The graph just keeps going in the right direction, week after week. 3 weeks of above average inflows into the dams.
Just how far above average is this winter going to be!?!
The graph just keeps going in the right direction, week after week. 3 weeks of above average inflows into the dams.
Just how far above average is this winter going to be!?!
This is looking hopeful. Now we just have to keep the red dots above the green line!
The latest data point on the cumulative storage for Cape Town dams shows that inflows are now tracking the median value for the last 70 years. If the rains pick up even more, we could start beating the average, which is vital if we want make up the shortfall created by the last few years. If it falls back, then it is even more critical that we maintain a conservative approach to water usage well into next winter.
The key is not to get complacent.
We appear to be following the 1 in 5 year or lower 20th percentile when it comes to water storage in Cape Town supply dams. To be anywhere near being “out of the woods” for the next few years, the red dots would have to be following the dark blue, or even light blue line. We’re not even above the green line! Best we all realise the water shortage is far from over and at this point, it looks like we’ll be living the “new normal” for some years to come.
Take advantage of the rain tank specials when the likes of Builders Warehouse starts trying to offload the stock they got in at the tail end of the panic buying.
Calculating the date for ‘Day Zero’ at any moment in time is tricky; it involves a number of factors which can vary from day to day. This results in the date ‘jumping’ about from week to week and can be confusing and disconcerting. We asked permission from DWS to publish the weekly graphs that they use to monitor the system drawdown, which may help a little to manage members’ fears and expectations.
This graph uses red dots to plot the ACTUAL water in the 6 major dams supply the CoCT (Theewatersdkloof, Voelvlei, Berg River Dam, Wemmershoek and the two Steenbras Dams) against PROJECTED levels that are the result of modelling the system. The projected storage assuming low inflows like last year are shown using the dark black dashed line and represent the MINIMUM TARGET. it is important that the storage RED DOTS remain above the BLACK DASHED LINE. That means we avoid dropping the levels of the dams below 13.5%, which gives us a narrow safety margin of about 5% before the water in the dams becomes unusable.
Keep RED above BLACK and we’re on TRACK…
If you look closely at the red dots you will see that around the 29th January they were beginning to diverge below the minimum target. However, subsequently due to the reduction in the combined agricultural and urban demands and the donation of some water by the Groenland Water User Association from Eikenhof Dam the red dots are starting to converge back towards and even beyond the target. This is in essence why “Day Zero” was shifted out into July.
It is conceivable that a wetter winter will be experienced than last year and the various coloured lines represent the probability of these scenarios. For instance, there is about a 50% chance that the storage will follow the green line and reach 700 million m3 providing the planned demand savings are achieved. Similally, there is a 10% chance of the dams filling and less than 2% chance that similar inflows to last year will be experienced.
The system was modelled taking the following variables into account:
c) Urban potable usage from the dams supplying CoCT
d) Agricultural usage from the dams supplying CoCT
It did NOT account for:
a) Augmentation from CoCT boreholes and desalination plants
b) Augmentation from Eikenhof dam
c) The slightly unseasonal rainfall and inflows received in November and December 2017
The BLACK DASHED line is the projected storage assuming low inflows like last year.
The RED Dots are the actual weekly storage of the system.
“Dead storage” is the water in the dams that cannot be accessed due to pumping limitations. Berms and temporary pumps are being installed to reduce the dead storage.
The reason that Misverstand dam is excluded is because it is a relatively small dam with only about 10 million m3 storage (of which about 80% was unavailable due to pumping limitations) which serves the West Coast and some irrigation.
The totals include the following dams: Theewaterskloof, Voëlvlei, Berg River, Wemmershoek, Upper and Lower Steenbras.
For those who need a bit of info on stochastic modelling:
The probabilistic trajectories were derived using stochastic modelling. “Stochastic” means being or having a random variable. A stochastic model is a tool for estimating probability distributions of potential outcomes by allowing for random variation in one or more inputs over time. The random variation is usually based on fluctuations observed in historical data for a selected period using standard time-series techniques. Distributions of potential outcomes are derived from a large number of simulations (stochastic projections) which reflect the random variation in the input(s).
Its application initially started in physics, although it is now being applied in engineering, life sciences, social sciences, and finance.
The stochastic streamflow generator used in the system model was developed by well known University of KZN Professor Emeritus, Geoff Pegram.
As beautiful as it is, the Western Cape is a water-scarce part of the world (much like other successful tourist regions like Southern California and Western Australia) and is vulnerable to the effects of climate change and susceptible to periodic droughts. At present the Western Cape is experiencing a significant drought. Traditionally we experience most of our rain during the winter period, starting May and continuing to August. However, rain can be experienced anytime of the year.
Cape Town and the Western Cape are open for business in spite of the current drought. Visitors and delegates will arrive in a place with a significant breadth and depth of experiences, and exceptional beauty, but we encourage you to be mindful of water-wise tourism and business travel when you’re here.
To counter the short-term effects of the drought, the City of Cape Town has put in place a number of initiatives to increase the supply of water and make provision for extreme water shortages. There are still many places across the Western Cape that are not as severely affected by the drought, such as the nearby Garden Route and the Cape Overberg.
Report nr. 89 (updated 12th February 2018) on the main dams serving
Last week, net outflows from the main dams dropped further to 5.8 M.cuM, or 0.7% of total dam capacity; vs the preceding week’s higher 7.2 M.cuM. Combined dam levels dropped during last week from 25.2% of capacity to 24.5% of capacity
In 2017, the main dams dropped by a far larger 10.4 M.cuM, falling 1.2% to 35.7% of full capacity.
Combined water stored in the 6 main dams fell to 218.1 M.cuM (133 M.cuM of easily accessible water) (last year, levels dropped to 317 and 235 M.cuM respectively over the same period).
It is now clear that DWS has cut the use of water for irrigation purposes at or about the agreed 40% level. At the same time, the non-agricultural use of water has also dropped sharply as the new level-6b restrictions come into effect. According to my calculations, this past week the use of 5.8 M.cuM of water from the dams could probably have been split more or less as follows:
Therefore the main target remains to drive use in the Metro down to the target of 450 ML/day and together with the other smaller municipalities down to a combined result less than 500ML/day.
The main irreducible current cause of the weekly drop in the combined dam levels is evaporation. Fortunately, evaporation will begin to decline as the ambient temperatures start to fall. By April it will be less than half of what it is now, and by June it will have halved again.
Of course a major once-off positive contributor over the coming 6-8 weeks will be water transferred from the Groenland Water Users Association pumped across into Steenbras Dam. This is expected to amount to some 8-10 M.cuM of fresh water, which should add two week’s supply to the WCWSS for the Metro and other municipalities. A life-saving, selfless donation by those farmers.
This unexpected inflow of water taken together with continued reduction in water use by residents indicates that water currently stored in the dams could well last until between mid- and end-June before the implementation of stage-2 (collection/rationing) of water supplies may be required.
The chart below indicates the position at the start of February. It is too early for a mid-month correction but the early indications are that my currently predicted water consumption for the month will again prove to be too high and that in February we will use less water than the 37.8 M.cuM expected. Remember also that the red block indicates that point where, had our water usage followed the same pattern as last year, we would already have hit “Day Zero”.
1) As this CoCT graph shows, most agricultural use of water has been closed off by DWS and the earlier steep rising usage curve is now starting to “flat-line” at/about the set maximum of 58 M.cuM for the total water used. Other than remaining pockets of unused quotas, use of water from the main dams by agriculture is all closed for this season.
2) It may be seen from the photo at the head of this report that DWS is modifying Voelvlei and Theewaterskloof dams to enable part of the water that lies in the deepest part of the dams to be pumped up to the level of the abstraction points, so that more of the water can be made available for the Metro and municipalities. At TWK (shown) the work involves creating a temporary berm to hold flows from the Sonderend River at a higher level for easier abstraction. Should these natural flows be insufficient, then more water will be pumped up from below this temporary berm to above it so that water can be sent through to the Berg River side. Through these modifications, DWS expects to be able to draw both these dams down to about 6% of capacity should that become necessary.
3) Residents of the Metro and other smaller municipalities are obviously making great strides to reduce their consumption of fresh water. As a result, Cape Town City which until recently seemed so stuck at a usage of 600ML/day has over a few weeks dropped sharply to ave 493ML/d during this past week. This is an outstanding result and shows just how well the residents are reacting to the call to use less water. The goal is to as soon as possible get this daily consumption down to 450ML/d or less. And it seems to me that could be achieved before end-February. We done everyone.
The following heavily altered CoCT tracker chart shows in overall terms what is going on (see here for a detailed explanation of how the chart is to be read).
City of Cape Town held its prediction of “Day Zero” at 11th May 2018 (point red ‘X’ in the chart). Although CoCT remains conservative in its estimates, this may be adjusted soon to a yet later date.
We are today at point red ‘Y’ (24.5% of capacity on 12th February). However, we are not only benefiting from the savings made by agriculture (the blue striped zone “E”, but more importantly as anticipated residential water usage reductions kick in (the blue-shaded zone “H”) we are starting to follow the curving dotted white line, trending toward point “I” on the revised lower line “C” at which the authorities would have to implement stage-2 collection/rationing of the disaster plan.
Our hope then is that winter rains together with early water production from augmentation initiatives (area “K”) will lift us on to the red dotted line “L” denoting steady recharge of the dam storage.
Therefore, I would like to suggest that instead of the dark negativity of “Day Zero” we now set ourselves a positive fixed target that we call “Success Day” and make that target getting to 30th June with at least 100 M.cuM of water left in the main dams. This would represent about 11% of capacity and, assuming that the DWS is indeed prepared to drop the dam levels down to 6-7%, would leave a safety margin of some 4-5%; so that even if we receive no rain at all there would still be enough water in the dams to support a stage-2 rationing program through until end-2018 by which time a number of augmentation initiatives will be producing extra water to relieve the situation.
In support of this notion of “Success Day” the present augmentation plans comprehend the production of 80ML/day of fresh water by July and 180ML/day of fresh water by December 2018.
More positively, if we can reach end of June with that much water still available, then we will be well into the rainy season and even with weak winter rainfall, recharge of the dams would have begun.
What are the authorities doing now?
The City of Cape Town reports that 526 ML/day of water was consumed from all sources but that it only used 493 ML/day drawn from the main dams. This implies that the augmentation initiatives have progressed to the point that they are producing the difference i.e. 33ML/d of fresh water.
The Metro has embarked on a massive information campaign using all possible ways to make the broader population aware of the problem and encouraging them to save water.
The Metro is also developing a program of volunteers to assist with the many tasks that will have to be dealt with if water supply to the taps is cut off, such as assisting at water collection points and caring for the most vulnerable. Read more here to see how you might apply to help.
The level-6b restrictions and sharply increased tariffs appear to be having a marked effect in encouraging less use of water. This is supported by further roll-out of pressure reduction systems to reduce losses through piping and system failures.
CoCT has announced that it intends to release details of the Points of Distribution on Sunday 18th February. Sensibly, work on these expensive installations will be delayed until the last possible moment, in the hope that they are not needed at all.
The two initial temporary desalination plants at Monwabisi and Strandfontein are reported to be about 70% complete and should start producing fresh water next month. On the other hand, work on the V&A desalination plant has been delayed by intervention of the DWS Minister wanting a desalination unit from Durban to be installed there.
Drilling into the Cape Flats and TMG aquifers is proceeding.
DWS is making rapid progress on constructing the berm and pumping installations at Voelvlei and Theewaterskloof dams. It should be noted the cost of this work, being R12-15 million in each case, has been funded by DWS.
Cooperative Government and Traditional Affairs Minister Des van Rooyen stated that central government is working on the possible proclamation of a national state of emergency. To date three provinces (Western, Eastern and Northern Cape) have been declared local disaster zones, but this planned escalation would mobilise more resources of the state to assist all parts of the country facing the widening shortage of water.
See details of Cape Town’s planned interventions to produce fresh water here.
Learn about water savings efforts by other Cape municipalities – read more here.
Hear me interviewed on Bok Radio here about the overall water situation in the western Cape
Do visit the City of Cape Town website to see additional graphically presented information regarding the water situation – very helpful.
1) See the full water status presentation here and
2) Check out water usage for your property and of neighbours, friends, using this interactive map.
1) Be “water warriors” at home and at the place of work. Make extra efforts to cut down on all possible use of water. By using a basin and large sponge, reduce the water used to shower to under one litre. One can do this daily with hair washed and oneself totally cleaned. All one gives up is the luxury of standing under a hot shower; a small price to pay for water security.
2) Join dependable social media groups and form local WhatsApp groups so as to stay in touch and benefit from tips and suggestions on how to reduce use of water. Have a look at this link.
3) Take care of personal hygiene and reduce health risks. Treat grey water being saved for flushing with Jik or vinegar to prevent smells and possible spread of bacteria. Wash hands regularly.
If you are a business owner or manager, I strongly recommend that, if you have not already done so, meet with your employees and take them into your confidence regarding what you believe may happen to your business as this situation unfolds. The situation is unprecedented and no one will have points of reference or past experience to draw upon. Employees are likely to be concerned and perhaps even fearful about their jobs, incomes and how they will cope.
By discussing the matter you would simultaneously make them all fully aware of the seriousness while encouraging their participation in implementing ways to cut down on water usage and may even generate good ideas on how to mitigate the possible negative impact of water rationing. One concept to consider – if it would be appropriate in the event of a possible slow-down or loss of some business – is to perhaps adopt a policy of work-sharing where those working in the same departments or doing the same work could between them share whatever reduced work might still be available in return for flex-time time off while earning proportionately reduced incomes. The main advantage being that some familiar work is far better than none.
Will the weather help?
Well, as predicted, that cold front came through last weekend and variable amounts of rain fell across the SW Cape. Gratifyingly some rain fell in all the dam catchments. Run-off will already have reached dams with more to come. A good 33 mm of rain was measured at Dwarsberg which feeds the Berg River and TWK dams.
As I write there is a low pressure system north of Cape Town feeding rain with the possibility of thundershowers from the North West down towards Agulhas. Rains could be fairly widespread as this chart from NOAA/CPC indicates, with the possibility of stronger rainfall behind the mountains in the catchments area of the large dams. If you are lucky enough to be under a cloud …
Here is the rainfall chart for the dam catchments for the period since 1st April 2017. This tracks rainfall that is measured actually falling at the dams.
In Summary: outflows exceeded inflows by 5.8 M.cuM and combined dam levels fell to 24.5%.
Here are the levels of the six main dams serving the Cape Town/Overberg/Boland area.
Here are some of our updated thoughts of possible implications of “Day Zero”.
Read about a D-i-Y household rainwater harvesting and tank system here
Read about South Africa’s desalination policies and initiatives.
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).
Retired international businessman with a background in Finance and IT; and now a fruit farmer.
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.
OK, so we’re all at some point in the journey to “50 litres per person per day”. None of us want to be queueing for 25l at a Point of Distribution. In the 1st post, we covered the need to find and read your water meter and know where the main stopcock is. In the 2nd we discussed the fact that the toilet in your house swallows more potable water than anything else, after any pool or garden you may have. Today, we talk about baths & showers.
Step 3. The shower.
Baths are so 2014; no one should be bathing much any more. You will battle to make the 50l per person target, if you are bathing instead of showering. If you have access to alternate sources of water (like a wellpoint, or rainwater) your bath can be used to store that water to be used for flushing the loo and cleaning the house. If you have a small child that needs to bath, you can either invest in a baby-dam, or buy a large basin.
Buy a low flow shower-head for your showers, or at least fit flow restrictors behind the showerhead. Shower every other day or every 3rd day if you can, using a washcloth and basin or a spray-bottle to sponge-bath on the days you don’t shower. You’re not going to die, and in fact you may find your skin will in fact be healthier for it. If you need to, use a bit more deodorant than you’re used to. Obviously if you work in a coal-mine every day, you’re going to have to be creative about bathing – maybe save some of the grey water to get the worst off!
Stand in a large basin while you shower, catch the cold water in a bucket while waiting for the hot to come through (and throw that in the bath) or better still, while summer is still baking the dry land, skip the hot and wash with cold. Wet yourself as quickly as you can, turn off the tap, soap and lather, then only turn the tap back on to rinse the soap off. This should not take more than 120 seconds and can be achieved in closer to 60 once you get practiced and if your hair is not as long as Rapunzel.
The grey water you catch in the basin you stood in can be transferred to one of a number of buckets you need to organise next your loo so that you no longer have to flush with clean potable water.
Another source of grey water is the washing machine, but more on that in the next post…
By now, we should all be aware that we need to reduce to 50 litres per person per day, or end up queueing for 25l at a Point of Distribution. For those wanting make sure they’ve covered all their bases, or are a little late in getting with the programme, we’re offering some unsolicited advice on what to focus on.
Step 2. The loo.
We’re assuming that you’re no longer watering lawns or flowerbeds or topping up your swimming pool with potable water. If you are, you need to stop RIGHT NOW. We are way beyond the point of even debating the ethics of doing that. Just stop. After lawns and pools (~35%), the next biggest culprit in most houses is the toilet (~30%).
You should not be flushing every time you pee any more. If the smell offends you, there are sprays you can get to minimise the odour (Wee Pong, Albex, Probac to name a few, or make your own using brown vinegar). The only time you should be flushing is for poo (#2’s). #2’s need to be flushed (preferably with grey water, but we’ll get to that). If you put toilet paper in the loo every time you do a #1, and you only flush for #2’s, your toilet is going to clog. Any paper that is used for #1’s should be placed in a small bin next to the loo, which has a lid that closes; this can be disposed of in the garbage, not down the loo. It’s a good idea to keep some medicinal charcoal in the house in case someone ends up with an upset stomach – lots of #2’s are going to deplete your grey water stocks fast.
Once you have your grey water system in place, turn off the stopcocks to the toilets – this reminds lazy people that they should only flush for #2.
If the situation gets very dire and there is no longer water to flush the loo, you may have to resort to the old bucket system. We’re not there yet, but it is worth considering your options and having a few 25l buckets with sealable lids on hand just in case. WWF have compiled a useful one-pager on sanitation during extreme water crises.
… tomorrow, we’ll tackle baths and showers… and grey water.
Cape Town is finally realising that climate change is not a myth and that there is a real chance CoCT may have to turn the taps off within the next few months if we do not make a plan to use less water. We need to reduce to 50 litres per person per day, or end up queueing for 25l at a Point of Distribution.
So, if you’re a little late to the party, here is what you need to do:
Step 1. The water meter.
You cannot manage if you do not measure. Every good manager knows that. Find your water meter and read it. While you are at it, find the stopcock that you can use to shut off the water to your home; if a leak develops somewhere your side of the water meter. With the new punitive tariffs you could end up with a massive bill if you can’t shut your water off quickly. Your meter should either be just outside or inside your fence, usually in one corner of your property.
Set a daily reminder on your phone. Take a photo with your phone or jot down the meter reading at the same time each day. If you don’t know how to interpret the dials and numbers, read here. Create a daily water use log and not down the readings, your daily household usage and the usage per person. Stick that on your fridge or door where the whole house can see it. You should be well under 50 litres per person per day on average; if not, you need to take action quickly!