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South Africa is literally on the rise.
Slowly and almost sneakily, the land in some places is creeping upward by about two millimetres a year. For ages, scientists figured this was all thanks to deep, fiery drama underground – molten rock plumes pushing their way up from the mantle over thousands of kilometres. Sounds epic, right?
But turns out, it’s not magma doing the heavy lifting, it’s drought. Yep, the lack of good old H₂O.
Instead of heat surging up from the Earth’s guts, what’s really lifting the land is what’s missing above it: water. As surface and underground water disappear, the ground gets lighter. That means less weight holding it down, so it subtly rebounds, kind of like a sponge after you stop squishing it.
This unexpected twist comes courtesy of researchers at the University of Bonn, who sifted through satellite and climate data from nearly a decade and basically flipped the script. The study, now published in Journal of Geophysical Research: Solid Earth, is making waves in how scientists think about water loss in our climate-changed world, The Brighter Side reported.
TrigNet: From Boring Survey Tool to Climate Spy
South Africa’s got a pretty slick network called TrigNet—a bunch of Global Navigation Satellite System (GNSS) base stations that were originally just supposed to help surveyors measure stuff. Yawn, right? But here’s where it gets interesting: TrigNet turned out to be a goldmine for science. It’s been clocking hyper-precise land movements for over 20 years. Quietly. Like a nerd in the corner taking notes on everything.
That data shows the land’s on the move, and not sideways, but up. Between 2012 and 2020, the researchers logged an average vertical uplift of six millimetres. Dr. Makan Karegar and his crew at the University of Bonn saw a pattern emerge. The uplift wasn’t random, it lined up with the areas that were getting hammered hardest by drought.
Now, for the longest time, everyone pointed fingers at the Quathlamba hotspot. The theory went like this: hot stuff deep underground pushes the crust upward, the same way it does under volcanic zones like Germany’s Eifel fields. Totally plausible… except, it didn’t quite explain the quicker, more local shifts showing up in South Africa.
Karegar and his team had a hunch that something else, something a lot drier, was going on.
Drought, Not Deep Heat
So, how do you prove the land’s being lifted by drought and not some molten upwelling? You turn to satellites, of course.
The team mashed up GPS data with readings from NASA’s GRACE satellites. These bad boys detect tiny changes in Earth’s gravity caused by shifts in mass, like when water disappears from the ground.
And bingo. Where GRACE showed major water loss—soil moisture, surface water, groundwater—you guessed it: the GPS stations showed the biggest lifts. Not a fluke either. This same pattern showed up again and again, over multiple years, across large parts of South Africa.
Dr. Christian Mielke from the team broke it down: GRACE doesn’t give pretty pictures like weather satellites, but it does reveal sweeping water trends. “These results can be used to calculate the change in the total mass of the water storage,” Mielke said.
But wait, there’s more! The team also used snazzy hydrological models that simulate how water moves through soil, plants, and air. Plugging those into the mix confirmed the theory—this lift wasn’t geological; it was hydrological. It wasn’t magma, it was missing moisture.
The Earth Is Basically a Foam Ball
Here’s a visual for you. Picture a foam ball squashed under your palm. Keep your hand there, and it stays squished. Move your hand? It slowly springs back. That’s the land. When you remove the weight of water, boom, it rebounds.
This is more than a cool science fact. It’s a tool. By watching how the ground lifts during droughts, scientists can estimate how much water has vanished. That’s huge, especially in a place like South Africa, where a lot of the water hangs out underground in aquifers you can’t just eyeball.
“We believe that it’s also possible that a loss of groundwater and surface water is responsible for the land uplift,” Karegar said.
And the need for this kind of tech is very real. Remember the Cape Town water crisis? Between 2015 and 2019, the city was staring down “Day Zero”, the moment the taps might actually run dry. That wasn’t just a scare tactic. The reservoirs were plummeting, and the nation was sweating bullets.
Turns Out, TrigNet’s a Lot Cooler Than We Thought
So yeah, TrigNet started off as a glorified tape measure for land surveyors. But scientists quickly saw it could do way more. Early studies used it to watch the ionosphere and track water vapour. But then, bam, it became clear this thing was also a killer crustal motion detector.
And that crust? It’s not as static as we thought.
South Africa isn’t exactly a tectonic thrill ride like Japan. The country sits on the stable old Nubian plate, with very little horizontal movement. But there is vertical movement, and it’s caught geologists’ attention. While deep mantle forces might still be in play, this new research shows that drought might be the real MVP when it comes to short-term land lift.
Now, don’t get it twisted, tectonics still matters. Some areas, especially near gold mining operations or along the eastern border, have higher earthquake risk. According to seismic hazard maps by Midzi and colleagues, those regions still have to keep an eye on geological threats. But for the rest of the country? It’s the climate, not quakes, that’s moving the land.
The Cheapest Drought Detector Ever
Here’s what makes this whole thing even cooler: it’s dirt cheap. No drilling, no installing new sensors. Just rethinking how we use the GPS data we already have. Those TrigNet stations? They’re working 24/7, no coffee breaks, no salary.
And this method isn’t just for academic show-and-tell. If an area starts rising, officials could take that as an early warning sign- start rationing, roll out water restrictions, brace for impact. It’s a heads-up before the crisis hits.
Over time, scientists can bake this data into climate models to get a clearer picture of how climate change is squeezing water supplies, not just in South Africa, but around the globe.
As Mielke put it, “This data also showed that the land uplift could primarily be explained by drought and the associated loss of water mass.”
That’s a game-changer. It means the ground isn’t just sitting there quietly, it’s reacting. Rising. Responding. Almost like it’s trying to tell us something.
[Source: The Brighter Side]
