Conference Abstracts

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.

Abstract

Edible vegetable oil (EVO) substrates have been successfully used to stimulate the in situ anaerobic biodegradation of groundwater contaminated chlorinated solvents as well as numerous other anaerobically biodegradable contaminants like nitrates and perchlorates at a many commercial, industrial and military sites throughout the United States of America and Europe. EVO substrates are classified as a slow release fluid substrate, and comprise of food grade vegetable oil such as canola or soya bean oil. The EVO substrate serves as an easily biodegradable source of carbon (energy) used to create a geochemically favorable environment for the anaerobic microbial communities to degrade specific contaminants of concern. EVO substrate's can either be introduced into the subsurface environment as pure oil, in the form of light non aqueous phase or as an oil/water emulsion. The emulsified vegetable oil substrates holds several benefits over non-emulsified vegetable oil as the fine oil droplet size of the commercially manufactured emulsified oils can more easily penetrate the heterogeneous pore and fracture spaces of the aquifer matrix. The use of this technology to stimulate in situ biodegradation of groundwater contaminants is still relatively unknown in South Africa. This paper will give an overview of the EVO technology and its application, specifically looking at the advantages of using this relatively inexpensive, innocuous substrate based technology to remediate contaminated groundwater within fractured rock environments commonly encountered in South Africa. {List only- not presented}

Abstract

This study was aimed at developing an integrated groundwater-surface water interaction (GSI) model for a selected stretch of the Modder River by considering the following five different aspects of the GSI: 1) the distribution of different aquifer systems (structural connectivity) along the river 2) the hydraulic connectivity between the aquifer systems, 3) the volumes of water abstracted from the aquifers by streamside vegetation, 4) the volumes of water replenished to the groundwater system through rainfall recharge, and 5) the exchange fluxes between the various components of the groundwater-surface water system. The distribution of the aquifer systems was investigated by means of a) geo-electrical surveys, and b) in situ slug tests while their hydraulic connectivity was investigated by hydrogeochemical routing. The volumes of water abstracted by streamside vegetation were estimated by the quantification of the transpiration from individual plants and the groundwater recharge was estimated by a root zone water balance. The water exchange fluxes between the groundwater and surface water were determined from a simple riparian zone groundwater budget. The results of the geo-electrical surveys and slug tests allowed the delineation of the riparian area aquifers (RAA) and the terrestrial area aquifers (TAA) on both the south-eastern and north-western sides of the river. Based on the results of hydrochemical analyses, saturation indices and inverse mass balance modelling, the GSI involves flow of water from the TAA to the RAA, and finally to the river on the south-eastern side while it involves flow from the river into the RAA with a limited exchange with the TAA on the south-eastern side. The dominant vegetation on the study area was found to be the Acacia karroo and Diospyros lycioides. The close similarities in isotope compositions of the xylem sap and the borehole water samples suggested that the Acacia karroo sourced its water from the groundwater storage while differences in isotope compositions suggested that the Diospyros lycioides did not source water from the groundwater storage at the time of measurement. The results of groundwater recharge estimation in the study area highlighted the fact that both the antecedent moisture and the rainfall amounts determine whether recharge to the groundwater system will take place. Finally, the results of baseflow estimation indicated that the river is a gaining stream along the south-eastern reach while acting as a losing stream along the north-western reach.

Abstract

A groundwater assessment was conducted to identify and predict the contamination and transport properties of a groundwater system. The motivation for the study was the rising concern of a farm owner about the deteriorating water quality of the aquifer system. An investigation of the surface and groundwater quality indicated that two fertilizer dumpsites were the sources of pollution. Water analyses revealed elevated concentrations of Ca, Mg, K, F, NO3, SO4, Mn and NH4 within boreholes near the pollution sources. The NH4 and NO3 concentrations were exceptionally high: 11 941 mg/L and 12 689 mg/L, respectively. These high concentrations were the direct result of the dumping of fertilizer. The rise in these concentrations may also have been catalysed by the nitrogen cycle and the presence of the Nitrosomonas bacterium species. Due to the high solubility of NO3, and because soils are largely unable to retain anions, NO3 may enter groundwater with ease, and could migrate over large distances from the source. Elevated NO3 in groundwater is a concern for drinking water because it can interfere with blood-oxygen levels in infants and cause methemoglobinemia (blue-baby syndrome). A geophysical study was undertaken within the area of investigation to gain insight on the underlying geological structures. The survey indicated preferential flow paths within the aquifer system along which rapid transport of contaminant is likely to occur.
Key words: aquifer system, groundwater quality analyses, fertilizer, nitrogen cycle, Nitrosomonas species, geophysics.

Abstract

The national water balance is primarily based on the availability of surface water and the historic allocation thereof. The changes that are required the next 20 years to ensure sustainable development of the nation will be painful, but is unfortunately at present not part of the public discussion, it is essentially ignored in favour of more "popular water topics".This paper intends to look at a few core aspects, they include the current water allocation in the national water balance, the relative value of the utilisation, the position of groundwater resources in changing the current relative allocation and the current groundwater utilisation. The paper further intends to be a less formal presentation of these aspects with the required data, references and conclusions available for distribution afterwards.

Abstract

The current study investigated the subsurface of aquifers in Heuningnes Catchment focusing on aquifer characteristics for groundwater resource assessments. Surface geophysical resistivity method was adapted for mapping the shallow subsurface layers and hydrogeologic units at selected sites within the catchment. The aim was to provide a preliminary overview of the subsurface nature of aquifers within the study area, by establishing features such as geological layers, position of weathered zones, faults and water bearing layers. The multi-electrode ABEM SAS 1000 resistivity meter system, using the Wenner array, was used to obtain 2D resistivity data of the subsurface. The acquired data was processed and interpreted using Res2DINV software to produce the 2D resistivity models. The analysis of the resistivity models of the subsurface reveals maximum of four layers; sandstone, shale, poor clayed and brackish water saturated layer. On comparing the model results with the surficial geological formation of the catchment geological map, the identified layers were found to correspond with the geology of the area. The findings i) provide insights on sites that can be drilled for groundwater exploration, ii) show possible water-type variations in the subsurface. Although the results are not conclusive but they provide basis for further research work on quality and flow dynamics of groundwater.

{List only- not presented}
Key words: aquifer properties, hydrogeologic units, geo-electric model, electrical-resistivity method

Abstract

Artificial Intelligence (AI) has been used in a variety of problems in the fields of science and engineering in particular automation of many processes due to their self-learning capabilities as well as their noise-immunity. In this paper, we describe a study of the applicability of one of the popular branch of AI (Artificial Neural Network (ANN)) as an alternative approach to automate modelling of one-dimensional geoelectrical resistivity sounding data. The methodology involves two ANNs; first one for curve type identification and the other one for model parameter estimation. A three-layer feedforward neural network that was trained from geoelectrical resistivity data taken at boreholes with geology logs was used to predict earth models from measured data without the need to guess the initial model parameters or use synthetic data as is done with most conventional inversion approaches. The motivation for using the ANN for geophysical inversion is that they are adaptive systems that perform a non-linear mapping between two sets of data from a given domain. For network training, we use the back-propagation algorithm. An example using data from southern Malawi shows that the ANN results outperforms the conventional approaches as the results after adequate training, produce reasonably accurate earth models which are in agreement with borehole log data.

Abstract

In the wake of the ongoing water restrictions in South Africa, the issue of groundwater potential for drought relief has been debated on many environmental and socio-economic platforms, nationally. Consequently, the development of groundwater and its related vulnerabilities has become a key topic to the decision makers and stakeholders. Currently, the recruitment of water professionals into government and private water sectors adds substantial value to understanding the importance of protecting this precious resource. This has allowed the monitoring of groundwater to gain ever increasing momentum. Groundwater monitoring has become an essential scientific tool for role-players to achieve robust and verifiable data used for modelling aquifer potential and vulnerability to pollution and over-abstraction. The data is generally sourced from various hydrogeological and environmental investigations which include groundwater development, vulnerability assessment and remediation projects. Groundwater and environmental consulting firms are tasked with imperative roles for implementing groundwater monitoring programmes to the ever growing industrial, commercial, agricultural and public sectors in South Africa. However, groundwater monitoring data, especially in the private sector, are reliable but remains mostly inaccessible due to confidentiality clauses. This does limit our accuracy and comprehensive understanding for determining aquifer potential and vulnerability risks at large. The conceptualisation and modelling of vast monitoring datasets has been recognised as an important contributing factor to enhance groundwater sustainability. This research emphasises the significance of groundwater monitoring for development, protection and remediation of aquifers. Comparing monitoring results from typical sites and methods, provides scientific validation to support good governance of water. Deterioration of groundwater potability in the sight of an existing drought can have irreversible environmental and economic implications for South Africa.

Abstract

Faced with a burgeoning population and property growth, and in preparation for a future drier climate regime; the coastal town of Hermanus in the Western Cape has set up two wellfields to abstract groundwater from the underlying aquifer in order to augment the constrained surface water supply from the De Bos Dam.
Water Use Licences (WUL) were issued to the Overstrand Municipality in June 2011 and December 2013. The licences authorise a maximum annual abstraction of 1 600 Ml of water from the Gateway wellfield and 800 Ml of water from the Volmoed and Camphill wellfield via several boreholes. The water abstracted from the Gateway wellfield is pumped via a booster pump station to the Preekstoel Treatment Plant. The Volmoed and Camphill wellfield are situated at a higher altitude allowing for a gravity feed pipeline.
Earth Science Company, Umvoto Africa, has the responsibility to ensure Resource Quality Objectives are met which include balancing the need to protect the resource on the one hand; and the to develop sustainable utilisation of the Hermanus groundwater resources and compliance with the WUL on the other. The consultancy provides hydrogeological support, wellfield management and technical advice in operating the boreholes, pumps, boosters and related infrastructures.
Running the operations of the wellfield relies on a high-tech, semi-automated system, incorporating a remotely controlled, telemetry based structure. Vital parameters are monitored by electronic sensors, feeding data to processors which alters pump performance to maintain specified boundary levels. Data is simultaneously communicated via telemetry to a central control which uses data acquisition software to portray information to the operators. Warning alarms both alert operators via SMS and in certain instances auto-shut down the system.
To ensure ecological sustainability of the ground water resource, the wellfield also requires hydrogeological monitoring at far field locations within the recharge areas. Some of these locations are in remote areas making data download costly. The high-tech telemetry approach is used with positive results.
Any automated telemetry system is prone to malfunction and environmental hazards. The challenge lies in managing this and providing sufficient back up and duplication of systems.
The paper gives an overview of the components and flow of data based on the experiences gained during the evolution and development over 12 years of operation. Automation produces vast data bases which are often not sufficiently analysed, the premise that "once collected, the task is done". However data is only as good as the people who drive the systems and this paper provides a critical analysis of human intervention in an automated system and the decisive role of quality-checks. Finally the paper seeks to provide a pragmatic guideline for water users to comply with the WUL and institutional regulations.

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.

Abstract

The hydraulic parameters of heterogeneous aquifers are often estimated by conducting pumping (and recovery) tests during which the drawdown in a borehole intersecting the aquifer is measured over time, and by interpreting the data after making a number of assumptions about the aquifer conditions. The interpreted values of the hydraulic parameters are then considered to be average values that represent the properties of the bulk aquifer without taking into account local heterogeneities and anisotropies. An alternative and more economic approach is to measure streaming potentials in the vicinity of the borehole being tested. The streaming potential method is a non-invasive geophysical method that measures electrical signals generated by groundwater flow in the subsurface through a process known as electrokinetic coupling. This method allows data to be recorded at a high spatial density around the borehole. The interpretation of streaming potential data in terms of aquifer hydraulic parameters is facilitated by a coupled flow relationship which links the streaming potential gradient to the hydraulic gradient through a constant of proportionality called the electrokinetic coupling coefficient. In the current study, field measurements of streaming potentials were taken during the pumping and recovery phases of pumping tests conducted at two sites with dissimilar geological and geohydrological conditions. The recorded streaming potential data were interpreted by calculating the hydraulic head gradient from the streaming potential gradient, and by using the potential field analytical solution for the transient mode, which relates the streaming potential field directly to the average hydraulic conductivity. Hydraulic conductivity values estimated from the streaming potential method were of the same order as values determined from the analysis of drawdown data, with a relative error of 0.2. This study demonstrates that the streaming potential method is a viable tool to compliment pumping tests and provide a spatial representation of the hydraulic parameters.

Abstract

The SADC Grey Data archive http://www.bgs.ac.uk/sadc/ provides a chronology of groundwater development within the constituent countries of the SADC region. Early reports show how groundwater development progressed from obtaining water by well digging to the mechanical drilling of boreholes for provision of water for irrigation, township development, transport networks and rural settlement. During the 1930s steam driven drilling rigs were supplanted by petrol engine driven cable tool percussion drilling. Dixey (1931), in his manual on how to develop groundwater resources based on experiences in colonial geological surveys in eastern and southern Africa, describes aquifer properties, groundwater occurrence and resources as well as water quality and groundwater abstraction methods. Frommurze (1937) provides an initial assessment of aquifer properties in South Africa with Bond (1945) describing their groundwater chemistry. South African engineers transferred geophysical surveying skills to the desert campaign during World War II. Paver (1945) described the application of these methods to various geological environments in South Africa, Rhodesia and British colonial territories in eastern and central Africa. Test pumping methods using electric dippers were also developed for the assessment of groundwater resources. Enslin and others developed DC resistivity meters, replacing early Meggar systems, produced data that when analysed, using slide rules with graphs plotted by hand, identified water bearing fractures and deeply weathered zones. Tentative maps were drawn using interpretation of aerial photographs and heights generated using aneroid altimeters. The problems faced by hydrogeologists remain the same today as they were then, even though the technology has greatly improved in the computer era. Modern techniques range from a variety of geophysical surveying methods, automated rest level recorders with data loggers to GPS location systems and a whole host of remotely sensed data gathering methods. Worryingly, using such automated procedures reduces the ability of hydrogeologists to understand data limitations. The available collection of water level time series data are surprisingly small. Surrogate data need to be recognised and used to indicate effects of over abstraction as demand grows. As the numbers of boreholes drilled per year increases the number of detailed hydrogeological surveys undertaken still remains seriously small. Has our knowledge of hydrogeological systems advanced all that much from what was known in the 1980s? Case histories from Malawi, Zimbabwe and Tanzania illustrate a need for groundwater research with well-judged sustainability assessments to underpin safe long-term groundwater supply for the groundwater dependent communities in the region.

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.

Abstract

Groundwater monitoring, especially from the end users' point of view, is often considered an add-on, or even unnecessary overhead cost to developing a borehole. Simply measuring groundwater level over time can however tell a story on seasonal rainfall fluctuations as well as the response of an aquifer to the removal of an abstracted volume of water. In this case an artesian borehole of high yield and exceptional quality was drilled in an area of minimal groundwater use because of known poor quality and low yields. The borehole was drilled in two stages with the deeper drilling resulting in significantly higher yields and the artesian flow. Sediment free water, deep artesian water strikes and a lack of flow around the casing led to the conclusion that capping at surface would control the visible artesian flow of 4 L/s. A slight drop in pressure indicated that subsurface leakage may however be occurring. Neighbouring boreholes with automated water level monitoring provided data showing a correlation of drop in water level to the second deeper drilling event. The artesian borehole was yield tested and this too was visible in the water level monitoring data. Hereafter it became apparent that each activity performed at the artesian borehole had an impact on the monitoring boreholes, and that a subsurface leak was causing local depressurization of a semi-confined to confined aquifer. An initial attempt to save the artesian borehole was unsuccessful, resulting in the necessary blocking and abandonment of a high yielding, superior quality borehole. If monitoring data was not available the local drop in water level would never have been noticed with disastrous effect and no evidence for the cause. Simple water level monitoring has averted this and kept neighbourly relations and ground water levels intact

Abstract

Water scarcity is a growing issue in South Africa. The consumption of water is rising and as such, water is becoming a scarce and valuable resource. Given the circumstances that South Africa is facing, improving the use of ground water could help tackle water scarcity in South Africa. Groundwater has been an important source of water and it can bring socio-economic benefits if properly used. Studies have proved that groundwater resources play a fundamental role in the security and sustainability of livelihoods and regional economies throughout the world. However, in South Africa, groundwater still remains a poorly managed resource and this hinders socio-economic development. This paper examines the current state of ground water management in South Africa. The paper also examines how ground water in South Africa is currently allocated and used, and explores some of the consequences of current water management arrangements. {List only- not presented}

Abstract

Underground Coal Gasification (UCG) is an emerging, in-situ mining technology that has the advantage to access a low cost energy source that is currently classified as not technically or economically accessible by means of conventional mining methods. As such it offers significant potential to dramatically increase the world's non-recoverable coal resource.

Groundwater monitoring in the South African mining industry for conventional coal mining as an example, is well established, with specific SANS, ASTM and ISO Standards dedicated for the specific environment, location and purposes. In South Africa a major impact of the coal mining industry can be a reduction in the groundwater quantity and quality. South-Africa's groundwater is a critical resource that provides environmental benefits and contributes to the well-being of the citizens and the economic growth. Groundwater supplies the drinking water needs of a large portion of the population; in some rural areas it represents the only source of water for domestic use. Utilization and implementation of groundwater monitoring programs are thus non-negotiable.

The groundwater quality management mission, according to the Department of Water and Sanitation in South-Africa, is set in the context of the water resources mission and is as follows:

"To manage groundwater quality in an integrated
and sustainable manner within the context of the National
Water Resource Strategy and thereby to provide an
adequate level of protection to groundwater resources
and secure the supply of water of acceptable quality."

The scope of this paper is to propose an implemention strategy and a fit-for-purpose groundwater monitoring program for any Underground Coal Gasification commercial operation. It is thus important to pro-actively prevent or minimise potential impacts on groundwater through long-term protection and monitoring plans. A successful monitoring program is one that consists of
(1) an adequate number of wells, located at planned and strategic points;
(2) sufficient groundwater sampling schedules; and
(3) a dedicated monitoring program and quality control standard.

In order to have an efficient monitoring program and to prevent unnecessary analysis and costs, it is also critical to determine upfront what parameters have to be monitored for the specific process and site conditions.

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

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.

Abstract

Monitored Natural Attenuation (MNA) refers to the monitoring of naturally occurring physical, chemical and biological processes. Three lines of evidence are commonly used to evaluate if MNA is occurring, and this paper focusses on the second line of evidence: The geochemical indicators of naturally occurring degradation processes and the site-specific estimation of attenuation rates.

The MNA geochemical indicators include the microbial electron acceptors (e.g. dissolved oxygen, nitrate and sulphate) and the metabolic by-products (manganese (II), iron (II) and methane). In addition, redox and alkalinity are important groundwater indicators. So as to properly assess the geochemical trends a groundwater monitoring well network tailored to assessing and defining the contaminant plume is required.

The expressed assimilative capacity (EAC) is used to estimate the capacity of the aquifer to degrade benzene, toluene, ethylbenzene and xylene (BTEX compounds) using the concentrations of geochemical indicators. Using the EAC, the groundwater flow through a perpendicular cross-section of the source area, and the source mass, the life of the contaminant source can be made.

A practical example of the performance monitoring of MNA using geochemical parameters is described for a retail service station in KwaZulu-Natal, which has groundwater impacted by a petroleum hydrocarbon plume. This includes a description of the monitoring well network, the geochemical measurements, the calculation of the EAC, and the estimated life of the contaminant source.

Abstract

There are various software packages used by hydrogeologists for a variety of purposes ranging from project management, database management, data interpretation, conceptual and numerical modelling and decision making. Software is either commercial (produced for sale) or open source (freely available to anyone and for any purpose).

The objective of this paper is to promote open source software that can be used by the hydrogeological community to reduce expenses, enhance productivity and maximise efficiency.

Free software was previously associated as being inferior in quality in the corporate world. Companies often use commercial software at a hefty price, but little do they know that open source is often equal to, or superior to their commercial counterparts. The source code of open source software can freely be modified and enhanced by anybody. Open source software is a prominent example of open collaboration as it is developed by users for the user community. Companies using open source software do not need to worry about licensing and do not require anti-piracy measures such as product activation or a serial number.

However, the decision of adopting open source software should not just be taken just on the basis of the low-cost involved. It should entail a detailed analysis and understanding of the requirements at stake, before switching to open source to achieve the full benefits it offers and to understand what the down side is. There are plenty of open source products that can be used by hydrogeologists. The packages considered in this article are those that are frequently used by the author and do not necessarily mean that they are the best available. Software gets updated or abandoned with time and what is considered powerful today may be obsolete in a few years.

Some of the well-known open source packages recommended for hydrogeologists include: OpenLibre for project management, Blender 3D or Sketchup for 3D conceptual modelling, QGIS for GIS mapping and database management, SAGA GIS for interpolation and ModelMuse for numerical modelling (comprising of Modflow for finite difference, Sutra for finite element and Phast for geochemical modelling). In addition, there are a number of free software packages developed by the USGS, various universities and consultants across the globe that can be used for aquifer test interpretation, borehole logging and time-series data analysis. A saving of more than R250,000 can be made per hydrogeologist by utilising such open source packages, while maintaining high quality work that is traditionally completed using commercial software.

Abstract

PMWIN5.3 has been one of the most commonly used software for groundwater modeling because of its free source and the adoption of popular core program MODFLOW. However, the fixed formats required for data input and lack of GIS data support have posted big challenges for groundwater modelers who are dealing with large areas with complicated hydrogeological conditions. In South Africa, most geological and hydrogeological data have been captured and stored in GIS format during various national research projects such as WR2005, NGA and etc. Therefore, a proper linkage between PMWIN and ArcGIS is expected to do the preprocessing for modeling in PMWIN. Visual Basic for Application (VBA) embedded in ArcGIS 9.3 was used to develop the linkage. Based on the conceptualization of the study area, the model dimension, discretization and many value setting processes can be easily carried out in ArcGIS other than directly in PMWIN. Then the grid specification file and other input files can be exported as the PMWIN-compatible files. The functions of move, rotation, refinement, sub-model, deleting and inserting row(s) or column(s) of the model have also been developed to avoid the inconvenience aroused from model modification. The linkage can be used with a higher version of PMWIN or ArcGIS. It has been applied to several gold fields in the Witwatersrand gold basin to simulate the groundwater flow and mass transportation for various conditions and scenarios. One of the applications will be presented in this paper. It has been proved that the linkage is efficient and easy to use. {List only- not presented}

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

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.

Abstract

Annually, UNICEF spends approximately US$1B in water, sanitation and hygiene programming (WASH), approximately half of which is spent in humanitarian contexts. In emergencies, UNICEF supports the delivery of water, sanitation and hygiene programming under very difficult programming contexts – interruptions to access, power supply and a lack of reliable data. Many of these humanitarian situations are in contexts where water scarcity is prevalent and where the demand and competition for water are increasing, contributing to tension between and within communities. While water scarcity is not new to many of these water-scarce areas, climate change is compounding the already grave challenges related to ensuring access to safe and sustainable water services, changing recharge patterns, destroying water systems and increasing water demand. Incorrectly designed and implemented water systems can contribute to conflict, tension, and migration. Ensuring a comprehensive approach to water security and resilient WASH services can reduce the potential for conflict and use water as a channel for peace and community resilience. This presents an enormous opportunity for both humanitarian and development stakeholders to design water service programmes to ensure community resilience through a four-part approach: 1. Groundwater resource assessments 2. Sustainable yield assessments (taking into consideration future conditions) 3. Climate risk assessments 4. Groundwater monitoring/early warning systems UNICEF promotes this approach across its WASH programming and the sector through technical briefs, support and capacity building.

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

Abstract

Groundwater in South Africa is the most important source of potable water for rural communities, farms and towns. Supplying sufficient water to communities in South Africa becomes a difficult task. This is especially true in the semi-arid and arid central regions of South Africa where surface water resources are limited or absent and the communities are only depended on groundwater resources. Due to a growing population, surface water resources are almost entirely being exploited to their limits. These factors, therefore, increases the demand for groundwater resources and a more efficient management plan for water usage. For these reasons, the relation between the geology and geohydrology of South Africa becomes an important tool in locating groundwater resources that can provide sustainable quantities of water for South Africans. It was therefore decided to compile a document that provides valuable geohydrological information on the geological formations of the whole of South Africa. The information was gathered by means of interviews with experienced South African geohydrologists and reviewing of reports and articles of geohydrological studies. After gathering the relevant information, each major geological unit of South Africa together with its geohydrological characteristics was discussed separately. These characteristics include rock/aquifer parameters and behaviour, aquifer types (primary of secondary), groundwater quality, borehole yields and expected striking depths, and geological target features and the geophysical method used to locate these targets. Due to the fact that 90 % of South Africa's aquifers are classified as secondary aquifer systems, groundwater occurrence within the rocks of South Africa is mainly controlled by secondary fractures systems; therefore, understanding the geology and geological processes (faulting, folding, intrusive dyke/sills & weathering) responsible for their development and how they relate is important. However, the primary aquifers of South Africa (Coastal Cenozoic Deposits) should not be neglected as these aquifers can produce significant amounts of groundwater, such as the aquifer units of the Sandveld Group, Western Cape Province. Drilling success rates and possibility of striking higher yielding boreholes can be improved dramatically when an evaluation of the structural geology and geohydrological conditions of an area together with a suitable geophysical method is applied. The ability to locate groundwater has been originally considered (even today) a heavenly gift and can be dated back to the Biblical story of Moses striking the rock to get water: "behold, I will stand there before thee there upon the rocks thou shalt smite the rock and there shall come water out of it" (Exodus 17:6).

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.

Abstract

The complexity of real world systems inspire scientists to continually advance methods used to represent these systems as knowledge and technology advances. This fundamental principle has been applied to groundwater transport, a real world problem where the current understanding often cannot describe what is observed in nature. There are two main approaches to improve the simulation of groundwater transport in heterogeneous systems, namely 1) improve the physical characterisation of the heterogeneous system, or 2) improve the formulation of the governing equations used to simulate the system. The latter approach has been pursued by incorporating fractal and fractional derivatives into the governing equation formulation, as well as combining fractional and fractal derivatives. A fractal advection-dispersion equation, with numerical integration and approximation methods for solution, is explored to simulate anomalous transport in fractured aquifer systems. The fractal advection-dispersion equation has been proven to simulate superdiffusion and subdiffusion by varying the fractal dimension, without explicit characterisation of fractures or preferential pathways. A fractional-fractal advection-dispersion equation has also been developed to provide an efficient non-local modelling tool. The fractional-fractal model provides a flexible tool to model anomalous diffusion, where the fractional order controls the breakthrough curve peak, and the fractal dimension controls the position of the peak and tailing effect. These two controls potentially provide the tools to improve the representation of anomalous breakthrough curves that cannot be described by the classical-equation model. In conclusion, the use of fractional calculus and fractal geometry to achieve the collective mission of resolving the difference between modelled and observed is explored for the better understanding and management of fractured systems.

Abstract

Artesian boreholes are a common feature worldwide in confined aquifers, but the hydraulic testing of these boreholes, and estimation of aquifer properties from such tests, still poses a challenge for hydrogeologists. Common hydraulic tests, such as step-drawdown or constant-discharge rate tests require a static water level at the start of the test, and the measurement of drawdown (increasing over time) and abstraction rate (fixed for a period of time). Usually, when undertaking a pumping test in an artesian borehole, the drawdown is measured from ground level, and the drop in hydraulic head between static pressure and ground level is often ignored. This procedure also implies that the starting time of the test is not at the static water level. A constant-head test, set at ground level, is the other option. However, the decrease in flow rate is not only dependent on the hydraulic properties of the aquifer, but also masked by pipe hydraulic effects within the well. This kind of test would also limit the available drawdown to be utilized for the test. Hence, it was required to develop a method for undertaking hydraulic tests in strong artesian boreholes, allowing for the drawdown to fluctuate between levels both above and below ground and avoiding the pitfalls described above. The solution is a specially designed and constructed wellhead for the installation of the pump and monitoring equipment prior to the hydraulic test. The standard tests are slightly modified and are only undertaken after sealing the wellhead and reaching static hydraulic pressure. The recommended wellhead construction and subsequent hydraulic tests were implemented at a strong artesian borehole in the Blossoms Wellfield, south of Oudtshoorn in the Western Cape province of South Africa.

Abstract

The costs of acid mine drainage (AMD) monitoring result in the quest for alternative non-invasive method that can provide qualitative data on the progression of the pollution plume and ground geophysics was the ideal solution. However, the monitoring of AMD plume progression by ground geophysics (time-lapse electrical resistance) proves to be non-invasive but also time consuming. This gave way to a study that focuses on the modeling of different scenarios of the karstic aquifer. The models use the field parameters such as the electrical resistivity of the host rock and the target rock, depth to the target, noise level and electrode configuration in order to ensure that the model outcomes represent the field data as much as possible. This geoelectric modeling process uses Complex Resistivity Model (CRMod) and Complex Resistivity Tomography (CRTomo) to generate geoelectric subsurface images. Different resistivity values are applied to targets in order to assess the difference against the baseline model for each target scenario. The model resistivity difference is reduced to the smallest difference possible between the reference and new models in order to gauge the lowest percentage change in the model at which the background noises start to have impact on the results. The study shows that the behavior of targets (aquifer) could be clearly detected through resistivity difference tomography rather than inversion tomography. The electrode array plays a significant part in the detection of target areas and their differences in resistance because of its sensitivity. This therefore indicates that the electrode array should be chosen according to study requirements. Furthermore, the model geometry also plays a role and this can be seen with the modelling of different target sizes, alignments and shapes. Future studies that can provide a correlation between the field quantitative data from sampling and the model outcomes have the ability to add to the knowledge field of geophysical modelling therefore reducing costs associated with field based plume AMD monitoring300-500 words without references; reach your conclusions rather than only delivering promises.

Abstract

South Africa has committed to achieving the United Nations Sustainable Development Goals (SDG's) by 2030. But what does this mean and how does groundwater fit in to this? SDG 6 in particular focuses on ensuring universal access to safe and affordable drinking water for all by 2030. SDG 6 requires that the country protects and restores water-related ecosystems such as forests, mountains, wetlands, aquifers and rivers which are essential if we are to mitigate water scarcity. To accomplish this, South Africa has proceeded to align various plans, strategies, and policies to encompass the targets of the SDG's. This paper will focus on SDG sub-goal 6.3 which incorporates improvement of water quality and sub-goal 6.6 which involves protection and restoration of ecosystems. The methodology given by the UN for the groundwater in indicator 6.3.2 stipulates that countries are required to report on "proportion of water with good ambient water quality", in South Africa however we had to domesticate the indicator i.e. render it suitable for South African conditions so we changed the methodology to "proportion of water the conforms to the Water Quality Objectives (WQO's)" but there are virtually no WQO's developed for groundwater. Four core groundwater quality parameters (Electrical Conductivity, pH, Nitrate and Sulphate) are available through ZQM stations categorized through 65 hydrogeological (Vegter) regions. Groundwater water quality baseline is calculated as a reference period/range per hydrogeological region. For SDG 6.6, the indicator required for groundwater is "Quantity of groundwater within aquifers" The methodology received by the UN for "Quantity of groundwater within aquifers" required a baseline (average reference period of five years) in meters per hydrogeological region. This indicator is again domesticated for South Africa and based on the 40-60 percentiles of groundwater levels per hydrogeological region. There are a number of future indicators that can be included for aquifers under SDG 6.6, but the groundwater sector needs to come together and decide what is important to report on. These SDG targets reporting has given the Water and Sanitation sector a new look at data. It has forced us to critically think of concepts such as baseline and performance monitoring. We now know where our data gaps and targets are, and we have to provide an action plan to address these.

Abstract

The so-called apparent increase of transmisivity (T) or hydraulic conductivity (K) with scale is an artifact and does not exist in the field. The reason for the apparent increasing of T with scale is due to the use of the "not applicable" random log Gaussian stochastic models that are used by geohydrologists. In the petroleum field, which uses deterministic methods, the apparent increase of T with aquifer volume does not occur. Groundwater practitioners have to change their view and use models that do not show this effect.

By using intuitive inspection of geological, fracture and connectivity data as well as real pumping test data, this paper shows that up-scaling must be performed with an exponential decaying function, where T always decreases with scale
.
Two types of heterogeneities exists namely a.) horizontal and b.) vertical. Connectivity between fractures is extremely important in both cases, but it is only in semi-confined and watertable aquifers that the vertical heterogeneities are really important (typical case of fracture dewatering)
{List only- not presented}

Abstract

The Gravity Recovery and Climate Experiment (GRACE) satellites detect minute temporal variation in the earth's gravitational field at an extraordinary accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores (snow, groundwater, surface water and soil moisture) due to increases or decreases in storage. The GRACE monthly TWS data are being used to estimate changes in groundwater storage in the Vaal River Basin for a period (2002 to 2014). The Vaal River Basin has been selected, because it is one of the most water stressed catchments in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands, it is critical to monitor and calculate changes in groundwater storages as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin were mostly localised focusing mainly on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, but many of these models do not take into account the groundwater component. Thus, there is a significant gap in the understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks are often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is a good approach to estimate changes in hydrological storages as it covers large areas and generates real time data. It does not require information on soil moisture, which is often difficult to measure. The accuracy of calculating change in groundwater storage lies in the processing of GRACE data and smoothing radii. For this study, smoothing radii of 1500, 900, 500, 300, 150 and 1 km are used. Currently the associated error with different smoothing radii is unknown. The preliminary results indicate that the study area experienced a loss in TWS of -31.58 mm equivalent water height over a period of 144 months in TWS at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamics, which will improve water management practices.

Abstract

It is estimated that the three coal layers in the Springbok Flats contain about 5 TCF of coal bed methane (CBM). Two sedimentary basins, namely the southern Tuinplaas basin and the northern Roedtan basin, exist with coal layers with a total thickness of 7m which occurs mainly in three mayor seams. The coal layers are located between 20 m to more than 600m.
Farmers in the Flats are concerned about the environmental impact of fracking the coal beds. They are mostly worried about the risk of groundwater pollution; the drawdown of the water table and the producing of a bad quality water during the mining process. They set up an EPA for the Springbok Flats in 2010 and until now, they have stopped more than 6 companies to conducted exploration (stopped strictly on account of the different laws in SA that were not adhered too).
On average, 1000 liters of water is produced for every 2000 cubic feet coal bed methane mined in the USA. The quality of the produced water is not good (with typical Na values of more than 5 000 mg/l) and cannot be used for irrigation purposes.
It is thus expected that about 500 million m3 of bad quality water will be produced for every 1 TCF mined in the Flats. This groundwater will be removed from the system and it is expected that a drawdown of up to 30m will be evident at places in the Springbok Flats. There are also a large number of dykes and faults in the Flats which imply that the upward movement of methane and water will be very probable after abandonment of each coal methane well.

Abstract

Coastal wetlands are complex hydrogeological systems in which groundwater have a significant influence on both its water balance and hydrochemistry. Differences in groundwater flow and groundwater chemistry associated with complex hydrogeologic settings have been shown to affect the diversity and composition of plant communities in wetland systems. A number of wetlands can be found across the flat terrain of the Agulhas Plain, of which the most notable is the Soetendalsvlei and the Vo?lvlei. Despite the ecological and social importance of the Vo?lvlei, the extent to which local, intermediate and regional groundwater flow systems influences the Vo?lvlei is poorly understood. The aim of this work is to characterize the spatial and temporal variations in surface water and groundwater interactions in order to demonstrate the influence of groundwater flow systems on the hydrology of the Vo?lvlei. The specific objectives of the study are; 1) to establish a geological framework of the lake sub-surface, 2) to determine the physical hydrological characteristics of the Vo?lvlei and 3) to determine the physical-chemical and isotopic characteristics of groundwater and surface water. Data collection will be done over the period of a year. Methods to be used will include the use of geophysical (electrical resistivity) to determine high water bearing areas surrounding the wetland, a drilling investigation (the installation of piezometers at 5-10m depths and boreholes at 30m depth, sediment analysis (grain size analysis, colour and texture), hydraulic (slug testing to determine hydraulic properties; hydraulic conductivity and transmissivity), hydrological (to estimate groundwater discharge; Darcy flux and hydraulic head difference between groundwater level and lake level), physical-chemical (electrical conductivity, temperature and pH) and stable environmental isotopic (oxygen and hydrogen) analysis of surface water and groundwater, to determine flow paths and identify processes. Thus far, results obtained for the geophysical survey has revealed that the sub-surface of this wetland system is highly variable. Three traverses were done on the South-Western, South-Eastern and Northern side of the wetland (See Figure 1). In VOEL1 (South west), the upper couple of meters show areas of very low resistivity, which is associated with clays, poor water quality and water which has high dissolved salts. The changing of medium to high resistivity values on the North-eastern side is usually indicative of weathered sandstone (Table Mountain Group). VOEL2 (South eastern), indicates that the subsurface is of low resistivity. These low values are the result of noticeable salt grains in the sand. VOEL3 (Northern), indicated upper layers of low resistivity, while the lower depth indicate areas of high resistivity. It is expected that the results of this study will provide a conceptual understanding of surface water-groundwater interactions and the processes which control these interactions, in order to facilitate the effective management and conservation of this unique lacustrine wetland.

Abstract

The groundwater quality in semi-arid aquifers can be deteriorated very rabidly due to many factors. The most important factor affecting the quality of groundwater quality in Gaza Strip aquifer is the excess pumping that resulting from the high population density in the area. The goal of this study to investigate the future potential deterioration in groundwater salinity using scenario analysis modeling by artificial neural networks (ANN). The ANN model is utilized to predict the groundwater salinity based on three future scenarios of pumping quantities and rates from the Gaza strip aquifer. The results shows that in case the pumping rate remains as the present conditions, chloride concentration will increase rapidly in most areas of the Gaza Strip and the availability of fresh water will decrease in disquieting rates by year 2030. Results proved that groundwater salinity will be improved solely if the pumping rate is reduced by half and it also will be improved considerably if the pumping rate is completely stopped. Based on the results of this study, an urgent calling for developing other drinking water resources to secure the water demand is the most effective solution to decrease the groundwater salinity.

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}

Abstract

This article present field evidence on the effect of artefacts other than the horizontal groundwater flux on the single-borehole tracer dilution test. The artefacts on the tracer dilution were observed during two single-borehole tracer dilution tests conducted in an alluvial channel aquifer in the main Karoo Basin of Southern Africa. Field evidence shows that early time of the tracer dilution plot can be affected by artefacts other than the horizontal groundwater flux. These artefacts have great potential to increase the early time gradient of tracer dilution curve leading to overestimation of the horizontal groundwater flux. A qualitative approach that can be used to isolate and remove portion of the dilution plot that has resulted from artefacts other than the groundwater flow prior to calculating the horizontal groundwater flux is proposed.

Abstract

POSTER Researching a subject on the internet the slogan "Water flows upstream to money" popped up. The context was drought, and the meaning clear. If politics come into play as well, it would seem that science is relegated to a distant third place. The proclamation of the National Water Act, of 1998 (Act 36 of 1998), recognized the importance of groundwater and its role in the hydrological cycle and water supply issues. Groundwater governance has grown since then and is becoming increasingly important. One of the most important tenets on which groundwater based is the concept of sustainability. Various definitions of sustainability is used with the best know being "?development which meets the needs and aspirations of the present generation without compromising the ability of future generations to meet their own needs." Even though the basic understanding of sustainability may have been around for much longer than the term, it is the application of the theory in our current context that present us with challenges. Concepts like the precautionary principle, corporate governance and other buzz words that is being used does not always ensure good groundwater governance. One of the greatest problems is often the lack of scientific understanding and knowledge. Groundwater systems tend to be more complex and thus more difficult to manage than surface water. Understanding how groundwater and surface water interact, and that it is actually a linked water resource adds to the complexity. Add to this its importance in the functioning of groundwater dependent ecosystems that is still poorly understood. This article will look at principles for good groundwater governance and the tools that are needed to achieve it. It will finally look at real case studies where scientific considerations fall by the wayside for the requirements of the economy and political goals.

Abstract

It has become increasingly apparent that understanding fractured rock mechanics as well as the interactions and exchanges between groundwater and surface water systems are crucial considering the increase in demand of each in recent years. Especially in a time where long term sustainability is of great importance for many water management agencies, groundwater professionals and the average water users. Previous callow experience has shown that there is a misunderstanding in the correct interpretation and analyses of pumping test data. The fracture characterisation (FC) method software provides a most useful tool in the overall understanding of a fractured rock aquifer, quantification of the aquifer’s hydraulic (flow regime and flow boundary conditions) and physical properties, only if the time-drawdown relationships are correctly interpreted and when the theoretical application principles are applied. Interpretation is not simply a copy and paste of the aquifer test data into the software to get a quick answer (especially when project time constraints are considered), however, recent experiences with numerous field examples, required intricate understanding of the geological environment, intended use and abstraction schedules coupled with the academic applications on which the software was based for correct interpretation.

Through the application of correct interpretation principles, a plethora of flow information becomes available, of which examples will be provided in the presentation itself. By achieving this, flow can be conceptualised for inputs into a conservative scale three-dimensional numerical flow model and calibrated based on measurable data in a fraction of the time of a conventional regional model. Although higher confidence levels are achieved with these practical solutions, monitoring programmes are still required to provide better insight of the aquifer responses to long-term abstraction and recovery.

Abstract

POSTER About 97% of the earth's freshwater fraction is groundwater, excluding the amount locked in ice caps (Turton et al 2007) and is often the only source of water in arid and semi-arid regions and plays a critical role in agriculture, this dependency results in over-exploitation, depletion and pollution (Turton et al 2007). Groundwater governance helps prevent these issues. CSIR defines governance as the process of informed decision making that enables trade between competing users of a given resource, as to balance protection and use in such a way as to mitigate conflicts, enhance security, ensure sustainability and hold government officials accountable for their actions (Turton et al 2007). Realising the issues of groundwater governance is a requirement for developing policy recommendations for both national and trans-boundary groundwater governance. Groundwater level decline has led to depletion in storage in both confined and unconfined aquifer systems (Theesfeld 2010). There are about six institutional aspects, namely voluntary compliance, traditional and mental models, administrative responsibility and bureaucratic inertia, conflict resolution mechanisms, political economy and information deficits (Theesfeld 2010). Each of these aspects represents institutional challenges for national and international policy implementation. Traditional local practices should not be disregarded when new management schemes or technological innovations are implemented. The types of policies that impact governance include regulatory instruments, economic instruments and voluntary/advisory instruments. Regulatory or command and control policy instruments such as ownership and property right assignments and regulations for water use are compulsory. Economic policy instruments make use of financial reasons such as groundwater pricing, trading water right or pollution permits, subsidies and taxes. Voluntary /advisory policy instruments are those that influence voluntary actions or behavioural change without agreement or direct financial incentives. These are ideal types though no policy option ever relies purely on one type of instrument. The aim of these policies is to have an impact on governance structures (Theesfeld 2010). The national water act (1998) of the Republic of South Africa is not widely recognized as the most comprehensive water law in the world even though it is the highlight of socio-political events; socially it is still recent in most sites although the law was implemented 15 years ago (Schreiner and Koppen 2002). Regulations for use include quantity limitations, drilling permits and licensing, use licenses, special zone of conservation and reporting and registering requirement. In general when drilling and well construction are done commercially they increasingly fall under the scope of regulatory legislation. This paper will focus mostly on traditional and mental models; procedures that a certain community is dependent on should be taken into account before replacing with technological advanced tools. Consultation of the public can cause conflicts which lead to poor groundwater management.

Keywords: Groundwater governance, policy, policy instruments.

Abstract

There is an urgent need to support the sustainable development of groundwater resources, which are under increasing pressure from competing uses of subsurface geo-resources, compounded by land use and climate change impacts. Management of groundwater resources is crucial for enabling the green transition and attaining the Sustainable Development Goals. The United Nations Framework Classification for Resources (UNFC) is a project-based classification system for defining the environmental-socio-economic viability and technical feasibility of projects to develop resources and recently extended for groundwater. UNFC provides a consistent framework to describe the level of confidence in groundwater resources by the project and is designed to meet the needs of applications pertaining to (i) Policy formulation based on geo-resource studies, (ii) Geo-resource management functions, (iii) Business processes; and (iv) Financial capital allocation. To extend use in groundwater resources management, supplemental specifications have been developed for the UNFC that provide technical guidance to the community of groundwater professionals to enhance sustainable resource management based on improved decision-making. This includes addressing barriers to sustainably exploiting groundwater resources, avoiding lack of access to water and also related to ‘common pool resources’ in which multiple allocations are competing with domestic water supply (e.g. geo-energy, minerals, agriculture and ecosystems, and transboundary allocation of natural resources). UNFC for groundwater resources is designed to enhance governance to protect the environment and traditional users while ensuring socio-economic benefits to society. Consequently, it is a valid and promising tool for assessing both the sustainability and feasibility of groundwater management at local, national and international levels.

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.

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.

Abstract

In the management of water resources especially groundwater resources, implementing existing regulations is one of the much needed aspects ensuring water security through the regulated use. However, such regulations are not regulated to ensure that they served the intended purpose in their original formulation. In South Africa, a study was carried out to assess the relevance and efficient of adhering to procedural requirements during water use licence application (WULA) process. Lived-experiences and observation methods were used to collect data. The department of water and sanitation was used as a case study. Interpretative analysis approach was used to provide the meaning on the analysed information. The WARMS database was accessed where the number of days that WULA process was extracted. The regulation No. 40713 about WULA process was analysed. The five-year-data prior and post the promulgation of regulation No. 40713 were extracted from WARMS database and evaluated in terms of the duration each application took to be processed for WULA. Data on water use for abstractions from all the regions were obtained from WARMS database and assessed. Dates when applications were submitted and when such applications were finalised were analysis per month and per years for temporal analysis. The number of entitlements received during the particular period and the number of applications recommended to be declined and issued were assessed using exploratory data analysis methods. Graphical method was adapted to increase results visualisation on water use entitlements. Key results showed that the process of WULA was generally slow and reasons were provided for such outcome. However, the temporal analysis revealed an increasing trend in the post promulgation of regulation No. 40713 suggesting that regulations when re-regulated serve its intended purpose. Although such findings are not conclusive but they inform a basis for re-regulating enforcement regulations in Southern African countries with issues similar to South Africa on water entitlement.

Abstract

Fine ash is a by-product generated during coal combustion and gasification. It is often disposed of as slurry and stored on tailings dams over long periods of time, where it is exposed to weathering. Weathering causes soluble ions to go into solution and to be transported along preferred pathways through the tailings dam. This study was conducted to assess the leaching behaviour of fresh and weathered fine ash and to evaluate the impact on the underlying aquifers. A kinetic test was conducted over 21 weeks to analyse the leachate composition of progressively-aged fine ash and to calculate the release rates for major ions and trace metals of environmental concern. The leachate composition was compared to the groundwater composition of the underlying aquifers to assess the environmental impact of long term ash leaching. The study showed that the release rate of Ca decreased with increasing depth and age of the fine ash. The release rate of Mg, Na, K, Mo, V, Ba, Cr and Mo increased slightly between 22 m and 28 m in the tailings dam. Aluminium had a decreasing release rate from 28 m depth onwards. It was concluded that fine ash leaching influenced the water composition of the underlying aquifers because similarities were observed in the water type trend. The shallow aquifer south of the tailings dam contained Ca/Mg/SO4/Cl/NO3 water with a significant increase in Ca, Mg, Na, Cl and SO4 over time. These ions were expected to be found in the pollution plume due to their high release rate observed in the fine ash. The deeper aquifer northeast and south of the tailings dam showed a reverse trend of decreasing Ca, Mg and NO3 with time. This is possibly due to decreasing release rates in the aging fine ash and due to the cation exchange capacity (CEC) of the aquifer retarding the movement of Ca and Mg in the pollution plume. The shallower aquifer northwest of the tailings dam showed a decrease in Ca and Mg but an increase in K, while the water composition of the deeper aquifer increased in Ca, Mg, Na, K and Cl. This indicates that the pollution plume moved from the shallower to the deeper aquifer and that most of the Ca and Mg content in the fine ash has been leached from the tailings dam after more than 30 years of storage. The study confirmed that leaching of elements from the fine ash tailings dam had a negative influence on the underlying aquifers and that the clay lining was not sufficient in retaining the leachate.

Abstract

This study explores some of the principle issues associated with quantifying surface and groundwater interactions and the practical application of models in a data scarce region such as South Africa. The linkages between the various interdependent components of the water cycle are not well understood, especially in those regions that suffer problems of data scarcity and there remain urgent requirements for regional water resource assessments. Hydrology (both surface and groundwater hydrology) is a difficult science; it aims to represent highly variable and non-stationary processes which occur in catchment systems, many of which are unable to be measured at the scales of interest (Beven, 2012). The conceptual representations of these processes are translated into mathematical form in a model. Different process interpretations together with different mathematical representations results in the development of diverse model structures. These structural uncertainties are difficult to resolve due to the lack of relevant data. Further uncertainty is introduced when parameterising a model, as the more complex the model, the greater the possibility that many different parameter sets within the model structure might give equally acceptable results when compared with observations. Incomplete and often flawed input data are then used to drive the models and generate quantitative information. Approximate implementations (model structures and parameter sets), driven by approximate input data will necessarily produce approximate results. Most model developers aim to represent reality as far as possible, and as our understanding of hydrological processes has improved, models have tended to become more complex. Beven (2002) highlighted the need for a better philosophy toward modelling than just a more explicit representation of reality and argues that the true level of uncertainty in model predictions is not widely appreciated. Model testing has limited power as it is difficult to differentiate between the uncertainties within different model structures, different sets of alternative parameter values and in the input data used to run a model. A number of South African case studies are used to examine the types of data typically available and explore the extent to which a model is able to be validated considering the difficulty in differentiating between the various sources of uncertainty. While it is difficult to separate input data, parameter and structural uncertainty, the study found that it should be possible to at least partly identify the uncertainty by a careful examination of the evidence for specific processes compared with the conceptual structure of a specific model. While the lack of appropriate data means there will always be considerable uncertainty surrounding model validation, it can be argued that improved process understanding in an environment can be used to validate model outcomes to a degree, by assessing whether a model is getting the right results for the right reasons.

Abstract

POSTER As the National Water Act has evolved to provide for more effective and sustainable management of our water resources, there has been a shift in focus to more strategic management practices. With this shift come new difficulties relating to the presentation of sensitivity issues within a spatial context. To this end it is necessary to integrate existing significant spatial layers into one map that retains the context, enables simple interpretation and interrogation and facilitates decision making. This project shows the steps taken to map and identify key groundwater characteristics in the Karoo using Geographic Information Systems (GIS) techniques. Two types of GIS-based groundwater maps have been produced to assist with interpretation of existing data on Karoo Aquifer Systems in turn informing the management of groundwater risks within Shell's applications for shale gas exploration. Aquifer Attribute and Vulnerability maps were produced to assist in the decision making process. The former is an aquifer classification methodology developed by the project team, while the latter uses the well-known DRASTIC methodology. The overlay analysis tool of ESRI's ArcGIS 10.1 software was used, enabling the assessment and spatial integration of extensive volumes of data, without losing the original detail, and combining them into a single output. This process allows for optimal site selection of suitable exploration target areas. Weightings were applied to differentiate the relative importance of the input criteria. For the Attributes maps ten key attributes were agreed by the project team to be the most significant in contributing to groundwater/aquifer characteristics in the Karoo. This work culminated in the production of a series of GIS-based groundwater attributes maps to form the Karoo Groundwater Atlas which can be used to guide groundwater risk management for a number of purposes. The DRASTIC model uses seven key hydrogeological parameters to characterise the hydrogeological setting and evaluate aquifer vulnerability, defined as the tendency or likelihood for general contaminants to reach the watertable after introduction at ground surface.