South Africa’s Land is Rising: Study Links Uplift to Drought Conditions
A recent study reveals that South Africa’s land is rising due to drought. Between 2012 and 2020, the region rose an average of 6 millimeters, according to GPS measurements. This uplift is correlated with drought patterns and water loss. Researchers from the University of Bonn are linking these physical changes to climatic conditions, indicating a need for further study and improved drought monitoring strategies.
Recent research has revealed a surprising phenomenon: the land beneath South Africa is rising annually. Between 2012 and 2020, the country experienced an average uplift of about 6 millimeters (0.2 inches), a new GPS-based study suggests, largely driven by drought and the resultant water loss. This rise isn’t just a random occurrence; scientists believe it is closely linked to shifts in seasonal wet and dry periods and corresponding drought cycles.
For over a decade, it’s been known that South Africa is rising. Initially, many experts theorized that a geothermal process known as a mantle plume was responsible. This happens when superheated material from deep within the Earth pushes against the crust, causing the land above it to elevate. However, a new angle is emerging. Makan Karegar, a geodesist from the University of Bonn in Germany, found that the timing of uplift events often coincided with drought periods. Specifically, he and his team noted significant uplift correlating with the extreme “Day Zero” drought that affected Cape Town from 2015 to 2018, when the city faced the possibility of shutting down its municipal water supply altogether.
“We started to think there should be a link between this pattern and water loss,” Karegar mentioned. To dig deeper into the causes, the research team gathered GPS data from permanent monitoring stations that are strategically placed throughout South Africa. These stations allow for precise measurements of height changes over time—accurate to mere millimeters. The study, released on April 9 in the Journal of Geophysical Research: Solid Earth, not only detailed these uplift patterns but also connected them to alterations in water storage throughout the country.
The researchers explained the uplift phenomenon using an analogy with memory foam: as water vanished from reservoirs and soil, the land would elevate as the weight was lifted. Notably, while there were some regional and seasonal discrepancies, the overall uplift averaged 6 mm during the study period. Some regions, particularly near depleted reservoirs, rose as much as 0.4 inches (10 mm) due to water loss.
“The biggest surprise for us was that we saw an uplift over most parts of South Africa,” remarked Christian Mielke, another coauthor of the study. “We were expecting that this would probably just affect regions close to cities where reservoirs are concentrated.” The team was able to authenticate their findings by comparing land height variations with existing water storage models rooted in satellite data and weather specifics. Their conclusions showed a healthy agreement between the two, signaling that the main impetus behind the uplift is indeed water loss, despite any influence from the underlying mantle.
This means the uplift might not be a long-term change. If precipitation returns and reservoirs refill, the land may gradually sink back. Determining the pace at which this could occur remains uncertain. Bill Hammond, a geodesist from the University of Nevada Reno, commented on the challenge of accurately interpreting data over a relatively short 30-year GPS measurement period, especially when much of this time has involved drought conditions.
In the immediate future, researchers are optimistic that their GPS measurements could assist in monitoring drought conditions, a tactic that’s becoming increasingly important. Makan Karegar highlighted that while many GPS stations in South Africa are quite distanced from one another, denser networks elsewhere globally could be instrumental in effective water management—further indicating the versatility of GPS data in environmental science.
Freelance science journalist Skyler Ware reports on topics from chemistry to Earth science. She has experience with various science publications and holds a Ph.D. in chemistry from Caltech, showcasing her expertise in the field.
The findings emphasize a significant connection between drought and land uplift in South Africa, leading researchers to rethink previous theories about geological forces. The study leveraged GPS technology to link water loss with land changes, opening new avenues for drought monitoring. While the uplift may not be permanent, it highlights the impact of climate patterns on the landscape, warranting further investigation. Importantly, there’s a potential for GPS to play a critical role in managing water resources in the face of climate change.
Original Source: www.livescience.com
