Lot of flow in rivers is from the city's sanitation system.
In the dry season in Johannesburg, there is more leaked water running in the Jukskei River than naturally occurring river water, a study has found.
This raises troubling questions about the state of Johannesburg's water reticulation.
The river's identity crisis was revealed by hydrologist Simon Lorentz, who started analysing water samples from the Jukskei's daylight point (the point at which the water emerges above ground for the first time) in 2018.
Lorentz subjected the samples to isotope analysis, a process that investigates the ratio of oxygen and hydrogen isotopes in order to determine, among other things, where the water comes from.
Lorenz found that the "isotopic signature" of those water samples was consistent with water from Johannesburg's water pipes.
Here's the technical description in the report:
"The source of water sampled from the Jukskei main channel discharge is either a reticulated water or sewage water leak.
"Characteristic of reticulated water isotope signals, those sampled from the taps in the upper Jukskei catchment reflect an evaporated state, being positioned to the right of the local meteoric water line (LMWL Pretoria).
"This verifies the evaporation process in the supply dams and reservoirs of the reticulated water. The water sampled from the Jukskei main channel has the same evaporated signature."
Another way researchers can tell that a lot of the water flowing in the Jukskei comes from unnatural sources is to look at the amount of water entering Hartbeespoort Dam downstream. Water management specialist Stuart Dunsmore, who has been working on a catchment management plan for the Upper Jukskei, has done just this.
According to Dunsmore, the Jukskei covers 19% of the Hartbeespoort Dam's supply catchment, yet it contributes almost 40% of its annual inflow.
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the {{IssueName}} edition of {{MagazineName}}.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 9,000+ magazines and newspapers.
Already a subscriber? Sign In
Djokovic unclear on Murray's job
Novak Djokovic would not commit to working with Andy Murray again as his coach after the Serb retired from the Australian Open semifinals yesterday with injury.
Blitzboks off to flying start
The Blitzboks qualified for the knockout round of the Perth Sevens with a game to spare after they picked up two wins on yesterday's opening day of the tournament.
Weekend focus shifts to the battle for survival
It's a big weekend for all six teams in this year's Betway SA20, with the two bottom-placed teams, the Pretoria Capitals and Durban's Super Giants, in must-win matches today if they're to stand any chance of making it into the play-offs.
To save or to invest...
DIFFERENCE: SO MANY BENEFITS FROM INVESTING THAN SIMPLY SAVING
Continental club form very pleasing
I don't know about you but I'm still buzzing over the fact that South African teams are doing well in the Caf inter-club competitions.
Barca have to halt the slide
Barcelona must harness the euphoria of their thrilling Champions League victory at Benfica to halt a miserable run of La Liga form against an improving Valencia side tomorrow.
Rivals look for grunt
DERBY: LIONS & BULLS BOTH ANTICIPATING A MASSIVE PHYSICAL BATTLE
Sinner sets up a classic Zverev decider
Defending champion Jannik Sinner (right) blew past Ben Shelton 7-6 (7/2), 6-2, 6-2 in the Australian Open semifinals yesterday to set up a showdown with Alexander Zverev for the title.
Free Agents dreaming big
Free Agents FC coach Olaitan Oladeru says he still wakes up in the middle of the night and wonders if his ABC Motsepe League side are really playing Kaizer Chiefs in the Nedbank Cup last-32.
Questioning climate change is reasonable
Just as one can talk of an oil lobby, one can also talk of a climate change lobby.