Dams – Latest levels: Winelands and Cape Town

Latest report (updated 31st July 2017) on the main dams serving

Cape Town City and nearby Boland/Overberg towns

Due to the lack of solid rains in the catchment last week, net inflows to the main dams slowed and total water stored rose by only 4.0 M.cuM (0.4% of capacity) to stand at just 27.5% of capacity. 

Last year the dams levels rose 10x faster by 40.8 M.cuM during the same week to reach 47.8% of capacity due to excellent rains over the same seven days.

Our year-on-year comparison shows that net water used in 2017 is now 81.2 M.cuM (288 minus 207.8) higher than that used in 2016, essentially because of the far higher rainfall received that recharged the dams at this time last year.

[Why since 1st November? that was when level 4 restrictions were imposed].

Current status?

There is now a total of 244 M.cuM (159 M.cuM of easily accessible) water left in the dams (last year same time this stood at 425 and 341 M.cuM respectively).

So: we have 81 M.cuM less water available to meet our needs than we had last year.

Our alarm is now ringing wildly! We are not getting nearly enough rain. Unless we receive unusually heavy rainfall in the dam catchments over August, we will end winter way below our safe target of 500 M.cuM of water stored in the dams.

How many days of water are left?

At the low winter usage rate estimated at 6.2 M.cuM per week, theoretically we now have 26 weeks supply on hand; enough to last to end-January, 2018. Will the authorities be able to restrict overall water usage to this level? Never!

Due to commencing agricultural irrigation, seasonal visitors and the naturally higher consumption and evaporation in summer  water consumption rate should soon double.

So, calculating more realistically, assuming that we will still grow the storage by another 50-60 M.cuM, we would finish September with some 300 M.cuM in storage (= nominally 215 M.cuM of accessible water). Then assuming consumption will ramp up with the summer agricultural and holiday usage similarly to 2016, the available water would be gone by end-January 2018.

At the moment, if nothing else changes and just average rainfall arrives, our estimates point to the available potable water possibly being exhausted by end-January 2018.

Obviously this cannot be allowed to happen.

The authorities would have to act vigorously.  Read here what steps we believe the authorities would then have to take to ensure our ‘survival’ through until the winter of 2018.

Spare a thought for farmers.

For many farmers, “zero water day” has already arrived. This is a very sad and testing time for them as they contemplate not having enough water to maintain their crops and financial disaster stares them in the face. What is happening to farmers is an example of what could later happen in towns and cities in the Cape. Farmers are forced to face the problem right now.

Why is that?

Most farms have a natural local water system – they are reliant on rainfall to water the plants and for run-off to recharge their dams and tanks, supplemented by boreholes tapping into underground water accumulated over previous years. All their water has to be harvested or produced and stored – there is no municipal tap that they can turn on in the kitchen. 

The effects are the same as they would be for businesses and households facing a water shortage in the city areas.

Think about it:

• Without solid rains, there is too little water available to do all the farm’s normal activities.
• Hard decisions then need to be taken now which plants to give water and which to starve on minimum maintenance levels only when they awaken in Spring.
• This in turn means that the crops will be far smaller and farm income will reduce sharply.
• Many animals will need to auctioned and slaughtered.
• There will be less work available and some staff will have to be laid off or all will have to suffer a proportional reduction in income if available work remains spread between all. Personal incomes will reduce sharply.
• In due course, hardship will expand, families will struggle, food shortages may set in.
• Unemployment will increase and petty and serious crime may escalate. Security will suffer.
• If rains fail again next year, then people will leave the land seeking water and work. Civil unrest may follow.

In a similar way, what is happening on the farms might start to happen in the towns and city: businesses may start to struggle; turnovers would fall; jobs may be lost (or shared); incomes could decline; food shortages may arise and daily life could become a struggle for all.

If you think that this is exaggerated, please don’t.

On our farm in the Klein Karoo we have had less than 70mm of rain so far this year (usually we would have had around 200mm by now), the rivers have not run for 3 years, only one out of six of the farm’s dams has water in it; only two out of six boreholes are still giving water – our remaining lifeline. So, instead of being able to farm the whole 40Ha of vines and trees we will possibly only have enough to water 6-7 Ha of plants. Revenues are likely to crash by 70%+. We have already discussed with our workers that work will have to be cut by 50%-60%, so their incomes will tumble as well.

Farm dam; now empty vs full in better times.

It is a rather desperate situation. “Zero Water Day” is already arriving for many farmers.

What ought households to be doing? 

The situation is becoming ever more stark.

1. It is increasingly likely that we will finish winter with stored water in dams way below the safe level.

2. There is no indication that authorities are taking any specific steps to credibly solve the situation but they may have no option other than to further sharply cut water consumption.

3. Therefore, the onus is now on households to take concrete steps to deal with the situation.

• make households more water-resilient (read my suggestions on how to).
• develop and practice ways to cut your household’s use of water and maximise re-use.

Time is running out. You need to start doing something now to prepare your household to deal with the water shortage challenge. No matter how small, do something to capture and store water.

What are the authorities doing now?

Some weeks ago I sent a comprehensive set of questions to the CoCT regarding various aspects of the water shortage and what steps may be being taken to deal with this.

Unfortunately, after several weeks I received back what can best be described as a series of ‘non-answers’. There was nothing new and the main point made was that the City is studying over 100 RFI submissions for additional ways to produce fresh water (read more here). Who knows where that might lead?

So here we are, perhaps only 4-6 months away from a total melt-down of the area’s fresh water supplies and the authorities – who internally may well believe that they are doing all they can – once more fail to treat us as adults and fail to honestly advise us on practical options available and steps that can and are being taken to ward off disaster.

CoCT continues to state that it is preparing an operational plan for possible “Zero water” conditions; still to be “published within a few weeks”. We will judge that when we finally see it

Level-4B water restrictions are in force (read full details of restrictions and tariffs here). Essentially this mean reduce potable water usage to below 87 litres per person per day or less.

Will the weather help?

Two relatively weak cold fronts will strike the Cape today and tomorrow. The first will strike the Cape more vigorously, while the second front has already been “knocked on its back” by the high pressure and therefore may slip by to the south without much effect.

These should bring combined rainfall of 20-30mm, also in the mountain catchments.

This NOAA/CPC chart shows the cumulative amount of rain that may be expected between 1st and 3rd of August.

This is nothing like what we need but the extra rain run-off will help to keep slowly adding to the stored water levels..

What else may we expect?

August being a traditionally high rainfall month we may safely expect more rain.

At present the forecasts predict two cold fronts:

• The first should arrive on 6th August and bring 15-25mm of rain.
• The next front should arrive on 13th August and could bring 3 days of wider 25-40mm of rain.

Other than that, occasional showers will happen at different times. No other major weather systems are predicted for the month, but that can quickly change.

Previously El Niño has been discounted from influencing matters; but perhaps the reverse might happen as the Pacific sea temperature has recently been dropping fast.

There now seems a chance that the colder La Niña may kick in as it did in 2016. If it does manifest in time then the high pressure may shift more northwards and permit the cold fronts to strike the Cape more full on, possibly bringing more rain.

So there is a possibility that, if this trend towards La Niña continues, we may yet enjoy a late unstable wet spell at the end of winter. We will track this development again next week.

Here is the latest historic rainfall chart for Cape Town Airport produced by UCT. Take a look at the chart yourself – find it here. [Thanks UCT]. What is interesting is that when you click on the line for 2016, one can see how the accumulated rainfall almost doubled during August that year. Let us hope that something similar happens in 2017 as well.

How much rain has fallen in the dam catchment areas? Last week good rains fell in the Wemmershoek and Berg River Dams catchments with a smaller amount at Steenbras. Little rain fell at Voelvlei and almost none fell at Theewaters. All dams benefitted slightly from run-off of previous rains. Water is still being pumped across from Berg River to Theewaters dam.

Disappointingly, July 2017 has ended with a mixed rainfall result. Overall, the rains were slightly below average. All hopes now rest on a strong rainfall pattern in August and September.

In Summary: net inflows continued, with a modest 4.0 M.cuM rise in the dams levels, up from 27.0% to 27.4% of capacity. Further rains this coming week will help but levels are now dangerously low. Continued water savings is essential.

Here are the levels of the six main dams that serve the Cape Town/Overberg/Boland area. Also shown is the total water storage level of all the dams in the whole greater Western Cape.

Read our Indoors Water Savings Ideas here.

Read our outdoors Water Savings Ideas here

Read about a D-i-Y household rainwater harvesting and tank system here

Our water-wise landscaping and water-wise gardening suggestions.

Read about South Africa’s desalination policies and initiatives.

Click here to see Winelands Weather forecast of possible near-term rain.

Report instances of piping failures and incorrect use to municipalities.

In Cape Town the contact details of the 24-hour Technical Operation Centre are: Email: waterTOC@capetown.gov.za Telephone: 0860103089 (choose option2: water-related faults) or SMS: 31373 (max 160 characters).

Note: To calculate number of days of water left we first reduce reported water stored volume by 10% of capacity (i.e. 89 Million cuM) to allow for water that usually can’t be extracted or processed and then divide the remainder by the net outflow rate during the previous week. 

Tom.

Views expressed in this article, and comments in response, are those of the writer and commenters alone and do not necessarily reflect the views and opinions of ShowMe, nor is any warranty hereby given as to suitability for any purpose of a reviewed enterprise or as to the quality of offered advice, products, services or value. Copyright ShowMe Paarl. All rights reserved. Copy only with prior permission.