Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 551 - 600 of 795 results
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Abstract

The past few years hydraulic fracturing has been a hotly researched topic. Currently, most published documents are just speculation of what can happen if hydraulic fracturing is to take place in South Africa. There is very little work done to firstly establish a baseline on the current groundwater quality and secondly look at the current state of the groundwater around the Soekor wells. For these reasons a geochemical investigation was launched looking at the Soekor wells and the surrounding boreholes to determine a valid baseline.

Looking at the two Soekor wells; geochemical analyses was conducted on water, soil and rocks. The drill core of the wells; soils from the waste ponds and water at or nearby the wells were sampled and analysed. By making use of XRF; XRD, Stable Isotopes and water chemistry analyses, a better picture of these wells and groundwater can be developed to give better guidelines to what should happen during the monitoring of hydraulic fracturing wells.

Abstract

Northern India and Pakistan face some of the world’s most challenging surface water and groundwater management issues over the coming decades. High groundwater abstraction, widespread canal irrigation, increases in glacier melt and changes to rainfall impact the dynamics of surface water/groundwater interactions in the Indus Basin and Upper Ganges. Studies using newly available data from long-term hydrographs, high-frequency stable isotope sampling and campaign sampling for groundwater residence time indicators are shedding light on the complex interactions between groundwater, surface water and rainfall. Interactions vary spatially: (1) with distance down the catchment, related to the prevailing rainfall gradient, and (2) with position in the canal command, both distance from barrage and distance from feeder canals. Interactions are also observed to vary with time due to (1) the historical evolution of the canal network, (2) patterns in precipitation over the past 120 years, (3) changes in river flow due to glacial melting, and (4) increased pumping, which has also led to increased capture of surface water. Only by understanding and quantifying the different processes affecting groundwater/surface water coupling in the Indus and Upper Ganges is it possible to forecast future groundwater storage changes.

Abstract

Groundwater is the most important source of potable water in rural areas of Acholiland, a sub-region of northern Uganda. Installation of handpumps has been the focus of local government and international aid to provide safe drinking water in Uganda. However, non-functional handpumps are one reason for the abandonment of groundwater resources. For handpumps to be sustainable for years, appropriate siting and construction is required, as well as monitoring. This is common knowledge to specialists working in rural supply, but gaps in knowledge transfer and field skills may exist for the persons installing and maintaining handpump wells. This is a case study of a ten-day field campaign designed to train local participants who actively work in the rural groundwater supply sector. Nine non-functional handpump sites were identified for repair and hydrogeology and geophysical studies. A non-governmental organization, IsraAID, along with Gulu University implemented training by hydrogeology specialists to build local capacity. The training included handpump functionality tests, downhole inspections, electrical resistivity tomography surveys, and water quality sampling, including a novel Escherichia coli test that did not require an incubator. Functionality tests and downhole inspections provided simple but effective ways to assess handpump and well issues. Training in water quality empowered the participants to complete rapid assessments of the quality of the water and start monitoring programs. The success of the project was based on collaboration with multiple organizations focusing on the development of local capacity. The lessons learnt from this campaign should be considered for other rural groundwater supply scenarios.

Abstract

Transboundary aquifers in Europe are managed according to the Water Framework Directive (WFD) through international river basin districts (IRBD) management plans. Paragraph 11 in the WFD states that each Member State shall ensure the establishment of a programme of measures, PoM, for each river basin district, RBD, or part of an IRBD within its territory. Easy access to harmonized data from neighbouring countries part of the aquifer is essential to analyse the groundwater status and make proper PoMs. The datasets must be available in machine-readable format via an Application Programming Interface (API) and, where relevant, as a bulk download. The metadata describing the data shall be within the scope of the Infrastructure for Spatial Information in the European Community (INSPIRE) data themes set. The datasets must also be described in a complete and publicly available online documentation describing the data structure. Using a questionnaire survey of nine European countries, groundwater sampling and analysis routines are compared to evaluate if data are comparable and accessible across borders.

Abstract

Periodic climate variability, such as that caused by climate teleconnections, can significantly impact groundwater, and the ability to predict groundwater variability in space and time is critical for effective water resource management. However, the relationship between climate variability on a global scale and groundwater recharge and levels remains poorly understood due to incomplete groundwater records and anthropogenic impacts. Moreover, the nonlinear relationship between subsurface properties and surface infiltration makes it difficult to understand climate variability’s influence on groundwater resources systematically. This study presents a global assessment of the impact of climate teleconnections on groundwater recharge and groundwater levels using an analytical solution derived from the Richards equation. The propagation of climate variability through the unsaturated zone by considering global-scale climate variability consistent with climate teleconnections such as the Pacific-North American Oscillation (PNA) and the El Niño/Southern Oscillation (ENSO) is evaluated, and it is shown when and where climate teleconnections are expected to affect groundwater levels. The results demonstrate the dampening effect of surface infiltration variability with depth in the vadose zone. Guidance for predicting long-term groundwater levels and highlighting the importance of climate teleconnections in groundwater management is provided. The obtained insights into the spatial and temporal variability of groundwater recharge and groundwater levels due to climate variability can contribute to sustainable water resource management.

Abstract

Streamwater and groundwater are changing in the Arctic region because of significant climate warming. Arctic amplification has intensified the melting of snow cover, glaciers and permafrost, leading to a prominent variation in the annual discharge of rivers, the groundwater occurrence, and their relationships. In high-latitude regions, evaluating groundwater flux/storage and river discharge is challenging due to a lack of hydrogeological data. Changes in river flows and groundwater discharge will alter freshwater and terrigenous material flux, with implications for freshwater and marine ecosystems. Consequently, a more timely and accurate evaluation of surface and groundwater is required. In this framework, through the ICEtoFLUX project (MUR/PRA2021/project-0027), hydrology, geophysics and geochemical-isotopic surveys have been started during 2022 in the Bayelva River catchment (W-Svalbard) from its glaciers and periglacial/proglacial systems up to the Kongsfjorden. The study aims to quantify hydrologic processes and related transport of matter (solid transport, chemical solutes flux) and investigate how subsurface and surface waters interact during active layer development. The first results suggest that electrical conductivity and total suspended solids increase from glaciers to the Bayelva monitoring station, about 1 km from the coast. Seasonal evolution of physical-chemical features was also observed. Results from geophysics data and piezometers indicate that the underground flow is spatially and temporally heterogeneous, both quantitatively and from a physicochemical-isotopic point of view. Springwater characteristics testify to a deep and well-organized groundwater flow path system. This study highlights the high complexity of these systems and their high sensitivity to the meteo-climatic regimes.

Abstract

The Reconciliation Strategy for the Olifants River Water Supply System (ORWSS) indicated that the surface water resources in the Olifants Water Management Area are already overallocated, and recommended that the potential of the Malmani Subgroup dolomites along the Limpopo and Mpumalanga escarpment as an additional water resource be investigated. The Feasibility Study for Groundwater Resource Development of the Malmani Dolomites within the ORWSS considered among other aspects the hydrogeology, hydrology, artificial recharge potential, groundwater - surface water interaction and wellfield design options. A key aspect of the analysis and study findings was determining the amount of water that can be provided additionally, as the groundwater development was conceived as impacting on and reducing the ORWSS system yield. Hence, the implementation strategy was designed to address this mistrust in the groundwater potential and to allow for increasing the confidence in the yield estimates over time. The implementation strategy identified several possible recipients of the water, influencing the prioritisation of wellfield development. The scheduling of implementation should first address community water supply shortfalls in the area, followed by releases to the Olifants River to cater for environmental requirements and then direct development for bulk water supply schemes. Out of the twelve identified wellfield target zones (WFTZ), eleven are recommended for potential wellfield development. Seven Malmani Subgroup dolomite aquifer WFTZs have high groundwater development potential with proven high borehole yields (>10 l/s) and are recommended for priority full-scale wellfield development, through a phased monitor-model-manage approach. The total proposed groundwater development comprises 48 wellfields with a combined yield of >40 million m3/a. Although several organisations are suitable for implementing the scheme, or parts thereof, the DWS should maintain oversight function to ensure that the several parts of the scheme development are implemented in a coherent manner and in accordance to the implementation strategy.

Abstract

Water scarcity has driven many countries in arid regions, such as Oman, to desalinate seawater for freshwater supply. Episodic problems with seawater quality (e.g., harmful algae), extreme weather events that affect energy supply and hence the desalination process have nurtured the urgent need to store desalinated seawater (DSW) in the aquifers for use during emergency and peak demand time. Aquifer Storage and Recovery (ASR) using injection wells is a possible strategic option for Oman Water and Wastewater Services Company (OWWSC) to augment aquifer storage using excess desalinated water during low demand times. ASR strategically serves as a water supply backup to optimize production capacities against seasonal demand patterns. The technical-economic feasibility of implementing ASR schemes was investigated in Jaalan, Oman, using hydrogeological and geophysical field measurements, groundwater flow and hydraulic modelling, and economic analysis. Analysis of modelled scenarios results revealed that the Jaalan aquifer is suitable for storing and recovering about 4,000 m3 /hr in 2045. Various well field designs have been tested and optimized numerically using MODFLOW 6, showing that with 160 dual-purpose wells, 7.9 Mm3 can be injected and abstracted within the constraints defined for a robust and sustainable ASR system. Simulations with the density-dependent flow model (MF6 BUY) show that the injected volume can be fully recovered considering the drinking water quality standard. Other sites were also studied. ASR capacity was found to be site-specific, and the groundwater developments near the ASR site governed its feasibility

Abstract

The paper presents the groundwater monitoring data collected at Eskom's Thyspunt Site over the eleven-year period from January 2008 to January 2019. The Thyspunt site is underlain by an upper unconfined intergranular aquifer of the Algoa Group sediments, called the Algoa Aquifer, and a deeper semi-confined fractured-rock aquifer of the Table Mountain Group, called the TMG Aquifer. In the Algoa Aquifer, the highest water levels were recorded after the very good winter rains of 2011 and 2012. Between 2013 and January 2019 the recorded water levels in this aquifer have been declining to the lowest measured levels since monitoring started in 2008. This decline varies from 11.0 m in the Oyster Bay dune field recharge zone to 0.8 m in the Langfonteinvlei discharge zone. The deeper TMG Aquifer shows a similar decline over the last four years ranging from 10.1 m in the inland recharge zone where the TMG outcrops to 1.3 m at the near coastal discharge zone.

Abstract

Continued population growth, economic development and climatic change have increased the demand for water supply in South Africa. As a result, most surface water systems have been exhaustively developed, increasing dependency on groundwater, including on meager aquifers during dry spells. This study aims to characterize the hydrogeology of the Pietermaritzburg Formation, a poorly productive aquifer that has been targeted for borehole sitting during drought years though with poor success rate. Pumping test analyses, monthly monitoring of groundwater level, electrical conductivity (EC), pH, water temperature and environmental isotopes (?2H, ?18O) were undertaken in 2018. Analyses of the pumping test data of the pumping well using the Theis and Cooper-Jacob method has returned hydraulic conductivity (K), transmissivity (T) and storativity (S) values of 4.12*10-6 m/day, 1.56*10-4 m2/day and 1.52*10-4, respectively. Analyses of observation well data located west 20 m from the pumping well gave K, T and S values of 1.79*10-7 m/day, 6.95*10-6 m2/day and 2.8*10-10, respectively. A second observation well located 33 m north from the pumping well did not show any water level response to the pumping. Additionally, the rate of water level recovery was very slow both in the pumped well and one of the observation wells. These test results indicate that the investigated aquifer is not only poorly productive but also heterogeneous, compartmentalized in nature and not feasible for sitting water supply wells. Rainfall recharge estimated using the water table fluctuation method (WTF) based on monitored groundwater level data is about 28 mm/a or 3.5% of mean annual precipitation (MAP). The groundwater level, temperature and EC monitoring indicate that as new rainfall recharge reaches the aquifer, the groundwater level and temperatures increases while the EC decreases as a result of salinity reduction because of dilution. Similarly, as the groundwater level declines as a result of prolonged dry seasons, the groundwater temperature drops, while EC increases due to increased salinity. Furthermore, monthly environmental isotope monitoring shows that all the samples plot along the local meteoric water line (LMWL) indicating that groundwater is recharged from local precipitation. The groundwater at the studied site is characterized by Ca-Na-HCO3 hydrochemical facies indicating an early stage of rock-water interaction

Abstract

POSTER All groundwater is vulnerable to contamination, and natural in homogeneity in the physical environment results in certain areas being more vulnerable to contamination than others. Inherent in the agricultural, domestic and industrial sectors of Pietermaritzburg, is the generation of contaminants which, upon reaching the aquifer, result in the deterioration of the quality of groundwater, thus resulting in the water no longer being fit for its intended use. The DRASTIC method is used to calculate the groundwater vulnerability of a 670 km2 region, including the city of Pietermaritzburg. The suggested ratings of each parameter are scrutinised and adapted, according to their relevance to the region and according to known geological occurrences. The use of this method enables the user to generate a regional scale vulnerability map of the groundwater in Pietermaritzburg. The vulnerability map generated has the ability to effectively highlight vulnerable areas to groundwater contamination, which is of critical importance in correct land-use planning, as well as in indicating areas of particular concern, where further detailed investigations are needed. The results of such an assessment are used as an input, together with a contamination inventory to assess the potential risk of groundwater pollution in a groundwater risk map. Furthermore, the result informs local decision-makers and enables proactive prevention of groundwater pollution, in accordance with section 13 of the 1998 National Water Act. The intrinsic vulnerability of the Pietermaritzburg region was found to range from low to very high. The area found to be highly vulnerable is the region northeast of Springbank which requires investigation at a local scale.

Abstract

Emerging contaminants (e.g. pharmaceuticals or pesticides) are increasingly detected in aquatic environments. The most apparent contamination source of river water pollution by pharmaceuticals is sewage treatment plant stations that discharge treated sewage effluent to the rivers. The river bank filtration systems (RBF) can effectively remove these contaminants. The two RBF sites were examined for pharmaceuticals: Śrem and Gorzów waterworks. The water samples for pharmaceuticals investigation were taken from the river and four continuously pumped wells at each site. Two wells near the river were chosen at each site (40-50 m) and two at a greater distance from the river (70 m in Śrem and 110 m in Gorzów). A visible increase in pharmaceutical concentrations was observed along the river. The sum of pharmaceuticals concentration is 8151 ng/l in Śrem (upstream), while in Gorzów (downstream) concentration is 9142 ng/l. A very big differentiation in pharmaceutical occurrence was observed. In Śrem, the sum of pharmaceuticals concentration is between 657 and 3290 ng/l, while in Gorzów, despite the higher concentrations of pharmaceuticals in the river, these substances were detected only in one well located at a close distance from the river (two substances at a concentration of 92 ng/l).

The research proves a very big differentiation of pharmaceutical concentration even on sites located at similar hydrogeological conditions and demonstrates the necessity of its monitoring, especially in groundwater strongly influenced by river water contamination (like at RBF sites). This work has received funding from the National Science Centre Poland (grant no. 2021/41/B/ST10/00094).

Abstract

PFAS and pharmaceuticals in groundwater are two of many synthetic compounds currently under the attention of many researchers and environmental administration in Europe, especially in light of the revision of the EU Groundwater Directive 2006/118/EU. The two types of substances were first included in the voluntary groundwater watch list and were first formally regulated at the EU scale. This regulation implies that they will be obligatory to be monitored within national monitoring programmes for groundwater body status assessment procedures across the EU. While there is no doubt about the need to regulate the presence of these substances in groundwater, sampling procedures and QC/QA protocols may be challenging to implement as no official guidelines exist. Although scientific literature allows us to define protocols usually based on precautionary principle, these may be too difficult and expensive to implement at the national scale monitoring. This article describes a work that the Polish Geological Institute – National Research Institute undertook to define an optimal sampling process for PFAS and pharmaceuticals in groundwater. Experimentally tested factors included cleaning pumps between sampling sites, the need for using protective suits during sampling and the influence of ambient air on sample quality. Results showed that sampling protocols for PFAS and pharmaceuticals do not need to be modified concerning current protocols as these seem to be sufficient to protect groundwater samples from unintentional cross-contamination.

Abstract

The development of satellite technologies creates more and more opportunities to build modern tools for monitoring the state of groundwater. The use of the GRACE satellites to monitor GWS changes has become widespread, but the degree of accuracy with which remote sensing data can estimate these changes is unclear. In this study, we quantified changes in the GWS in Poland from 2009 to 2022 using GRACE observations, in-situ data, and GLDAS. Long-term trends and seasonality were calculated and analysed for each time series. The correlation analysis between GRACE TWS, GWS obtained from GRACE and GLDAS, and GWS in situ was performed using linear regression. Pearson and Spearman’s methods show that GRACE performance is good in the region of shallow (up to 3 m) presence of thick (above 5 m) unconfined porous aquifers; however, performance is worse in a region with multiple aquifer systems, including fissured and karst aquifers. In addition, an unrepresentative groundwater GRACE signal is obtained in regions with surface water storage, such as the Baltic Sea area. It was also found that there is very high consistency between the GRACE observations and wells water level changes, while the GWS series obtained from GRACE and GLDAS do not provide adequate compatibility. According to the GRACE data, the results suggest that evapotranspiration and the hydrodynamic system have the greatest impact on the sensitivity of the GWS estimation. The results are important for better processing the GRACE data to obtain a representative signal for the GWS assessment.

Abstract

Shallow groundwater dynamics play a crucial role in wetland ecosystems and are key to climate change resilience. Therefore, conserving and restoring wetland areas requires excellent knowledge of groundwater flow dynamics, which are often rapidly changing following extreme weather events and anthropogenic impacts such as groundwater extraction. Traditional methods to estimate groundwater flow require extensive modelling or rely on point measurements, missing the effect of crucial short-term events and impeding quick actions to conserve the wetlands’ ecohydrological status. Here, we present a newly developed sensor that can measure real-time groundwater flow velocity and direction. The sensor probe consists of two bidirectional flow sensors that are superimposed. It is installed in a dedicated pre-pack filter and can measure a broad range of groundwater flow velocities from 0.5 cm/ day to 2000 cm/day. With an IoT (Internet of Things) system, sensor data is wirelessly transmitted and visualized in real-time on an online dashboard. In addition, we show a selection of results from a case study in the Biebrza National Park (Poland) and a nature reserve in Damme (Belgium). In both ecosystems, we could capture changes in groundwater flow velocity and direction resulting from precipitation and evapotranspiration events. As such, we are confident that our sensors provide new insights into rapidly changing groundwater dynamics and will become an invaluable tool in ecohydrological studies worldwide, ultimately leading to more integrated management strategies to protect and conserve remaining wetlands.

Abstract

There is a transboundary groundwater reservoir on the Polish–Ukrainian borderlands, which is of key importance in shaping strategic groundwater resources. Due to the particular importance of this reservoir, the two neighbouring countries are obliged to undertake joint actions to protect it. One of the main difficulties in building a common platform for the management of TBAs in the Polish-Ukrainian border area is the differences in the approach to the identification of GWB, monitoring methodologies and assessment of the condition of GWB, and the inconsistent hydrogeological databases between the two countries. A transboundary numerical groundwater flow model was developed to support internationally integrated management. The model research helped diagnose potential problems by determining the scope of the area with cross-border flows and quantifying the flows between Poland and Ukraine. In addition, the numerical model was used to define the optimal cross-border management unit and the conditions needed to exploit the Lublin–Lviv Reservoir sustainably. Abstraction on a current level slightly increased the transboundary groundwater flow from Poland to Ukraine and minimally reduced the flow in the opposite direction but did not reverse the direction of water flow at the border. The simulated drawdowns do not have a transboundary range, but negative effects on surface water resources are noticeable. Joint management should focus on a broader legal consensus, improvement of institutional relations, and integration of monitoring and groundwater status assessment systems.

Abstract

Groundwater numerical models are commonly used to determine the impact that groundwater abstraction has on the ability of surrounding areas to supply water, and thus to inform Water Use Licence (WUL) Applications. However, data available is often limited to that generated by relatively short-term geohydrological studies and pumping tests. In most cases this data and the degree of defined uncertainty in the model results are sufficient. However, for large scale abstractions (such as municipal abstraction) and in sensitive or complex geological areas, a more rigorous approach to calculating the impact from pumping is recommendable. The study area is located on a syncline consisting of two sandstone aquifers. However, there was a lack of data to quantify the connectivity between the two aquifers. SRK Consulting (South Africa) (Pty) Ltd undertook a rigorous, long-term approach, which included a 3- year monitoring plan of the area, input from stakeholders, extending the hydrocensus to the entire catchment and monitoring of pumping in the area. Using this comprehensive data set, the existing numerical groundwater model was updated, re-calibrated and validated such that predictive scenarios could be run to assess the long-term potential impact of the municipal wellfield. These results were submitted for the final allocation of the WUL. Along with mitigation measures, recommendations could also be made on where to focus monitoring and future testing. This rigorous methodology and the use of long- term comprehensive monitoring data is recommended for future use in similarly complex environments to decrease uncertainty on the expected impacted area from large-scale abstractions.

Abstract

The lack of reliable groundwater level monitoring data hinders the comprehensive understanding and sustainable management of our aquifers. New remotely sensed data products could present novel possibilities to fill in situ data gaps. For example, continuous monthly groundwater storage anomaly estimates at a spatial resolution of 0.25° (28 km) are made available through the Global Data Assimilation System Version 2.2 (GLDAS-2.2) data products that assimilate Gravity Recovery and Climate Experiment (GRACE) data. In this study, it was hypothesised that the open-source, higher resolution Climate Hazards Group InfraRed Precipitation With Station Data (CHIRPS) precipitation data and Moderate Resolution Imaging Spectroradiometer (MODIS) evapotranspiration data could be used to downscale groundwater storage anomalies (GWSA) for local scale investigations. Using an intergranular and fractured aquifer, as well as a karst aquifer as case studies, both enclosed within the Steenkoppies Catchment (A21F), two respective random forest regression (RFR) models were developed to downscale GLDAS-2.2 GWSA. Sampling monthly training data without accounting for temporal lagging resulted in an increased correlation, index of agreement (IA) and improved RMSE for the intergranular and fractured aquifer. Where the correlation between the observed groundwater storage changes and the GLDAS-2.2 groundwater storage estimates were weaker, however, accounting for the temporal lags resulted in an improved RMSE. The final product is a 0.05° (5.5 km) grid of monthly time-series GWSA estimates that can improve groundwater resource assessments, understanding aquifer recharge, modelling accuracies and better overall decision-making regarding Integrated Water Resource Management (IWRM).

Abstract

he Namphu and Rangbua subdistricts in Ratchaburi province, in western Thailand, are affected by groundwater contamination. According to site characterization results, the aquifer has been contaminated with volatile organic compounds and heavy metals since 2014. Membrane filtration technology is an alternative method for treating groundwater to produce safe drinking water for household use. Nanofiltration membrane is a relatively recent development in membrane technology with characteristics that fall between ultrafiltration and reverse osmosis (RO). This study aimed to determine the hydrochemistry of contaminated groundwater and examine the efficiency of nanofiltration membranes for removing pollutants in groundwater and the potential implementation of the membrane. The membrane module used in this study is cylindrical in shape of 101.6 cm long and 6.4 cm in diameter, and the membrane surface charge is negative with monovalent rejection (NaCl) of 85-95%.

The filtration experiments were conducted at a pressure of 0.4-0.6 MPa, which yielded flow rates of approximately 2 L/min. To examine the nanofiltration membrane efficiency, groundwater samples were extracted from four monitoring wells and were used as feed water. According to laboratory results, the nanofiltration maximum removal efficiencies for 1,2-dichloroethylene, vinyl chloride, benzene, nickel, and manganese were 97, 99, 98, 99, and 99%, respectively. However, the treatment efficiency depends on several factors, including pretreatment requirements, influent water quality and the lifespan of the membrane. Further research should be conducted to determine the maximum concentration of VOCs and heavy metals in the feed water before applying this treatment method to a large scale.

Abstract

The use of groundwater in the Robertson area, Western Cape, specifically to the south of the town is underdeveloped. The Breede River is the primary source for irrigation of vineyards and livestock watering through various channels and waterways. In an attempt to secure an additional water supply, small scale groundwater exploration was conducted which has culminated into an extensive network of boreholes with varying yields and geochemical signatures. As demand for usable water increases, a better understanding of the quality of the groundwater is as significant as the quantity of groundwater available for informed decision-making. This study area overlies a plunging asymmetrical syncline which comprises of the Rietvlei sandstones of the Table Mountain Group (TMG) and the younger Bokkeveld Group. The TMG forms mountain ranges on the southern and northern limbs of the syncline. Boreholes of higher blow yields were selected to undergo yield tests to determine sustainable yields. Higher yielding boreholes with an average yield of 7.4 L/s were drilled into the highly fractured and quartz-rich sandstones, while lower yielding boreholes with an average yield of 2.2 L/s were drilled into the Bokkeveld Group. The only existing borehole in use, situated on the northern limb of the syncline along the Sewefontein Fault, had a higher yield than neighbouring boreholes and a significantly better groundwater quality, somewhat of an anomaly in this section of the study area. In an attempt to access groundwater from the same formation, additional geophysical exploration, drilling and testing was conducted. The results however indicated low blow yields and poor quality groundwater. AQTESOLV software was used to further characterise and classify aquifer parameters. Descriptive statistics together with graphical hydrological methods were used to characterise the geochemical composition of the groundwater. The lithology of the study area indicates that the syncline has been extensively fractured as a result of post depositional folding and faulting. Fractures with a primary strike direction of 120° to 140° provide flow paths across the different formations, indicated by geological logs and borehole connectivity. Mean transmissivity values for the TMG are almost double that of the Bokkeveld Group, and salinity of the latter is significantly higher than that of the TMG. Transmissivity provides an indication of residence time (with an inverse relation) and thus leads to the assumption that groundwater flow rate is slower in the Bokkeveld Group. Elevation also plays a role, with a negative correlation to salinity. Recharge is delayed in lower lying areas which are predominantly underlain by Bokkeveld Group rocks, and clay rich derivative soils. Water readily ponds here and undergoes increased evapouration. The resultantsalt precipitation gets flushed into the saturated zone during future rainfall events. Recharge that does reach the saturated zone increases in salinity along its flow path due to ion absorption and cation exchange with clay minerals. Higher lying areas have little to no soil cover, with the thin soils comprising almost solely of quartz grains - considered chemically inert. As groundwater flows from the TMG into the Bokkeveld Group, residence time increases and salinity levels increase significantly.

Abstract

Water security is pivotal for economic growth, sustainable development and poverty reduction in SADC. Increasing aridity and dwindling surface water supplies are resulting in new opportunities for groundwater as a source for domestic, agricultural and industrial use. We carried out an assessment of groundwater governance in the SADC region to determine the effectiveness of provisions to regulate groundwater. Numerous sources of information were solicited, reviewed, and data was mined using framework analysis and qualitative context analysis approaches. This provided a systematic model for managing and mapping the data. There is a good understanding of aquifer systems at the regional level. Transboundary aquifers have been delineated and areas prone to groundwater drought have been identified. Information systems to manage groundwater data, however, are disparate throughout the region and institutions to manage groundwater are inadequate and are functioning within an environment of scarce financial and human resources. The hydrogeological capacity in public institutions such as government departments is a major concern and regulations to protect groundwater resources are often not in place. This includes instruments to control groundwater abstraction and potentially polluting activities. Where regulatory instruments are in place, often no enforcement or sanctions of unlawful activities are taking place. There is also limited coordination with other sectors such as energy and mining. Furthermore, the implementation of groundwater management action plans, where developed, is weak. Overall, groundwater management in the SADC region was found to be poor. Whilst the groundwater governance challenges are great, there are opportunities to support diagnostic analysis of transboundary aquifer systems, competency development, establishing regional groundwater monitoring networks, strengthening institutional frameworks, and development of groundwater resources, e.g. to clear the backlog in access to improved water supply.

Abstract

The International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial, sustainable aquifer development and management. The Stampriet Transboundary Aquifer System was selected as one of the three case studies funded by UNESCO. The Stampriet Aquifer System is located in the arid part of the countries (Botswana, Namibia and South Africa) where groundwater is a sole provider for water resource. The area is characterised by the Kalahari (local unconfined aquifer) and Nossob confined aquifer

Abstract

Pietersen, KC; Musekiwa, C; Chevallier, L

Groundwater plays an integral role in the fresh water supply for both rural and urban populations of the Southern African Development Community (SADC). However, the sustainable use of groundwater is negatively impacted by persistent and recurring droughts in the region. Understanding the characteristics of drought and the risk to groundwater, will contribute towards better planning and management of water supply in the region. In this study, a novel approach is demonstrated, that uses data from the Gravity Recovery and Climate Experiment (GRACE) to map and characterise the risk to groundwater storage from drought, across the SADC region. In addition, this study also demonstrates and evaluates the inclusion of this new feature, groundwater storage sensitivity, as an additional input into a revised Groundwater Drought Risk Mapping and Management System (GRiMMS), in-order to update the SADC groundwater drought risk map developed in 2013. Specifically, the GRACE Groundwater Drought Index is calculated and used to characterise the total length, average intensity and trend, in groundwater storage drought conditions. These three factors are then combined into a new layer, groundwater storage sensitivity, and validated through comparison with groundwater level data. The groundwater storage sensitivity, which represents the risk to groundwater drought associated with groundwater storage deviations, is then included at the modular level in the GRiMMS algorithm. The inclusion of the GRACE derived groundwater storage sensitivity further highlights regions of known hydrological drought, emphasising the impact groundwater storage plays in mitigating drought risk. In conclusion, GRACE provides a unique tool that can be used to map the impact of drought across the SADC region.

Abstract

What are the key institutions, both formal and informal, that determine actual groundwater use in the Ramotswa aquifer? Are current institutions at regional, national and sub-national levels adequate to collaborate for equitable benefit-sharing for the future? These are the questions that the paper will address based on early findings of a project aimed at determining the role the Ramotswa aquifer can play in addressing multiple-level water insecurity, drought and flood proneness, and livelihood insecurity. Groundwater resources are critical in the SADC region

Abstract

Groundwater is a strategic long-term water resource used by an estimated 70% of the populations in sub-Saharan Africa for drinking, irrigation and a wide range of economic activities. Understanding groundwater recharge processes is key for effectively using and managing water resources. Very few studies have used direct groundwater observations to assess the impact of different farming systems on groundwater recharge processes. This study focused on assessing basement aquifer recharge in 4 instrumented catchments in Malawi (Chitedze), Zambia (Liempe and Kabeleka) and Zimbabwe (Domboshawa) within the SADC region between 2019-2022. Employing a range of methods, including direct field observations (groundwater hydrographs, precipitation data, stable isotopes, chloride mass balance and residence time tracer data), we quantify the amount of groundwater recharge as well as the timing and nature of recharge processes under both conservation and conventional tillage systems in these four study sites. Groundwater recharge was measured in most years across the study sites. The study reveals the strong climate controls on seasonal groundwater recharge volumes, the influence of low permeability layers in the unsaturated zone, and the likely magnitude of impact from different farming practices. Groundwater residence times are high (i.e. low fractions of modern recharge, interquartile range 1-5%, n=46), even in shallow piezometers, suggesting these unpumped systems may be highly stratified. The results provide an evidence-based suite of data that reveals much about key controls on groundwater recharge in basement aquifers in sub-humid drylands and will inform the development and management of such groundwater systems.

Abstract

The Sagole hot spring is located in the northern Limpopo Province of South Africa. Investigations were carried out in order to investigate the groundwater aquifer and water chemistry. Results were envisaged to the understanding of the geothermal potential of the area. Regional scale airborne magnetic data and geology were used for identifying structures and lithological boundaries that are associated with thermal groundwater aquifers. Detailed ground follow-up and verification surveys were  carried  out  across  the  target,  using  magnetic,  electrical  resistivity  tomography  (ERT), frequency-domain electromagnetic (FDEM) and radiometric methods. Water samples were collected from the spring eye and archival groundwater data was analysed. The interpretation of the airborne magnetic data revealed the presence of west to east, northwest and intersecting lineaments at the hot spring. From magnetic data, the groundwater aquifer was found to be capped by basalt with heat rising to the surface along possible geological contacts, faults or fractures. The FDEM profile data across the aquifer zone had peak values above 100 mS/m. The inversion of ERT data defined a highly electrical conductive, low resistivity with thickness of about 60 m. Chemical analysis of the ground water revealed that the water does not have any indication of pollution. The thermal water was found to be of meteoric origin. The drilling of artesian thermal boreholes through the capping basalt should be explored. The hot-water boreholes will be utilised by the community for domestic, irrigation and possible development of micro-geothermal systems.

Abstract

Saldanha Bay Local Municipality appointed Skytem to conduct an airborne geophysical 3D aquifer mapping survey. As part of improving the sustainable management of the groundwater resources and exploring the options of Managed Aquifer Recharge, a better understanding of the aquifers is required. The Skytem technology unlocked a rich understanding of the subsurface geology and the groundwater contained in it.

Before the main survey commenced, a trial survey was conducted to investigate the quality of the data that may be expected from the main survey. The trial survey was conducted over the existing water supply wellfield where there were existing groundwater data including borehole lithology from drilling and ground geophysics. Consequently, the main survey commenced and consisted of the following:
1) Magnetic survey providing information regarding bedrock composition and where it changes due to faults or deposition,
2) Time Domain Electromagnetic survey providing conductivity/resistivity of the subsurface,
3) Detailed elevation along flight paths, and
4) 50Hz signal to understand where interferences can be due to power lines.

The survey interpretation showed the following important aquifer characteristics that will be useful for future management of the aquifer system:
1) Bedrock elevation and paleo topography, 2) Areas with different bedrock composition, 3) Geological faults in the bedrock, 4) Bedrock below the surface, 5) Areas with thick dry sand, 6) Clay layer extent and area without clay, 7) Areas with different water quality, and 8) Areas with very high concentrations of salt.

The survey output and interpretations are regarded as very useful for the update of the conceptual models for the area. Data can now be used to update the numerical models and improve the management of the wellfields.

Abstract

Saldanha Bay is partially dependent on groundwater as part of their bulk water supply, as surface water resources in the area are extremely limited and fully allocated. Due to this, there is lots of pressure on the groundwater resources by industrial development and residential growth. Despite studies being conducted on these aquifer systems since 1976, they are still poorly understood especially with regards to their recharge and discharge processes. This study aimed at providing better insight and understanding on the natural groundwater recharge and discharge processes in order to assist in the better management of groundwater resources in Saldanha Bay. Recharge investigations included a Time Domain Electromagnetic airborne geophysical survey, the assessment of groundwater levels, infiltration tests, hydrochemical analyses as well as stable and radioactive isotope analyses. These methods allowed for the delineation of the geological layers and extent, determination different water quality spatially across the aquifer, determination of flow paths through the saturated and unsaturated zones, identification of inter-aquifer flow as well as different recharge processes in the area. The results of this study showed that is highly likely that the Saldanha Bay Aquifers are mainly recharged via deep flow paths from the Aurora Mountain Range and Moorreesburg region. Investigations also showed that it is unlikely that the Aquifer Systems are recharged by local rainfall due to thick unsaturated sands and low annual rainfall, except for runoff at the foot of granite hills through focused recharge processes. The Berg River, Langebaan Lagoon and the Atlantic Ocean were identified as being the main discharge zones for the area. It is recommended that further hydrogeological investigations are conducted in the Moorreesburg region in order to get a fuller picture of the regional groundwater recharge processes and flow to Saldanha Bay.

Abstract

Surface water has traditionally been the primary resource for water supply in South Africa. While relatively easy to assess and utilise, the surface water resource is vulnerable to climatic conditions, where prolonged periods of drought can lead to an over-exploitation and eventually water shortness and supply failure. Following the drought in 2018, more focus has been given to the groundwater resource to supplement the water supply in South Africa.

In the Saldanha Bay municipality the water supply is based on a combination of surface water and groundwater, with plans to supplement this with desalination and managed aquifer recharge (MAR) in the future. For an efficient and sustainable utilisation of the different water resources, a Water Supply Management System is developed that can be used to manage water mix from multiple resources. The system builds on top of a flexible WaterManager system developed for operation of complex water supply infrastructures, which in the study is extended by implementing operational rules for optimal management.

The operational rules provide recommendations for the day-to-day management, but also consider seasonal and long-term utilisations. To achieve this, the rules will rely on real-time monitoring data combined with results from hydrological modelling, providing estimated system response to selected scenarios to which the water supply must be resilient. In the present study the combined Water Supply Management System is developed and tested using synthetic data, which will be presented in the paper.

Abstract

Introduction: Verlorenvlei catchment in the renowned potato Sandveld area is shared by three main towns where agriculture is a primary economic activity. This semi-arid catchment, receives low winter rainfall, but has a dynamic groundwater system providing almost all water services in the catchment and sustaining the acclaimed Verlorenvlei RAMSAR site. There have been recurring concerns of land use as a potential threat to water resources and the sustainability of Verlorenvlei RAMSAR site. The Minister of Water and Sanitation as custodian of water resources requires that surface water use less than 18 250 m3 and ground water use less than 3 650 m3/a to be granted under general authorization. All water use above such general authorization volumes is to be registered (Government Gazette No. 20526 of 1999). Water use registration, is identified as a tool used to achieve the effective management and governance of water resources. Water use above general authorization, is associated with larger scale land use activity, which may have an impact on water resources and the environmental at large. The following study, seeks to examine and compare catchment water use for land uses, to catchment water availability using water use registration data. Comparing water allocation and catchment capacity, this study further seeks to explore the effectiveness of water use registration in achieving good governance of water resources. Purpose: The purpose of this study was to determine effectiveness of water use registration in promoting good governance in the Verlorenvlei catchment Results: Of 124 registered water users identified in the Verlorenvlei catchment, only two of these water users are within the legislative limit outlined by Government Gazette No. 20526 of 1999. Overall, permissible water use is 447 547 259.5 m3/a, over 10 times the catchment capacity of 40 000 000 m3/a. Conclusion: Overall, excessive water use for land use activity is observed within the catchment, despite provision of legislature guiding against excessive water use. Increased water use registration, does however correlate with improved land use practices for agricultural production (Potato SA, 2014) suggesting probability of good governance. Lastly, there is a need for monitoring; improved water and land use efficiency, Integrated Water Resources Management and good governance in the catchment.

Abstract

The proximity of aquifer systems to sources of contamination exposes them to severe environmental threats. Pollutants that leak from petrol stations, industrial areas and landfills eventually seep through the vadose zone to reach shallow groundwater, leading to groundwater contamination. One of these pollutants is Methyl Tertiary-Butyl Ether (MTBE), which is a polar organic compound that is volatile at room temperature. As a result of its high solubility compared to other gasoline additives, MTBE can cause serious environmental issues. The aims of this study were to characterize the extent of MTBE in groundwater and characterize natural attenuation in a Saudi Arabian MTBE and methanol manufacturing company.

The aims were achieved by analyzing monthly MTBE concentrations (to observe the seasonal changes of MTBE) and annual MTBE concentrations (to observe long-term changes) in 5 out of 18. Groundwater samples were collected, and in each year the MTBE, Total organic carbon (TOC) and Electrical conductivity (EC) concentrations were recorded. Because of inconsistency in the data, the results for the monthly data were from 2007 to 2010, and from 2007 to 2012 for the annual data. The results indicated a positive relationship between MTBE and TOC, and as a result TOC can be used to monitor and indicate the presence of MTBE. There was plume growth in 2 of the 5 wells (well 4 and well 14) with well 4 recording the highest MTBE concentration in all years. The reason for the high concentration might be because of spillages during truck loading. The other 3 wells showed signs of natural attenuation. Results from seasonal data suggested that temperature influences MTBE concentrations and therefore the rate of natural attenuation. There are many methods to remediate MTBE and each of them is site specific, but bioremediation was recommended for this site due to its cost-effectiveness.

Abstract

Siloam, a village in the Northern province of South Africa (SA) has groundwater reportedly characterised by concentration of fluoride greater than the permissible limit of 1.5 mg/L by the World Health Organization (WHO). In response to reported high incidences (80%) of dental fluorosis in Siloam, sources of fluoride in the groundwater of Siloam village was investigated. Earlier hypothesis suggest that the source of fluoride could be fluorite. Physicochemical parameters were determined using a combined multimeter; while total fluoride (TF) was determined using Ion Chromatograph and Fluoride Ion Selective Electrode. Mineralogy of the rocks and soil in the village was determined using X-ray Fluorescence and X-ray diffraction, respectively. Results revealed that groundwater fluoride concentration ranged from 3.92 to 4.95 mg/L, which are far above the WHO permissible limit and South African National standard. Na-Cl water type was found to be dominant in the water samples which could be due to the heavy weathering of plagioclase present in the parent rocks. TF content of the rocks and soils of the village ranged from 10 to 2000 mg/L. Leachates were obtained by soaking the pulverised rocks and soil in de-ionized water over a period of 24 hours. TF in leachates ranged from 0.27 to 14.88 mg/L and 0.05 to 10.40 mg/L at induced, and non-induced temperature, respectively. Although, previous research hypothesize fluorite to be the possible source of fluoride in the village, this research shows that the main contributors of fluoride to groundwater in Siloam were smectite clays and the muscovite present in the sandstone, Investigation also revealed that the geothermal temperature of groundwater in the area is also a major factor enhancing the release of fluoride from the clay material into the groundwater.

Abstract

This study developed operating rules for groundwater supply from a probabilistic (risk-based) approach. Groundwater supply systems are often operated without relating groundwater yield/availability to demand which makes groundwater resource planning and management challenging and unpredictable. Risk-based approaches for developing groundwater operating rules comprehensively incorporate assurance of supply and also account for uncertainty due to model inputs, model structure and climate variability. A groundwater resource unit (GRU) was delineated and its hydrogeological conceptual model developed. A program for generation of monthly groundwater levels for the GRU was coded in FORTRAN based on the GW-PITMAN model. The model was calibrated using groundwater levels from a neighbouring borehole due to lack of observed representative data for the GRU. Validation was done by establishing the realistic nature of simulated runoff, recharge and groundwater levels. A Variable Length Block (VLB) bootstrapping model was used for simultaneous generation of stochastic inputs (rainfall, evaporation and groundwater levels) of the operating rules model. Operating rules were developed from statistical analysis of 100 base yields for the GRU simulated from 5-year long stochastically generated inputs. The hydrogeological conceptual model indicated presence of faults and diabase dykes which influence preferential flow paths and storage of water in the aquifer. Majority of the historical statistics were mostly well preserved by VLB, except for skewness. Superimposing the cumulative demands on the base yield curves and analysis of percentages of water demands that can be supplied indicated that the groundwater system could not meet the water demands at all times. The operating rule curves indicated that if priority classification is used all water demands are met up to a maximum groundwater level of 25 m. The operating rule curves are therefore expected to improve water supply to both domestic and productive water uses, if they are adequately implemented and hence improve livelihoods.

Abstract

This study assessed the chemical and microbial quality of groundwater and potential risks to human health in Siloam Village, South Africa. Due to lack of access to potable water, residents in rural areas drill private boreholes within their homesteads without considering the potential sources of groundwater pollution. This exposes them to health risks associated with groundwater pollution. Water samples from 11 boreholes were collected from August 2013 to January 2014. pH and EC were measured using a multimeter and turbidity was measured using a turbidity meter. Non-metals and metals were analysed using Ion Chromatography and Atomic Absorption Spectroscopy, respectively. Colilert quanti-tray method was used to determine total coliforms and Escherichia coli. Descriptive statistics were used to determine the overall water quality status. Potential risks to human health were inferred based on Department of Water and Sanitation guidelines for domestic use. Water quality parameters found to have serious potential health effects on human beings were correlated with selected water quality parameters at a significance level (α) of 0.05 to understand the nature of correlation and possible sources of contamination. The study determined that nitrates and fluorides were the only parameters with excessively high concentrations in groundwater which are associated with health effects on human beings. Correlation of fluoride with calcium and pH indicated that further investigations are required to identify the local sources and fluoride control mechanisms in the study area. Correlation of nitrate with chloride and potassium indicated that faecal contamination and fertilisers are sources of nitrate pollution in the study area, though faecal contamination was the dominant source. Faecal contamination was confirmed from total coliforms and E.coli in most boreholes. The study identified the need to educate borehole owners in such villages of possible strategies to minimise groundwater pollution. 

Abstract

Water stress is frequently experienced in many parts of South Africa. To ensure the longevity of the country’s water resources, particularly groundwater, accurate quantification of the resource and prediction of the responses of each water resource unit to natural and anthropogenic stresses are necessary. To this endeavour, Simbithi Eco-Estate, located at Shaka’s Rock, KwaZulu-Natal requires the implementation of a Water Management Plan that includes a hydrogeological investigation. A hydrogeological conceptual model was developed for the eco-estate, based on which a numerical groundwater flow model was calibrated to simulate the impacts of different rates of groundwater abstraction within the estate. Hydrometeorological information, subsurface geology, hydraulic head, hydraulic characteristics of the aquifer units and hydrochemical data were analysed to develop a two-layer hydrogeological conceptual model. The conceptual model was used as the main input to the numerical groundwater flow model. The calibrated steady-state numerical model, developed using the finite-difference groundwater modelling code, MODFLOW, was used to determine the sustainability of groundwater abstraction within the eco-estate. During calibration, the hydraulic conductivities of the hydrostratigraphic units, and recharge were varied. The Model calibrated recharge was 5.5 % of the mean annual precipitation (MAP). The five abstraction scenarios considered were: Scenario 1, which is the sustainable abstraction rate determined from the analysis of pumping test data, and Scenario 2 to 5 which are assigned progressively increasing abstraction rates of Scenario 1, by a factor of 20%, 50%, 100%, and 1000%, respectively. The numerical model simulations indicate that Scenario 1 is most sustainable in terms of groundwater level drawdown and saltwater intrusion. The simulated groundwater drawdown progressively increased throughout the succeeding four scenarios.

The simulation results of the 5th scenario indicate that part of the model domain within the vicinity of the northern boreholes becomes dry and subsequent application of forward particle tracking on the simulation results predicts saltwater intrusion from the Indian Ocean towards the south eastern boreholes. It is accordingly recommended that groundwater resource development should be limited to below the abstraction rates of Scenario 4. Additionally, continuous monitoring of all boreholes within the eco-estate is recommended to generate time-series groundwater level information, which would be used to improve the predictive capabilities of the current steady-state model through a transient numerical groundwater flow model. To that end, an immediate establishment of a groundwater level and specific electrical conductivity (EC) monitoring network, equipped with data loggers, is recommended.

Abstract

It's been said that you cannot manage what you cannot measure. This is especially true with groundwater management; where we have limited data allowing us to 'see' the underground source. All over the world, people are spending aquifers full of money (bucket loads) on monitoring programmes and hydro census's. They capture borehole locations, water levels, abstraction rates, rainfall measurements and water quality analysis, then typically store the product, the deliverable, their valuable data, in a massive amount of spreadsheets. They have measured, but struggle to manage effectively because the data has not been stored in a centralised, consolidated fashion. Join us for a journey through Dagbreek, an open cast pit at Sishen mine, one of the largest open cast iron ore pits in the world and certainly part of the biggest dewatering project in South Africa. See how Sishen utilised technology to eliminate manual, paper-based data collection and spreadsheets. See how they utilised a cloud-based information management system to centralise and consolidate their data before transforming the data into valuable visualised information. See how this is equipping Sishen's decision makers with easy to interpret and up-to-date information, empowering them to make more effective operational and management decisions about their dewatering and groundwater management strategy

Abstract

The City of Cape Town (CoCT) commenced a study into the feasibility of the Table Mountain Group aquifers (TMGA) for augmenting the water supply to the city in 2002. It comprised drilling of exploration boreholes in several target areas and the establishment of a hydrogeological and ecological monitoring network. Due to the prolonged drought and associated water crisis, the CoCT decided to fast-track the TMGA development in 2017. The first wellfield is currently developed within the catchment area of the Steenbras Dam comprising production boreholes targeting the Skurweberg and the Peninsula aquifers of the TMGA. Since groundwater abstraction from the Peninsula and Skuweberg aquifers might have a short-term or long-term impact on aquatic ecosystems (i.e. streams and wetlands) that are linked to the TMGA. As a result, evaluation of the potential impact of groundwater abstraction from this aquifer system requires an understanding of the nature and extent of groundwater dependency of the ecosystems. A variety of data sets and parameters have been measured over the last decade at ecological monitoring sites across the study area, of which two sites are located within the Steenbras catchment that are probably connected to the Skurweberg Aquifer. Recently further boreholes and monitoring sites have been added. This paper describes the various methods used and results of the analysis towards a conceptual understanding and quantification of the groundwater dependency of the selected ecosystems. While groundwater contribution is only one factor in ecosystem functioning, sustainable and adaptive management of the groundwater use must be based on the conceptual model and ongoing monitoring of the ecosystem responses.

Abstract

The interaction between groundwater and wetlands is poorly understood, even though it has been the topic of many research projects, like the study done at the Langebaan Lagoon. This interaction is complex as it lies at the intersection between groundwater and surface water, but each situation is unique, with different conditions regulating the interaction. Wetlands can be the source of water that recharges groundwater systems on the one hand, while the other is dependent on the groundwater systems. This interaction became part of the project looking at how to implement Managed Aquifer Recharge for Saldanha Bay Local Municipality without having a negative impact on the groundwater-dependent ecosystems, such as the springs and wetlands in the area. Ten wetlands were identified on the Langebaan Road Aquifer Unit, and a monitoring programme was developed. The purpose of the monitoring was to determine the status of the wetlands as a baseline before the implementation of managed aquifer recharge and to determine the level of groundwater dependence. The latter was done by hydrochemical analysis of rainwater, groundwater and water from the wetlands and stable isotope analysis. The ability of the wetlands to act as a recharge point to the groundwater system will be investigated through column experiments and lithostratigraphic analysis of soil columns taken at the wetlands. Groundwater levels will also be plotted as contour lines to determine the intersection of the water table with the wetlands in the area.

Abstract

Using citizen science approach to influence implementation of science-policy interface concept leads to optimal use and protection of groundwater resources that ensures sustained research for practical policy dialogue. Mere determination of water resource classes, the reserve and resource quality objectives within the resource directed measures (RDM) concept for protection of groundwater water resources without considering implementation aspects, propels for defiance in policy implementation at local scale. Although water resource classes and resource quality objectives have not yet been implemented at any catchment at this stage, however findings indicate that in some areas challenges have been experienced with preliminary Reserve implementation at local level, especially in water use license applications. There is a need for an orthodox link between RDM and Source Directed Controls (SDC) to complement current methods used and processes followed in GRDM projects for uncontested RDM implementation to ensure sustainable groundwater resource protection especially at local site where the resource reside. The argument in this paper is that a feasible implementation for GRDM at local level provides science-policy interface platform for the sustained operation of the science-citizen approach. The objective of study was to design a field-tested conceptual model of science-policy interaction that monitors and evaluates GRDM intervention. How policy implementation and evaluation utilizes scientific research outputs at local level were examined using ecological model. Key findings  indicated that (i) systems analysis approach was lacking at local level (ii) practical assessments of GRDM at local specific quaternary catchment scale was not adequate (iii) optimal reserve determination methodology for uncontested water utilisation was not clear to provide proper guidance for water use license application (iv) Reflective operational plan (GRDM monitoring) to enhance science-policy interaction was not available at quaternary catchment scale (v) Best practices of adaptive management principle to sustain groundwater resource protection were limited at local level. From these results, it can be said that the up scaling of the current approach for RDM especially GRDM requires refinement for practical uptake of scientific results. The study recommended that a feasible implementation plan for GRDM at local level that provides science-policy interface platform for the sustained operation of the science-citizen approach need to be designed, implemented, monitored and evaluated with citizens to inform reflective policy implementation. Although, the results of this study are not conclusive, the insights as a starting point for proactive buy in approach is provided to ensure that science-policy interaction remain practical and relevant to scientists and policy makers as well as society.

Abstract

The City of Windhoek in Namibia has developed wellfields and a managed aquifer recharge scheme within the fractured Windhoek Aquifer to ensure a sustainable potable water supply to the city during drought. A three-dimensional numerical groundwater model of the aquifer was developed using the finite-difference code MODFLOW to determine the potential impacts of varying pump inlet depth elevations and varying production borehole abstraction rates for optimal wellfield and aquifer management. The initial steady-state numerical model was calibrated to September 2011 groundwater levels, representing the best approximation of “aquifer full” conditions (following a good rainfall period and best available data). The subsequent transient numerical model was calibrated against groundwater level fluctuations from September 2011 to August 2019, the period after steady-state calibration for which data was available (and during which monitored groundwater abstraction occurred). The calibrated transient model was used to run various predictive scenarios related to increased emergency groundwater abstraction and estimate potential impacts on the Windhoek Aquifer. These predictive scenarios assessed groundwater level drawdown and recovery, aquifer storage potential, and potential abstraction rates under different pump elevations. Model results indicated a sharp initial groundwater level drop followed by a gradual decrease as groundwater levels approached the 100 m saturated depth mark. Pumping elevations were subsequently updated with recommended abstraction rates and volumes for the entire Windhoek Aquifer. The numerical groundwater model, in association with extensive groundwater monitoring, will be used to assess/manage the long-term sustainable and optimal utilisation of the Windhoek Aquifer.

Abstract

Water and contaminant transport processes in the vadose zone through preferential flow paths can be understood using environmental and artificial tracer methods. Further improvement in tracer techniques can be achieved by applying numerical modelling techniques of both water and solute transport, accounting for additional information on water movement and the matric potential of the vadose zone. The vadose zone is often ignored as a key component linking the land surface to the groundwater table, even though it acts as a filter that removes or stores potential contaminants. The water transit time between the surface and the groundwater table is frequently investigated using artificial tracers that normally show conservative behaviour. The main advantage is that the input function can be clearly defined, even though artificial tracers can generally only be applied over a relatively small area. The research is expected to provide insight into the selection and use of environmental and artificial tracers as markers for detecting and understanding the contaminant transport processes and pathways of contaminants in altered vadose zone environments (open-pit quarry). The impact is improved characterisation of the pathways, transport and migration processes of contaminants, and residence times, leading to the development of appropriate conceptual and numerical models of vadose zone flow processes that consider various contaminant sources. The principal aim is, therefore, to systematically examine the transport mechanisms and associated pathways of different environmental and artificial tracers in an open-pit quarry.

Abstract

In order to establish sound groundwater resource management within towns and Municipal areas the development of a training manual on groundwater resource management and groundwater governance for Municipalities is of utmost importance. A Training Manual can be extensively used for capacitating municipal official, technicians, managers, and decision-makers, as well as communities where villages and towns are partially or solely reliant on groundwater resources. Increased knowledge and skills will not only lead to more effective groundwater resource management, but also to more sustainable groundwater use and protection of groundwater resources. This also forms part of provisions made by the National Water Act 1998 (Act 36 of 1998). Before a training manual can be compiled, training needs assessments of all reachable training institutions in South Africa and Free State Municipalities and Northern Cape Municipalities as identified as pilot areas in the proposal of the Training Manual for Groundwater Resource Management and Groundwater Governance for Municipalities in South Africa needed to be performed. Training needs assessment determines if a gap exist regarding available training and training needs on Groundwater Resource Management and Groundwater Governance. If a gap exists then it proofs that the development of a Training Manual on Groundwater Resource Management and Groundwater Governance for Municipalities in South Africa is required, as well as the accessibility to such a training course is of utmost importance.

Abstract

Test-pumping drawdown curves do not always sufficiently indicate aquifer characteristics and geometry and should never be analysed in isolation. Using derivative analysis and flow dimension theory, inferring the regional geometries and flow characteristics of fractured aquifers that are otherwise unknown or inconclusive is possible. As the drawdown and/or pressure front propagates through the aquifer, it reaches various hydrogeological objects that influence flow regimes and imprints a sequence of signatures in the drawdown derivative curve. The conjunctive interpretation of these flow regime sequences and hydrogeological data results in a robust, well-informed conceptual model (in terms of both local groundwater flow and the aquifer), which is vital for sustainable groundwater resource management. Derivative and flow regime analysis was applied to the test-pumping data of confined and unconfined Nardouw Aquifer (Table Mountain Group) boreholes within Steenbras Wellfield (Western Cape). Major NE-SW trending folding and transtensional Steenbras-Brandvlei Megafault Zone, in association with cross-cutting faults/fractures and younger False Bay Suite dykes, make the Nardouw Aquifer (and deeper Peninsula Aquifer) hydrogeologically complex. The sequential flow regime analyses reveal domains of conceptual flow models, including open vertical fractures, T-shaped channels, double (triple) porosity models, and leaky/recharge boundary models, amongst others. Appropriate analytical flow models (type curve fitting) are then applied for accurate aquifer parameter estimations, which are used to evaluate recommended long-term yields through predictive pumping scenarios. The outcome is an improved hydrogeological understanding and enhanced conceptual model of the aquifer, which informs numerical modelling, ecological protection, and groundwater resource management.

Abstract

South Africa faces serious water scarcity challenges not only because it is a semi-arid country but also due to climate change. One of the most significant effects of climate change is an increase in temperature, which inevitably increases evaporation. Increased evaporation directly reduces the availability of surface water resources. Groundwater is less susceptible than surface water resources to evaporation and thus offers resilience against the impacts of climate change. Many South African cities, communities, and farmers depend on groundwater for domestic or other socio-economic purposes. This implies that groundwater resources which are currently or potentially utilisable should be identified, and suitable legal measures should be implemented to protect these resources from potential risks of harm or damage posed by anthropogenic activity. First, This article evaluates the effectiveness of the country’s existing regulatory framework to effectively protect South Africa’s groundwater resources and finds that the framework can be improved significantly. Secondly, it explores regulatory opportunities within the existing legal framework to strengthen South Africa’s groundwater governance regime, including using land use planning instruments to facilitate the implementation of groundwater protection zones

Abstract

Changes to South African water law and policy since the mid-90s have promoted integrated water resource management (IWRM) and the wider application of the principle of subsidiarity (decentralization), underpinned by the Constitutional emphasis on equity, human rights and redress. New water management organisations aim to promote equity, universal access to water, economic prosperity and gender equality but the reality, especially for groundwater, is less inspiring. The Water Act of 1998 envisages new organisations including Catchment Management Agencies (CMAs), Water User Organisations (WUAs) and Water Service Authorities (WSAs), but in many cases these organisations have inadequate capacity or do not exist at all. Only two of the nine (formerly nineteen) CMAs have been formed in more than fifteen years, and neither is yet financially self-reliant. The onerous process necessary to found a WUA and other disincentives have meant that fully-fledged WUAs as envisaged by the Water Act are rare. Hydrogeologists are unusual at Water Service Authority level, and the Department of Water and Sanitation (DWS) still assesses most groundwater resources. This has stoked argument between DWS and WSAs over long-term sustainable municipal water supplies. Our mandated organisations are not delivering the outcomes for groundwater that policy makers envisaged. Municipalities campaign for surface water instead of groundwater, yet groundwater is still the mainstay of rural water supply and has the most promise for underserved areas. Intractable problems with operation and maintenance are wrongly blamed on the primary groundwater resource, or on "shortages" of one kind or another. There is a need to emphasise function and outcomes rather than trust that these will follow automatically once "the right" organisations are in place. A hybrid of top-down expertise with a genuine focus on local outcomes is called for. We currently pay a considerable opportunity cost for delays, turf-wars and finger pointing - including reputational damage to groundwater as well as less reliable water supplies for the poorest South Africans.

Abstract

The Anglo-American Municipal Capability & Partnership Program (MCPP) has partnered with the Council for Scientific and Industrial Research (CSIR) to implement programs focused on Strategic Water Management and Strategic Planning within the Gamagara and Tsantsabane Local municipalities within the Northern Cape Region. The CSIR appointed GEOSS South Africa (Pty) Ltd to assist with Municipal Groundwater Capacity Development and Support for these two municipalities. This work explores multi-level groundwater governance systems between the local municipality, government, the mining industry, and the private groundwater sector. The scope of the work focused on developing a comprehensive and practical groundwater management plan detailing the standard operating procedures for each municipality. These operating procedures have been drawn up using principles of best practice guidelines for groundwater monitoring and management but have taken site-specific details of the groundwater supply to the respective Municipalities into account. Workshops were conducted where Municipal staff were trained in basic principles pertaining to groundwater and practical skills in monitoring and managing their supply. This has proved very successful in informing Municipalities about their local groundwater system and aquifer. The capacity-building development aspect will ensure that Municipalities have the resources and the knowledge to manage their groundwater resource effectively. GEOSS has undergone several training workshops and offers weekly technical support to the two Municipalities. As the confidence of the municipal staff to manage their resource grows, their independence from the mining companies should lessen.

Abstract

The importance of groundwater in South Africa has become evident over the past decades, especially as pressure on surface water resources intensifies in response to increasing water supply demands. Research has significantly progressed on the shallow groundwater resources conventionally used for water supply, and leading on from this deeper groundwater resources have become a focus point as a future water source. This focus on deep aquifers is driven by new developments, such as shale gas development, injection of brines into deep aquifers, carbon sequestration and geothermal energy. The understanding of deep groundwater in South Africa is often limited due to insufficient data at these depths. To develop a body of knowledge on deep geohydrology in South Africa, an investigation on the currently available information was launched to assess potential deep groundwater resources. The investigation formed part of the larger WRC Project K5/2434 (Characterisation and Protection of Potential Deep Aquifers in South Africa). The geology of South Africa was reviewed from a deep groundwater perspective to provide an initial analysis of potential deep groundwater aquifers. The main potential deep aquifers were identified for further investigation using a ranking system, where Rank 1 shows a positive indication, Rank 2 shows some indication, Rank 3 shows a neutral indication, and Rank 4 shows a negative indication for deep groundwater systems. The Rank 1 geological groups include (in no particular order): the Limpopo Belt, Witwatersrand Supergroup, Transvaal Supergroup, Waterberg and Soutpansberg Groups, Natal Group, Cape Supergroup, Karoo Supergroup. In a number of the identified potential deep aquifers, the indicator for deep groundwater flow systems was the presence of thermal springs. Additionally, deep groundwater occurs below the traditionally exploited weathered zone, and the importance of fractured aquifers becomes paramount in the investigation of potential deep aquifers. In conclusion, three main components were considered for the investigation of potential deep aquifers systems, 1) geological groups; 2) thermal springs and 3) depth of fractures. These three components should be used holistically going forward to best characterise the potential deep aquifers of South Africa.

Abstract

Unconventional gas mining is a new and unprecedented activity in South Africa that may pose various risks to groundwater resources. According to legal experts, South Africa does not currently have the capacity to manage this activity effectively due to various lacunae that exist in the South African legislation. The possible impacts of unconventional gas mining on groundwater, as well as governance strategies that are used in countries where unconventional gas mining is performed; have been analysed and will be discussed. Based on possible impacts and strategies to manage and protect groundwater internationally, possible governance options for the management of South Africa’s groundwater resources are proposed.

Abstract

The intermediate vadose zone underlies the plant root zone and comprises soil and rock. Different soils have different hydraulic and mechanical properties, and the vertical and spatial distributions are variable at a small scale. In South Africa, except for the Cenozoic and Quaternary deserts and coastal deposits, rock forms most of the vadose zone, and the rock fractures exacerbate the complexity. The vadose zone is observed at a small scale and dictates what happens in large scale, as adhesion to mineral surfaces happens first, and cohesion between water molecules is next. The original consideration of the intermediate vadose zone was a black box approach measuring what goes in from the surface and what goes out as groundwater recharge, not accounting for the movement of the vast majority of the freshwater supplied through precipitation. That doesn’t address the preferential flow, velocity, and pore water changes in the medium. Soil science addresses the soil or plant root zone very well. This zone governs the vertical movement of water and controls the ecosystems and biodiversity. However, all evapotranspiration disappears below this zone, and capillarity and gravity both move water into and through the intermediate vadose zone. Movement is no longer solely vertical and will be affected by soil types, intergranular porosity in soil and rock, changing water content, and secondary fractures with different properties in rock. This presentation will cover concepts and advances in this field, emphasising how and why water moves in the intermediate vadose zone.

Abstract

Research on Fracking in the Karoo basin yielded results that, if not considered “unexpected”, can be considered as “should have been foreseen”. Some aspects substantially impacting research on fracking are often overlooked when undertaking scientific research on an emotional topic such as fracking. This presentation aims to provide insights and recommendations based on the experiences and outcomes of current research on hydraulic fracturing or “fracking” in the Karoo basin of South Africa. Fracking has been a subject of significant research and debate over the past decade. Topics, each with its challenges, include 1) The scale of exploration/production extent (Site specifics), 2) Importance of robust and independent research, 3) Need for stakeholder engagement and participation, 4) The complexity of environmental risks and impacts, 5) The need for a precautionary approach, 6) Regulatory and policy challenges. Several methodologies can be relied upon to compare outcomes of different aspects of fracking research in the Karoo, such as 1) Comparative analysis, 2) Meta-analysis, 3) Stakeholder mapping and analysis and 4) Data visualisation. A combination of these methodologies can be used to compare outcomes of different aspects of fracking research in the Karoo and provide insights and recommendations for future decision-making and planning. Ultimately, the decision to allow Fracking should be based on a balanced assessment of potential risks and benefits, considering long-term impacts on the environment, economy, and communities.