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Discussion > Sao Paulo drought. Climate change?

I have been finding out a bit more - mostly from my good lady wife, but also from the major newspaper, Folha de São Paulo. The situation is now quite desperate, with reservoir levels down to less than 5% of capacity, and some of the higher areas of the city being almost entirely without water due to lower pressures.
The lack of water infrastructure in the city has been well known for many years. This includes frequent flooding when there is heavy rainfall due to an excess of concrete and inadequate drainage systems. There is also an additional problem of water management. One of the two reservoirs is also an hydro-electric scheme. Down river there are also many hydro schemes, including the 14GW Itaipu dam on the Paraguay border. Given that rainfall is seasonal - winters being drier than summers - there is a potential conflict between power generation and conserving water in case of prolonged drought.
The substance behind the suggestion that the drought is caused by deforestation and climate change is the more interesting story. This I hope to post upon in the next day or two.

Oct 27, 2014 at 12:19 AM | Unregistered CommenterKevin Marshall

4mm of rain was recorded on Sunday
The big rains have been put back, but 26mm is forecast for Saturday 1st Nov

Oct 27, 2014 at 9:22 AM | Registered Commenterstewgreen

Kevin Marshall
I'm sure land usage change in itself can cause problems even without natural changes in climate. I am a believer in things being cyclical, life is like being on a cartwheel in a farmyard sometimes you're in the sunshine and someones you're in the sh*t. Deforestation, as I understand it, leads to quicker run-off of rain meaning more floods during rainy times and more severe droughts in dry times.

I'll be interested in the updates.

Oct 27, 2014 at 10:31 AM | Unregistered CommenterSandyS

The election is over . Dilma Rousseff won again.

Now we might get unspun government information on Sao Paulo's water situation.

The Brazilian Grand Prix is in Sao Paulo on 9th November. This will focus international interest on the city.

Oct 27, 2014 at 11:11 AM | Unregistered CommenterEntropic man

Entropic man
Let's hope for a repeat of last years

and 2012

2010 qualifying was on a drying track, so recent history suggests it might be damp or wet.

Oct 27, 2014 at 7:45 PM | Unregistered CommenterSandyS


I hope so. They are going to need it.

I was looking at the sabesp water company website and this month's rainfall has been about 50% below the historical average. (Apologies. For some reason I can't install the link)

Oct 27, 2014 at 11:48 PM | Unregistered CommenterEntropic man

SandyS, I think it's generally accepted (a consensus?) that Lewis Hamilton can probably out-drive anyone in the wet.

So no chance of an El Nino saving Rosberg.

Oct 28, 2014 at 12:32 AM | Unregistered Commentermichael hart

I have traced the source of Entropic Man's reference to the São Paulo drought being due to deforestation and climate change. The theory is that there are "flying rivers" of water vapour. These originate in the Atlantic, and cross onto land at the Amazon Delta. They then continue ESE to the Andes, depositing and picking up water vapour. At the Andes, the air stream heads south and then South West, shedding water vapour as rainfall from São Paulo to Northern Argentina.
There are three problems with this explanation of the drought.
First is that São Paulo rainfall may consist of 50% or more of non-Amazon evaporation, whilst the Amazon has declined by 22%. It does not explain why this is the worst drought in 84 years.
Second, the proponents of the "flying rivers" have not made falsifiable empirical tests of their hypothesis.
Third, there is evidence in 2014 that the easterly winds flowing onshore have temporarily shifted south from the moist Amazon Delta to the much drier state of Bahia. There is a potential and verifiable natural explanation that is far more plausible to the human-caused one.
I have documented the details at "São Paulo Drought – Climate Change is NOT the cause" with references that others can verify for themselves. There appears to be an interesting back story that I touch upon. There is a "flying rivers" project in Brazil funded for at least five years by State-owned oil company Petrobras (they usually sponsor the Brazilian Grand Prix). The project leader is a pilot, engineer and firm believer in stopping further degradation of the rain forest. A major part of the project is to finance a seaplane and light aircraft. None of the other project employees (about 10) are listed as pilots. Most of the current work is spreading the message to schools, with scientific work largely stopped in mid-2012.
There is still the issue of the real causes of the near-exhaustion of the water supply to the largest city in the southern hemisphere to explore.

Oct 28, 2014 at 1:46 AM | Unregistered CommenterKevin Marshall

Kevin Marshall
Interesting links in your posting

Oct 28, 2014 at 7:34 AM | Unregistered CommenterSandyS

I posted this on Kevin's website.

"Kevin Marshall

A little more about the "flying river concept.

In the first half of daylight rainforest trees take up water from the soil and evaporate it from their leaves, evapoteanspiration. This is driven by absorbed light warming the leaves.
In the afternoon thewarm air carrying all this water vapour cools and it falls as rain. This soaks into the soil and is evapotranspired the following day.

The result is that water travels downwind across the rainforest in jumps of 100-200 kilometres per day. If you remove a large area of rainforest this transport chain is broken. Without the trees there is much less evaporation and the water flows into rivers instead.

Rainforest downwind no longer receives rainwater and goes into decline too.

At the end of the chain are East coast cities such asSao Paulo whose watersheds are receiving much less water. Instead of being transported there by the evapotranspiration chain it has gone down the Amazon river instead."

Oct 28, 2014 at 7:02 PM | Unregistered CommenterEntropic man

Kevin Marshall

Is this paper the type of study you had in mind?

There is also a lay description of the paper here .

Oct 28, 2014 at 7:23 PM | Unregistered CommenterEntropic man

Forecast for the next fortnight. Looks like the onset of the wet season at the end of the month.

Hope it will be enough. The water riots have started in Itu

Oct 28, 2014 at 10:49 PM | Unregistered CommenterEntropic man

Looks like this weekend's Brazil GP will have rain for the practice sessions at least

Nov 5, 2014 at 10:16 PM | Unregistered CommenterSandyS

118mm was recorded on Nov 1st
Seems it's raining almost every day since .. forecast to continue into 2015 .
- seems that newspapers were running scare stories right until the last minute before the rain ..don't they check the dam forecats ? eg : "The source of water collapse of São Paulo, dam turns to dust" etc. (sometimes in the photos I see green vegetation on top of the hills above the dams)
Only to run a few days later : Rain raises the levels of the reservoirs in Sorocaba

Nov 6, 2014 at 1:12 PM | Registered Commenterstewgreen


Good, the wet season is finally under way. Hope you long term forecast is correct.

Nov 6, 2014 at 6:35 PM | Unregistered CommenterEntropic man

Natural variation strikes the unwary again.

Nov 6, 2014 at 10:00 PM | Unregistered CommentersandyS

Cantareira hit 10% capacity today , down from 11.7% on November 3rd. The rains don't seem to be helping.

10% is the point at which the level drops below the outflow and they start pumping sediment ponds.

Nov 19, 2014 at 11:56 PM | Unregistered CommenterEntropic man

The figures for the reservoirs are susceptible to big swings.
Compare the 3.0% on the 23rd October to the 13.6% a day later.
A few days without rain does not mean the resumption of the drought, but it can mean the levels falling quite quickly. There is a reason for this. The two principle reservoirs have been in place since the 1930s. Since that time the population has increased from one million to eighteen million.
The BBC is currently forecasting for Sao Paulo light showers for tomorrow (Fri 21st) then rain on every day through to the 29th.
Let us hope that the rainfall is steady but not too heavy. Another feature of Sao Paulo is frequent flooding due to too much concrete and inadequate drainage.

Nov 20, 2014 at 8:32 AM | Unregistered CommenterKevin Marshall

The rains don't seem to be helping.

Let me see, what does this tell us, maybe they are using too much water or someone forgot to build extra dams for all those extra people.

EM Drama queening again.

Nov 20, 2014 at 9:18 AM | Registered CommenterBreath of Fresh Air

Kevin Marshall

I think the jump from 3.6% to 13.6% on the 23rd October was due to a change in accounting.

Previously they set their zero capacity point at the level of their outlet pipes. They then installed extra pipelines and pumps to extract water from the sediment ponds below the normal minimum level. This gave them an extra 10% capacity from the same reservoir.

This is why I thought it worth mentioning. They are now pumping water from the sediment ponds of Cantareira, their emergency reserve.

Nov 20, 2014 at 11:50 AM | Unregistered CommenterEntropic man

@EM it hovered around 3-6% last month

you can play with the dates on the page he links to
but better go the page which shows other Sao Paulo reservoir systems (upto 65% full now)
but Cantareira is particularly low (weekly rates)
2/10 6.6 %
9/10 5.3 %
16/10 4.1 %
23/10 3.0 %
(The next day as @Kevin Marshall says it lept to 13.6% as if the levels are being controlled by sluice gates, not just rain & demand, or the figures are being manipulated)
30/10 12.6 %
6/11 11.7 %
13/11 10.8 %
20/11 9.9 %

Where did EM get his Drama queening ideas from ?
"So even the rain that falls isn't actually going to fill our dams and our river systems, and that's a real worry for the people in the bush." who said that ? (ABC website 11/02/2007)

Nov 20, 2014 at 12:37 PM | Registered Commenterstewgreen

There has been discussion, in this thread, of building desalination plants.

I have come across some R&D that focuses on graphene oxide framework (GOF) membranes for water desalination. The blurb said that, because it uses a hundredth of the energy of conventional desalination, it could become mainstream ( :) ).

My points are that reducing pollution is good (already said), larger reservoirs are a long term investment (already implied) and these two conventional policies could postpone the need for desalination, if it was needed at all. It would allow this new technology to advance and, heaven forbid, become cheaper!

As the city is at an elevation of 760 m (2,493.4 ft), I would have thought that reservoirs around city at this elevation would save pumping sea water up the hill, though using windmills would be a good method as intermittent wind would not be a big problem, if there was some some wind! I believe the Dutch used to do it.

Part of the problem with windmills is that, with the near limitless subsidies they have received, so many of the same have been built, with little time to assess what has passed.

Nov 20, 2014 at 3:58 PM | Registered CommenterRobert Christopher

Floods on Wednesday in Sao Paulo . The weather gods have a keen sense of irony.

It has not done much to help the drought. Cantareira is at 8.9%, down 0.7% for the week.

Nov 29, 2014 at 7:23 PM | Unregistered CommenterEntropic man

Entropic man
Did they appoint a Minister for Drought? I have nothing but a gut feeling after a lifetime watching headlines but don't droughts more often than not end in heavy rain and floods?

Nov 29, 2014 at 10:44 PM | Unregistered CommenterSandyS

'Floods', 'drought' ... Nature don't give a damn man.

Nov 30, 2014 at 2:04 AM | Registered Commentershub