Cape Town 90 days away from running out of water

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Cape Town 90 days away from running out of water

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Re: Cape Town 90 days away from running out of water

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Be a worry for those who live there. When's there wet season? :-k
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Re: Cape Town 90 days away from running out of water

Unread post by Simon Culling »

I have appended the Wikipedia climate table for Cape Town and it shows an annual rainfall of around 500mm, but most of this falls between April and September, so they will need an early start to the 'wet' season to stock up the reservoirs. I was surprised to see (in the Wikipedia article on the city) that the metro area population was 3.7 million people, although I would guess that not all of those would have mains water to their houses in the way we are used to. The BBC article mentions some quite stringent restrictions that are about to be introduced that I am not sure we would be too pleased about if it happened in the UK or NZ.

http://www.bbc.co.uk/news/world-africa-42731084
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Re: Cape Town 90 days away from running out of water

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Bob Henson has written a good piece on this subject on his W'Underground blog:

https://www.wunderground.com/cat6/its-t ... y-shutdown
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Re: Cape Town 90 days away from running out of water

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This tweet from the NASA gives a graphic picture of how low the rainfall has been in recent years in the far SW of Africa as well as the rapid increase in demand for water due to urbanisation and possibly miss-management of this resource. It charts the level of water in the Theewaterskloof reservoir, which is a little way to the east of Cape Town and is an important source of fresh water for the city. It is now at about 13% of capacity with a couple of months to go before the rains arrive.

https://twitter.com/NASAEarth/status/958201201350402049

There is a long trail of comments below the WMO bit.
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Re: Cape Town 90 days away from running out of water

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The bulk of Cape Town's annual rainfall occurs in the 6 months of April to September when just over 400m of the annual total of 515mm falls, i,e, 80%. They will need an above average winter season to give them any chance of avoiding a worse water scenario next year. They have made a big effort to reduce consumption, but these measures cannot be expected to persist for ever and the reduction in water usage has, and will continue to have, a significant impact on important revenue earners such as agriculture and tourism. Let's hope that the rains deliver this year, but if not, they are quite welcome to the rain we are enjoying here in the UK at the moment!

A few showers and thunderstorms in the last few days have delivered 6mm at the main airport (listed as DF Malan Airport on the SYNOPS, but now known as Cape Town International), but the current forecast is dry until next weekend - 7/8th April. The METAR code for this airport is FACT and the synop number 68816.
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Re: Cape Town 90 days away from running out of water

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You can follow the rainfall data for Cape Town on this excellent link. It gives the cumulative totals back to 1977 and you can superimpose any years you like:

http://www.csag.uct.ac.za/current-seaso ... cape-town/
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Re: Cape Town 90 days away from running out of water

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Re: Cape Town 90 days away from running out of water

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Rainfall in April has been small so far, but showery rain is expected tomorrow and next Monday. Totals up to the 16th were 6mm at Paarl, 5mm at Molteno Reservoir, 4mm at the main (DF Malan) Airport and just 1mm at Robertson.

The article below is a very good summary of the why's and what's of this situation:

https://thebulletin.org/what-cape-town- ... ought11698

The irony is that the City of Cape Town authority is proposing a 27% increase in water and sanitation tariff's.
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Re: Cape Town 90 days away from running out of water

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Heavy rain + thunderstorms affected the western Cape last night, although there was more rain in coastal areas rather than inland where the reservoirs are located. Indeed, flooding was reported in Cape Town. Rainfall totals for the 24 hours to 06:00GMT today (Thurs 26th April) were:

40mm at Robben Island
34mm at Cape Town International Airport
17mm at Molteno Reservoir + Table Bay
15mm at Paarl
11mm at Geelbek + Langebaan
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Re: Cape Town 90 days away from running out of water

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A plan to drag icebergs from the Antarctic has not been dismissed out of hand. I am not quite sure of the logistics of breaking it up when it gets to South Africa and turning it into drinking water, but what a story if they made it work!

http://uk.businessinsider.com/plan-to-s ... ica-2018-5

So far, it has been a slow start to the winter rains with showers only expected on Mon/Tues next week in the 7 day outlook.
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Re: Cape Town 90 days away from running out of water

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Capetown will get plenty of rain this winter/spring. It is similar to Perth and Auckland and gets a winter rainfall maximum from the disturbed westerlies.

I suspect the iceburg story is some journalists having a bit of fun.
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Re: Cape Town 90 days away from running out of water

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You may well be correct NZstorm!

So far this autumn/winter, the main synoptic site at Cape Town International (DF Malan) Airport has received 56mm of rain for April, but just 13.6mm for May up to the 13th. The next rain in the 7 day forecast is not until this Sunday (20th), so it will need a pick up in the rainfall to reach the monthly average of near 70mm.

For April, 60% of the total came from one thunderstorm day.
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Re: Cape Town 90 days away from running out of water

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The May monthly rainfall total for Cape Town International Airport was 67.4mm with 30mm of that falling on the last day. This is very close to the monthly average.

More heavy showers are in the forecast for Sat/Sun but it then looks dry for next week.
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Re: Cape Town 90 days away from running out of water

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Rainfall at the Cape Town Intl Airport up to the 26th of June was 80mm from the synops which is close to the monthly average. The forecast has showers on Friday and again for the first couple of days of July, so the rains are falling. A recent blog entry on W'Underground suggests that the reservoir levels are improving, but if demand increases (as it inevitably will with rain falling regularly) this issue will just resurface next year. New sources will definitely be required - start floating them icebergs into town.... :lol:

https://www.wunderground.com/cat6/Winte ... y-How-Long
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Re: Cape Town 90 days away from running out of water

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Given a developing El Nino, the spring rainfall could be good there this year. El Nino could bring the rainy westerlies a bit further north, later into spring.

The population of Capetown is 3.8 million up from 2.7 million in the year 2000. So perhaps some bad planning has contributed to their problem.
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Re: Cape Town 90 days away from running out of water

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The final rainfall total for Cape Town Intl Airport for June was 93mm from the synops. July has started very wet with 30mm at this station in the first two days. However, the current forecast indicates 7 days of sunny weather and no rain until next Tuesday, the 10th July.

The METARS for the airport show the temperature dropping to 8*C in the rain (and thunderstorms) in the early hours of Monday (2nd July) morning and the cold front responsible for the wet weather delivered some snow over the higher ground a bit further inland in the Western Cape.

https://www.iol.co.za/capetimes/news/ca ... s-15795535

This link also gives an update on the dam levels which are now increasing steadily.
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Re: Cape Town 90 days away from running out of water

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The rainfall total for July so far at Cape Town International Airport was 48.6mm (from the synops) up to the rainfall day of the 14th which is a little above the average for the month. However, the forecast for the week ahead is dry with some warm sunny days - no rain in this forecast out until at least Saturday (2st July).

Incidentally, it was a cold start to the day this morning (Sunday 15th) with an overnight low of just 1.9*C.

Below is a link to an interesting study, but it seeks to attribute cause to just one source, i.e. climate change. Whilst this is likely to be part of the reason, rapid population growth in Cape Town and a seeming lack of corresponding infrastructure spend are more likely to have as big or greater effect. Still worth a read, though.

https://www.worldweatherattribution.org ... th-africa/
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Re: Cape Town 90 days away from running out of water

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I would like to a see a comprehensive study on the jet stream pattern for South Africa and for the southern hemisphere as a whole.
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Re: Cape Town 90 days away from running out of water

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The second half of July was very dry at the Cape Town International Airport site with just 1.8mm of rain which gives a monthly total of only 50.4mm which is about 60% of the average. Let's hope the rains continue well into spring.

A counter view to just blaming climate change is made in this link - to Nature magazine. The usual imprint of government indecision rears its head:

https://www.nature.com/articles/d41586-018-05649-1
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Re: Cape Town 90 days away from running out of water

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A big boost to the August rainfall total at the main Cape Town Airport in recent days (24mm on the 26th) to give a running total of 57mm for the month of August. However, this is some way short of the average of 77mm displayed in the table at the start of this thread.

Some patchy rain or showers in the forecast for today and tomorrow, but then it is back to warmer and drier weather.

EDIT: Some places in and around the city had a bit more than the airport - 50mm+ in a few places (with hail reported), so there was a convective element.

https://twitter.com/SAWeatherServic/sta ... 3514987521
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Re: Cape Town 90 days away from running out of water

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The total rainfall (from the synops) for August for the airport site was 60.4mm which appears to be a little below average. However, September has supplied a bit more rain with a total of 32.4mm up to this morning (10th) and this is close to the monthly average. Only a few showers in the forecast this week on Weds + Fri.

The cold front that passed through the Western Cape over the weekend gave snow to the mountains and the link below gives a couple of photos of animals you would not expect to see in the snow - elephants and giraffes.

https://twitter.com/StormchaserUKEU/sta ... 6204656640

EDIT: The pictures were taken in the Asanta Sana Game Reserve which is in the Eastern Cape - approx. 400km to the east of Cape Town.
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Re: Cape Town 90 days away from running out of water

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The rainfall total for the Cape Town airport site for September was 64mm from the synops. This is roughly 50% more than the average and I am sure was warmly welcomed as we now head towards the dry season. Average rainfall for October is around 30mm.

For dams in and around the Cape Town area, the percentage levels (to full) were 74% for the week ending 24/9/2018, which compares to just 37.5% at the corresponding time in 2017. A significant improvement.

http://www.capetown.gov.za/Family%20and ... dam-levels
Last edited by Simon Culling on Wed 17/10/2018 01:01, edited 1 time in total.
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Re: Cape Town 90 days away from running out of water

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So they should get through summer if the water restrictions are maintained
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Re: Cape Town 90 days away from running out of water

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Water restrictions were eased slightly from the 1st October for Cape Town residents as the level was reduced from 6B to 5. This means that residents can now use 70L per day per person - a rise from 50L. This is not a lot of water by western standards. Water tariffs have also been reduced considerably.

https://www.news24.com/SouthAfrica/News ... 5-20180910

Some of the biggest water use reductions have been made by the agricultural sector and it remains unclear how this will affect production levels and yields over the next couple of years.

Apart from a few mm's at the beginning of the month, October looks dry until at least mid-month, and warming up. The averages for the next few months for Cape Town are roughly 30mm for October, 14mm for November and 17mm for December.
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