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!