eNews

#05 2024

Hydrogeology research: Exploring international developments and collaboration opportunities

By Dr Retang Mokua, Postdoc, Ndlovu Node, NRF-SAEON

In September this year, Dr Retang Mokua travelled to Davos, Switzerland to take part in the International Association of Hydrogeologists (IAH) World Groundwater Congress 2024. This congress, one of the largest hydrogeology events held annually, attracts over 200 researchers from around the world. 

The purpose of Retang’s participation in the conference was to learn about the new technologies, challenges and current trends in hydrogeological research, as well as explore collaborative opportunities with international researchers.

During the congress, Retang presented her research titled “Tracer-based hydrograph separation approach to quantify groundwater contribution to stormflow in the Table Mountain Group geological region”. Her study focused on using a multi-approach method to understand runoff generation during rain events by combining hydrometric measurements, hydrochemistry and water stable isotopes.

As Retang’s research is one of the few that has applied this technique, her presentation garnered significant interest, particularly among South African researchers who attended the conference. This has led to potential future collaborations to enhance hydrological research in South African mountainous catchments.

Dr Retang Mokua at the International Association of Hydrogeologists (IAH) World Groundwater Congress 2024.

Retang (front row, third from right) with some of the South African participants at the IAH World Groundwater Congress in Davos, Switzerland.

Exploring Alpine geology and hydrogeology 

As part of the congress, participants were privileged to visit some of the hydrological research sites in Switzerland, led by the Büro für Technische Geologie (BTG) and the University of Neuchâtel. They visited the Brienz/Brienzauls rock fall and large-scale landslide. This is one of the largest active landslides in Switzerland, which sparked considerable geological and hydrological investigation to understand the mass movement processes, the role of groundwater in the landslide and how the impacts can be mitigated.

The field trip included a visit to the early warning and monitoring systems centre and the 650-metre-long drainage tunnel under construction that runs through the Brienz village to slow down the landslide.

Retang at the Brienz/Brinzauls drainage tunnel near the town of Brienz, Switzerland.

On the last day of the congress, participants were greeted by the first snowfall of the winter season of 2024 in Davos.

Federal Institute for Geosciences and Natural Resources 

As part of her postdoctoral studies, Retang paid a two-week visit to the Federal Institute for Geosciences and Natural Resources (BGR) isotope laboratory in Spandau (Berlin, Germany) to carry out plant water extraction work and water-stable isotope (ẟ2H and ẟ18O) analysis. The primary objective is to determine the water source of the vegetation in the catchment and their seasonal water use patterns to enhance the hydrological model, which will showcase the impact of vegetation change on river flows in the Upper Klaserie River catchment. This research aims to model the effects of the contemporary vegetation (the transition from forestry to savanna-grassland) change on flows in the Klaserie River.

A comprehensive understanding of runoff processes is crucial for predicting and managing freshwater supplies in these areas, and for planning and motivating land management interventions to improve supplies in the Upper Klaserie catchment.  For this purpose, the SAEON Ndlovu Node is collaborating with BGR to facilitate plant water and soil extraction, and stable isotope analysis at their laboratories in Spandau, Berlin.

Retang’s short visit guided her on plant water extractions (120 samples) and water stable isotope analysis of the extracted water. The Ndlovu Node scientists plan to continue collecting plant and soil samples from 2024 through to 2025 and perform the extractions and analysis at the BGR facilities to achieve the study objective. The findings will be used to validate the hydrological model for the Upper Klaserie River catchment.

Plant water extraction setup with the extraction in processes at BGR, Berlin.

Picarro Cavity Ring-Down spectrometer (CRDS, L2140i– analyser, Piccaro Inc, USA) for water stable isotope (ẟ2H and ẟ18O) analysis.

Retang’s relationship with BGR began while she was studying for her MSc at the Technische Universität Darmstadt in southern Germany. She conducted her scientific training and master’s thesis work in stable isotopes at BGR under the supervision of Dr Paul Köeniger.

After completing her MSc, she was able to maintain a close working relationship with her mentor and supervisor. With this research, SAEON scientists plan to strengthen their collaborative partnership with BGR and hopefully extend to other European institutions.

Dr Retang Mokua, Dr Paul Köeniger and Dr Amani.

Retang at the BGR facilities in Spandau, Berlin.