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08 April 2025 | Story Andre Damons | Photo Andre Damons
DrSophie-Biskop_ProfFrancois-Engelbrecht
Dr Sophie Biskop from the Department of Geography at the Schiller University Jena, Germany, and Prof Francois Engelbrecht, a Professor of Climatology at the Global Change Institute (GCI), University of the Witwatersrand, at the Southern African Mountain Conference (SAMC).

The severe El Niño drought of 2015/16, which culminated in the Vaal dam reaching an alarming low water level (~25%), prompted scientists to try and predict whether climate change could bring a drought so severe and long lasting that Gauteng could run out of water. 

Prof Francois Engelbrecht, a Professor of Climatology at the Global Change Institute (GCI), University of the Witwatersrand, is one of the scientists working on this project and says though they cannot predict a Day Zero drought with certainty, he thinks it is possible that Gauteng might run out of water in the 2030s or 2040s.

 “This is the biggest climate change risk South Africa faces”, he said.  

Prof Engelbrecht and Dr Sophie Biskop from the Institute of Geography at the Friedrich Schiller University Jena, Germany, together with other scientists are working on a project involving hydrological modelling to predict and prevent a Day Zero from happening. Dr Biskop presented their research paper titled ‘Projected hydrological futures of South Africa's mega-dam region’ at the second Southern African Mountain Conference (SAMC2025) in March, indicating there is a high risk that the water demand in Gauteng will exceed available water resources within the Integrated Vaal River System (IVRS) under future climate change.

 

Gauteng may be severely compromised

The IVRS, a large, complex water system comprising water resources of different river basins, and several mega-dams within, has been constructed to secure the water supply of the Gauteng province, the economic hub in South Africa. 

According to the researchers, Southern Africa is a water-stress hot spot and is projected to become significantly warmer and likely also drier under global climate change, increasing the risk of devastating hydrological droughts. The IVRS, Dr Biskop told the attendees, is vulnerable to the occurrence of multi-year droughts as experienced between 2012 and in 2016. The alarming low water level of the Vaal dam after a period of drought of 2015/16 provided early warning that water security of Gauteng may be directly and severely compromised in a changing climate. Potential evapotranspiration will increase as a consequence of strong regional warming.

 

Answering questions

“There is consequently a high risk that the water demand in the Gauteng province will exceed available water resources within the IVRS under future climate change. This raises the question if under ongoing climate change the natural hydrological system (without considering water transfers between dam catchments) can maintain dam levels in South Africa’s eastern mega-dam region, and particularly within the Lesotho Highlands,” explained Dr Biskop. 

 “To answer this question, the aim of our study is to quantify future water balance changes of several dams under changing climate conditions using the Jena Adaptable Modelling System (JAMS), a software framework for component-based development of environmental models. For this purpose, we build process-based hydrological models for several dam catchments.”

She said an ensemble of high-resolution regional climate change projections is subsequently used as forcing, to generate future hydrological projections. The analysis of projected changes in hydrological system components (precipitation, evapotranspiration, run-off) provides probabilistic estimates of the occurrence of a regional climate change tipping point - when the natural water supply can no longer achieve the full storage capacity of the mega-dams which supply the Gauteng region.

 

Working to prevent Day Zero 

According to Prof Engelbrecht, they are working with the City of Johannesburg, the National Department of Water and Sanitation and Rand Water on this project. Their hope for this research is to create awareness in order to try and prevent Day Zero from happening. They also hope to assist these role players in building resilience and help them prepare for Day Zero. Their work with the City of Johannesburg also includes helping the city to reduce water wastage and change water users’ behaviour as well as formulating a disaster management plan should Day Zero happen. 

The Southern African Mountain Conference (SAMC) series is unique as it seeks to integrate science, policy and practitioner sectors for sustainable interventions in southern African mountains. SAMC events are conceptualised by the Afromontane Research Unit (ARU) of the University of the Free State (UFS), the African Mountain Research Foundation (AMRF) and Global Mountain Safeguard Research (GLOMOS), a joint initiative between Eurac Research and the UNU Institute for Environment and Human Security. These three organisations form the Primary Partners, with the SAMC series being implemented by The Peaks Foundation (a non-profit company). SAMC2025 is being held under the patronage of UNESCO.

News Archive

Water research aids decision making on national level
2015-05-25

Photo: Leonie Bolleurs

With water being a valuable and scarce resource in the central regions of South Africa, it is no wonder that the UFS has large interdisciplinary research projects focusing on the conservation of water, as well as the sustainable use of this essential element.

The hydropedology research of Prof Pieter le Roux from the Department of Soil, Crop and Climate Sciences and his team at the UFS focuses on Blue water. Blue water is of critical importance to global health as it is cleared by the soil and stored underground for slow release in marshes, rivers, and deep groundwater. The release of this water bridges the droughts between showers and rain seasons and can stretch over several months and even years. The principles established by Prof Le Roux, now finds application in ecohydrology, urban hydrology, forestry hydrology, and hydrological modelling.

The Department of Agricultural Economics is busy with three research projects for the Water Research Commission of South Africa, with an estimated total budget of R7 million. Prof Henry Jordaan from this department is conducting research on the water footprint of selected field and forage crops, and the food products derived from these crops. The aim is to assess the impact of producing the food products on the scarce freshwater resource to inform policy makers, water managers and water users towards the sustainable use of freshwater for food production.

With his research, Prof Bennie Grové, also from this department, focuses on economically optimising water and electricity use in irrigated agriculture. The first project aims to optimise the adoption of technology for irrigation practices and irrigation system should water allocations to farmers were to be decreased in a catchment because of insufficient freshwater supplies to meet the increasing demand due to the requirements of population growth, economic development and the environment.

In another project, Prof Grové aims to economically evaluate alternative electricity management strategies such as optimally designed irrigation systems and the adoption of new technology to mitigate the substantial increase in electricity costs that puts the profitability of irrigation farming under severe pressure.

Marinda Avenant and her team in the Centre for Environmental Management (CEM), has been involved in the biomonitoring of the Free State rivers, including the Caledon, Modder Riet and part of the Orange River, since 1999. Researchers from the CEM regularly measures the present state of the water quality, algae, riparian vegetation, macro-invertebrates and fish communities in these rivers in order to detect degradation in ecosystem integrity (health).

The CEM has recently completed a project where an interactive vulnerability map and screening-level monitoring protocol for assessing the potential environmental impact of unconventional gas mining by means of hydraulic fracturing was developed. These tools will aid decision making at national level by providing information on the environment’s vulnerability to unconventional gas mining.

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