South Africa’s landmass is slowly rising, and new research suggests the surprising cause may not be deep within the Earth but rather due to repeated droughts and water loss.
A study from the University of Bonn, Germany, analysing over two decades of satellite data has found that the country experienced a vertical uplift of around 6 millimetres between 2012 and 2020.
Scientists say this change is linked to the loss of surface water, with the land rising in response to the weight being lifted.
The study used data from the Global Navigation Satellite System (GNSS) base stations across the country to track vertical land movement. Researchers originally considered that this might be due to geological forces such as mantle flow and dynamic topography, the slow, deep movements in the Earth’s crust and mantle. However, they now say the evidence points to a different explanation.
“Our evidence suggests that land water loss from multiple droughts is a major driver of the observed uplift,” the researchers wrote.
To reach this conclusion, the team analysed daily height records from Global Positioning System (GPS) stations between 2000 and 2021. They applied a method known as Singular Spectral Analysis (SSA) to separate long-term trends and seasonal variations from random noise in the data.
The results showed a strong connection between the vertical land movement and changes in total water storage, as confirmed by comparisons with satellite gravity data from the GRACE mission and a leading hydrological model.
In some provinces, the GPS-based data correlated as much as 94% with these models on a monthly scale.
Even when looking at long-term national trends, the correlation remained significant at 46% and 53% respectively reinforcing the link between water loss and ground uplift.
“These long-term total water storage trends provide strong evidence that the observed land uplift in South Africa is primarily of hydrological origin.”
This discovery adds to growing evidence that climate-related changes, including more frequent droughts, are reshaping not just ecosystems and water supplies, but the very surface of the Earth itself.
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