Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 1 - 50 of 795 results

Title	Presenter Name	Presenter Surname	Conference year	Keywords
Exploring The Potential Of The GRACE Derived Groundwater Drought Index (GGDI) To Forecast Groundwater Drought In South Africa	Kopano	Mokoena	2019	GRACE, Drought
Abstract Water has been recognized and acknowledged as a fundamental natural resource that sustains environmental diversity, social and economic development (Liu et al., 2017; Fisher et al., 2017). With increasing populations, climate change and limited monitoring networks for both ground and surface water, freshwater resources are becoming difficult to assess due to rapid changes in water supply and uses. Several efforts have been devoted towards the monitoring and management of water resources and discovery of alternative sources of freshwater. One of the more recent efforts is using gravity information to track changes in water storage on the earth's surface. The Gravity Recovery and Climate Experiment (GRACE) mission (https://www.nasa.gov/mission_pages/Grace/index.html) holds great potential for assessing our water resources in areas with little monitoring data. The increasing interest in the use of GRACE as a water resource information and monitoring tool, is due to its cost effectiveness and user-friendly system which affords a broad understanding of the world we live in and its processes, specifically in water resource management and hydrological modelling. South Africa's National Water Act (NWA) of 1998 highlights the importance of the sustainable development of water resources. However, it is difficult to sustainably manage South Africa's groundwater resources due to the difficultly in measuring and understanding our complex aquifers. The challenges in establishing sustainable monitoring of groundwater resources and its Reserve, are due to insufficient knowledge about the contribution that groundwater makes to surface water, and methods which reliably monitor groundwater resources. The GRACE is a joint satellite mission by the Deutschen Zentrum fur Luftund Raumfahrt (DLR) in Germany and the United States National Aeronautics and Space Administration (NASA). The satellite was launched on 17 March 2002 and provides monthly temporal differences of earth's gravity field and its mean gravity field (Schmidt et al., 2008). It can afford insights into the location of groundwater resources, and their changes. GRACE can however, only determine the change in total water storage and therefore information on other components of the water balance are required to isolate the groundwater component. Therefore, the integrated Pitman Model is ideal to be applied together with GRACE and the Model can isolate surface water, soil moisture and groundwater into various components. Many studies have evaluated GRACE-derived groundwater storage changes as a response to drought (Famiglietti et al. 2011; Scanlon et al., 2012), while Thomas et al. (2017b) evaluated a groundwater drought index based on GRACE observations in an effort to understand and identify groundwater drought. Typically, GRACE is applied at scales of 150 000 km2, however Thomas et al., (2017) has developed a recent method that allows for the application of his GRACE derived Groundwater Drought Index (GGDI) at smaller scales. This study applies Thomas et al. 2017 GGDI in South Africa to the Crocodile, Sedgefield and Doring catchments, in hopes to to evaluate drought characterisation using data from GRACE satellites, focusing on the total water storage deficits to characterise groundwater drought occurrence.
Characterising The Hydrological Regime Of The Rietvlei Wetland: Implications For Ecohydrology	Nathasha R	Gariremo	2019	Poster, ecohydrology
Abstract In the following study, the soil and groundwater regime of the Rietvlei wetland near Cape Town are characterised. This has been done by means of logging the subsurface material during the construction of 8 shallow wells, complimented with field observations, and surveying the dug wells. The water stemming from these wells was sampled and analysed for Oxygen 18 and Deterium. Downhole salinity logs of the wells were also undertaken and rainfall samples were analysed for the aforementioned stable isotopes. Results indicate a distinct relationship between elevation and soil structure. Through the use of the water table method, it was found that the relationship between elevation and soil moisture had a direct impact on spatially distributed groundwater recharge on an event basis. Furthermore, higher salinities were found with depth in groundwater in the same wells which had higher recharge values. Isotopic results indicate that groundwater all stems from rainfall, with the exception of Well 8 is influenced by the river due to its proximity to the surface water body. The various water chemistries and soil profiles have a direct impact on the type of flora and its distribution throughout the study area. This study managed to conceptualize the relationship between groundwater, soil profiles and the various plant types surviving in the Rietvlei wetland. Future studies can focus on computer based approaches in order to predict how changes in groundwater characteristics caused by natural or anthropogenic factors would affect other ecohydrological processes within the wetland. These findings can be incorporated in decision making processes concerning groundwater management.
Study on the Relationship between Water Quality and Wetland Plant Community in Huixian Karst Wetland	L	Shen	2023	Huixian Karst Wetland, Water quality, Wetland Plant Community
Abstract Huixian Karst National Wetland Park is the most typical karst wetland in the middle and low latitudes of the world and has become an internationally important wetland. The relationship between water quality and aquatic organisms in Huixian Wetland is a hot research topic in wetland ecology. This article focuses on the relationship between the current water quality situation in Guilin Huixian Karst Wetland and the growth of wetland plants. Sixteen sampling points are set up in the wetland to monitor and analyze water quality in wet, normal, and dry seasons. The Kriging index interpolation method is used to obtain a comprehensive water quality interpolation map in the survey area during normal water periods and in combination with the wetland plant survey sample data and the landscape status. A comprehensive analysis of the relationship between wetland plant growth and water quality. The results show that the centre of Huixian Wetland receives recharge from surrounding groundwater, which is greatly affected by the surrounding water quality. The comprehensive water quality is relatively good in the dry season, relatively poor in the normal season, and the worst in the wet season. Agricultural production, non-point source pollution, rural domestic sewage, and human interference affect wetland water quality, which directly affects the structure and function of plant communities and the ecological service function of wetlands.
Change, Challenge And Opportunity – Some Reflections On Hydrogeology Education, The Sustainable Development Goals And Global Change	B	Misstear	2017	education, training, IAH, Strategic Overview papers, SDGs
Abstract This keynote paper addresses several issues central to the conference theme of “Change, Challenge and Opportunity”. For hydrogeologists to exert greater influence on groundwater management globally, proper education and training is essential. Universities play a key role in educating hydrogeologists in the fundamental principles of groundwater science through taught Masters and other degree programmes. Scientific associations such as the International Association of Hydrogeologists (IAH) also have an important part to play in education and training through short courses, conferences and mentoring schemes, and in enhancing groundwater science through journal and book publications and scientific commissions. IAH’s mission is to promote the wise use and protection of groundwater and, in this respect, a series of Strategic Overview papers have been prepared to inform professionals in other sectors of the interactions between groundwater and these sectors. Two of the Strategic Overview papers focus on the SDGs and global change, and some of the groundwater challenges in these areas are described. Whilst these challenges will provide hydrogeologists with opportunities to influence global water issues in the 21st century, hydrogeologists will need to be able to communicate effectively with all of the stakeholders, using traditional and more modern forms of communication, including social media.
Hydrogeochemical processes in the shallow aquifer of the Lubumbashi river basin: multivariate statistical approach	Lumu	Moussa Antoine	2015
Abstract Understanding the hydrogeochemical processes that govern groundwater quality is important for sustainable management of the water resource. A study with the objective of identifying the hydrogeochemical processes and their relation with existing quality of groundwater was carried processes in the shallow aquifer of the Lubumbashi river basin. The multivariate statistical approach includes self organizing maps (SOM'S) of neural networks, hierarchical cluster (HCA) and principal component analysis of the hydrochemical data were used to define the geochemical evaluation of aquifer system based on the ionic constituents, water types, hydrochemical facies and groundwater factors quality control. Water presents a spatial variability of chemical facies (HCO3- - Ca2+ - Mg2+, Cl- - Na+ + K+, Cl- - Ca2+ - Mg2+ , HCO3- - Na+ + K+ ) which is in relation to their interaction with the geological formation of the basin. The results suggests that different natural hydrogeochemical processes like simple dissolution, mixing, weathering of carbonate minerals and of silicate weathering and ion exchange are the key factors. Added to this is the imprint of anthropogenic input (use of fertilizers, septic practice poorly designed and uncontrolled urban discharges). Limited reverse ion exchange has been noticed at few locations of the study.
The importance of rainfall data in water resource planning and risk management	Nicolette	Vermaak	2015	rainfall data
Abstract Water resource management and risk management rely heavily on the availability of data and information. This includes the volumes of water needed, the volumes of water available, where the available water is and where it would be needed, etc. Historical records help to determine past use and gives a way to predict future use in the case of water resource planning while it helps to predict the possibility of floods and droughts when it comes to risk management. Rainfall data can provide valuable data for both water resource planning and risk management, since it is the input to the hydrologicalcycle. It is possible to determine dry and wet cycles using the cumulative deviation from mean that is calculated from the measured rainfall data. This was done for the Gnangara Mound in Australia, with the results giving a fair representation of the dry and wet cycles in the area. Data measured over a period of about 30 years for the Zachariashoek sub-catchment analyzed in the same fashion provided wet-dry cycles of about 8 years. The rainfall measurements had been taken at various settings around the catchment, and varied from place to place and differed from that measured at the WeatherSA stations in the vicinity. This article will draw a comparison between the Zachariashoek data and the WeatherSA data to determine whether the WeatherSA data followed the same patterns for the wet-dry cycles observed in Zachriashoek. It will then analyse the longer data record available for the WeatherSA data from 1920 to 2012. It is expected that the shorter wet-dry cycles seen in Zachariashoek will become part of longer wet-dry cycles that can be used in water resource planning and risk management. Rainfall is also dependent on a number of factors
Comparitive analyses between LAK3 package and the high K techniques used for numerical simulation of lake-aquifer interactions	Jannie	Weitz	2015
Abstract Modelling of groundwater systems and groundwater-surface water interaction using advanced simulation software has become common practice. There are a number of approaches to simulate Lake-aquifer interactions, such as the LAK Package integrated into MODFLOW, the high conductivity and fixed stage approaches. LAK and the high conductivity approaches were applied and compared in simulating Lake- aquifer interaction in the Lake Sibayi Catchment, north-eastern, South Africa using the finite difference three-dimensional groundwater flow model, Visual MODFLOW Flex under steady state conditions. The steady state model consisted of two layers: an upper layer consisting of the Sibayi, KwaMbonambi, Kosi Bay and Port Durnford Formations which have similar characteristics, and a lower model layer representing the karst, weathered and calcareous Uloa Formation. The bottom model boundary is constrained by the impermeable Cretaceous bedrock. The model area covers the surface and groundwater catchments of Lake Sibayi which is constrained in the east by the Indian Ocean. A no-flow boundary condition is assigned to the northern, western and southern sides and a constant head boundary is assigned to the eastern side. The Mseleni River and neighbouring plantations were modelled using the River and Evapotranspiration boundary conditions respectively. Input parameters for the various boundary conditions were obtained from the previously developed high resolution conceptual model, including recharge
Review of Groundwater Use in Varying Climatic Conditions	Lindelani	Lalumbe	2019	Poster, Climate
Abstract Groundwater levels in E33F quaternary catchment are at their lowest level ever. The impact of climatic variation and increasing abstraction were determined to be the main factor. There are 115 registered groundwater users in E33F and the monthly abstraction volumes are not being measured. There is a need to use land use activities as well as the population to estimate groundwater use. The main objective is to use non-groundwater monitoring data to estimate groundwater use in order to protect the aquifer and ecosystem in general in varying climatic condition. Land use activities information was used to estimate groundwater use in E33F quaternary catchment. The estimated groundwater use volumes were compared to allocated and measured volumes. For domestic groundwater use estimation, population data and an estimation 100 litre per person per day were used. The water requirements for the types of crops being cultivated together with the area (m2) were used to estimate groundwater use volumes for irrigation. The number and type of live stocks were used with the water requirements for each livestock type to estimate the groundwater use volumes. 96 % of groundwater users are using groundwater for irrigation purposes with 9 966 105 m3/a allocated for irrigation. Mining, industries, domestic and livestock are allocated 100 200 m3/a. The estimated groundwater use volume for irrigation is 30 960 000 m3/a, which is three times higher than the allocated volume. Groundwater use volume for domestic use is estimated to be 38 225 m3/a which is higher than the 31 000 m3/a allocated. The total estimated groundwater use volume in E33F is estimated to be 30 998 225 m3/a, which is three times higher than the allocated groundwater use volume of 10 066 305 m3/a. This estimation could be higher as only registered boreholes were used and estimations from mining, Industries and live stocks were excluded due to lack of data
The Groundwater Data Acquisition and Management Strategy for the Department of Water and Sanitation	Mxolisi	Mukhawana	2015
Abstract Data acquisition and Management (DAM) is a group of activities relating to the planning, development, implementation and administration of systems for the acquisition, storage, security, retrieval, dissemination, archiving and disposal of data. Data is the life blood of an organization and the Department of Water and Sanitation (DWS) is mandated by the National Water Act (No 36 of 1998) as well as the Water Services Act (No 108 of 1997), to provide useful water related information to decision makers in a timely and efficient manner. In 2009 the DWS National Water Monitoring Committee (NWMC) established the DAM as its subcommittee. The purpose was to ensure coordination and collaboration in the acquisition and management of water related data in support of water monitoring programs. The DAM subcommittee has relatively been inactive over the years and this has led to many unresolved data issues. The data extracted from the DWS Data Acquisition and Management Systems (DAMS) is usually not stored in the same formats. As a result, most of the data is fragmented, disintegrated and not easily accessible, making it inefficient for water managers to use the data to make water related decisions. The lack of standardization of data collection, storage, archiving and dissemination methods as well as insufficient collaboration with external institutions in terms of data sharing, negatively affects the management water resources. Therefore, there is an urgent need to establish and implement a DAM Strategy for the DWS and water sector, in order to maintain and improve data quality, accuracy, availability, accessibility and security. The proposed DAM Strategy is composed of the six main implementation phases, viz. (1) Identification of stakeholders and role players as well as their roles and responsibilities in the DWS DAM. (2) Definition of the role of DAM in the data and information management value chain for the DWS. (3) Development of a strategy for communication of data needs and issues. (4) Development of a DAM life Cycle (DAMLC). (5) Review of existing DAMS in the DWS. (6) Review of current data quality standards. The proposed DAM Strategy is currently being implemented on the DWS Groundwater DAM. The purpose of this paper is to share the interesting results obtained thus far, and to seek feedback from the water sector community.
Packer Testing and Analytical Modelling For Groundwater Inflow Estimation for Proposed Shafts	Robel	Gebrekristos	2015
Abstract Two ventilation shafts were proposed to be excavated to depths of 100 and 350 m to intersect an underground mine, in the Bushveld Complex. The area is made up of fractured aquifers and the assignment was to identify the exact positions of the permeable zones within the shafts profiles as well as estimate the groundwater inflow rates at every 5 m interval along the shafts profiles. The project was budget and time constrained and therefore the preferred hydrogeological characterisation techniques, particularly the percussion drilling, aquifer testing and numerical modelling could not be conducted. The study was completed by conducting packer tests in HQ sized holes drilled at the exact positions of the proposed shafts. The packer test data was then interpreted using Thiem equation, a modification of Darcy Equation for radial flow, to estimate the steady state inflow rates into the shafts. Transient state flow is more challenging to calculate analytically, as it is time and aquifer storage dependent. However, transient state flow in shafts exists for the first 10 - 15 days only and is short lived. Thereafter, a steady state flow occurs where the rate is nearly fixed for the rest of the life of mine, unless new external stresses, such as mine dewatering, takes place within the radius of influence. Six months later the shafts were excavated and the permeable zones were encountered at the exact positions as predicted using the packer testing. In addition, the inflow rates calculated using analytical modelling was successful in estimating the inflow rates recorded after the shafts were excavated. The packer testing and analytical modelling was therefore effective in assisting the mine to plan the necessary pumps and management plans within the allocated budget and timeframe.
The effect of geology on the mobility and rebound of light non-aqueous phase liquids	Sedzani Elia	Muravha	2015	LNAPLS
Abstract Hydrogeological environments are commonly determined by the type of underlying geology; these environments may have a tremendous effect on the mobility and recovery of LNAPLs. Hydrogeological environment include intergranular sediments and bedrocks of contrasting permeability and porosity. This paper synthesizes several case studies and conceptual models of different hydrological environments and illustrates how they affect the flow characteristics and rebound of LNAPLs.
The National State of Water in South Africa - the Annual Reporting	Kwazikwakhe	Majola	2015
Abstract POSTER The Department of Water and Sanitation (DWS) is the custodian of South Africa's water and thus is imperative that it reports on its state as the National Water Act of 1998 requires regular reporting to Parliament by the Minister. Hence, the annual compilation of report entitled "The National State of Water in South Africa." This report aims to give an overview of the status and trends of water quality and quantity, further assisting with international water reporting obligations to SADC Region, African Continent, and Globally e.g. the United Nations Commission on Sustainable Development. This information empowers the public and provides knowledge to water managers for informed decision-making. The main purpose is to enhance quality, accessibility and relevance of data and information relating to the goal of Integrated Water Resource Management towards attaining holistic Integrated Water Management, and Integrated Water Cycle Management in future. Three distinct requirements for collecting data by DWS are: (i) assessing and comparing the status and trends for both quantity and quality; (ii) monitoring for water use and (iii) monitoring for compliance to licence conditions. Such information is further used to assess the effectiveness of policies implemented and identify the existing gaps. Various challenges to the country's water demand proper integrated water resources planning and management. The report is divided into Themes such as, Resource Management, Water Services/Delivery, Water Development and Finance, based on selected indicators. The indicators are strategically selected to provide a representative picture of the state, as well as the changes over time to the drivers, pressures, impacts and responses related to the chosen themes. These Indicators include: Climatic Conditions, Water Availability, Water Use, Water Protection, Water Quality, Water Service Delivery, Water Infrastructure, Water Finance, and Sanitation. The report for Hydrological Year 2013/2014 has been completed and it shows that the amount of water available varies greatly between different places and seasons, and from one year to another. The average total storage was around 85% of full supply capacity in September 2014. Surface water quality is generally facing a threat from eutrophication and microbial pollution emanating mainly from mismanaged water (and waste) treatment plants and related landuse activities. Groundwater quality is generally good except in some localised areas where mining and industrial activities are prevalent. With regards to infrastructure; vandalism, lack of maintenance & management skills reflect on/as non-revenue water, highlighting the need for more funding towards maintenance, especially in groundwater which is normally wrongly deemed as an unreliable resource. In the past 20 years, water services delivery to communities has improved as the Millennium Development Goals have been met and surpassed, while the sanitation access goals were likely to be met.
Groundwater Resource Quantification And Impact Assessment: We Need A South African Code Similar To SAMREC	Koos	Vivier	2015
Abstract Quantification of groundwater is important as it should determine the maximum sustainable use of the resource. The SAMREC Code that is required for mineral resource quantification sets out minimum standards, guidelines and recommendations for public reporting of exploration results for mineral resources and reserves. The code serves as the basis for mineral asset valuation and provides quality assurance to the process and an understanding of the results. In groundwater far too often, various methods are used for resource quantification that leads to various results even should the same resource be investigated by two different hydrogeologists. In far too many cases, the resource is not quantified properly which leads to vast over or under estimations. The result is a lack of trust in groundwater resources. As has been done in the international arena, it is similarly proposed that a code be developed for South Africa to ensure that the sustainability of groundwater resources is determined and the impacts of utilization on the water Reserve and the environment be quantified at a minimum level and that basic hydrogeological principles are followed. A South African Groundwater Regulation Code for sustainable resource quantification and impact assessment (SAGREC) is developed that is proposed to guide groundwater investigations and development processes from planning to baseline assessments, drilling and aquifer testing to resource quantification and sustainability modeling. The aim is to ensure trust being built on groundwater as a resource due to projects that follow a formal process that quantifies the assurance of supply and determines the environmental impacts.
A scientific method of assessing the groundwater contribution to lakes and wetlands	Roger	Parsons	2015
Abstract The intangible nature of groundwater provides challenges when trying to understand and quantify the role of groundwater in the hydrology of lakes and wetlands. This task is made even more difficult by the frequent absence of data. However, by adopting a scientific approach, it is possible to assess the hydrogeological contribution
The UNESCO IHP project "Groundwater Resources Governance in Transboundary Aquifers" (GGRETA) - Legal and Institutional Aspect	Ramogale	Sekwele	2015
Abstract This study intent to share the legal and institutional analysis of the UNESCO IHP project "Groundwater Resources Governance in Transboundary Aquifers" (GGRETA) project for the Stampriet Transboundary aquifer. The Intergovernmental Council (IGC) of the UNESCO International Hydrological Programme (IHP) at its 20th Session requested the UNESCO-IHP to continue the Study and Assessment of Transboundary Aquifers and Groundwater Resources and encouraged UNESCO Member States to cooperate on the study of their transboundary aquifers, with the support of the IHP. The GGRETA project includes three case studies: the Trifinio aquifer in Central America, the Pretashkent aquifer in central Asia and the Stampriet aquifer in southern Africa. This study focuses on the Stampriet Transboundary Aquifer System that straddles the border between Botswana, Namibia and South Africa. The Stampriet system is an important strategic resource for the three countries. In Namibia the aquifer is the main source of water supply for agricultural development and urban centers in the region, in Botswana the aquifer supplies settlements and livestock while in South Africa the aquifer supplies livestock ranches and a game reserve. The project methodology is based on UNESCO's Shared Aquifer Resources Management (ISARM) guidelines and their multidisciplinary approach to transboundary aquifers governance and management, addressing hydrogeological, socio-economic, legal, institutional and environmental aspects. The GGRETA builds recognition of the shared nature of the resource, and mutual trust through joint fact finding and science based analysis and diagnostics. This began with collection and processing of legal and institutional data at the national level using a standardized set of variables developed by the International Groundwater Resources Assessment Center (IGRAC). This was followed by harmonization of the national data using common classifications, reference systems, language, formats and derive indicators from the variables. The harmonized data provided the basis for an integrated assessment of the Stampriet transboundary aquifer. The data assisted the case study countries to set priorities for further collaborative work on the aquifer and to reach consensus on the scope and content of multicountry consultation mechanism aimed at improving the sustainable management of the aquifer. The project also includes training for national representatives in international law applied to transboundary aquifers and methodology for improving inter-country cooperation. This methodology has been developed in the framework of UNESCO's Potential Conflict Cooperation Potential (PCCP) program. The on-going study also includes consultation with stakeholders to provide feedback on proposals for multicountry cooperation mechanisms. It is anticipated that upon completion of the study, a joint governance model shall have been drawn amongst the three countries sharing the aquifer to ensure a mutual resource management.
Complexity versus Simplicity: A comparative analysis of complex geology in hydrogeological modelling	Anton	Lukas	2012	modelling, FEFLOW
Abstract This paper was presented at the GWD Central Branch Symposium, Potchefstroom in 2012 Numerical modelling of hydrogeological systems has progressed significantly with the evolution of technology and the development of a greater understanding of hydrogeology and the underlying mathematical principles. Hydrogeological modelling software can now include complex geological layers and models as well as allow the pinching out of geological features and layers. The effects of a complex geology on the hydraulic parameters determined by numerical modelling is investigated by means of the DHI-WASY FEFLOW and Aranz Geo Leapfrog modelling software packages. The Campus Test Site (CTS) at the University of the Free State in Bloemfontein, South Africa was selected as the locale to be modelled. Being one of the most studied aquifers in the world, the CTS has had multiple research projects performed on it and as a result ample information is available to construct a hydrogeological model with a high complexity. The CTS consists primarily of stacked fluvial channel deposits of the Lower Beaufort Group, with the main waterstrike located on a bedding-plane fracture in the main sandstone aquifer. The investigation was performed by creating three distinct hydrogeological models of the CTS, the first consists entirely of simplified geological strata modelled in FEFLOW by means of average layer thicknessand does not include the pinching out of any geological layers. The second model was created to be acopy of the first, however the bedding-plane fracture can pinch out where it is known to not occur. The third and final model consisted of a complex geological model created in Leapfrog Geo which was subsequently exported to FEFLOW for hydrogeological modelling.
A framework for conjunctive use at local government level	Kornelius	Riemann	2015	Conjunctive use, IWRM, framework
Abstract Conjunctive use of surface water and groundwater resources offers huge advantages to municipalities. It can significantly increase the resilience of the municipal water supply to drought situations. Optimal use and integration of different sources would result in a yield of the total system that is higher than the combined yield of each source separately. However, integrated water resource management (IWRM) in general and planned conjunctive use of both groundwater and surface water resources in particular have not been successfully implemented yet in South Africa. Six selected case studies of municipalities across South Africa, which utilize both surface water and groundwater for the water supply to specific towns, have undergone a review of their current water governance provisions wrt groundwater, surface water and conjunctive use. The review has been based on a questionnaire for direct interaction with the local government officials, supported by other readily available documents such as municipal Integrated Development Plan (IDP) and Water Services Development Plan (WSDP), municipal websites, Blue Drop and Green Drop Assessment Reports, Municipal Strategic Self-Assessment (MuSSA) and the All Towns Reconciliation Strategy reports. These case studies reveal the different institutional arrangements for water resource management and water supply services that exist in municipalities. The advantages and disadvantages of the institutional arrangements for each case study have been determined. Problem areas identified include split of responsibilities for surface water and groundwater resources between different institutions, lack of financial and HR support within the government spheres, lack of formal and structured stakeholder engagement, insufficient monitoring for both sources, inter alia. Based on this comparative study of different municipalities, a draft framework of optimal institutional arrangements and governance provisions at local government level is developed to support the integration and optimisation of surface water and groundwater supply. The proposed framework is based on three pillars; viz. leadership and clear structures within the responsible local government institution, formal engagement with all relevant internal and external stakeholders and a sufficient monitoring network that supports the stakeholder engagement and decision making.
Characterisation And Protection Of Deep Aquifers In South Africa: Consolidation Of Data Sources	Francois D	Fourie	2017	Deep aquifers, data sources
Abstract This paper describes the results of study aimed at consolidating the available data sources on deep aquifers and deep groundwater conditions in South Africa. The study formed part of the larger WRC Project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). Since very little is known about the aquifer conditions below depths of 300 m, all groundwater information from depths greater than 300 m was considered to represent the deep aquifer systems. Various confirmed and potential sources of data on deep aquifers and groundwater conditions were identified and interrogated during this study, namely: 1. Boreholes of the International Heat Flow Commission (IHFC). The IHFC database indicates the location of 39 deep boreholes ranging in depth from 300 to 800 m, with an average depth of 535 m. 2. The Pangea database of the International Council for Science (ICSU). The Pangea database has information on 119 boreholes in South Africa, of which 116 are deeper than 300 m. 3. A database on deep boreholes at the Council for Geoscience (CGS). This database contains information on 5 221 boreholes with depths exceeding 300 m. 4. Information on the deep SOEKOR boreholes drilled during the 1960s and 1970s (at least 38 boreholes). 5. Information on deep boreholes from the database of the Petroleum Agency SA. 6. The National Groundwater Archive (NGA) of the Department of Water and Sanitation (DWS). 7. Information derived from the thermal springs in South Africa. 8. Boreholes drilled as part of the Karoo Research Initiative (KARIN). 9. Information on the locations and depths of underground mines in South Africa. Information on the occurrence of deep groundwater could potentially be obtained from these mines. The study shows that, although information on a vast number of deep groundwater sites is listed in the various databases, the data relevant to the geohydrological conditions are scant at most sites. This paucity of geohydrological data implies that the deep aquifers of South Africa are currently poorly understood.
Numerical Modelling Of a Coal Mine to Improve the Understanding of Mine Water Decant: A 1000-Piece Puzzle	Amy	Allwright	2017	coal ash, dolomites, Mining , numerical modelling
Abstract A coal mine in South Africa had reached decant levels after mine flooding, where suspected mine water was discharging on the ground surface. Initial investigations had indicted a low-risk of decant, but when ash-backfilling was performed in the defunct underground mine, decant occurred. Ash-backfilling was immediately suspended as it was thought to have over-pressurised the system and caused decant. Contrariwise, a number of years later decant was still occurring even though ash-backfilling had been terminated. An investigation was launched to determine whether it was the ash-backfilling which had solely caused decant, or if additional contributing factors existed. Understanding the mine water decant is further complicated by the presence of underlying dolomites which when intersected during mining produced significant inflows into the underground mine workings. Furthermore, substantial subsidence has taken place over the underground mine area. These factors combined with the inherent difficulty of understanding unseen groundwater, produced a proverbial 1000-piece puzzle. Numerical groundwater modelling was a natural choice for evaluating the complex system of inter-related processes. A pre-mining model simulated the water table at the ground surface near the currently decanting area, suggesting this area was naturally susceptible for seepage conditions. The formation of a pathway from the mine to the ground surface combined with the natural susceptibility of the system may have resulted in the mine water decant. This hypothesis advocates that mine water was going to decant in this area, regardless of ash backfilling. The numerical groundwater flow model builds a case for this hypothesis from 1) the simulated upward flow in the pre-mining model and 2) the groundwater level is simulated above the surface near the currently decanting area. A mining model was then utilised to run four scenarios, investigating the flux from the dolomites, subsidence, ash-backfilling and a fault within the opencast mine. The ash-backfilling scenario model results led to the formation of the hypothesis that completing the ash-backfilling could potentially reduce the current decant volumes, which is seemingly counterintuitive. The numerical model suggested that the current ash-backfill areas reduce the groundwater velocity and could potentially reduce the decant volumes; in spite of its initial contribution to the mine water decant which is attributed to incorrect water abstraction methods. In conclusion, the application of numerical models to improve the understanding of complex systems is essential, because the result of interactions within a complex system are not intuitive and in many cases require mathematical simulation to be fully understood.
#GWD: The use of social media for science communication	Tercia	Strydom	2015
Abstract For a long time, professionals regarded social media as a superficial, unprofessional platform where internet users would submerge themselves in a virtual world, detached from real-life issues. Slowly, the myths and stigmas surrounding the use of social media has faded as more and more professionals and scientists have realized that these social platforms could be positively exploited in a professional manner which could be beneficial. In a digital age where information at our fingertips is the norm, professionals should co-evolve and ensure that their work is just as accessible and appealing, without the unnecessary jargon. Currently, science is mostly restricted to a very particular audience and conveyed in one direction only. Using a social media platform such as Twitter-which limits messages to only 140 characters-challenges scientists to convey their work in a very concise manner using simpler terminology. Furthermore, it dismisses the usual one-way form of communication by opening dialogue with fellow Twitter users. At conferences, Twitter can serve as a useful tool for active engagement which will not only "break the ice" between delegates but also ensure that important information is communicated to a much wider audience than only those in attendance. This idea was tested at the 2014 Savanna Science Network Meeting held in Skukuza, Kruger National Park, where the hashtag #SSNM was used. More than 63% of the Twitter users who participated in the #SSNM hashtag were actually not present at the conference. These external "delegates" were interested individuals from five different continents and in different professions besides Science. This highlights how social media can be exploited at conferences to ensure that key messages are conveyed beyond the immediate audience at the event.
Characterisation And Protection Of Deep Aquifers In South Africa: Characterisation	Francois D	Fourie	2017	Deep aquifers, Aquifer characterization, groundwater flow, Groundwater Quality
Abstract This paper describes the characteristics of the deep aquifer systems in South Africa as derived from the available data. The study formed part of the larger WRC project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). A review of the available literature relevant to potential deep aquifers in South Africa was done to allow characterisation of these aquifer systems. In addition, data obtained from the geological logs of the SOEKOR and KARIN boreholes were considered. This paper focuses on deep aquifers in 1) the Karoo Supergroup, 2) the basement and crystalline bedrock aquifers, 3) the Table Mountain Group, 4) the Bushveld Igneous Complex and 5) the dolomites of the Transvaal Supergroup. From the available data the deep aquifer systems are described in terms of the following characteristics: lithology, occurrence, physical dimensions, aquifer type, saturation level, heterogeneity and degree of isotropy, formation properties, hydraulic parameters, pressurisation, yield, groundwater quality, and aquifer vulnerability. The results of the study show that the deep aquifer systems of South Africa are generally fractured hard-rock aquifers in which secondary porosity was developed through processes such as fracturing and dissolution. The primary porosity of most of the rocks forming the aquifers is very low. Apart from the dolomite aquifers, most of the water storage occurs in the rock matrices. Groundwater flow predominantly takes place along the fractures and dissolution cavities which act as preferential pathways for groundwater migration. The aquifers are generally highly heterogeneous and anisotropic. The deep aquifers are generally confined and associated with positive hydraulic pressures. The groundwater quality generally decreases with depth as the salinity increases. However, deep dolomite aquifers may contain groundwater of good quality. Due to the large depths of occurrence, the deep aquifer systems are generally not vulnerable to contamination from activities at surface or in the shallow subsurface. The deep dolomite aquifers are a notable exception since they may be hydraulically linked to the shallower systems through complex networks of dissolution cavities. The deep aquifers are, however, very vulnerable to over-exploitation since low recharge rates are expected.
Depth Discrete Multilevel Monitoring In Fractured Rock: State Of The Technology And Implications	John A	Cherry	2017	Monitoring, fractured rock, Hydrochemistry, MLS technologies
Abstract Well-established engineered systems for depth-discrete monitoring in fractured rock boreholes (referred to as a Multilevel System or MLS) are commercially available and offer much diversity in design options, however, they are used infrequently in professional practice and have seen minimal use in groundwater research. MLSs provide information about hydraulic head and hydrochemistry from many different depths in a single borehole and, therefore, magnify greatly the knowledge value of each borehole. Conventional practice globally is devoted to standard monitoring wells, either alone as longer single screened wells or in clusters or nests with a few wells screened at different depth intervals. These are the mainstay of the groundwater science and engineering community and severely limit prospects for each borehole to provide the information needed to solve the complex problems typically posed by fractured rock. This paper outlines the nature and evolution of MLS technologies and points to recent literature showing how MLSs add important insights that cannot be obtained using conventional wells. Also, it reviews commercially available MLS technologies, which present a range of robust options with each system having different characteristics and niches depending on characterization and monitoring goals and site conditions. The paper also describes refined MLS criteria aimed at improving the cost effectiveness and expanding capabilities of MLSs, so as to improve their accessibility for high resolution data acquisition in the context of both groundwater system characterization and long-term monitoring.
Blast curtain optimized with a numerical model for TSF seepage control	Robel	Gebrekristos	2015
Abstract Preventing the spread of seepage from tailings storage facilities (TSF's) in groundwater is necessary as it often contains toxic contaminants. Experience has shown that seepage from TSFs is inevitable and that zero seepage remains difficult even with complex liner systems. Multiple seepage control methods are often required to minimise seepage to ensure that environmental regulations are met. Control methods can be grouped into either barrier or collection systems. Barrier systems are used to hinder seepage whereas collection systems are used to intercept seepage. A blast curtain, which is the focus of this article, is a type of collection system that is still at a conceptual level but has seen little or no application worldwide. It works in principle, similarly to a curtain drain, but is typically extended to greater depths depending on the aquifer vulnerability. Numerical modeling has shown that this mitigation measure could add another line of defence for seepage control. The depth and effectiveness of the curtain can be optimized with a numerical model to ensure optimal interception of contaminated seepage around the TSF. Depths of up to 30 m in fractured aquifers have been simulated in this study. A blast curtain is constructed by drilling a set of boreholes around a TSF in close proximity to one another and then fracturing the rock using either explosives or fracking methods to create a more permeable zone. This is then combined with a series of scavenger wells or natural seepage to abstract the contaminated water. Numerical simulation has shown that blast curtains are effective especially if groundwater flow is horizontal. The effectiveness decreases if the vertical flow component is significant. A blast curtain can result in the lowering of the water table, however, local depression is a less of a concern than potential groundwater contamination. {List only- not presented}
Governance and Management of Water Resource in the SA Context - A Review	Kornelius	Riemann	2015
Abstract Water management is a difficult and complex business requiring appropriate institutional arrangements as well as guidance and support from government, which is often unable to act effectively to address day-to-day water resource management (WRM) issues. Theoretically, water as a 'common pool resource' is best managed by users self-organised at a local level and within a basin framework. Water users and other stakeholders have detailed and up-to-date local knowledge as well as an interest in ensuring effective management to share water equitably between different users and to control pollution. This approach is supported by South Africa's National Water Act (NWA), which provides for the establishment of Catchment Management Agencies (CMAs) to perform a range of WRM activities within the framework of a National Water Resource Strategy (NWRS). Hence, water resource management in general and conjunctive use in particular requires cross sector and cross level cooperative governance. Relevant institutions include the DWA at national and regional level, the CMA, if established, provincial departments that might impact on the water resources, water user associations, water services authorities, water services providers, water boards, and individual water users. These institutions are responsible for various activities and often require some level of inter- and intra-institutional cooperation. Ideally, multiple organisations, policies, legislation, plans, strategies and perspectives should be involved in water-related decision-making, which in turns creates complex leadership challenges. Globally, the lack of sustainable groundwater management can be ascribed to poor governance provisions. These include, but are not limited to, institutional arrangements and political will, including fragmented and overlapping jurisdictions and responsibilities, competing priorities, traditional approaches, rights and water pricing systems, diverging opinions, incomplete knowledge, data as well as uncoordinated information systems. Adding the poor operational and maintenance issues, decision-makers often view groundwater as an unreliable resource and are hesitant to make significant investments in groundwater infrastructure and capacity. The recent Worldbank and WRC report on groundwater governance in South Africa revealed that the technical, legal, institutional and operational governance provisions were found to be reasonable at the national level but weak concerning cross-sector policy coordination. At the local level, basic technical provisions such as hydrogeological maps and aquifer delineation with classified typology are in place but other governance provisions such as institutional capacity, provisions to control groundwater abstraction and pollution, cross-sector policy coordination and the existence and implementation of groundwater management action plans are weak or non-existent. It appears from this review that the major hindrances for sustainable groundwater governance and more so for integrated water resource management and conjunctive use scenarios are the discrepancy between groundwater and surface water provisions in the relevant legislation, associated guidelines and their implementation at regional and local, and the lack of skills and clear responsibilities for implementing water resource management actions at municipal level. This is demonstrated with several case studies.
A methodology for uncertainty quantification of dewatering volumes under the context of open-cast mining	C	Rivera Villarreyes	2023	FEFLOW, Groundwater Modelling, mining, PEST, PESTPP
Abstract Groundwater modelling at the mine sites involves assumptions from the geological model, mining stages, parametrization, and fractures, among others. Modelling work mainly focuses on calibrating against historical measurements before operations (pre-mining) or afterwards (transient calibration). Calibration is carried out mainly with gradient-based algorithms. However, the majorlimitation is the number of model runs, since the number of parameters can easily reach hundreds or more. PEST has become the common tool for parameter estimation. The Jacobin calculation required for the Levenberg Marquardt algorithm requires several model runs. This, a limited factor for the calibration and, subsequently, uncertainty quantification. The next generation of PEST, named PESTPP, is gained popularity in the groundwater community. The great advantage of PESTPP,, compared to the classical PEST, is its new module, Iterative Ensemble Smoother (IES). PESTPP-IES covers both parameter estimation and uncertainty quantification in one goal. Its empirical formulation of the Jacobian matrix reduces the number of runs; thus, the numerical bottleneck can be significantly reduced. PESTPP-IES has been extensively tested in an open-pit mine at the geological complex conditions in the Peruvian Andes. The work involves the task of model simplification, e.g., from a regional model to a detailed local pit model, calibration and uncertainty quantification of pit dewatering volumes. Detailed model was kept calibrated based on hydraulic-head measurements, and dewatering volumes were predicted. All these consider transient changes in the mining plan within the same FEFLOW model. Results validate the methodology and practicability in mining applications.
Fly Ash Leaching Dynamics And Implication On Groundwater Contamination	Nadine	Swartz	2019	fly ash, contamination
Abstract South Africa utilizes coal for energy and chemical feedstock thereby generating millions of tons of ash every year. The ash is stockpiled in surface waste facilities where it poses a risk of leaching and contaminating groundwater. This study utilizes standard leaching tests, TLCP and SPLP, to evaluate and predict the mobility of different elements that leach from fly ash. Two different fly ash samples (Ash M and Ash T) were used in the study. A QEMSCAN analysis was also performed on the samples as well as the coal to determine the elementary and mineralogical compositions. Both Ash samples were generated from bituminous coals and had similar physical properties. Both ash samples were mixed respectively with the two different leachates one more acidic (Leachate A) the other more basic (Leachate B). Trace elements are present in ash in small amounts, but still at lower levels still pose threat to the environment and human health. Only three trace elements were found present in both ash samples. The detected trace elements in an increasing concentration order are: Manganese>Chromium>Copper. It appears the leaching behaviour of these trace elements is similar to the other metals, being insoluble at near neutral and alkaline pH range while dissolvable at low pH ranges. The results show that Leachate B was found to extract more material than Leachate A on a milligrams per gram of ash basis. The risk to groundwater contamination can be minimized by understanding the leaching dynamics and water retention of fly ash dumps as the results show.
The connectedness of transboundary groundwater researchers: from network analysis to network-building	A	Fernald	2023	network analysis, network-of-networks, transboundary groundwater
Abstract The Transboundary Groundwater Resilience (TGR) Network-of-Networks project brings together researchers from multiple countries to address the challenges of groundwater scarcity and continuing depletion. Improving groundwater resilience through international research collaborations and engaging professionals from hydrology, social science, data science, and related fields is a crucial strategy enabling better decision-making at the transboundary level. As a component of the underlying data infrastructure, the TGR project applies visual analytics and graph-theoretical approaches to explore the international academic network of transboundary groundwater research. This enables the identification of research clusters around specific topic areas within transboundary groundwater research, understanding how the network evolved over the years, and finding partners with matching or complementary research interests. Novel online software for analysing co-authorship networks, built on the online SuAVE (Survey Analysis via Visual Exploration, suave.sdsc.edu) visual analytics platform, will be demonstrated. The application uses OpenAlex, a new open-access bibliographic data source, to extract publications that mention transboundary aquifers or transboundary groundwater and automatically tag them with groundwater-specific keywords and names of studied aquifers. The analytics platform includes a series of data views and maps to help the user view the entire academic landscape of transboundary groundwater research, compute network fragmentation characteristics, focus on individual clusters or authors, view individual researchers’ profiles and publications, and determine their centrality and network role using betweenness, eigenvector centrality, key player fragmentation, and other network measures. This information helps guide the project’s data-driven international networking, making it more comprehensive and efficient.
Use Of Environmental Isotopes To Determine Hydraulic Connectivity Across The Surrounding Aquifers At Majuba UCG	Gundo	Mathoho	2015
Abstract Environmental isotope techniques have been successfully applied in the field of hydrogeology over the last couple of decades and have proved useful for understanding groundwater systems. This paper describes a study of the environmental isotopes for Oxygen (18O) and Hydrogen (1H, 2H-Deutrium, 3H-Tritium) obtained from various points in and around the underground coal gasification (UCG) site in Majuba, South Africa. UCG is an alternative mining method, targeting deep coal seams that are regarded as uneconomical to mine. The process extracts the energy by gasifying the coal in-situ to produce a synthetic gas that can be used for various applications. The site consists of shallow, intermediate and deep aquifer systems at a depth of 70m, 180 and 300m respectively. The intermediate aquifer is further divided into the upper and lower aquifer systems. Samples were taken from each aquifer system together with supplementary samples from the Witbankspruit and an on-site water storage dam. A total of 15 samples were submitted for isotope analyses. By investigating the various isotopic signatures from all the samples taken, it will be possible to determine if there are similar or contrasting isotopic compositions by deducing possible water source for each sample due to isotopic fractionation caused by physical, chemical and biological processes. This will also be supported by deducing the mean residence time (MRT) for each water source sampled based on the Tritium data as well as the chemistry data already available for different sources. The chemistry data established linkages between the upper and lower intermediate aquifers.{List only- not presented} Key words: Environmental isotopes, UCG, Water source, Isotope fractionation
Water Quality Guidelines: Which to use and where applicable?	Lerize	Van Wyk	2021	Poster, Water quality, guidelines, SAWQG, SANS, WHO, WUL
Abstract When conducting water quality monitoring, questions arise on which water quality guidelines to use and where to apply them. For example, the use of South African Water Quality Guidelines (SAWQG) for Domestic usage compared to the use of the South African National Standards (SANS) for Potable Water Quality when monitoring drinking water quality. The World Heath Organization (WHO) published a set of water quality guidelines for drinking water which can also be used instead of SANS. Using various water quality guidelines to assess water quality can give different outcomes on the state of water quality of a particular site. For example, SANS water quality guidelines are less strict when compared to the SAWQG target values, however, SAWQG are comprised of different sets of standards for different usages. SAWQG distinguish between drinking water, livestock and irrigation, aquatic systems and industrial usage while SANS are only used for potable or bottled water. The International Finance Corporation (IFC) that is part of the World Bank Group published the Environmental, Health, and Safety (EHS) Guidelines for Environmental Wastewater and Ambient Water Quality, guidelines set specifically for wastewater and ambient water quality. Utilizing this poster, I will explain when to use which guidelines with different types of water samples. I will also discuss the stringent water use license limits applied at some sites compared to the national standards of South Africa.
OFF-SOURCE: A network to address the potential use of offshore freshened groundwater as an unconventional source of potable water in coastal cities.	H	Wazaz	2023	Offshore groundwater, COST Action, scientific networking, unconventional water resources, Transboundary aquifer
Abstract One-third of the world faces water insecurity, and freshwater resources in coastal regions are under enormous stress due to population growth, pollution, climate change and political conflicts. Meanwhile, several aquifers in coastal regions extending offshore remain unexplored. Interdisciplinary researchers from 33 countries joined their effort to understand better if and how offshore freshened groundwater (OFG) can be used as a source of potable water. This scientific network intends to 1) estimate where OFG is present and in which volumes, 2) delineate the most appropriate approaches to characterise it, and 3) investigate the legal implications of sustainable exploitation of the offshore extension of transboundary aquifers. Besides identifying the environmental impact of OFG pumping, the network will review existing policies for onshore aquifers to outline recommendations for policies, action plans, protocols and legislation for OFG exploitation at the local to international levels. Experienced and early-career scientists and stakeholders from diverse disciplines carry out these activities. The Action leads activities to foster cross-disciplinary and intersectoral collaboration and provides high-quality training and funded scientific exchange missions to develop a pool of experts to address future scientific, societal, and legal challenges related to OFG. This interaction will foster new ideas and concepts that will lead to OFG characterisation and utilisation breakthroughs, translate into future market applications, and deliver recommendations to support effective water resource management. The first exchange mission explored the Gela platform carbonate reservoir (Sicily), built a preliminary 3D geometrical model, and identified the location of freshened groundwater
Platinum mines will leave behind a sustainable legacy which will form a vital building block to meet future water demands	Fanie	Botha	2015	aeration and aerobic storage facilities, Nitrate
Abstract Slightly more out of the box idea is the use of anthropogenic aquifers as storage and chemical conditioners. This concept was first introduce by Eland Platinum Mine(EPM) and reported on in previous papers. At EPM water is used through a serious of natural aeration and aerobic storage facilities to reduce nitrate levels. In 2013 another group introduced pilot studies by virtue of abstraction in support of the water conservation and demand management strategy; which has proven that it could enable the operations to overcome water shortage periods and reduce pressure on Rand Water (RW). The pilot sites would deliver water into the dirty water circuit, but within five to ten years it may further be used to overcome months with zero potable water supply. . In platinum mines the more the aquifers are used the cleaner the water becomes, simply because introduced pollutants are not constant sources and country rock is mostly inert. In the future these aquifers have the potential to become larger storage facilities protected from floods and limited evaporation losses. It is foreseen that some of the mines in the western belt may have more water stored in primary aquifers than water stored within major water dams. Yields from these aquifers for individual aquifers may be up to 450 m3/hour and storage of 18 Mm3. . Why then this paper if we are already using it? The issue is that the true value of these aquifers an only be unlocked when they are used as recharging aquifers and thereby actively storing dirty water within a dirty water aquifer. Once we are able to undertake this the positive environmental gains such of environmental overflows, condition dirty water, reduction of pollution and significant reduction of the use of potable water from RW. {List only- not presented}
High Resolution Site Characterisation (HRSC) In South Africa: Challenges, Successes And Lessons Learned	Samuel D	Mohr	2015
Abstract Inadequate characterization of contaminated sites often leads to the development of poorly constructed conceptual site models and consequently, the design and implementation of inappropriate risk management strategies. As a result, the required remedial objectives are not achieved or are inefficient in addressing the identified risks. Unfortunately, it is all too common to find remedial intervention strategies that run for lengthy periods of time at great cost while generating little environmental benefit due to inadequate characterization of site conditions. High resolution site characterization (HRSC) can provide the necessary level of information to allow for development of rigorous conceptual site models, which can be used to develop and implement appropriate risk management solutions for environmental problems. At the outset, the HRSC approach generally has comparatively higher costs than traditional state-of-the-practice assessment methods. However, the project lifecycle costs can be substantially reduced due to development of optimal risk management strategies. In developing countries where there is a lack of legislation relating to soil and groundwater contamination or, a lack of enforcement of legislation which is present, the long-term liabilities related to contaminated sites are often not immediately apparent to the parties responsible for the sites. This often creates a reticence to employ HRSC techniques due to their increased cost, especially when much of the technology must be imported on a project specific basis from either Europe or the United States. The Authors provide information from several case studies conducted in South Africa where HRSC techniques have been employed to gain a greater understanding of subsurface conditions. Techniques employed have included surface-based geophysical techniques such as electrical resistivity tomography (ERT) and multi-channel analysis of seismic waves (MASW), passive soil gas surveys, deployment of Flexible Underground Technologies (FLUTe?) liners, diamond core drilling, fluid electrical conductivity profiling, downhole geophysical logging tools, the Waterloo Advanced Profiling System (APS), and the use of field laboratories. Several of the techniques required importing equipment and personnel from Europe or the US, and in several case studies, were a first to be employed in South Africa, or the continent of Africa for that matter. The Authors present data obtained using the HRSC techniques from the case studies and elaborate on how the information obtained was used to drive effective decision making in terms of managing long term environmental risks at the various sites, which has been positively embraced by local clients. The authors also highlight key challenges in conducting HRSC investigations in an emerging market context.
Water resource management in tectonically active volcanic regions: Towards an in-depth understanding of Mt. Fuji’s hydrogeology	Stephanie	Musy	2023	SW-GW interactions; tracers; modelling
Abstract Mt. Fuji is the iconic centrepiece of a large, tectonically active volcanic watershed (100 km2 ), which plays a vital role in supplying safe drinking water to millions of people through groundwater and numerous freshwater springs. Situated at the top of the sole known continental triple-trench junction, the Fuji watershed experiences significant tectonic instability and pictures complex geology. Recently, the conventional understanding of Mt. Fuji catchment being conceptually simple, laminar groundwater flow system with three isolated aquifers was challenged: the combined use of noble gases, vanadium, and microbial eDNA as measured in different waters around Fuji revealed the presence of substantial deep groundwater water upwelling along Japan’s tectonically most active fault system, the Fujikawa Kako Fault Zone [1]. These findings call for even deeper investigations of the hydrogeology and the mixing dynamics within large-scale volcanic watersheds, typically characterized by complex geologies and extensive networks of fractures and faults. In our current study, we approach these questions by integrating existing and emerging methodologies, such as continuous, high-resolution monitoring of dissolved gases (GE-MIMS [2]) and microbes [3], eDNA, trace elements, and integrated 3-D hydrogeological modelling [4]. The collected tracer time series and hydraulic and seismic observations are used to develop an integrated SW-GW flow model of the Mt. Fuji watershed. Climate change projections will further inform predictive modelling and facilitate the design of resilient and sustainable water resource management strategies in tectonically active volcanic regions
A Study Of Interaction Between Groundwater And Surface Water Using Environmental Isotopes, Hydrochemistry And Feacal Coliform BA	Bongizenzo	Nyawo	2015
Abstract The Table Mountain Group (TMG) Formation in the Uitenhage region, in the Eastern Province of South Africa, has many groundwater users, which could result in the over-exploitation of the underlying aquifer. Consequently, several investigations have been conducted to help in the planning and management of groundwater resources within the region. Traditionally, these investigations have considered groundwater and surface water as separate entities, and have been investigated separately. Environmental isotopes, hydrochemistry and feacal colifom bacteria techniques have proved to be useful in the formulation of interrelationships and for the understanding of groundwater and surface water interaction. The field survey and sampling of the springs, Swartkops River and the surrounding boreholes in the Uitenhage area have been conducted. After full analysis of the study, it is anticipated that the data from the spring, Swartkops River and the surrounding boreholes show interannual variation in the isotope values, indicating large variation in the degree of mixing, as well as to determine the origin and circulation time of different water bodies. ?D and ?18O value for the spring ranges from ?18.9? to ?7.4?, and 5.25? to 4.82?, respectively, while ?D values for borehole samples range from ?23.5? to ?20.0? and ?18O values range from ?5.67? to ?5.06?. In the river sample, ?D values ranges from ?12.1? to ?4.2?, ?18O from ?3.7? to ?1.13?, respectively. The entrobacter aerogen and E.Coli bacteria were detected in the samples. E. coli population for spring and the artesian boreholes indicated low value while the shallow boreholes had higher values are relatively closer to those of the middle ridges of the Swartkops River. The EC values for the spring samples averages at 14 mS/m, borehole samples ranges from 21 mS/m to 1402 mS/m, and surface water ranges from 19 mS/m to 195 mS/m. Swartkops River is an ephemeral, therefore it is expected that diffuse recharge occurs into the shallow aquifer.
Vapour Intrusion Risk Assessment: Case Studies using Modelling and Direct Measurement from Contaminated Sites in South Africa	Stephen	McKeown	2015
Abstract Vapour intrusion (VI) is recognized to drive human health risk at numerous sites that have been contaminated by petroleum products and other volatile contaminants. The risks related to VI are typically evaluated using direct measurement (vapour sampling) or modelling methods. ERM has developed a toolbox approach using a combination of exclusion distance criteria, direct measurement and modelling methods to assess risks and achieve closure. For direct measurement, samples of vapour are taken beneath the floor slab of buildings (sub-slab sampling) or from the air inside the buildings (indoor air sampling). Modelling methods are often used to estimate the partitioning of volatile contaminants from soil or groundwater sources into the vapour phase and the subsequent transport of vapours from the subsurface environment into habitable buildings. A limitation of modelling approaches is that they are designed to be conservative to be adequately protective of sensitive receptors. VI models also do not typically take into account the degradation of hydrocarbon vapours in the presence of oxygen, which has been found to be a significant process for petroleum hydrocarbons. The authors have compiled a dataset of petroleum vapour and groundwater results from over 50 petroleum release sites in southern Africa. These data were used to develop exclusion distance criteria for vapours emitted from contaminated groundwater sources (i.e. distance from the source at which sufficient aerobic attenuation has occurred for the VI risk to be negligible). A standard "lines of evidence" approach has been applied to the assessment of VI risk by firstly applying the exclusion distance criteria to sites with groundwater contaminant plumes beneath buildings, and if these are met, the sites are considered to have no unacceptable VI risk. Where exclusion screening criteria are not met, risk is estimated using modelling, and if a potential risk is predicted, then direct sub-slab measurements are taken to more accurately assess the risk. Lastly, where sub-slab assessment predicts a potential VI risk, indoor vapour measurement are taken to evaluate actual risk, taking into account interferences from other sources and background levels of contaminants. Mitigating measures can then be applied as appropriate. Various case studies will be presented including direct measurements at industrial and residential sites overlying contaminant plumes and modelling methods at residential properties adjacent to service station sites. A risk-based approach to the assessment of contaminated land provides a sustainable and cost effective methodology, and also avoids unnecessary remediation. The results show that VI risks can be adequately addressed with a toolbox approach using multiple lines of evidence.
The Role Of High Resolution Site Characterisation In Informing Remediation Decisions At A Petroleum Release Site Overlying A Fra	Steve	McKeown	2015
Abstract Inadequate characterization of petroleum release sites often leads to the design and implementation of inappropriate remedial systems, which do not achieve the required remedial objectives or are inefficient in addressing the identified risk drivers, running for lengthy periods of time with little benefit. It has been recognized that high resolution site characterization can provide the necessary level of information to allow for appropriate solutions to be implemented. Although the initial cost of characterization is higher, the long-term costs can be substantially reduced and the remedial benefits far greater. The authors will discuss a case study site in the Karoo, South Africa, where ERM has utilized our fractured rock toolbox approach to conduct high resolution characterization of a petroleum release incident to inform the most practical and appropriate remedial approach. The incident occurred when a leak from a subsurface petrol line caused the release of approximately 9 000 litres of fuel into the fractured sedimentary bedrock formation beneath the site. Methods of characterization included: - Surface geological mapping of regionally observed geological outcrops to determine the structural orientation of the underlying bedding planes and jointing systems; - A surface electrical resistivity geophysics assessment for interpretation of underlying geological and hydrogeological structures; - Installation of groundwater monitoring wells to delineate the extent of contamination; - Diamond core drilling to obtain rock cores from the formation for assessment of structural characteristics and the presence of hydrocarbons by means of black light fluorescence screening and hydrocarbon detection dyes; - Down-borehole geophysical profiling to determine fracture location, fracture density, fracture dip and joint orientation; and - Down-borehole deployment of Flexible Underground Technologies (FLUTe?) liners to determine the precise vertical location of light non-aqueous phase liquid (LNAPL) bearing joint systems and fracture zones, and to assist in determining the vertical extent of transmissive fractures zones. ERM used the information obtained from the characterization to compile a remedial action plan to identify suitable remedial strategies for mitigating the effects of the contamination and to target optimal areas of the site for pilot testing of the selected remedial methods. Following successful trials of a variety of methods for LNAPL removal, ERM selected the most appropriate and efficient technique for full-scale implementation. {List only- not presented}
A More Focused Approach To Developing Groundwater Resources In Rural Communities.	Nadene	Goosen	2019	Groundwater, rural communities, resources, Management
Abstract Water scarcity is a global challenge, particular in South Africa, which is a semi-arid country. Due to the continuing drought, appropriate groundwater management is of great importance. The use of groundwater has increased significantly over the years and has become a much more prominent augmentation component to the supply chain especially in rural communities. However, the approach used to develop groundwater resources, specifically in rural areas, can be improved in numinous ways to ensure drilling of successful boreholes that could meet water demands. A recent study done in the Thaba Nchu area focused on an adapted approach, which resulted in drilling successful boreholes that would be able to sustain their augmentation role in the long term. The adapted approach involves (i) a hydro-census that includes local knowledge and focused field observations, (ii) study of aerial photographs and geological maps on a regional scale, rather than on a village scale area, (iii) an optimised geophysical investigation to identify and map geological structures to drill production boreholes, (iv) conducting aquifer pump test to determine an optimum sustainable yield, (v) collecting water samples to determine if water quality is suitable for its specific use (vi) providing a monitoring program and abstraction schedule for each borehole. The adapted approach highlights the following improvements: (i) drilling of new production boreholes during times of bounty to allow for better time management on the project; (ii) including an experienced geohydrologist during planning phases, (iii) including a social component focussing on educating local communities on the importance of groundwater and introducing them to the concept of citizen's science, (iv) establishing a communication channel through which villagers can report any mechanical, electrical, quantity or quality issues for timeous intervention. Through applying these small changes to established components of development of groundwater resources, budgets and time management were optimised and additional communities could be added to the project without additional costs. This approach not only emphasised ways to improve the awareness and potential of groundwater resources, but also affects the economical-, social- and environmental welfare in rural communities.
The Roussillon coastal aquifer: using multiple-point statistics and multi-model ensemble to characterize geological uncertainty impact on water resources estimation	Valentin	Dall’ Alba	2023	Coastal aquifer, Groundwater Modelling, Multi-model ensemble, Uncertainty analysis
Abstract Coastal groundwater is a vulnerable resource, estimated to sustain the water needs of about 40% of the world’s population. The Roussillon aquifer is a regional aquifer near Perpignan (southern France). It covers over 800 km2 of land and is used for irrigation, drinking water, and industrial purposes. The aquifer has experienced significant piezometric lowering in the last decades, weakening the regional resource. An important aspect of modelling the hydrodynamic of this aquifer is the need to integrate data from agriculture and drinking water abstraction, natural and anthropogenic recharge, and account for the aquifer’s complex sedimentary arrangement. An ensemble of groundwater models has been constructed to understand the spatial evolution of the saline/freshwater interface and evaluate the impact of groundwater abstraction. Three sets of physical parameter modelling approaches were used. The first is based on the direct interpolation of pumping tests. The second uses sequential indicator simulations to represent the geological uncertainty. The third is based on a detailed conceptual geological model and multiple-point statistics to represent the detailed geological structure. These models provide parameter fields that can be input for the transient state hydrodynamic simulations. Overall, the ensemble approach allowed us to understand the Roussillon plain’s hydrological system better and quantify the uncertainty on the possible evolution of the main groundwater fluxes and water resources over the last 20 years. These models can help to inform management decisions and support sustainable water resource development in the region.
Groundwater and Surface Water Interaction Study for the Ingula Wetland	Christie	Terrell	2015
Abstract The Bedford Dam is the upper storage dam for the Ingula Pumped Storage Scheme and is situated in the Ingula/Bedford Wetland. This wetland has a high structural diversity which supports a unique assemblage of plants and invertebrates. The flow regulation and water purification value is of particular importance as the wetland falls within the Greater Vaal River catchment. Concern was raised with respect to the potential negative impact of the newly constructed dam on the dynamic water balance within the wetland. An assessment of the extent to which groundwater drives / sustains the wetland systems and the water requirements needed to sustain the wetland processes was determined. This includes establishing the impact of the Bedford Dam on the groundwater and wetland systems as well as providing recommendations on management and monitoring requirements. The hydropedological interpretations of the soils within the study area indicate that baseflow to the wetland is maintained through perennial groundwater, mainly recharged from infiltration on the plateau, and was confirmed through isotope sampling and hydrometric measurements. It is apparent that the surface flows in the main wetland are fed by recent sources, while the subsurface layers in the wetland are sustained by the slower moving near-surface and bedrock groundwater. The movement of groundwater towards the wetland is hindered by the numerous dykes creating a barrier to flow. Nevertheless, there seems to be a good connection between the groundwater sources in the upland and the surface drainage features that conduct this water to the contributing hillslopes adjacent to the main wetland. The surface flows of the main wetland are sustained by contributions from tributary fingers. The discharge out of the wetland is highly seasonal
Building a Groundwater Educational Pipeline from Elementary to Continuing Education	Todd	Halihan	2023	K-12, PSM, Drilling, online education, professional master’s programs
Abstract Water resources worldwide are stressed, and the number of groundwater professionals required to manage those resources is not being generated in sufficient numbers. Groundwater educational resources must be placed in schools to generate excitement and raise awareness. Additionally, people entering the workforce need training throughout their professional careers. Oklahoma State University partnered with the U.S. National Ground Water Association to develop a framework for providing education and training programs in groundwater that allow for interactive online education at all levels. The Awesome Aquifer 360 program targets grades 5-8, allowing students to conceptually explore aquifers and the people who manage them. The Drilling Basics Online program provides a 40-hour basic safety and drilling training to recruit professionals into the groundwater industry and reinforce safe operations. These programs and future plans for the technique will be discussed.
Variability In Borehole Responses During Yield Testing: Case Studies Deviating From Ideal Drawdown Curves.	Reuben	Lazarus	2019	yield-testing, theory vs practice, realistic aquifers
Abstract The expectation that during yield tests, a borehole will react within the expected framework of the existing numerical models, is often not met within real-world scenarios. This is mainly due to the observation that the Theis solution for confined aquifers, Neuman solution for unconfined aquifer and Barker Generalised Radial Flow Model for hydraulic tests in fractured rocks all include idealised assumptions regarding the physical aspects of a hypothetical. In order to interpret the data from a yield test these methods, along with the Flow Characteristic method for sustainable yield estimates, are commonly used. However, as these assumptions are not always met, the analysis is usually focused on time periods within the test that approximate these solutions. In some cases, the extent to which these assumptions are not met can produce drawdown data that is not well described by the usual analytical models used to analyse this data. This study addresses some of the shortcomings experienced during testing in non-ideal aquifers, as well as briefly describing some tests where small budgets, short deadlines, a lack of information and/or unforeseen circumstances resulted in similar challenges to analyses. This study does not present new solutions to drawdown data analyses, but rather discusses how the mentioned solutions were used during testing to accommodate for the shortcomings experienced.
Comparative use of groundwater by invasive alien PROSOPIS SPP and co-occurring indigenous V. Karoo in a semi-arid catchment	Sebinasi	Dzikiti	2015
Abstract Groundwater is a vital source of water for many communities in South Africa and elsewhere. Besides the changing climate, rapidly spreading invasive alien plants with deep roots e.g. Prosopis spp, pose a serious threat to this water source. Dense impenetrable thickets of Prosopis occur in the drier parts of the country mainly along river channels in the Northern, Eastern and Western Cape Provinces. Few studies have quantified the actual water use by this species outside of the USA where it is native. Consequently the impacts of Prosopis invasions on groundwater resources are not well documented in South Africa. The aim of this study was to quantify the actual volumes of water used by Prosopis invasions and to establish the effects on groundwater. Because deep rooted indigenous trees that normally replace Prosopis once it has been cleared also use groundwater, we sought to quantify the incremental water use by Prosopis over and above that used by indigenous trees in order to determine the true impacts on groundwater. The study was conducted at a site densely invaded by Prosopis at Brandkop farm near the groundwater dependent town of Nieuwoudtville in the Northern Cape. One in seven trees at the site is the Vachellia karroo (formerly A. karroo) which is the dominant deep rooted indigenous tree species. Actual transpiration rates by five Prosopis and five V. karroo are being measured using the heat pulse velocity (HPV) sap flow technique. Additional HPV sensors were installed on the tap and lateral roots to study the water uptake dynamics of the trees. Groundwater levels are being monitored in four boreholes drilled across the site while sources of water used by the trees (i.e. whether soil or groundwater) is being determined using O/H stable isotopes. For similar size trees, V. karroo had higher transpiration rates than Prosopis because of the larger sapwood to heartwood ratio in V. karroo than in Prosopis. However, at the stand level Prosopis consumed significantly larger amounts of water than V. karroo. This is because Prosopis invasions had a much higher tree density than V. karroo. From August 2013 to July 2014, annual stand transpiration for Prosopis (~ 372 mm) was more than 4 times higher than that of V. karroo (~ 84 mm). Tree water uptake was correlated to changes in groundwater levels (R2 ~ 0.42) with groundwater abstractions of ~ 2600 m3/ha/y by Prosopis compared to ~ 610 m3/ha/y for V. karroo. In addition, Prosopis showed evidence of hydraulic redistribution of groundwater wherein groundwater was deposited in the shallow soil layers while V. karroo did not. Results of this study suggest that clearing of Prosopis to salvage groundwater should target dense stands while less dense stands should be prevented from getting dense. {List only- not presented}
Starting From The Problem And Working Backwards	John	Doherty	2019	model calibration, decision-support
Abstract Many groundwater models are commissioned and built under the premise that real world systems can be accurately simulated on a computer - especially if the simulator has been "calibrated" against historical behavior of that system. This premise ignores the fact that natural processes are complex at every level, and that the properties of systems that host them are heterogeneous at every scale. Models are, in fact, defective simulators of natural processes. Furthermore, the information content of datasets against which they are calibrated is generally low. The laws of uncertainty tell us that a model cannot tell us what will happen in the future. It can only tell us what will NOT happen in the future. The ability of a model to accomplish even this task is compromised by a myriad of imperfections that accompany all attempts to simulate natural systems, regardless of the superficial complexity with which a model is endowed. This does not preclude the use of groundwater models in decision-support. However it does require smarter use of models than that which prevails at the present time. It is argued that, as an industry, we need to lift our game as far as decision-support modeling is concerned. We must learn to consider models as receptacles for environmental information rather than as simulators of environmental systems. At the same time, we must acknowledge the defective nature of models as simulators of natural processes, and refrain from deploying them in a way that assumes simulation integrity. We must foster the development of modelling strategies that encapsulate prediction-specific complexity supported by complexity-enabling simplicity. Lastly, modelers must be educated in the mathematics and practice of inversion, uncertainty analysis, data processing, management optimization, and other numerical methodologies so that they can design and implement modeling strategies that process environmental data in the service of optimal environmental management.
Variability In Kd And How It Relates To The New Guidelines For Contaminated Land	Michelle	Papenfus	2015
Abstract Globally, a growing concern have been that the heavy metal contents of soil are increasing as the result of industrial, mining, agricultural and domestic activities. While certain heavy metals are essential for plant growth as micronutrients, it may become toxic at higher concentrations. Additionally, as the toxic metals load of the soil increases, the risk of non-localized pollution due to the metals leaching into groundwater increases. The total soil metal content alone is not a good measure of risk, and thus not a very useful tool to determine potential risks to soil and water contamination. The tendency of a contaminant to seep into the groundwater is determined by its solubility and by the ratio between the concentration of the contaminant sorbed by the soil and the concentration remaining in solution. This ratio is commonly known as the soil partitioning or distribution coefficient (Kd). A higher Kd value indicate stronger attraction to the soil solids and lower susceptibility to leaching. Studies indicate that the Kd for a given constituent may vary widely depending on the nature of the soil in which the constituent occurs. The Kd of a soil represents the net effect of several soil sorption processes acting upon the contaminant under a certain set of conditions. Soil properties such as the pH, clay content, organic carbon content and the amount of Mn and Fe oxides, have an immense influence on the Kd value of a soil. Kds for Cu, Pb and V for various typical South African soil horizons were calculated from sorption graphs. In most cases there were contrasting Kd values especially when the cations, Cu and Pb, had high contamination levels, the value for V was low. There is large variation between the Kds stipulated in the Framework for the Management of Contaminated land (as drafted by the Department of Environmental Affairs) and the values obtained experimentally in this study. The results further indicate that a single Kd for an element/metal cannot be used for all soil types/horizons due to the effect of soil properties on the Kd. The results for Cu and Pb indicated that the Kds can range in the order of 10 to 10 000 L/kg for Cu and 10 to 100 000 L/kg for Pb. The variation in V Kd was not as extensive ranging from approximately 10 to 1 000 L/kg. {List only- not presented}
The Colenso Fault System - What Recent Geohydrological Investigations Taught Us	Nicolette	Vermaak	2019	investigations
Abstract A large number of groundwater investigations have been carried out in the Western Cape over the last decade or so. Most of them were related to water supply options for individuals, agriculture, businesses, industries, government departments and municipalities. Some of these developments have confirmed what we already knew about the groundwater characteristics and aquifers of the Western Cape, while others provided us with surprises - surprises so significant that we may have to re-write what we thought we knew. This paper will not be able to cover all the interventions and groundwater studies that have been done. Two case studies linked to the major geological structure in the Western Cape, namely the Colenso Fault (also known as the Franschhoek-Saldanha Fault), will therefore be used as an illustration of the lessons that were learnt by comparing them with our historical understanding of the associated groundwater characteristics. It will also show that there is a need for updated groundwater maps on smaller scale and a reassessment of the aquifers status.
A predictive study to better protect groundwater at Underground Coal Gasification site	Venessa	Aphane	2015	underground coal gasification
Abstract Underground coal gasification (UCG) is considered a cleaner energy source as its known effect on the environment is minimal; it is cheaper and a lesser contributor to greenhouse gas emissions when compared to conventional coal mining. It has various potential impacts but the subsidence of the surface as well as the potential groundwater contamination is the biggest concerns. Subsidence caused by UCG processes will impact on the groundwater flow and levels due to potential artificial groundwater recharge. The geochemistry of the gasifier is strongly depended upon site specific conditions such as coal composition/type and groundwater chemistry. Independent of the coal rank, the most characteristic organic components of the condensates is phenols, naphthalene and benzene. In the selection of inorganic constituents, ammonia, sulphates and selected metals and metalloids such as mercury, arsenic, and selenium, are identified as the dominant environmental phases. The constituents of concern are generated during the pyrolysis and after gasification as dispersion and penetration of the pyrolysis take place, emission and dispersion of gas products, migration by leaching and penetration of groundwater. A laboratory-based predictive study was conducted using a high pressure thermimetric gasification analyser (HPTGA) to simulate UCG processes where syngas is produced. The HPTGA allows for simulation of the actual operational gasifier pressure on the coal seam and the use of the groundwater sample consumed during gasification. A gasification residue was produced by gasifying the coal sample at 800 °C temperature and by using air as the input gas. The gasification residue was leached using the high temperature experimental leaching procedure to identify the soluble phases of the gasified sample. The leachate analysis is used to determine the proportion of constituents present after gasification which will be removed by leaching as it is exposed to external forces and how it will affect the environment. The loading to groundwater for the whole gasifier is then determined by applying the leachate chemistry and rock-water ratio to the gasifier mine plan and volumes of coal consumed.
Management of water-related risks in drinking water supplies	Barbara	Cencur Curk	2023	risk analysis, water-related hazards, water safety plan, water supply system
Abstract With the revision of the European Drinking Water Directive (Directive on the quality of water intended for human consumption 2020/2184) in December 2020, the preparation of Water Safety Plans (WSP) is foreseen according to the guidelines of WHO. Within the EU Interreg Adrion MUHA project, a decision support tool (DST) has been developed to provide a holistic approach to drinking water infrastructure risk analysis. The project mainly addresses four water-related risks: accidental pollution, floods, droughts and earthquakes. The core of the DST is the inventory of hazardous events (causes, their consequences and impacts) for each component of the drinking water supply chain: (1) drinking water source - catchment area, (2) water supply system, and (3) domestic distribution system. For each identified potential hazard, the type of hazard was determined (e.g., biological, chemical, radiological, or physical hazard (including turbidity), inadequate availability of water supplied to customers, safety to personnel, external harm to third parties, including liability). The DST was tested in the partner countries (Italy, Slovenia, Croatia, Serbia, Montenegro and Greece) to verify the resilience of the measures and elaborate the WSP. In the end, the REWAS-ADRION strategy was elaborated, aiming to increase the resilience of drinking water supplies to floods, droughts, accidental pollution, and earthquake-related failures by improving the water safety planning mechanism based on the concept of inter-agency cooperation to support water utilities, civil protection organizations, and water authorities.
Evaluating Groundwater Availability Based on Land Cover and Local Hydrogeology - A Groundwater Balance Approach	Hendrik	Botha	2019	land cover, water balance
Abstract The main purpose of this paper is to present a case study where a water balance concept was applied to describe the expected groundwater safe yield on a sub-catchment scale. The balance considers effective recharge based on local hydrogeology and land cover types, basic human needs, groundwater contribution to baseflow, existing abstraction and evaporation. Data is derived from public datasets, including the WRC 90 Water Resources of South Africa 2012 Study, 2013-2014 South African (SA) National Land Cover and Groundwater Resource Assessment Ver. 2 (GRAII) datasets. The result is an attempt to guide a new groundwater user regarding the volume of groundwater that can be abstracted sustainably over the long-term.
A numerical simulation of solute transport in dry coal ash dumps with a case study in South Africa	Innocent	Muchingami	2015
Abstract An understanding of the movement of moisture fluxes in the unsaturated zone of waste disposal sites play a critical role in terms of potential groundwater contamination. Increasing attention is being given to the unsaturated or vadose zone where much of the subsurface contamination originates, passes through, or can be eliminated before it contaminates surface and subsurface water resources. As the transport of contaminants is closely linked with the water ?ux in through the unsaturated zone, any quantitative analysis of contaminant transport must ?rst evaluate water ?uxes into and through the this region. Mathematical models have often been used as critical tools for the optimal quantification of site-speci?c subsurface water ?ow and solute transport processes so as to enable the implementation of management practices that minimize both surface and groundwater pollution. For instance, numerical models have been used in the simulation of water and solute movement in the subsurface for a variety of applications, including the characterization of unsaturated zone solute transport in waste disposal sites and landfills. In this study, HYDRUS 2D numerical simulation was used to simulate water and salt movement in the unsaturated zone at a dry coal ash disposal site in Mpumalanga, South Africa. The main objective of this work was to determine the flux dynamics within the unsaturated zone of the coal ash medium, so as to develop a conceptual model that explains solute transport through the unsaturated zone of the coal ash medium for a period of approximately 10 year intervals. Field experiments were carried out to determine the model input parameters and the initial conditions, through the determination of average moisture content, average bulk density and the saturated hydraulic conductivity of the medium. A two dimensional finite-element mesh of 100m x 45m model was used to represent cross section of the ash dump. Two dimensional time lapse models showing the migration of moisture fluxes and salt plumes were produced for the coal ash medium. An explanation on the variation of moisture content and cumulative fluxes in the ash dump was done with reference to preexisting ash dump data as well as the soil physical characteristics of the ash medium. {List only- not presented}
Alluvial Wellfield Optimisation And Management Using Numerical Flow Modelling And Seasonal River Stages	Brendon	Bredenkamp	2017	Alluvial aquifer, wellfield management, numerical modelling, river stages
Abstract Three dimensional numerical flow modelling has become one of the best tools to optimise and management wellfields across the world. This paper presents a case study of simulating an existing wellfield in an alluvial aquifer directly recharged by a major perennial river with fluctuating head stages. The wellfield was originally commissioned in 2010 to provide a supply of water to a nearby Mine. Ten large diameter boreholes capable of abstracting ±2 000 m3 /hour were initially installed in the wellfield. The numerical groundwater flow model was used to evaluate if an additional 500 m3 /hour could be sustainably abstract from the alluvial aquifer system. A probabilistic river flow assessment and surface water balance model was used to quantify low and average flow volumes for the river and used to determine water availability in the alluvial aquifer over time. Output generated indicated that the wellfield demand only exceeded the lowest 2% (98th percentile) of measured monthly river flow over a 59 year period, thereby proving sufficient water availability. Conceptual characterisation of the alluvial aquifer was based on previous feasibility studies and monitoring data from the existing hydrogeological system. Aquifer parameters was translated into the model discretisation grid based on the conceptual site model while the MODFLOW River package was used to represent the river. Actual river stage data was used in the calibration process in addition to water levels of monitoring boreholes and pump tests results. The input of fluctuating river water levels proved essential in obtaining a low model error (RMSE of 0.3). Scenario modelling was used to assess the assurance of supply of the alluvial aquifer for average and drought conditions with a high confidence and provided input into further engineering designs. Wellfield performance and cumulative drawdown were also assessed for the scenario with the projected additional yield demand. Scenario modelling was furthermore used to optimise the placement of new boreholes in the available wellfield concession area.