovery thereafter. Free-flow and pumping tests were carried out on four boreholes between the 12th May 2014 and the 29th June 2014. The boreholes were all equipped with data-loggers to record pressure and flow-meters to determine the flow-rate. Recovery of the aquifer after the testing is still being continuously monitored. Results from the month and a half flow-test show that there is no interaction between the deep confined Peninsula Aquifer and the shallower Nardouw Aquifer beneath the southern part of the wellfield. Because the water-use licence stipulates that there can be no negative impact from Peninsula Aquifer abstraction on the Nardouw Aquifer, which is utilised by farmers in the region, this issue is of paramount importance. The hydrochemical signature of the two aquifers is also different. Recovery monitoring emphasised that the northern block is better inter-connected through fracture systems than the southern block, because those boreholes recovered to their original potentiometric surface almost immediately, whereas the southern boreholes took days for recovery. Two boreholes in the south are still recovering eight months later, which is most likely due to their being drilled into the limb of folded rock systems and not the more fractured hinge zone (as with the more connected boreholes). Using the drawdown and recovery curves ('Horner plots'), the transmissivity and storativity of the aquifer is calculated analytically by the Theis equation. The results show a large variation in storativity (1.0E-1 to 1.46E-4) and transmissivity (9-20 m2/day) between the various boreholes, emphasising the heterogeneity of the aquifer. The aquifer properties gained from this testing are essential in better understanding the aquifer system, and developing numerical models for future wellfield testing and model simulation.
Emergency Response To Drought - The City Of Cape Town's Groundwater Abstraction And MAR Scheme (South Africa)	David	McGibbon	Cape Town	2019	Drought, MAR
Abstract The Western Cape region in South Africa is currently experiencing its worst drought since 1904. As a result, the City of Cape Town (CoCT) implemented emergency response projects to augment water supply through desalination, re-use of treated effluent and groundwater abstraction from several groundwater systems. Amongst the targeted aquifers, the Cape Flats Aquifer (CFA) presents unique challenges and opportunities for abstraction and managed aquifer recharge (MAR). The CFA is a coastal unconfined primary aquifer within the urban and peri-urban environment. As such it is well situated to take advantage of enhanced recharge from treated effluent and urban stormwater. MAR is currently being tested and implemented with a three-fold purpose: (1) create hydraulic barriers against seawater intrusion and other contamination sources, (2) protect groundwater dependent wetlands and RAMSAR sites and (3) increase storage to enhance resilience to drought. Due to local hydrogeological characteristics and a high demand for open land, in the short term, high quality treated effluent will be injected directly through boreholes. Numerical modelling has supported siting and quantifying necessary injection rates. Current estimates indicate that available treated effluent will increase sustainable yields from the aquifer two-fold, as well as providing an additional storage volume equivalent to 2 to 3 years abstraction. In the future this is expected to be complemented with the re-design of urban water drainage to further enhance the recharge of stormwater. Given the time-constraints of an emergency response project, long-term testing and study of the system to support design and implementation have been significantly reduced and had to be replaced by a 'learn by doing' approach. We aim to present the on-going challenges of implementing MAR to complement an emergency response, as well as an overview of the scheme, new data and insights gained through the process.
Hydrochemical Analysis Of Groundwater In The Danakil Depression, Northern Ethiopia	David C	McGibbon	Ethiopia	2017	hydrostratigraphy, hydrochemical, hydrothermal influx
Abstract An investigation of surface and groundwater chemistry was undertaken as part of a resource assessment of water-supply for potash solution-mining in the Danakil Depression of the Afar Rift, situated in northern Ethiopia on the N/S-trending Ethiopia-Eritrean arm of the East African Rift System. Four hydrostratigraphic units are recognised in the area: 1) Basement Tsaliet Group rocks, low yielding and with poor water quality; 2) Adigrat Formation and Antalo Group fractured sandstones and karstic limestones, high yielding with good water quality; 3) Danakil Group and Zariga Formation fine-grained sediments, forming a good regional aquifer; 4) Dogua Formation alluvial fans, forming a major, regional, primary aquifer with high yields and poor water quality (yields of >50 l/s but 3 times the salinity of sea water). In the mining concession area the only available target for groundwater exploration is the Dogua alluvial-fan system that extends off the Dogua Mountain range to the west. During 2015 and 2016, 5 production and 5 exploration/monitoring boreholes were drilled into the fans, thereafter test pumped and sampled for hydrochemical and isotope analysis. The aquifer stress test proved that there is sufficient groundwater available for the life of mining, but that the water quality is poor. The hydrochemical analysis found that in general, water quality is poor (brine with TDS values >100 000 mg/l and a density >1.05 g/cm3 ) and with temperatures of ~50°C. Water quality degrades from south to north, possibly due to recharge of fresh water from the Antalo limestones in the south and lesser quality water from the Tsaliet basement in the north. The high salinity and temperature found throughout the fans is due to hydrothermal influx along rift-boundary faults that extend downwards into the thermally active, volcanic rift zone. Prolonged pumping results in the degradation of the water quality in the southern boreholes and improvement of quality in the northern boreholes; this is likely as the groundwater heads towards equilibrium, with a similar hydrochemical signature to that of the dominant hydrothermal influx. Stable and radiogenic isotope sampling and analysis was undertaken to determine the source of the recharge, the results showing that it is likely a combination of evaporation from fresh water, lateral recharge of ancient sea water along faults from the Red Sea, and hydrothermal recharge from the sub-surface leaching of young Afar and Red Sea Basalts in the active rift zone.
Groundwater/Wetland Interactions In A Coastal Aquifer In The Eastern Cape Province Of South Africa.	Desmond	Visser	Eastern Cape	2013	Groundwater, coastal wetland, coastal aquifers, aquifer, surface water
Abstract This study, near Thyspunt between St. Francis and Oyster Bay in the Eastern Cape Province of South Africa, focused on identification and quantification of surface water–groundwater links between the mobile Oyster Bay dune field and the coast. The specific objective was to establish the extent to which important wetlands such as the Langefonteinvlei and the numerous coastal seeps along the coast are directly or indirectly dependent on groundwater as their main water source. A further objective was to establish the extent to which any of the coastal seeps derive their water from the Langefonteinvlei, and are thus interdependent on the integrity of this system. The study also investigated the contribution of the Algoa and Table Mountain Group aquifers to these wetlands. The monitoring network established as part of this study focused on unpacking the interrelationships between surface and groundwater flows, aquifer hydrochemistry and wetland function, as related to the Langefonteinvlei and the coastal seeps in particular. Results indicate that the Langefonteinvlei is fed by groundwater flowing from the mobile Oyster Bay dune field in the north and the water divide in the northeast, which emerges at the foot of the high dune in the north and northeast of the wetland. However, the majority of the vlei area is ‘perched’ above the local water table on a layer of organic-rich sediment. The coastal springs located southwest and west of the Langefonteinvlei are not fed by water from the Langefonteinvlei. They emerge near the coast, where the bedrock lies close to the surface, and are fed by groundwater draining directly from the Algoa and Table Mountain Group aquifers to the Indian Ocean.
Aquifer Water Level Behaviour In Relation To Deluge And Drought At Eskom's Thyspunt Site, Oyster Bay, Eastern Cape	Desmond	Visser	Oyster Bay, Eastern Cape	2019	Drought, water levels
Abstract The paper presents the groundwater monitoring data collected at Eskom's Thyspunt Site over the eleven-year period from January 2008 to January 2019. The Thyspunt site is underlain by an upper unconfined intergranular aquifer of the Algoa Group sediments, called the Algoa Aquifer, and a deeper semi-confined fractured-rock aquifer of the Table Mountain Group, called the TMG Aquifer. In the Algoa Aquifer, the highest water levels were recorded after the very good winter rains of 2011 and 2012. Between 2013 and January 2019 the recorded water levels in this aquifer have been declining to the lowest measured levels since monitoring started in 2008. This decline varies from 11.0 m in the Oyster Bay dune field recharge zone to 0.8 m in the Langfonteinvlei discharge zone. The deeper TMG Aquifer shows a similar decline over the last four years ranging from 10.1 m in the inland recharge zone where the TMG outcrops to 1.3 m at the near coastal discharge zone.
Integrating reductive dehalogenase enzyme production into reactive transport modelling to simulate chloroethene biodegradation in groundwater pollution plumes	Diego	Di Curzio		2023	Biodegradation; Chloroethenes plume; Reactive Transport Modeling; Enzyme-Based Kinetics; Reductive dehalogenase enzymes; Groundwater
Abstract Degradation of chloroethene in groundwater primarily occurs via microbially-mediated reductive dechlorination (RD). Anaerobic organohalide-respiring bacteria (OHRB) use chloroethenes as electron acceptors to gain energy. They produce reductive dehalogenase enzymes (RDases) to perform this function by transcription of functional genes into mRNA and translation to proteins (metabolic regulation). However, how hydrodynamics and hydrogeochemistry control the metabolic efficiency of OHRB in biodegrading chloroethene is essential for effective bioremediation design yet an under-investigated topic. For this reason, we implemented a virtual experiment (1D reactive transport model) to investigate the effects of site conditions on transcription-translation and, hence, biodegradation processes within chloroethene plumes. In the model, RD was simulated using Enzyme-Based Kinetics, explicitly mimicking the production of RDases via metabolic regulation, calibrated on microcosm experimental data gained from literature. Features of an actual contaminated site (Grindsted, Denmark) were then used to set up the virtual experiment. Here, chloroethene leaked from a former pharmaceutical factory migrates through a sandy aquifer and gets discharged into the Grindsted stream. Preliminary results show that substrate (electron donors) limiting conditions caused by competing electron acceptors and dispersion and high flow rates represent the key factors controlling biodegradation via RDase production.
A Baseline Study of Scarce Groundwater Resources in Anticipation of Fracking in the Karoo	Divan	Stroebel	Eastern Cape, Karoo	2015	Shale gas, Fracking, sampling
Abstract The anticipated exploration and exploitation of Shale Gas in the Eastern Cape Karoo through hydraulic fracturing has raised considerable debate regarding the benefits and risks associated with this process for both the Karoo, and the country as a whole. Major concerns include the potential impact of hydraulic fracturing on ecological, environmental and especially scarce water resources. The Eastern Cape Karoo region is a water stressed area and with further climate change it will become increasingly so. Thus, effective and reliable groundwater management is crucial for sustainable development in this region. This research aims to hydrochemically characterise both the shallow groundwater (<500m) and deeper saline groundwater in the vicinity of the Shale Gas bearing formations, based on major and trace elements, as well as gas isotope analyses. Sampling will include water sampling and gas measurements from shallow boreholes (<300m), SOEKOR drillholes (oil exploration holes drilled in the 60's and 70's up to 4km deep) and thermal springs (source of water >500m). To-date, a desktop study includes the collation of information determining the areas with the highest potential for Shale Gas Exploration throughout the Eastern Cape Karoo, from which the research area has been determined. This includes the identification of the respective oil companies' exploration precincts. A Hydrocensus has been initiated across this area, which includes slug testing and electrical conductivity profiling of open, unequipped boreholes. Further borehole selection will be finalised from this acquired information. The boreholes will be sampled and analysed a minimum of three times per year, which will occur after summer (April/May) and winter (October/November), after which the hydrochemistry will be analysed. The sampling will be preceded by purging of all inactive boreholes. The possible hydraulic connectivity between the shallow and deep aquifers will be tested, particularly in those areas where dolerite intrusions as well as fault systems may enhance preferential flow of water, using the chemical forensics complemented with passive seismic profiling/imaging and deep penetrating Magneto-Telluric (MT) imaging. The data collected will form a record against which the impact of fracking can be accurately determined. The research is a critical first step towards the successful governance of groundwater in light of the proposed Shale Gas development. In its absence, effective regulation of the sector will not be possible.
Groundwater Monitoring: Typical Methods To Improve The Understanding Of Aquifer Potential And The Associated Vulnerabilities	Donovan Craig	Samuels		2019	Monitoring
Abstract In the wake of the ongoing water restrictions in South Africa, the issue of groundwater potential for drought relief has been debated on many environmental and socio-economic platforms, nationally. Consequently, the development of groundwater and its related vulnerabilities has become a key topic to the decision makers and stakeholders. Currently, the recruitment of water professionals into government and private water sectors adds substantial value to understanding the importance of protecting this precious resource. This has allowed the monitoring of groundwater to gain ever increasing momentum. Groundwater monitoring has become an essential scientific tool for role-players to achieve robust and verifiable data used for modelling aquifer potential and vulnerability to pollution and over-abstraction. The data is generally sourced from various hydrogeological and environmental investigations which include groundwater development, vulnerability assessment and remediation projects. Groundwater and environmental consulting firms are tasked with imperative roles for implementing groundwater monitoring programmes to the ever growing industrial, commercial, agricultural and public sectors in South Africa. However, groundwater monitoring data, especially in the private sector, are reliable but remains mostly inaccessible due to confidentiality clauses. This does limit our accuracy and comprehensive understanding for determining aquifer potential and vulnerability risks at large. The conceptualisation and modelling of vast monitoring datasets has been recognised as an important contributing factor to enhance groundwater sustainability. This research emphasises the significance of groundwater monitoring for development, protection and remediation of aquifers. Comparing monitoring results from typical sites and methods, provides scientific validation to support good governance of water. Deterioration of groundwater potability in the sight of an existing drought can have irreversible environmental and economic implications for South Africa.
Cadmium contamination of groundwater in South Africa - the potential hazard of phosphate fertilizers	Dylan	Blake	Hermanus	2015	Cadium contamination
Abstract Cadmium is a highly mobile and bioavailable non-essential element that is toxic to plants, and is an animal and human carcinogen (affecting the kidneys and bones in vertebrates). Since the late-1970s the effects of cadmium on the environment have become a global issue of concern, and many countries have conducted evaluations on the exposure of their populations to cadmium in phosphate fertilizer (a major non-point source of anthropogenic cadmium). A scoping project, funded by the Water Research Commission, aimed to review cadmium contamination of South African aquifer groundwater systems (predominantly) via phosphate fertilizer use. Topics reviewed included fertilizer composition and types, metal speciation, metal mobility in soil and groundwater systems, metal bioavailability, health and environmental effects, and local South African contamination case studies. A preliminary study site, namely the greater Hermanus region, was identified for trace metal and groundwater quality studies (which incorporated urban and agricultural areas in various hydrogeological settings). Hermanus was selected due to: 1) the discovery of cadmium concentrations of 20 ?g/l (in comparison to the SANS 241-1:2011 cadmium limit of 3 ?g/l) in a golf estate irrigation borehole, during drilling and test-pumping of the borehole at the end of 2012
Oudtshoorn Groundwater Project: Exploratory drilling results from the Blossoms Wellfield	Dylan	Blake	Eastern Cape	2015
Abstract {List only- not presented}
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.
Groundwater Resource Assessment Of The Malmani Subgroup Dolomites Within The Olifants River Water Supply Scheme	Dylan	Blake	Limpopo, Mpumalanga	2017	wellfields, Conjunctive use, artificial recharge
Abstract The 2011 Olifants River Water Supply Scheme (ORWSS) Reconciliation Strategy recommended that the Malmani Subgroup dolomites along the Limpopo-Mpumalanga escarpment be investigated as a potential groundwater resource for input into the ORWSS. The Department of Water and Sanitation - Directorate: Water Resource Planning Systems (DWS D: WRPS) in turn initiated a 2-year project that began in mid- 2016 to develop a feasibility plan for the groundwater resource development of the Malmani Subgroup dolomites within the ORWSS, with the main aims of the project being: 1) to secure groundwater as a long- term option to augment the water supply to the ORWSS by optimising surface water-groundwater conjunctive use; and 2) to determine the artificial recharge potential of the dolomitic (and/or other) aquifers within the ORWSS. The ~2000 m thick, Late Archaean (~2.6-2.5 billion year old) Malmani Subgroup is comprised of stromatolite-bearing dolomites and limestones (i.e. chemical sediments including chert, with some local clastic shale and quartzite), and forms part of the Chuniespoort Group (lower Transvaal Supergroup) with the overlying banded ironstones of the Penge Formation, and mudstones, dolomites and limestones of the Duitschland Formation. The Malmani Subgroup dolomites (and Transvaal Supergroup as a whole) have undergone deformation, fracturing/faulting and dyke intrusion by a range of tectonic events (including the Bushveld Complex intrusion and slumping, Vredefort meteorite impact, “Transvaalide fold-and-thrust belt”, Pan African Orogeny, Gondwana breakup and current East African Rift development), which have resulted in the development of a high yielding (>10 l/s sustainable yields and transmissivities of ~500-2500 m2 /day per borehole in the vicinity of large regional faults/fractures or dolerite intrusions) fractured dolomitic karst aquifer. Quaternary alluvial deposits (of up to 30-40 m thickness) also occur within valleys incised into the Malmani Subgroup at Fertilis (Mohlapitse River), Penge (Olifants River and associated tributaries), Ga-Maditsi (Steelpoort River), and along the Ohrigstad, Blyde and Treur River valleys. Groundwater quality within the Malmani Subgroup dolomitic aquifers in the ORWSS area is generally good (EC of <70 mS/m), however poorer water quality can be present (e.g. elevated EC, nitrates and trace metals) as a result of contamination from human settlements, agricultural irrigation, mining, and recharge from contaminated surface water e.g. the Olifants and Steelpoort Rivers. Current work completed/being undertaken as part of the project includes: identification of two preliminary regional hydrogeological targets and twelve related wellfield target zones (WFTZ); hydrocensus of selected DWS NGA and GRIP boreholes within these two preliminary targets; re-testing of selected high yielding GRIP boreholes at constant discharge rates of 20-25 l/s, and re-analysis of existing GRIP Malmani Subgroup data; macrochemical and dissolved trace metal analysis of groundwater chemistry from tested and drilled boreholes; development of a regional groundwater balance model to determine the groundwater potential per WFTZ; surface-groundwater interaction and artificial recharge assessments (the latter focusing on alluvial deposits overlying the Malmani Subgroup dolomites); identification of potential wellfield sites within the WFTZs based on structural analysis, measured aquifer parameters, groundwater potential and geophysics; numerical groundwater modelling; and drilling/testing of exploration/monitoring boreholes within selected wellfield sites.
Celebrating hydro-geoheritage – the Table Mountain Dams Trail and Hermanus Water Walk (Western Cape, South Africa)	Dylan	Blake	South Africa	2023	Hydro-geoheritage, Water supply, Table Mountain Group aquifers, Cape Town, Hermanus, Social Hydrogeology
Abstract Hydrogeology and hydrology are commonly overlooked aspects of geoheritage, despite strong geological links. Water in all its forms has played a critical role in the development of Earth, and the shaping of its landforms (in addition to sustaining all life on the planet), and access to water has been the core reason for the establishment of numerous human settlements. The evolution of a settlement’s water supply tracks its development history across the Holocene, providing an excellent tool for teaching the public about human interactions with the Earth and our shared future going forward in a changing climate. To this extent, two self-guided trails (with associated guidebooks and mobile apps) have been developed in areas of the Western Cape province of South Africa with rich water supply histories and hydro-geoheritage – the Table Mountain Dams Trail in Cape Town and the Hermanus Water Walk in the Overberg region. The surface and groundwater supply systems that both trails cover have an inherently unique link with the Ordovician-Devonian Table Mountain Group fractured aquifer systems (including the complex tectonic and geomorphic evolutionary history that has led to the present landscapes), which most residents and international visitors are generally unaware of (despite being major tourist regions in South Africa). It is envisioned that through these guides/trails, the reader/walker will gain a better understanding of/appreciation for the value of water, a greater feeling of ownership for the natural history of the city/region they reside in, and will strive to preserve associated hydro-geoheritage for future generations.
Groundwater Development Of The Table Mountain Group Aquifers As Part Of The City Of Cape Town's New Water Programme	Dylan	Blake	Cape Town	2019	TMG, development
Abstract The original City of Cape Town (CCT) Table Mountain Group (TMG) Aquifer Feasibility Study and Pilot Project was initiated in 2002, the purpose being to evaluate the feasibility of augmenting the CCT's bulk water supply using groundwater from the TMG (specifically the fractured Peninsula and Nardouw Aquifers). CCT TMG groundwater exploration/development was fast tracked under the "New Water Programme" (NWP; from 2017-present) as a result of two interrelated water scarcity/demand factors, namely periodic drought (including the major 2015-2017 1:590-year event) and rapid urban growth. Initial NWP TMG groundwater development (including additional exploration via detailed geological mapping and heliborne geophysics) has occurred in the vicinity of the CCT-operated Steenbras Dam, in the form of a minimum 15-20 Ml/day wellfield scheme. The planned "Steenbras Wellfield" targets both TMG aquifers along the Steenbras-Brandvlei Megafault Zone on the southeastern limb of the Steenbras Syncline (which regionally occurs within the high groundwater potential Cape Fold Belt Syntaxis). Current drilling activities have included ultra-deep (up to 975 m depth, representing the deepest groundwater-specific boreholes outside of mining/resource activities in South Africa), wide diameter abstraction (using rotary air percussion, reverse circulation and hydraulic/water hammer techniques) and core exploratory boreholes into both TMG aquifers. Tested abstraction borehole yields range between 10-70 l/s, while artesian-discovery core holes into the Peninsula Aquifer from Steenbras towards Theewaterskloof Dam have surface pressures and flows of up to 800 kPa and 4 l/s respectively (from BQ-sized holes intersecting water strikes between 840-910 m). Further CCT TMG groundwater exploration and wellfield scheme development (potential total combined supply of ~50-150 hm3/a or ~140-400 Ml/day) is planned along major TMG structures within the Grabouw-Eikenhof and Theewaterskloof basins, Wemmershoek, Voelvlei, Berg River and the CCT South Peninsula region. This has, and will continue to include, monitoring of surface/groundwater-dependent ecosystems as a geo-ethical approach to minimise ecological/environmental impact.
Integrated Modelling of the Hydrological Dynamics of the Semi-arid Hout-Sand Catchment, South Africa	E	Bjerre	South Africa	2023	drylands, conceptual flow model, integrated dynamic hydrological modelling, water resources, assessment and management
Abstract The interaction between dryland hydrological fluxes and the high spatial and seasonal climate variability is inherently complex. Groundwater recharge is episodic, and rivers are ephemeral. When flow occurs in the river network, water is lost through the riverbed, giving rise to focused recharge, which could be a significant part of total recharge. We have used the integrated and physically based MIKE SHE modelling system to analyze the hydrological processes and fluxes in the 7,715 km2 Hout-Sand catchment in the South African part of the Limpopo River Basin. The discharge hydrograph measured at the outlet station is highly episodic, with a small baseline flow component superimposed by high flow events in response to intense rainfall. Likewise, the groundwater hydrographs from the area are characterized by rapid increases in groundwater levels in response to high rainfall events with recurrence intervals of several years. Due to the scarcity of basic measurements and information, we used data products from satellite platforms to supplement the information on rainfall, evapotranspiration, soil moisture, land use and irrigated areas. We applied MIKE SHE to test different conceptual flow models of the catchment by calibrating the different models against direct measurements of river discharge and groundwater levels and indirect estimates of evapotranspiration and soil moisture from satellite products. By analyzing the simulated model dynamics and the resulting values for the calibration parameters, we identified the most plausible conceptual model, which then forms the basis for water resources assessment and management recommendations for the Hout-Sand catchment.
The impact of groundwater temperature on water quality in the urban aquifer of the city of Vienna	E	Kaminsky	Vienna	2023	groundwater temperature, groundwater-surface water interaction, trends, Water chemistry
Abstract Rising shallow groundwater temperatures are observed in many cities worldwide and are expected to increase further over the next century due to anthropogenic activities and climate change. The impact of groundwater temperature increase on groundwater quality is poorly understood. This study conducted two high-spatial-resolution campaigns in Vienna (Austria, autumn 2021/ spring 2022). At 150 wells, a comprehensive parameter set (e.g. major ions, nutrients, and water stable isotopes) was analyzed in groundwater collected, and at 812 wells, the water temperature was measured. Results are compared to available long-term data on groundwater chemistry (1991-2020). In theory, temperature triggers a cascade of effects, where, finally, the depletion of dissolved oxygen (DO) causes a switch to anaerobic microbial processes and a deterioration of water quality. No direct relation between DO and water temperature was observed between 10 and 20 °C. However, many wells delivered anoxic groundwater, including the one with the highest measured temperature (27 °C). The highest temperatures were consistently observed near potential heat sources (local scale), with a rapid decrease in temperature with increasing distance from these sources. Long-term data from particular high-temperature wells revealed decreased dissolved oxygen after sudden temperature changes of > 5 K. On a regional scale, it is observed that groundwater-surface water interactions and aquifer properties play a pivotal role in oxygen availability and redox conditions. In conclusion, high-spatial-resolution sampling combined with long-term data analysis is needed to determine the impact of temperature on water quality.
Peculiarities of the chemical composition of the Ordovician aquifer as a source of potable water supply (St. Petersburg, Russia)	E	Kayukova	St. Petersburg, Russia	2023	aquifer properties, ground water contamination, radon, saturation index
Abstract The Ordovician aquifer of the Izhora deposit is widely used for drinking by the population of St. Petersburg and its suburbs. Carbonate Ordovician rocks are intensively karstified. The water is fresh (0,5-0,8 g/l), bicarbonate-calcium on the predominant ions, pH 7.6; calcium content is 50-80 mg/l, magnesium content is 30-60 mg/l and the total hardness is 7,6-8,0 mg-equ./l. Western, northern and northeastern boundaries of the Izhora deposit go along the Baltic Klint, which is evident on the relief. Its southern boundary is along the zone of the dip of Ordovician limestone beneath the Devonian sandstone. The territory of the Izhora plateau belongs to the areas of intensive economic activity. Often, objects of human economic activity are located near drinking water intakes. Almost all sites are marked by excess sanitary norms of chemical elements. Pollution of groundwater in the Ordovician aquifer has been identified in some areas. Priority substances have been identified for assessing the quality of groundwater: total hardness, Fe, Mn, Ba, and B. According to hydrochemical modelling data, Ordovician groundwater is saturated with calcite over most territory. There are many springs of underground water along the Baltic Klint, for example, near the village of Lopukhinka, Duderhof springs and others. The springs waters have natural radioactivity (due to the contact of groundwater with dictyonema shales), which makes their use hazardous to human health.
Development and calibration of tools for preliminary quantification of the Hydrogeological Interference Risk of tunnels in different geological settings	E	Pugliese	Italy, Switzerland	2023	Hydrogeological Risk, potential inflow, tunnel, Machine learning
Abstract Predicting and quantifying the hydrogeological interference of big underground works is a complex effort. This is due to the considerable uncertainty in estimating the key geomechanical and hydrogeological parameters affecting the area of potential interference of the projects. Moreover, the pattern of involved groundwater flow systems is hardly identified, either in natural or disturbed conditions. Base tunnels through mountain ridges are particularly complex in their interactions with groundwater. Several approaches and tools have been published to predict the magnitude and distribution of water inflows inside tunnels and their impact on many receptors (springs, rivers, lakes, wells, groundwater-dependent ecosystems). The research, co-funded by Italferr Spa (Italian railway national company for tunnel design), deals with calibrating and validating these methods based on huge datasets. Main engineering companies provided data from completed base tunnel projects. In particular, in this study, the Drawdown Hazard Index (DHI) method has been calibrated with a dataset of a 15 km long sector of the Gotthard base tunnel drilled through a crystalline geological setting. The calibration involved only the Potential Inflow (PI) parameter to verify the matching between the probability of inflow and the actual output of the excavation, according to the available data in the preliminary stage of the project. An alternative tool based on a machine-learning approach was then applied to the same dataset, and a comparison was presented.
How can collective groundwater resource management solutions benefit water governance at various levels? An example in a volcanic watershed in East Java, Indonesia	E	Cut	Indonesia	2023	groundwater governance, district level, collective solutions, stakeholders, volcanic watershed, Java Indonesia
Abstract On the slopes of Mount Bromo, East Java (Indonesia), the land use of the Rejoso watershed is dominated by rice fields and sugarcane ( lowland area ), agroforestry (midstream) and horticulture and pine plantation in the upstream part. During the last three decades, some land changes driven by socio-economic development, with conversion of agroforests to rice fields, tree monoculture and horticulture, and the development of urban areas nearby, increased pressure on the watershed. Intensive irrigated rice cultivation is using groundwater from free-flowing artesian wells. Due to a lack of management, the hydraulic head and discharge of the major spring are decreasing. Rejoso watershed, like others in urban and rural areas in Indonesia, is facing challenges to guarantee sustainable integrated water resources management. Collective solutions have been implemented between 2016 and 2022 within this watershed. In the downstream, sustainable paddy cultivation and wells management with local stakeholders, aiming at improving water efficiency, have been piloted on 65 ha with 184 farmers. Water governance at the district level was re-activated and strengthened thanks to the project. Various capacity-building tools were used via radio talk shows and workshops. Members of the watershed forum of Pasuruan took some actions to reshape the structure and set up a roadmap. The implementation of collective solutions in the field was a real catalyst and serves all levels of water governance, as it is replicable. This example will be explained and illustrated after the presentation of the socio-hydrogeological context.
Application of Environmental Tracers for Differentiation of Fresh and Re-Circulated Submarine Groundwater Discharge (Sgd) Into Knysna Estuary, South Africa	E.	Petermann	Knysna Estuary, South Africa	2017	Environmental tracers, Submarine Groundwater Discharge
Abstract In coastal areas worldwide terrestrial groundwater resources and the coastal sea are generally hydraulically connected thus allowing continuous groundwater/seawater interaction. This major form of land-ocean interplay is associated with two potential pathways of dissolved matter transport, namely (1) flux from the marine to the terrestrial environment in form of seawater intrusion into terrestrial aquifers and (2) flux of terrestrial groundwater into the coastal ocean manifested as submarine groundwater discharge (“SGD”). The sea-to-land pathway is of relevance due to the risk of irreversible salinization of coastal groundwater resources and is in most cases a manmade (and hence manageable) phenomenon set off by excessive groundwater exploitation that is not balanced by groundwater recharge. The land-to-sea pathway (i.e. SGD), on the other hand, occurs naturally everywhere an aquifer with a positive hydraulic head is connected to the ocean. It is of interest due to two potential threats, namely (i) the loss of freshwater to the ocean, an issue that is particularly relevant in climate zones characterized by water scarcity, and (ii) the detrimental impact of nutrient- or contaminant-laden groundwater discharge on the coastal water quality, an aspect that is of relevance along urbanized coastlines worldwide. The latter implies that SGD localization and quantification is of major relevance with regard to (i) the evaluation of the vulnerability of the coastal sea to groundwater pollution and for (ii) understanding the associated matter cycles including nutrients, organic compounds or inorganic contaminants. We present results of an environmental tracer based approach that aimed at evaluating short-term SGD dynamics into the Knysna estuary, South Africa. Both natural components of SGD, terrestrial freshwater (FSGD) and recirculated seawater (RSGD), were estimated individually. We conducted an end-member mixing analysis for time series of radon (222Rn) and salinity over two tidal cycles in order to determine four water fractions within the estuary: seawater, river water, FSGD and RSGD. The results were backed by stable isotope data (18OH2O and 2HH2O). End-member mixing ratio analyses revealed the mixing ratios that fit best to the observations at every time-step of the 24 h time series, which was carried out near the estuary mouth. Results indicated highest FSGD and RSGD fractions in the estuary water during low tide amounting to 0.2 % and 0.8 % for FSGD and RSGD, respectively. A radon mass balance for the whole estuary revealed a radon flux via SGD of 41 ± 7 Bq m^-2 d^-1, which equals a total FSGD of 4.6 10⁴ m³ d^-1 and RSGD of 1.5 10⁵ m³d^-1 . The results do imply that the majority of nutrient fluxes (DIN) into the estuary are SGD-derived.
Investigation of the probable infiltration from the wastewater ponds and its impact on the water quality of Pleistocene aquifer	EL-Said	Ahmed AL-Sayed Ragab	El Sadat	2015	Electrical Resistivity Tomography
Abstract 2-D Electrical Resistivity Tomography (ERT) and hydrochemical study have been conducted at El Sadat industrial city. The study aims at investigating the area around the waste water ponds to determine the possibility of water percolation from the wastewater (oxidation) ponds to the Pleistocene aquifer and to inspect the effect of this seepage on the groundwater chemistry. Pleistocene aquifer is the main groundwater reservoir in this area, where El Sadat city and its vicinities depend totally on this aquifer for water supplies needed for drinking, agricultural and industrial activities. In this concern, 7 ERT profiles were measured around the wastewater ponds. Besides, 10 water samples were collected from the ponds and the nearby groundwater wells. The water samples have been chemically analyzed for major cations (Ca+2, Na+, K+, Mg+2), major anions (Cl-, CO3-2, HCO3-, SO4-2), nutrients (NO2-, NO3-, PO4-3) and heavy elements (Cd, V, Cr, Zn, Ni, Cu, Fe, Mn, Pb). Also, the physical parameters (pH, Alkalinity, EC, TDS) of the water samples were measured. Inspection of the ERT sections shows that they exhibit lower resistivity values towards the water ponds and higher values in opposite sides. Also, the water table was detected at shallower depths at the same sides of lower resistivity. This could indicate a wastewater infiltration to the groundwater aquifer near the oxidation ponds. Correlation of the physical parameters and ionic concentrations of the wastewater (ponds) samples with those of the groundwater samples indicates that; the ionic levels are randomly varying and no specific trend could be obtained. Also, the wastewater samples shows some ionic levels lower than those detected in other groundwater samples. Besides, the nitrate level is higher in samples taken from the cultivated land than the wastewater samples due to the over using of nitrogen fertilizers. Then, we can say that the infiltrated water from wastewater ponds are NOT the main controller of the groundwater chemistry in this area, but rather the variable ionic concentrations could be attributed to local, natural and anthropogenic processes.
A review of groundwater resource protection measures in South Africa	Eberhard	Braune		2015

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.
Southern African Pre-Cretaceous Deep Groundwater Flow Regimes: Evidence And Drivers	Eddie	Van Wyk	South Africa, Botswana, Namibia	2013	groundwater flow, deep drilling
Abstract After drilling technology improvements in South Africa in the early 1900s, several deep (>300 m) exploratory drilling programmes were conducted to explore for pressurised groundwater resources. The results were not significant, except for the Cretaceous Uitenhage Artesian Basin and recent investigations in folded Table Mountain Group Aquifer systems. Large sedimentary units in Southern Africa do have the structural geometry to drive regional artesian systems; however, diverse climate and aquifer hydraulic limitations counteract these conditions to such a level that sustainable basin- like deep flow mechanisms are probably non-existing, except where enhanced by deep mining activities. On the contrary, several deep drilling projects in South Africa, Botswana and Namibia have undoubtedly proven the existence of pressurised groundwater strikes below 300 m (northern Kalahari) to as deep as 3 000 m (western Karoo Basin). Given the regional hydrogeological characteristics of these systems, the availability of sufficient recharge zones required to drive sustainable artesian flow or semiartesian conditions becomes a challenge. The existence of isolated pressurised compartments as a result of the lithostatic pressurisation in the deeper sections of many of the sedimentary successions may prove to be a more realistic explanation for these pressurised water strikes observed during deep drilling operations in Southern Africa.
A management plan towards the flooding of an opencast mine with adjacent underground sections.	Eelco	Lukas	Mpumalanga	2015
Abstract The colliery is situated in the Mpumalanga Coalfield, north of Trichardt in the Republic of South Africa. The opencast is already rehabilitated but still acts as an entrance to the underground sections of the mine. The Life of Mine indicates active mining until 2035. We were tasked to develop a mine closure plan. Two surface drainage systems are present, namely the Trichardt Spruit and the Steenkool Spruit. Both these systems have been diverted locally around the opencast with the necessary permission, to maximize coal extraction and protect the environment. Several passive treatment options were tabled to minimise the post closure environmental contamination. After careful consideration it was decided to develop a mine flooding plan to exclude oxygen from the mine thereby minimising the sulphate generation inside the opencast and underground sections. To start flooding as early as possible, sections of the underground mine were identified as natural or artificial compartments to store water. The rehabilitated opencast is flooded using recharge water from rainfall. The capacity of the rehabilitated open pit is enlarged to evaporate all the excess water in the pit making the need for a treatment plant unnecessary.
Selling the invisible: Communicating the Groundwater Message	Elanda P	Botes		2015	stakeholder communication, strategy, policy implementation
Abstract As we look at the legislation set out in the driving policies and its guiding frameworks, the need for able institutions to implement strategies that promise and deliver social growth and development, are highlighted. It is only possible to define an 'able institution' through its ability to fulfil its function and enable stakeholders to be part of the decision-making process. (Goldin, 2013) It is this relationship with the collection of stakeholders, in particular strategic water resource stakeholders, their linkages as well as the identification of specific stakeholder issues, that are critically reviewed. The recent Groundwater Strategy (2010) identified key strategic issues/themes. Each chapter listed a number of well thought out recommended actions that address specific challenges in each theme. It is the need for strategic direction (to put these strategies in place "plans into action") and to articulate the specific vision in the right context to the different stakeholders, (internal as well as external) that requires thinking. It is also the uptake of this information by publics (social action and intervention) and the impact of new learning that will need to be measured. This paper will present on a study where the groundwater sector and all its stakeholders are strategically examined to understand the process of communal thinking in the current environmental conditions. It would draw from current communication practices, style, strengths, sector experiences and trends and also reference specific and unique experiences as with the recent WRC Hydrogeological Heritage Overview: Pretoria project. {List only- not presented}
How groundwater temperature is affected by climate change: a systematic review and meta-analysis	Elena	Egidio	Italy	2023	Climate change, Groundwater, groundwater temperature, review, temperature
Abstract Groundwater (GW) is a target of climate change (CC), and the effects become progressively more evident in recent years. Many studies reported the effects on GW quantity, but of extreme interest is also the assessment of qualitative impacts, especially on GW temperature (GWT), because of the consequences they could have. This study aims to systematically review the published papers dealing with CC and GWT, to determine the impacts of CC on GWT, and to highlight possible consequences. Scopus and Web of Science databases were consulted, obtaining 144 papers. However, only 45 studies were considered for this review after a screening concerning eliminating duplicate papers, a first selection based on title and abstract, and an analysis of topic compatibility through examination of the full texts. The analysed scientific production from all five continents covers 1995-2023 and was published in 29 journals. As a result of the review, GWT variations due to CC emerged as of global interest and have attracted attention, especially over the past two decades, with a multidisciplinary approach. A general increase in GWTs is noted as a primary effect of CC (especially in urban areas); furthermore, the implications of the temperature increase for contaminants and groundwater-dependent ecosystems were analysed, and various industrial applications for this increase (e.g. geothermy) are evaluated. It’s evident from the review that GWT is vulnerable to CC, and the consequences can be serious and worthy of further investigation.