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Cape Town's groundwater plan targets 'impossible'

mercurial

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Jun 12, 2007
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37,653
#1
Cape Town – Key partners in the extraction of groundwater to augment the City of Cape Town's water supply believe that the city's current 100 million litres per day target is impossible.

Speaking as an audience member at a Muizenberg Festival gathering on Tuesday, Umvoto earth sciences consultancy director John Holmes explained that the total yield from groundwater extraction remains largely unknown.

Umvoto is one of the city's main partners to develop the Table Mountain Group Aquifer and Cape Flats Aquifer for groundwater extraction.

"Theoretically, it's possible to extract 100 million litres per day from that aquifer. Is that going to happen by December this year? Absolutely not," Holmes said.

"If you are thinking about the target for the whole programme, including desalination, [it] is 500 million litres a day. Essentially, we are saying [with the targets] we are going to replace the water supply of the city in six months - it is just not possible."

Holmes, an engineer, echoed the statements of his colleague, hydrologist Chris Hartnady, who said water extraction from the Table Mountain Group Aquifer is a long-term project.

Hartnady was invited to address the intimate gathering in the African Institute for Mathematical Sciences (AIMS) centre in Muizenberg under the theme of discussing Cape Town's water future.

He joined Piotr Wolski from the Climate System Analysis Group (CSAG), Jasper Slingsby from the South African Environmental Observation Network (SAEON); Kevin Winter from the environmental and geographical science (EGS) department at the University of Cape Town (UCT) and Tom Sanya from UCT's built environment department.

'We've delayed for too long'

During his presentation, Hartnady said their current expectation is to extract up to 10 million cubic meters per annum from the Table Mountain Group Aquifer, roughly 27 million litres per day.

"But implementing that in a short space of time is not going to be easy. We are not committing to any definite figures by any definite dates," he said.

"We've delayed for too long. We had five years more or less of kicking our heels and that's been [a] very frustrating experience."

Meanwhile, climatologist and hydrologist Wolski explained that South Africa's brightest weather forecasters and climate scientists forecasted in April that Cape Town would have a wetter-than-average winter.

"What happened in April this year we had a meeting of all the climate forecasting gurus in South Africa… And we couldn't agree, with all the models at hand and all the simulations, we couldn't agree [on] how will the winter develop," he said.

"And the only sort of faint agreement is that winter was going to be wetter than average. What happened is totally opposite."

'Isn't going to be enough'

Wolski said the meeting, the Winter Rainfall Outlook Forum, was attended by roughly 60 forecasters and climate scientists across South Africa.

At his turn, Slingsby, a trained ecologist, explained that up to three months of the city's water needs is lost through invasive species.

"At the moment, the existing invasive species in our primary catchments in Cape Town are using as much water as the entire Wemmershoek Dam," he said.

"So that's enough water for the city [for] roughly two to three months."

Slingsby said predictions indicate that in the next 30 years, invasive species will consume as much as the Berg River Dam, which is seven to nine months of the city's water needs.

"All the hope is on until next winter, in the hopes that it rains, but unfortunately raining next winter isn't going to be enough."

Slingsby said that research has proved that pine forestry, which is an invasive species, has only ever been an expense to the South African economy.

The costs to South Africa in terms of water is much worse, he said.

"In terms of clearing, I think it would be a hell of a lot cheaper than desalination or any of the alternatives the city is thinking of," Slingsby said.
Source
 

supersunbird

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#2
Slingsby said that research has proved that pine forestry, which is an invasive species, has only ever been an expense to the South African economy.
Is pine forestry really a thing the WC?
 

greg_SA

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May 24, 2005
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#4
Is pine forestry really a thing the WC?
Some more info...

Western Cape area is 13 000 000 hectares
Total Forestry is 60 000 hectares.
So 0.4% of area. Doesn't seem major, but maybe it is most dense in the catchment areas?

Of that 59 000 hectares is pine. So pine is definitely the main type of forestry in WC.

Other provinces have MUCH bigger forestry industries.
 

LazyLion

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Joined
Mar 17, 2005
Messages
99,889
#6
Let them drink seawater...

No but seriously, partially filtered sea water can be used for toilet flushing and showering and dish washing, etc.
It doesn't have to be 100% pure.

Keep the pure water for drinking purposes alone.
 

supersunbird

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43,565
#7
Let them drink seawater...

No but seriously, partially filtered sea water can be used for toilet flushing and showering and dish washing, etc.
It doesn't have to be 100% pure.

Keep the pure water for drinking purposes alone.
Sounds like a plan, but then I guess they will have log build a whole new secondary piping system...
 

Geoff.D

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7,262
#10
Let them drink seawater...

No but seriously, partially filtered sea water can be used for toilet flushing and showering and dish washing, etc.
It doesn't have to be 100% pure.

Keep the pure water for drinking purposes alone.
Not without straining the existing water purification plants as a result of the added salt load surely?

Of course in areas where the sewerage basically ends up in the sea anyway, it makes no difference.

Know of some on the West Coast that are already doing that.
 

Geoff.D

Executive Member
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7,262
#11
This quote is what I find interesting. It shows just how difficult it is to understand nature and the forces that drive the weather. It explains why we should not be over critical about those that try to forecast the weather and take what they offer as a genuine attempt at trying provide us with an interpretation of what is measured.

It is a lesson in humility if you try this for yourself.

Meanwhile, climatologist and hydrologist Wolski explained that South Africa's brightest weather forecasters and climate scientists forecasted in April that Cape Town would have a wetter-than-average winter.

"What happened in April this year we had a meeting of all the climate forecasting gurus in South Africa… And we couldn't agree, with all the models at hand and all the simulations, we couldn't agree [on] how will the winter develop," he said.

"And the only sort of faint agreement is that winter was going to be wetter than average. What happened is totally opposite."
 

LazyLion

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Mar 17, 2005
Messages
99,889
#12
Wouldn't it just corrode everything?
Not without straining the existing water purification plants as a result of the added salt load surely?
Of course in areas where the sewerage basically ends up in the sea anyway, it makes no difference.
Know of some on the West Coast that are already doing that.
The problem with existing Sea Water Distillation is the huge amount of energy required to completely remove ALL of the salt content.
But it is fairly easy to remove MOST of the salt with just normal filtering - it's just not fit for human consumption because of the briny taste.
There will be some corrosion long term, but not nearly as bad as with normal sea water.
It's one of those things of diminishing returns, it takes 80% of the power to remove the last 10% of salt.
But it is possible to remove 90% of the sea water with just 10% power (normal filtering).
 

Geoff.D

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7,262
#14
The problem with existing Sea Water Distillation is the huge amount of energy required to completely remove ALL of the salt content.
But it is fairly easy to remove MOST of the salt with just normal filtering - it's just not fit for human consumption because of the briny taste.
There will be some corrosion long term, but not nearly as bad as with normal sea water.
It's one of those things of diminishing returns, it takes 80% of the power to remove the last 10% of salt.
But it is possible to remove 90% of the sea water with just 10% power (normal filtering).
Ja know what filtered sea water tastes like after a trip to Tristan da Cunha on their supply ship. If you did not have drining water with you, you were in serious trouble.

So a possible alternative would be to filter sea water for householders to use for washing and flushing toilets, which could be collected at central points. Would only really work in close to the shore though.
 

konfab

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Jun 23, 2008
Messages
16,567
#15
Meanwhile, climatologist and hydrologist Wolski explained that South Africa's brightest weather forecasters and climate scientists forecasted in April that Cape Town would have a wetter-than-average winter.

"What happened in April this year we had a meeting of all the climate forecasting gurus in South Africa… And we couldn't agree, with all the models at hand and all the simulations, we couldn't agree [on] how will the winter develop," he said.

"And the only sort of faint agreement is that winter was going to be wetter than average. What happened is totally opposite."
:crylaugh: :crylaugh: :crylaugh: :crylaugh:

Did 98% of them agree on AGW as well?
 

Gaz{M}

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#16
The problem with existing Sea Water Distillation is the huge amount of energy required to completely remove ALL of the salt content.
This is an often repeated myth. Desalination uses roughly 4kWh of electricity per thousand litres of clean drinking water (and can be even more efficient than this). That's only R8 bucks worth at retail residential tariffs. Eskom is desperate to sell some of their 4000MW of excess power. A desal plant would only use around 40MW. There is plenty of electricity available and the water produced would be affordable, if only a bit more expensive than dam water.

There would be little benefit to building a salt water cleansing plant and millions of new pipelines. It is cheapest to just build a proper potable water desal plant, long term.
 

BTTB

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7,625
#17
We've delayed for too long'

During his presentation, Hartnady said their current expectation is to extract up to 10 million cubic meters per annum from the Table Mountain Group Aquifer, roughly 27 million litres per day.

"But implementing that in a short space of time is not going to be easy. We are not committing to any definite figures by any definite dates," he said.

"We've delayed for too long. We had five years more or less of kicking our heels and that's been [a] very frustrating experience."
Prof Hartnady was on Carte Blanche early this year with a report entitled Cape-Water-Crisis but I cannot seem to find the link again?
Here is an article from around the same period. Cape Town’s untapped water source explored
Look at the dates. The City muddled since 2011 when Overstrand Municipality installed their ground spike and just 120km from Cape Town there are no water restrictions there.
While tapping into the Table Mountain Aquifer will help us eventually, had the City not shelved it, it could have averted the potable water crises as it stands now.

My wife and I have removed ourselves from all Social Media platforms in regards to the potable water story, cannot stand this blow by blow account of maybe it will or wont rain and finger pointing, making a living is tough enough not to mention being drawn into the bureaucratic balls up of a Municipality and their shortcomings.
I think the post 2008 Electricity bombshell/bolt balls up was enough in one lifetime. What is the ongoing cost to our economy with that story, now its water, what’s next.

Each and every step of the way we have to continue to monitor our own Government, who have our money, make all the laws to restrict us, yet when they fail to perform are almost immune to litigation or any form of recourse or apology.

Its like 1998 when all the experts told Eskom, by 2008 we will run out of capacity.
Now we have experts like Hartnady who several years ago alerted the bureaucrats to the looming capacity problem with water, but once again they chose to ignore and shelve.

So after my little rant, let me make a prediction based on our recent past:
Electricity: 1998 to 2008 Eskom was warned, 2008 it broke. 2008 to 2017 prices hiked.
2017 we have too much capacity, price still too expensive, consumers cutting back and/or using alternatives.
Water: 2001 to 2016 Water Department/City of Cape Town warned of impending capacity problem and potential drought. 2004 to 2017 Prices increased with level 2/3 penalties. 2016, water system running dry, crisis looming, two dryer winters in a row. 2017, plans about plans about to be implemented. 2017 prices hiked through the roof.
Prediction 2019 to 2021-Cape of Storms, dams full to capacity, water crisis on hold, restrictions relaxed. High % of consumers have now switched over to alternative water sources, but using less potable water meaning less revenue for the City. City cant sell its full dams and now extended capacity through desalination and ground spikes at considerable expenditure. Cape returns to its former greener self, City of Cape Town encouraging people to use their water with the usual media spin of saving etc. All the time the non-paying consumers continue on as per normal.
 

Zoomzoom

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#18
Prof Hartnady was on Carte Blanche early this year with a report entitled Cape-Water-Crisis but I cannot seem to find the link again?
Here is an article from around the same period. Cape Town’s untapped water source explored
Look at the dates. The City muddled since 2011 when Overstrand Municipality installed their ground spike and just 120km from Cape Town there are no water restrictions there.
While tapping into the Table Mountain Aquifer will help us eventually, had the City not shelved it, it could have averted the potable water crises as it stands now.

My wife and I have removed ourselves from all Social Media platforms in regards to the potable water story, cannot stand this blow by blow account of maybe it will or wont rain and finger pointing, making a living is tough enough not to mention being drawn into the bureaucratic balls up of a Municipality and their shortcomings.
I think the post 2008 Electricity bombshell/bolt balls up was enough in one lifetime. What is the ongoing cost to our economy with that story, now its water, what’s next.

Each and every step of the way we have to continue to monitor our own Government, who have our money, make all the laws to restrict us, yet when they fail to perform are almost immune to litigation or any form of recourse or apology.

Its like 1998 when all the experts told Eskom, by 2008 we will run out of capacity.
Now we have experts like Hartnady who several years ago alerted the bureaucrats to the looming capacity problem with water, but once again they chose to ignore and shelve.

So after my little rant, let me make a prediction based on our recent past:
Electricity: 1998 to 2008 Eskom was warned, 2008 it broke. 2008 to 2017 prices hiked.
2017 we have too much capacity, price still too expensive, consumers cutting back and/or using alternatives.
Water: 2001 to 2016 Water Department/City of Cape Town warned of impending capacity problem and potential drought. 2004 to 2017 Prices increased with level 2/3 penalties. 2016, water system running dry, crisis looming, two dryer winters in a row. 2017, plans about plans about to be implemented. 2017 prices hiked through the roof.
Prediction 2019 to 2021-Cape of Storms, dams full to capacity, water crisis on hold, restrictions relaxed. High % of consumers have now switched over to alternative water sources, but using less potable water meaning less revenue for the City. City cant sell its full dams and now extended capacity through desalination and ground spikes at considerable expenditure. Cape returns to its former greener self, City of Cape Town encouraging people to use their water with the usual media spin of saving etc. All the time the non-paying consumers continue on as per normal.
There are several important things you are leaving out of those scenarios.

1. The energy 'crisis' was made up, the water crisis is not.

2. The DA, like Eskom WILL make sure the consumer pays through their nose for the shortages.

3. When all the consumers have adjusted to lower consumption, switched to whatever alternatives they can afford to install there WILL be some made up fake tariffs to make up for the loss of income because god forbid that anyone lose out financially because the bloody consumers actually LISTENED when they were told to use less.

Net result - there will be insane profits pocketed by someone, the consumer will suffer financially irrespective of how much they save, use less, switch to alternatives. There will never be a price decrease when there is plenty, in fact plenty, will some how mean even more price increases such as Eskom's 19% for next year for god knows what.
 

nightjar

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Aug 2, 2008
Messages
3,959
#19
There are several important things you are leaving out of those scenarios.

1. The energy 'crisis' was made up, the water crisis is not.

2. The DA, like Eskom WILL make sure the consumer pays through their nose for the shortages.

3. When all the consumers have adjusted to lower consumption, switched to whatever alternatives they can afford to install there WILL be some made up fake tariffs to make up for the loss of income because god forbid that anyone lose out financially because the bloody consumers actually LISTENED when they were told to use less.

Net result - there will be insane profits pocketed by someone, the consumer will suffer financially irrespective of how much they save, use less, switch to alternatives. There will never be a price decrease when there is plenty, in fact plenty, will some how mean even more price increases such as Eskom's 19% for next year for god knows what.

Summed up pretty well except that the water crisis is purely due to the inactivity of the DA Council which did fokal during the years that it was brewing.

All that is left now is for the Council to call in a witchdoctor to drum up some rain.
 
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