Wish All a very Happy Season and good rest over this holiday period. We are thankful that we could spend the year together - staying in touch and finding even more opportunity to meet and share. Let us take the best of the year moving forward and take on 2021 with renewed vigor, focus and intent.
11 x Zoom sessions. Interesting intersecting topics hosted by the different GWD Branches: Western Cape, North West, Eastern Cape, Gauteng, KwaZulu-Natal, Central (Bloemfontein).
Special mention of all the Stakeholders, Networks, Memberships, Trade partners of 2020:
BWA, WISA, SADC-GMI, GEOSS, UP, IHP-SA, GAKZN, UKZN, WRC, UWC, DWS, GSSA, CGS, IGS
There is little that delights as much as seeing (and drinking) water when you are thirsty.
It satisfies a fundamental need, it’s a sensory experience bar none and its presence or lack thereof, a deeply emotive issue.
Thus when a community bereft of water for so long, see the first blow of it – spectacularly - from underground, it’s indeed an emotional almost spiritual experience.
And rightly so that the country and press celebrates the fact with them. Celebrates the hands that make it possible. The awe and thankfulness of the people that can now for the first time, some ever, have water close at hand to drink, to wash, to sanitise.
Access to groundwater has changed many lives, particularly also over this year. That is something that the sector also celebrates, after all – this is their trade, their science. Their body of knowledge being honed and studied and shared and debated for decades already: how to bring groundwater - responsibly, sustainably, and with good quality – to those that needs it.
But there is a cloud that seems to obscure this bright sunbeams/ waterstreams of light and hope. It resides and lies uneasy in the stomachs of those that know and rests heavy on the shoulders of the custodians:
Spectacular results can often end in spectacular failures....or just make for some complications later
Geohydrologists (groundwater specialists) realizes that it is difficult to create excitement and buzz around a mostly unseen commodity. A river, dam and waterfall can awe and become part of a scenery – its visual and spatial and you can interact with it to create memories. Groundwater on the other hand – well yes, its hidden. The only thing indicative of it (if anything) is usually a windpump or pumphouse or a 2 dimensional map. Not very sexy or newsworthy. (Nowadays, it is the exciting new playground of the data modellers and animators that bring the science more to life! Watch the press on this one)
That said, nothing is as spectacular as a blow yield. Water shooting up in the sky and raining down with the promise of life-giving nourishment.
But seasoned geohydrologists and drillers know only too well that it is mostly all show. There needs to be a constant yield pumping test done for at least over 8 to 12 hours and water needs to be tested to see if it is indeed suitable for human consumption. The test pumping will indicate the actual yield that can be pumped sustainably at long term as to ensure the impact on the underground aquifer, and all the interconnected flow, is not permanent. That the well can not only give water until the press and its followers turn the camera’s off and move on to the next ‘story of the moment’.
Giving the gift of water is a blessing also for the many geohydrologists that can do it – daily – but it is done, carefully and measuredly - not to overpromise, not as a show but through consideration and in support of their science, their well-toned and constantly honed body of knowledge.
In the year ahead we will start sharing ‘Our Stories’. It will be about our members and member organisations’s experiences working in the groundwater field – with communities, Industry, government, learning institutions – individuals. There is excellent work being done out there and telling about and sharing that work and the impact it have on those giving and/or receiving , groundwater – making up 98% of freshwater on the planet – will ensure this resource is properly celebrated and made visible.
We are starting up a new feature on our website called ‘Our Stories’. We want to give a platform for our members to share their success stories/projects to the world. Tell us about your challenges with difficult drilling site and how you overcome it; the new method you applied in an area; the research that you are busy with, etc. We need to share.
We are requesting only a maximum of 200 words, a photograph/figure and contact details. The writing must consist of a title, short description, the results and the impact of the work.
The contact details need to contain your details, the company/organisation/university details as well as the company/organisation/university logo.
We invite all our member to share experiences with us. And if the media picks up on a story, you will be contacted and not the GwD. This is free advertising for you and your organisation.
To all those interested in undertaking postgraduate research in the field of hydrology and hydrogeology, we would like to call your attention to four PhD opportunities at/in collaboration with the British Geological Survey, fully-funded as part of the NERC Doctoral Training Partnerships. Two of the opportunities are hosted the BGS headquarters in Nottinghamshire and two are co-supervised at the BGS. For more information, please visit the relevant links below.
Water Cycling In High-Altitude Wetlands – Implications For Water Security In The Peruvian Andes (CENTA)
BGS, University of Birmingham, Imperial College London, CONDESAN Peru
Conceptual modelling of global groundwater variability and change (SSCP)
BGS, Imperial College London
Glaciers and future water supplies in the Himalayas (GW4+)
University of Exeter, BGS
Natural flood management impacts on groundwater-surface water dynamics in upland areas (E4)
University of Edinburgh, BGS, University of Dundee
A full list of BGS hosted and collaborative PhDs is available at https://www.bgs.ac.uk/geological-research/bufi/phd-opportunities/
SACNASP CPD EVENT
Sakala1,2, FD Fourie2, M. Gomo2 and G. Madzivire1,3
Council for Geoscience, Pretoria, South Africa
Institute for Groundwater Studies, University of the Free State, South Africa
The University of South Africa, Department of Environmental Science
In the Karoo coalfields, mining operations which release acid mine drainage (AMD) are threatening groundwater resources. An important parameter controlling the extent and severity of AMD impacts is the natural attenuation of rocks in response to introduced of AMD. Very little is known about such responses for Karoo rocks in saturated and unsaturated conditions, a research gap filled by this paper. Laboratory column leach experiments were used to study the responses of different rock types from Witbank, Ermelo and Highveld coalfields of South Africa. The results show that various rocks have varied responses and are a function of the quartz, plagioclase or carbonate mineral content. The presence of oxygen increased the rate of heavy metal removal from the AMD. For all rock samples under saturated and unsaturated conditions, the sulphate and chloride concentrations of the AMD remained unchanged after the leaching process, showing that these parameters are conservative and can be used as potential natural tracers of AMD movement in the subsurface.
The research shows that laboratory leach tests may be used to rank the various rock types found in the Karoo coalfields in terms of their capacities to buffer the impacts of AMD. Such a ranking could inform policy and decision-makers regarding the handling and storage of AMD-generating wastes, as well as the location and design of AMD waste storage facilities.
ABOUT THE PRESENTER
Dr Emmanuel Sakala is a Chief Scientist at the Council for Geoscience with expertise in natural resources exploration using geophysical techniques, design and application of artificial intelligence (AI) systems in geoscience. He has worked as a geophysicist in mining, research and consultancy services for 14 years in 11 African countries. He holds a BSc (Hons) degree in Applied Physics (2005), MSc degree in Geophysics (2007) from the National University of Science and Technology and a PhD degree in Geohydrology (2018) from the University of the Free State. In his career, he received five awards for outstanding research, conference proceedings and competitions.
AMD Natural Attenuation potential mapEnergy Source (Fluid & Pollutant Source; Transport, Trap, Aquifer); Relative Rock - AMD reactivity
Thank you Dr Sakala for sharing your Case Study with attendees.
We appreciate the insights into possible tracers, potential handling & storage of AMD-generating wastes, passive treatment and future research suggestions.
(Please contact Mr K Majola (GWD GAU Branch Chair) via firstname.lastname@example.org for CGS liaison regarding the presentation & event recording *CGS disclaimer)
D Question : Realistically, is 'clean coal' financially viable in the South African context? And if it is, why is no-one / so few applying the technology? As a non-mining geologist, I'm rather skeptical that any mining is 'little or no environmental harm'?
T Question: Would the idea not be to attempt neutralization before decanting? Has the thought of limestone being given as back filling material?
C Question: In dolerite what about pyroxene dissolution reactions?
A 2016 report by the Council for Scientific and Industrial Research (CSIR) titled Shale Gas Development in the Central Karoo: A Scientific Assessment of the Opportunities and Risks, recommended that “a comprehensive understanding of groundwater conditions is required prior to the commencement of exploration to ensure proper interpretation of changes in groundwater over time. [...] Monitoring data would also be used for calibration and verification of prediction and assessment models, for evaluating and auditing the success of management plans, and for assessing the extent of compliance with prescribed standards and regulations.”
Independent specialists and researchers from the Institute for Groundwater Studies (IGS) at the University of the Free State (UFS), in partnership with specialists from Carin Bosman Sustainable Solutions (CBSS), have been appointed by the Petroleum Agency of South Africa (PASA) to design a regional groundwater monitoring network for the Central Karoo. The specialists employed by the IGS and CBSS to undertake the project include SACNASP-registered scientists who have expertise and experience in geohydrology and the geology of the Karoo Basin, as well as experts in water governance (including the design and development of water monitoring programmes and the evaluation, interpretation, and visualisation of water quality data), and software developers who can handle large volumes of water monitoring data.
Visit the CBSS website and learn more & participate!!
SACNASP CPD EVENT
The GAKZN Webinar hosted, in association with the GWD and the University of KwaZulu-Natal, had two speakers presenting on current research findings:
TALK ABSTRACT: The Gravity Recovery and Climate Experiment (GRACE) satellite data interpretation provides an integrated measure of monthly terrestrial water mass changes. The GRACE satellite data has been successfully used to estimate the monthly changes of terrestrial water storage (TWS) including groundwater storage changes. This presentation will provide an overview and application of the GRACE satellite product to determine the groundwater storage changes in Usutu-Mhlatuze Drainage Region in north eastern South Africa.
ABOUT THE PRESENTER: Manish Ramjeawon is a Hydrology PhD candidate from the University of KwaZulu-Natal. His current research interest involves the impact of land use change on surface water and groundwater resources in northern KwaZulu-Natal.
GRACE, GRACE-FO, Modelling, land-use, Usutu-Mhlatuze Drainage Region, monthly images, surface water data, 3 lakes, eastern coast, 9 dams, global land data simulation, NASA, resolution, GLDAS, soil moisture, NOAH land surface model (LSM), storage, anomalies, mean 2002-2009, trend 2002-2006 decrease, DWS, variation, 2017-current steep decline, 2017-2018 gaps in data satellite, not operational, cloud cover, general trend, consistent, soil moisture anomaly, between 2014-2019 decline water levels, purpose of study, primary, secondary aquifer, storage for catchment, steep decline to 2020, groundwater storage, deviation of the mean, size of the secondary aquifer, decreased groundwater storage. Institute data, groundwater monitoring data, DWS stations, compare with GRACE on primary, similar trend, WMA, decreased rainfall, land-use, commercial forestry, eucalypti, 1000 hectares per annum and 35% drain, Lake Sibaya. Limited groundwater monitor stations, GRACE potential
Thank you to my research supervisors
Dr Molla Demlie - email@example.com
& Dr Michelle Tosha
TALK ABSTRACT: This presentation highlights the results of the development and the calibration of a steady-state and transient three-Dimensional numerical groundwater flow modeling based on a robust conceptual hydrogeological model of the area. The calibrated transient numerical groundwater flow model is further used to understand the advective transport of a hypothetical contaminant released from the site of a proposed nuclear power facility at Thyspunt. The information gained from the numerical groundwater flow and advective transport models help to understand the background hydrogeological conditions to be used as input in the environmental impact assessment and as a reference for future post development conditions of the area.
ABOUT THE PRESENTER: Mr Moneri Joel Modiba is a young professional hydrogeologist. He is a member of the GSSA and worked as a geologist at the Marula Platinum Mine. He holds a BSc honours Degree in Geology from University of Limpopo and a MSc Degree in Hydrogeology from the University of KwaZulu-Natal.
three-dimensional, numerical modelling, testpump area, nuclear station, EIA required, conceptional groundwater flow, hydrological condition, contaminant transport, isotope analysis, study advective transport, eastern cape, 120km west PE, high rainfall, winter, topography, 2 drainage systems, rivers, highlands to Indian ocean, meta-sedimantary rock, metholotic interconnect, geology, TMG fractured, outcrops, preferential pathways, intergranular, aquifers, fractured, less productive than, methodology, climate data, earth data, hydrostratigraphic unit, chemical, trace elements, iron oxidation, robust, 3d model, calibration, converted, advective transport model, hydraulic parameters, arteasian borehole, chemical, PH, EC, classification, fresh water, iron in mix, seawater and surface water, evaporation, tritium analysis, modern water, older water, software, Thyspunt, MODFLOW, upstream package, 2 layers, 2 formations, deepest borehole with constant elevation, pumping, model domain, specified head, model grid, top elevation, steady state, conversion, calibration test, water budget, total inflow, successful model, head distribution, relationship, similar observed, simulated, good fit, simulation, transient, forward particle, flowpath, injected, particles, indian ocean, future, proposed footprint, reversed, tracking, no seawater intrusion, domain, transport, tracking, recommendation, robust, mean absolute error, 4 decades, reach ocean, ongoing monitoring
Special thank you to Prof Demlie and Prof Tumara.
Funders and hosts acknowledged.
Talk 1 Q SN: Thanks Manish. Would like to please find out if there is any correlation with the lack of flood releases from Pongolapoort Dam (fills numerous pans) and groundwater recharge, probably focusing on the secondary aquifer.
Manish: Did not look into floodlands and correlation with data that I have. I will let you know if I find anything on that.
Talk 2 Q PR: An EIA has already been done for this site, including a groundwater specialist report including modelling? References - EIA specialist report missing?
MD responds: This study is independent of what has been already done. The researcher was not allowed to refer to the EIA.
Talk 2 Q PR: Figure 20. Conceptually, recharge is postulated to flow from the higher lying TMGA of the Kareedouw Mountains towards Cape St. Francis. Therefore not sure about the no-flow boundary across this area?
Moneri: I think the reason we assigned a north flow boundary from that area. We don't have (e.g. rivers) a groundwater divider that side , it was done not to allow water into the model domain.
Talk 2 Q PR: How were the aquifer parameters such as T and S derived - from test pumping or from previous work? Why not do advective transport from the proposed nuclear installation footprint?
Moneri: They were derived from pumping tests. Pumping test data analysis done by the research from data provided by NNR. Data that were already done in the field. Vector transport from Nuclear footprint was done but not included in the presentation.
Mr Pieter Labuschagne noted that these regular science sharing sessions are of great importance, arranged quarterly by the/ with the students & branch support, and thanked all that attended.
SACNASP CPD EVENT
TALK ABSTRACT Science is a living document; it grows and expands as more information becomes available and our knowledge grows. It makes use of hypothesis, experiments, observations, and measurements. Groundwater scientists have a difficult task. They work in a system that is not visible, and they cannot take it into a laboratory to study. They use geophysical methods and drill boreholes to get an idea of the groundwater system that they are studying. These become the building blocks – the puzzle pieces – that are used to develop the conceptual model. This is the hypothesis of the groundwater scientists. Fortunately, there is never a completely right or completely wrong conceptual model, as it depends on the information that is available and the quality thereof. The puzzle pieces that make up the conceptual model vary in size and importance. There are large puzzle pieces that are often easy to collect and fit together, while it is more costly and time consuming to collect the small puzzle pieces. When starting with a groundwater study, there are some pieces of information that may already be available, depending on the work that has been done in the area before. These may include maps, reports, hydrocensus information, drilling information, water level measurements, and water quality information. Additional information that may prove useful in the development of a conceptual model may be land use, vegetation, information on soil types and climate date. Anecdotal information from people that know the area well can prove to be valuable at times. When you work in an area where little or no work has been done, you will have to collect most of the information. In a study area where there is a large amount of information available, it will be necessary to sort through it and it is often necessary to cut through the clutter to get the most relevant information.
The West Coast aquifer system was used as a case study to illustrate the development of a conceptual model. Information about the site was included with an emphasis on the geology and geohydrology of the study area. The water levels and water quality, as well as the role they played in the development of the conceptual model were discussed. The conceptual model for the study area were presented in conclusion.
ABOUT THE SPEAKER Nicolette Vermaak has almost 12 years’ experience in her field, having worked at the Geohydrology Section of the Bellville Regional office of the Department of Water and Sanitation. She was responsible for the management of groundwater related issues in the Berg River Catchment, and recently submitted her PhD thesis looking at the management of the West Coast Aquifer System. She studied at the University of the Free State. Here she did a B.Sc. with Botany, Zoology and Entomology, followed by a B.Sc. Honours in Botany. She also did a Masters in Environmental Management and then a M.Sc. in Geohydrology from the same university.
To echo the commentary from the attendees received on the closing of the event: " Thank you for an excellent and well-prepared talk Nicolette. It definitely also contributes to our understanding of this very important aquifer in the Western Cape. "
"Thanks for sharing the presentation. Really impressive work. Your presentation really highlighted how important it is to understand the hydrogeological system and continue to collect new data to improve the conceptual model. Your work has a direct link to our work at Ladysmith and the MAR project in the West Coast area." Jan Kürstein, Rambøll Danmark A/S, Copenhagen
Recording Available (reduced quality):
Joseph Twahirwa Q: Thank you so much for your highly informed talk. What is your strategy when you complete your hydrocensus? The reason I ask this is because when I knock at the gate where I should ask if they have boreholes people tend to say no. But when you see beautiful flowers and other vegetation in place I always suspect that the answer given was not correct.
Jeanne Gouws Q: Thanks Nicolette. With regards to land use I assume you would also need to include the effects of mining as well? Especially if the mining is using groundwater and some of that water is recharging into the aquifer.
Caiphus Ngubo Q: At times the challenging component to obtain when dealing with conceptual modelling and water balance is evapotranspiration. Do you think it is a train smash if I don't use such data in my water balancing and conceptual modelling?
Jorette van Rooyen Q : Great presentation Nicolette 🙂 In addition to water level data was 72 h aquifer tests conducted on the boreholes in the well field? This is specifically helpful in determining the specific characteristics of the aquifers. 72 h testing also good for revealing geological flow barriers.
Camille Kraak <Comment>: I once had a conversation with a old man on a mine who had been working in maintenance there for many years. He was assisting us with some excavations. During our conversation he told me about the open pit that used to be in the very spot. No one on the project knew about the pit and had considered this area natural ground. Needless to say, we didn't find natural ground and now we knew why. SO important to get on the ground information from locals!
Let us Talk about It!
Email us your NAME & TALK THEME to add you to the List:
|1||Mrs Constance Mafuwane, SANBI||FRAMEWORK TO ENHANCE THE CURRENT DEGREE OF EFFICIENCY IN THE MANAGEMENT GROUNDWATER AND SPRINGS IN MPUMALANGA PROVINCE|
SACNASP CPD EVENT
Thank you to the Eastern Cape Chair: Mr Etienne Mouton, for making this great session possible!
TALK ABSTRACT Small water treatment plants are defined as water treatment systems that have to be installed in areas which are not adequately serviced and do not normally fall within the confines of urban areas. They are therefore mostly used in rural and peri-urban areas and include chlorination plants for water supplies from boreholes and springs, small treatment systems for rural communities, treatment plants of small municipalities and treatment plants for establishments such as rural hospitals, schools, clinics, forestry stations, etc. Most of these applications require small plants of less than 2.5 ML/d (although plants of up to 25 ML/d may sometimes also fall into this category).
The decision-maker selecting one of these small water treatment plants has a great number of local and international system designs to choose from. Especially in the case of novel and emerging systems, very little may be known of these systems in terms of cost, efficiency and the applicability to the intended application. Supplier information may be sketchy, or promising new technologies have not yet been fully evaluated under South African conditions. Socio-economic factors are also very important and should be taken into account in the selection of small water treatment systems in order to ensure sustainability.
Although some evaluation of a selected number of small water treatment plants has taken place under previous WRC projects (WRC Report No 450/1/97: Package water treatment plant selection, and WRC Report No 828/1/01: Field evaluation of alternative disinfection technologies for small water supply technologies), a number of other small water treatment plants, available on the international market, have not yet been assessed in any way for possible (beneficial) application in South Africa. This study is therefore seen as complementing existing guidelines in providing assistance in the selection and operation of specific small water treatment systems being marketed for the treatment of potable water for small communities.
A number of local and international studies have shown that the selection of the correct water treatment system is but a first step in ensuring a sustainable supply of potable water to small communities. Following of the correct operational and maintenance procedures is of even greater importance for ensuring sustainability of water supply. Although most suppliers of small water treatment systems provide their clients with some operational and maintenance guidelines, these may not be exhaustive, or certain important generic aspects may not be covered. Information on operation and maintenance aspects will be of significant value to the owners and operators of such small water treatment systems.
ABOUT THE SPEAKER Christian D Swartz is a consulting water utlization engineer specializing in drinking water treatment and water supply projects, and water reclamation and reuse. He holds degrees in Civil Engineering and a Masters in Water Utilization Engineering from the University of Pretoria. He is a registered professional engineer and previously worked at the CSIR as senior research engineer and project manager on numerous projects in the drinking water treatment field. He started his own private consulting engineering practice, Chris Swartz Water Utilization Engineers, in 1991 in Mossel Bay, and later also opened an office in Durbanville, Cape Town. Chris Swartz has more than 28 years’ experience in the water industry. Areas of expertise include project management on water supply projects, evaluation of water treatment technologies, evaluation of water and wastewater treatment plants, water reuse and desalination schemes, risk assessment and risk management, rural water supply, and lots more.
Chris, your talk just again highlighted the need for knowledge sharing and thank you for sharing so freely. This insightful, topical talk is packed with information and we all appreciate your time with us!
REFERENCE MATERIAL ON TALK
Connan Hempel (SRK Consulting) Q - via registration form: How would these systems deal with issues like elevated Arsenic & Fluoride?
Melissa Lintnaar-Strauss (DWS) Q: Chris, how many commercial labs are available in SA to test for the EDC`s and pesticides and what are the costs of tests?
Greta Pegram (Private) Q: What are your thoughts and how do you recommend removing substances such as hormonal or prescriptive medications that are increasingly being found in waste water discharges?
Sizwe Mabilisa (Private) Q: Deep rural communities who usually get their drinking water from rivers usually boil the water before drinking. How effective is this most? what other cost effective solutions can they explore?
Maphuti Kwata (CGS) Q: Since the small rural communities are using underground water such as wells and boreholes as water supply for drinking purposes with regard to leakage of CO2 which might be stored /contaminate underground water . What are the technologies/mitigation measures that could be used to prevent /reduce the CO2 as the contaminants /leakages to the under groundwater?
Sumaya Israel (UWC) Q: Is your talk more related to municipal treatment? As small rural communities may require point of use type treatment methods (filtration systems within the household).
Sumaya Israel (UWC) Q: Would you recommend in situ or ex situ application of the methods outlined?
SACNASP CPD EVENT
TALK ABSTRACT It’s commonly accepted that climate change will be experienced though water, particularly in developing countries. Several studies relating to the impacts of climate change on surface water have been undertaken while very little research exists on the potential impacts on groundwater. Hence, this talk aimed to discuss some of the current research with respect to climate impacts on groundwater. Various methods are proposed for estimating climate change impacts on groundwater, such as using hypothetical scenarios of progressive drying to assess stream flow sensitivity to drought, using MODFLOW to investigate projected effects of climate change on groundwater or using scenarios to analyze impacts of climate change on aquifer recharge.
ABOUT THE SPEAKER Chris Moseki has over 20 years of experience in groundwater development and water resources management. He also served as a research manager at the Water Research Commission responsible for development of tools and systems for adaptation to climate change for about 6 years. Chris is currently a climate change specialist scientist at the Department of Water and Sanitation. His interest includes research in groundwater and climate change as well as seeking solutions to climate and water related problems in the public sector.
DR CHRIS MOSEKI is also a longstanding member of the GWD and is revered and highly regarded. He has been instrumental in establishing WRM and Climate Change as Agenda points in the water sector strategies being work-shopped since the late 1990's, and driving forth and carrying the torch since then...And a great person with a warm smile. We appreciate you Dr Chris & also for sharing your knowledge, experience and material with us!
Well done and Thank you to the GWD Gauteng Branch Chair Mr Kwazi Majola for making the sharing & learning opportunity through this excellent presentation possible.
The following were discussed:
Kes Murray Q: With all the increases in GW use (and dependence) in recent years in RSA, as well as with the expected reductions in recharge from climate change in the future, what is DWS's role with regards to monitoring, managing and allocating the status of aquifer storage levels at a regional scale?
Victor Tibane Q: What are the differences between water stress and water scarcity, how is each event determined, and what are the possible technological advances for solutions?
Elsabe Swart, Department of Environment and Nature Conservation (DENC) Q_1: How do you distinguish between water extraction impacts and that of climate change?
Q_2: How do you distinguish between water extraction impacts and that of climate change?Are any of these studies being done in the Northern Cape province? Is monitoring of boreholes sufficient (especially in the Northern Cape as it is the most arid province where these impacts are expected to be most severe)?
Q_3: What communications go through to the National Minister - concern is specifically i.t.o. the pressure to extract more underground water as a source for water going forward in the country. Concerned about the feasibility overall, but again especially i.t.o. the arid Northern Cape?
Henk Coetzee Q: Chris, have you looked at Eddie van Wyk's work on recharge, which looked at recharge being strongly event-driven, especially in more arid areas?
Sonia Veltman Q: I'd like to add to Henk's question. What's the options for looking at event driven recharge, modelling these based on changes in expected higher rainnfall events and then takinng those numbers back to these models adding it as objects, instead of averaging. What we see in the field is rapid recharge during storm events, but lagged in time?
Comment by Mr Fanus Fourie: The issue around low rainfall vs high intensity rainfall event will average out. Eddie said that the duration of the rainfall event is very critical to allow recharge to happen. Quick and intense thunderstorm will not create recharge but runoff.
Sivashni Naicker Q_1: The areas highlighted within the Karoo that are high risk, are there any management interventions that can be included in planning that DWS can do, especially in the rural setting, whereby people are more vulnerable?
Q_2: Dr Moseki, should we add investigation of potential artificial recharge sites to our all towns/recon studies?
Comment by Dr Sumaya Israel: I agree with you Dr Moseki, monitoring and having reliable data is key to sustainable management and understanding of our hydrological and hydrogeological systems.
Nkadimeng Maletele (IUCMA) Q: Thank you very much for the lovely and educational presentation Dr Moseki, As new member in the groundwater studies family I would like to ask, after how many years is it effective to analyze groundwater quality and quantity data…And is the groundwater quality data important when quantifying the impacts of climate change on groundwater?
Thank you for your support in attending this Event.
SACNASP CPD EVENT
Well done and Thank you to the GWD Gauteng Branch Chair Mr Kwazi Majola for making this sharing & learning opportunity possible!
BACKGROUND TO THE TALK: Alongside the effects of climate change and anthropogenic factors, natural climate cycles have considerable impacts on the hydrologic cycle. In this study, we look at how global climatic oscillations cycles, like El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) affect total water storage and groundwater storage in the Orange-Senqu River Basin by analysing two large aquifers: the Stampriet Transboundary Aquifer System (STAS) shared between Botswana, Namibia and South Africa, and the Karoo Sedimentary Aquifer shared between Lesotho and South Africa. The findings could help decision-makers prepare more effective climate-change adaptation plans at both national and transboundary levels.
ABOUT THE PRESENTER: Tales Carvalho-Resende has more than 7 years of experience in the development and management of international cooperation projects on environmental issues, climate change and transboundary waters. He worked at the UNESCO Intergovernmental Hydrological Programme (IHP) where he coordinated and supported research and capacity-building activities on groundwater and climate change, water diplomacy, conflict resolution, and international water law that lead to the establishment of the first arrangements for the governance of a transboundary aquifer in Southern Africa (Stampriet Aquifer in 2017 – Botswana, Namibia and South Africa) and Central America (Ocotepeque-Citala Aquifer in 2019 – El Salvador and Honduras). He is Brazilian, PhD, Earth Scientist and holds an MA in International Affairs and LLM in Climate Change Law and Policy.
We appreciate his excellent presentation and the encouragement by Dr Tales for sharing of the materials.
In vain have you
if you have not
imparted it to others.
(Live questions and responses to these questions are transcribed and might contain capture errors. We will continue with the quality check and update the post accordingly.)
Q: Thanks Tales for the wonderful presentation. It is always encouraging to see the application of GRACE derived data particularly in Southern Africa given that GRACE is underrepresented. I would like to find out what was the time mean that was used to estimate the total water storage changes?
Tales: To give you further information about the GRACE satellite. The GRACE data have to be considered very careful. Why? Because it provides an overview on a large scale and not at local level. GRACE mainly ‘sees’ the fluctuations of shallow aquifers but not deep aquifers. Most of the time this is enough because most of the groundwater abstraction occurs from shallow aquifers. GRACE has been out in the skies since 2002. With the model we were able to add 20 more years going back to 1980 - which is fantastic. So this is what we tried to do, go back to the past to reconstruct these fluctuations.
Q: The applicability of GRACE on large aquifers (such as the Stampriet) you mentioned. So how is the applicability of GRACE on the smaller aquifers; and also the applicability of GRACE on a national scale for instance if you want to do it for the whole country total water storage estimations and what is the impacts on the water storage?
Tales: One of the aims of this study was to have a first picture of the correlations between groundwater and climate change at a large scale because there have been very few studies on that particularly in Africa. So, I would say a first step is to have a general big picture at large scale (i.e. the same study can be replicated at Southern Africa level) and then once we have that first picture, we can already identify some correlations. In Southern Africa, we can see that there is already an El Nino correlation and then you go into detail and further studies can be done. So, I can say that this study can easily be replicated at a large scale in other regions/ country level but is just to give a first ‘snapshot’ of the situation.. Then you follow with further studies at local level.
Q: Is there any reason why you chose this study area?
Tales: Well, we have chosen this area because we were working with the support of UNESCO in that region. We had support to assess these impacts of climate variability in the Stampriet aquifer and then we said ok let us see what is also happening in the Karoo Sedimentary aquifers so as to have a broad picture of groundwater dynamics in the Orange-Sengu Basin. We have also applied the same methodology of other regions of the world and the results were quite interesting.
Q: Did you fit groundwater level data with the modelled results? If so, how good was the model fit in validation?
Tales: If you have a look to slide 17. The answer is yes. We validated the model both in the GRACE (starting from 2002 until now) and the groundwater level data time-frame. Again, the groundwater level data might not have been representative of all of the basin but the very few that we could collect and were available, fitted very well and we felt confident to go further with these correlation of climate indices.
Q: Kwazi spoke about the scale with regards to applying GRACE data to a small scale. I personally tried that and the results were very coarse but looking at other studies, myself and others actually found that at scales greater than 150,000 km2 that is when you can start to see and get better results. We actually did not find absolute values in terms of values of total water storage but rather just the anomalies. Also using the soil moisture data and abstracting it from the GRACE the total storage data that actually gave us some insight into what is happening to groundwater level. So far we have not found or could use any long term data that is representative of areas less than the 150,000 km2 in SA and I think it is also the same issues that you faced when doing your study in the Stampriet. So I am not sure if you or somebody in your team have found some way to downscale so that can maybe be able to apply GRACE at a more local scale?
Tales: Yes, unfortunately for the time being we have not been able to go deeper into local scale. Exactly one of the challenging issues are the ones that you mention. So as you know groundwater fluctuates differently from one borehole to another, so a borehole that is only a few km away can have a different dynamic than another, and what we would need -I would say- to really make sure this model is robust is to have a strong groundwater level monitoring network at work in which you would allow you to have the average of all the groundwater level data. What GRACE does offer is usually an average of what is happening in the 150,000 km2 to give you one number. So that is the challenging issue. We did apply the same model in other aquifers that have a very good monitoring network mainly in the Unites States, and it worked very well. But as I said – this is only to show you what can happen at large scale.
Q: Is it possible to simulate the longer time effects of the Milankovitch cycles (100,000 year cycles) which effects of changes in Earth’s position relative to the Sun and are a strong driver of Earth’s long-term climate, and are responsible for triggering the beginning and end of glaciation periods (Ice Ages)
Tales: This is quite challenging as we don’t have good and reliable data on rainfall and evapotranspiration at long term to extend the model. The current version of the model starts at 1980 because our data on evapotranspiration starts by then.
Q: How long after the El Nino/La Nina has started do you start to see the impacts on the groundwater storage changes or was it not part of the study?
Tales: We could see here that it was highly responsive so only a couple of months afterwards we could already see the impacts. Again this is only for shallow aquifers but this is very important information in the sense that it is highly responsive. So if you know there is a drought coming you will have an impact very soon after and this is the reason why it is really important to really be in touch and discuss with the climate people e.g. the different meteorological agencies and so on, because if you can have a good forecast of what happens with the rainfall patterns then you can have a good forecast also for groundwater. In this case we have seen that the aquifers are highly responsive to rainfall patterns which are intrinsically linked with climate indices.
Q: What is your depth of "shallow" aquifers?
Tales: By shallow aquifers we mean here unconfined aquifer and the water table level that we could get here from the different chronicles were usually a couple of meters (approx. 10-20).
Q: What was the effect of human abstractions? How were these included in the model?
Tales: This is an interesting question as yes, it is difficult to get data on abstraction. This model here did not consider human abstractions but what we could see here and what we could see in other studies is that if you have a dry period it means that abstraction increases and the trend decreases. So in our study we talk about trends not numbers. The results of the model are shown in a normalized scale so abstraction can be “implicitly” considered because of that. It is very difficult to give you numbers on abstraction because it is not always very reliable data, so keep in mind the trends. The takeaway message here is that usually when you have a decreasing trend it also mean that you have more abstraction this means that the trend goes even down.
Q: The groundwater system seems to be more sensitive to human activities than climatic changes. Is long term still relevant or urgent? Long-term? 200 years or so
Tales: It is very difficult to separate what is the human component and what is the climatic component because both are together. When it comes to groundwater – if you have a drought – this means that you will abstract more so both are intrinsically linked. That is why it is very difficult to disaggregate both of them. In the long term, this is still relevant, because the information can help us to better set up some MAR schemes. For instance, we could see a AMO positive phase (current one since mid 1990s) could bring water storage down, and then once this cycle could flip to another phase we could have some better days. So this can already give us some time of what can happen and how we can prepare in the long term.
Q: Presumably the water level measurements were taken from boreholes, which normally would be associated with human abstraction?
Tales: Yes. We tried to collect the longest and most continuous water level chronicles. Unfortunately, there are very few.
Please contact Mr Kwazi Majola (Branch Chair GAU) for more information on this subject: MajolaK@nulldws.gov.za