Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 31 - 40 of 220 results
Title Presenter Name Presenter Surname Area Conference year Keywords

Abstract

Mahed,G

On a global scale, groundwater is seen as an essential resource for freshwater used in both socioeconomic and environmental systems; therefore forming a critical buffer when droughts occur. Due to its location in a dry and semi-arid part of South Africa, Beaufort West relies on groundwater as a crucial source of fresh water. Thus, proper management of their groundwater resources is vital to ensure its protection and preservation for future generations. Although fluctuations have occurred over the years, groundwater levels in the area have progressively dropped due to abstraction in well fields. However, in 2011, an episodic flooding event resulted in extreme groundwater recharge with groundwater levels North-East of Beaufort West recovering tremendously. This led to the overall groundwater levels of Beaufort West becoming relatively higher. The general flow of groundwater in the town, which is from the Nuweveld Mountains in the North to the town dyke in the South, is dictated by dykes occurring in the area. This study aims to expand on the understanding of episodic groundwater recharge around extreme climatic conditions of high precipitation events in a semi-arid region. This was done by analyzing historical data for the Gamka Dam spanning over 30 years; estimating recharge in the Beaufort West well fields caused by the flooding event; as well as studying the hydrogeological setting and lineaments in the area. It was found that sufficiently elevated recharge around the observed flooding event only occurred in areas where the correct climatic (precipitation, evaporation), geological and geographical conditions were met. Ultimately, gaining a better understanding of these recharge events should aid in the assessment of the groundwater development potential of Beaufort West.

Abstract

Monitoring groundwater storage is conducted in the study. World Health Organisation estimates, about 55 million people affected by drought yearly. However, Surface water holds 0.3 percent of the freshwater, and groundwater holds 30.1 percent of the freshwater. Hence, monitoring groundwater storage is vital. Though the GRACE (Gravity Recovery And Climate Experiment) satellite provides global-scale groundwater data, but does not provide any information about changes in groundwater flow systems and has uncertainties, due to large noise produced. A correlation has to be established between gravity changes and groundwater storage variations through a program that simulates the flow of groundwater. The relationship between developed numerical models and data derived from superconducting gravity is imperative. This study is conducted in South African Geodynamic Observatory Sutherland (SAGOS) area at Sutherland, South Africa. The study aims to develop a numerical geohydrological model to monitor subsurface variations in water distribution through superconducting gravimeters (SG) records. The interpretation of the SG measurements to directly compare to one another at a higher resolution is considered in the study, through the correlation of the developed model and installed superconducting gravimetric residual data. A numerical groundwater flow model is developed using model muse on MODFLOW. Assigned boundary conditions, fractured rocks were activated by the model. Hydraulic conductivities were simulated for any layer, including storage coefficient. Hence, hydraulic conductivity is an important aspect of the study. In conclusion, gravity is an excellent tool for measuring groundwater recharge within the immediate vicinity of the SAGOS. This implies that gravity can aid in monitoring groundwater recharge and discharge in semi-arid areas. The application of the hydrological model at various scales comparing the Superconducting Gravimeter and GRACE satellite data is paramount to improve modelling groundwater dynamics. The consideration of developing numerical hydrological to monitor groundwater storage will add much value to missing information.

Abstract

The Council for Geoscience has a corporate responsibility in rural development projects as part of the South African government initiative in food and water security. Geophysical surveys were carried out at Elizabeth Conradie School in Kimberley, Northern Cape Province South Africa aimed on siting production boreholes to supply the school with water. Traditional geophysical techniques including magnetic, electromagnetic and resistivity were used to locate groundwater bearing structures. The magnetic method was used to locate intrusive magnetic bodies (i.e. Dolerites), while electromagnetic and resistivity were used to map conductivity and resistivity distribution associated with the subsurface geology.

The magnetic method delineated possible groundwater bearing structures which may be related to dolerite dykes and sills. The electromagnetic method appears to have identified shallow fresh dolerite sill. The resistivity method was good in identifying areas of low resistivity which might be related to fractures and/or faults. The high resistivity values might be related to dolerite dykes or sill.

The results of the study showed that geophysical methods are useful non-intrusive tools for mapping groundwater resource. The 1:250 000 scale geological reconnaissance map used to constrain the geophysical interpretation is at a bigger scale when compared to the geophysical interpretation resolution. Considering this and also the ambiguity and none uniqueness in geophysical interpretation, results need to be consolidated by a local scale hydrogeological mapping and drilling results.

Abstract

South Africa is currently considering unconventional oil and gas (UOG) extraction as an additional energy resource to improve the country’s energy security. In a water-scarce country such as South Africa, which has experienced more frequent and more intense climate extremes due to climate change, the water-related impacts of UOG extraction is a concern. The South African government is however determined to proceed with UOG development as soon as regulations to protect natural resources have been drafted. The country’s intricate governance system can however not enforce such regulations effectively, as it experiences repeated inter-departmental miscommunication, fails to collaborate with stakeholders effectively, and lacks human and financial resources for enforcement. A lack of transparency in fracking operations and between stakeholders is another challenge for enforcing UOG extraction regulations. Poor regulatory enforcement presents an obstacle for the protection of groundwater resources if fracking were to commence.

This study, therefore, focuses on addressing the enforcement challenges of UOG regulations aimed at protecting groundwater resources. It proposes the use of civic informatics on a technology platform, specifically via a mobile application (FrackSA), to assist with on-the-ground enforcement of these regulations. While many UOG mobile applications are used internationally, they mostly focus only on UOG related aspects (news, information, pricing, geological information, and fracking well information). FrackSA uses civic informatics to address both groundwater monitoring and management as well as UOG extraction operations in a single platform, to enable regulators to protect groundwater resources more effectively during UOG extraction, while simultaneously enhancing transparency in the UOG industry.

Abstract

Mabenge B; Famah FIB

Groundwater resources are under increased pressure from population growth, climate change and human activities, leading to widespread groundwater depletion and pollution. It is important, as groundwater professionals to communicate to the younger generation and the broader community, about this vital resource. The Groundwater Kids Educational Program was initiated in November 2020, to educate and share groundwater knowledge amongst primary and high school learners. The program consists of a series of 1 – 2 hour groundwater educational workshops held at schools throughout Gauteng Province. Each workshop comprises a short educational video clip on a selected groundwater topic, followed by an activity that involves the topic of the day, and distribution of groundwater awareness material. Lessons are prepared based on the age group and the level of comprehension of the learners. Learners get the opportunity to engage in activities designed to make learning about groundwater more exciting. These workshops provide a knowledge base for our children participate in efforts to save this resource in generations to come.

Abstract

McGibbon, D; Riemann, K

The Cape Flats Aquifer Management Scheme (CFAMS) includes both abstraction of groundwater and managed aquifer recharge (MAR) as part of the City of Cape Towns (CoCT) New Water Programme to diversify their bulk water supply and build resilience against future droughts. Since the project was initiated in early 2018, over 250 boreholes have been drilled for exploration, monitoring, abstraction, and MAR. Rotary mud drilling was used for most of the drilling due to its suitability in unconsolidated geological material, typical of the CFA. As effective as rotary mud drilling is for large scale development, it lacks in accuracy for detailed geological interpretation used for borehole siting and design (gravel pack and screen aperture size and screen position). This is due to the mixing of material and the circulation of the drilling mud washing away fine sediment which can skew grain size analysis results and obscure the vertical position and thickness of thin confining clay or organic rich lenses. The clay and organic rich layers can cause surface flooding during injection as they act as confining layers which effects borehole design and more importantly siting of MAR boreholes. To overcome this, two additional drilling techniques were explored, sonic and air core. Air core was disregarded early on due to the air creating a cavity in the underlying unconsolidated sediments. Sonic drilling, however, was successful in retrieving a continuous undisturbed core log through high resonant energy that liquefies the sediments, which are then brought to surface in a core barrel. The undisturbed continuous nature of the log allows for accurate grain size analysis and detailed vertical geological logging which can be used for facies analysis to interpret the paleoenvironment and predict the lateral extent of clay or organic rich layers that influence borehole siting, design, and the hydrochemistry.

Abstract

The study area is located in a Swiss alpine valley at the border between Switzerland and France and is situated in Valais. It is delimited by the hydrologic catchment of the river “La Vièze de Morgins”. The catchment area is situated in the Municipality of Troistorrents and of Monthey. Its population is approximately 4500 inhabitants. From the geological point of view, the valley “Val de Morgins” is mostly comprised of sedimentary rocks, amongst others breccia, schist, flysch, limestone, and quaternary sediments. The valley is affected by several natural hazards, such as landslides, rockfalls, and avalanches. Hydrogeologically, the valley contains few main springs that are outlets of porous and fissured aquifers. For this study, an inventory and monitoring of springs and rivers has been carried out since 2018 until April 2021. Particularly, more than 110 springs and rivers have been registered and observed during this time. The data includes GPS coordinates, photos, measurements of physical-chemical parameters and flowrates. Complementary to measurements, specific geological and topographical maps, and site information have been gathered. The analysis and interpretation of this huge set of hydrogeological data will be concluded with a new and innovative approach using different data science libraries that are implemented for the Python programming language. In this case study, groundwater sampling training is used to increase the understanding of the water quality. Four years of field measurements enable a better understanding of the parameter variability in relation to seasonality. Furthermore, new data analysis can aid the integrated resource management for the municipal water supply. The sampling and monitoring are key aspects to ensure water security, in terms of quality and volume. Additionally, it can also unlock prospective groundwater resources for municipal water supply. Case study data will also be compared with South African and other Swiss dataset of similar aquifer type.

Abstract

This study investigates and elaborates the development and testing of a multilevel sampling device. The primary purpose of this device is to achieve multilevel sampling in a well simultaneously, producing samples that are representative of the in situ groundwater. The device has been designed to have four different depths from which extraction of groundwater samples can be performed. Testing of the device involves a two-part process. A laboratory based testing and field based testing. The laboratory testing was done in a simulated well where three water tests were performed; normal tap water, salt water and hot boiling water. The field based testing was done on existing boreholes in the Rietvlei Wetland Reserve in the Western Cape. In the two processes involved, hydrochemical parameters were used to test for the efficiency of the device in terms of its working performance and to furthermore analyse the water chemistry which enables us to determine the water quality.

Abstract

Estimating pumping rates for the purpose of equipping boreholes with suitable pumps that will not over abstract either the boreholes or the aquifer(s) that are intersected is often assessed through test pumping of the boreholes prior to pump selection. While the South African National Standard has guidelines on the methodologies and durations of these tests (SANS 10299-4:2003), many production boreholes in the agricultural and industrial sectors are still equipped based upon so called Farmer Tests or Pump Inlet Tests (PIT), often of a short (6-24 hour) duration. These tests are also frequently and incorrectly confused with a Constant Head Test (CHT), both of which are different in methodology to SANS 10299-4:2003 testing, which relies to a high degree on data collected during a Constant Discharge/Rate Test (CDT or CRT) and recovery thereafter. The study will assess differences in test pumping methodology, data collection, analysis methodology and final recommendations made between Farmer Tests and SANS 10299-4:2003 methodology tests for 20 boreholes in which both tests were performed. The selected sites cover a variety of geological and hydrogeological settings in the Western Cape. Test comparisons include boreholes drilled into the Malmesbury Group, Table Mountain Group and Quaternary alluvial deposits, with tested yields ranging from 0.5 – 25 L/s.

Abstract

Israel, S; Nel, J

Globally, cumulative plastic production since 1950 is estimated to have reached 2500 Mt of plastic. It is estimated up 60% of this plastic is either resting in landfills or the natural environment, including groundwater settings. Microplastics are small pieces of plastic ranging between 1μm – 5mm in size and have been found in every ecosystem and environment on the planet. Much of the available literature on microplastics is focused on marine environments with few in comparison focused on freshwater environments, and even fewer on groundwater settings. The aim of this study is therefore to investigate the attenuation process responsible for influencing microplastic transport in saturated sands. This research will adapt colloid transport theory and experiments to better understand the movement of microplastics through sandy media. Saturated aquifer conditions will be set up and simulated using modified Darcy column experiments adapted from Freeze & Cherry (1979). Modified microplastics will be injected into the columns as tracers and the effluent concentrations measured by Fourier-transform infrared spectroscopy (FTIR). Breakthrough curves will then be plotted using the effluent concentrations to determine the attachment efficiency (α). It is expected the attachment efficiency will vary by microplastic type and size range. The Ionic strength of the solution flowing through the column and the surface charges of both microplastics and sandy surfaces are likely to influence the degree of attenuation observed. The relationship between different types of microplastics and collector surfaces from a charge perspective and their influence on the degree of attenuation will be evaluated. Given the lack of literature, its ubiquitous presence and postulated effects on human health, this research is significant. Through this research, the transport and attenuation of microplastics through sandy aquifers can be better understood, and in the process inform future research and water resource management.