Water situation – statement by Mmusi Maimani

de-villiers-dam-table-mountain-coct

Date: February 6, 2018 | Posted in News | Plettenberg Bay News

 

Statement by DA Leader, Mmusi Maimani

Saving water is still the only way to defeat Day Zero

Day Zero is being progressively pushed back, but it is still a very real and present threat. All residents must keep within the 50 litre per day limit, which was the main message in my newsletter last week.

Thanks to a decline in agricultural usage, Day Zero has been pushed back to 11 May this week, from 16 April last week. And we can push this back still further in the coming weeks, through a combination of using less water and producing more water.

This has to be a team effort. We’ll only defeat Day Zero if we all pull together.

Using less water

Daily usage by the City of Cape Town is steadily coming down but at 547 million litres used per day, it is still far above our target of 450 million litres per day.

The city is reducing demand in two main ways.

  1. First, by implementing a stricter water restriction and tariff structure, which came into effect on 1 February restricting usage to 50 litres or less per person per day. The City is continuing with the mass roll out of water management devices at high consumption households. Over 30 thousand of these have been installed since 1 October 2017.
  2. And second, by reducing water pressure (“throttling”). It is not possible to water shed a specific area, like you would load shed electricity. The pipe system is a complex one, making it difficult to isolate specific areas. And letting the pipes run dry risks bursting them once water is returned to them. Even pressure reduction is a complex process. But the throttling will continue to intensify, meaning households will experience a noticeable drop in pressure and those in high-lying areas and in apartment blocks may be without water altogether for a period of no longer than 12 hours at a time. Nonetheless, an accelerated programme of pressure reduction valve installations has been in effect since last month, which allows the City’s engineers greater control over pressure. Not only does pressure management lower consumption by reducing the rate at which water flows to properties, it also reduces loss from leaks and pipe bursts.

In responding to droughts, demand management through restrictions and pressure reduction is recognized as international best practice. There was simply no way the City could have predicted the severity of this drought and been able to sustain ordinary supply levels to residents three years into the worst drought in history.

Producing more water

While expecting residents to do everything possible to use less water, it is also entirely fair that residents expect the City to do everything possible to produce more water.

For the next 60 days, an additional 67 million litres a day will be added to the system, transferred from the Palmiet-Kogelberg dam, which has had plentiful rainfall and is full. This has been a collaborative effort between the City and the farming community of the Elgin-Grabouw valley, to whom we are extraordinarily grateful.

Groundwater extraction from the Atlantis Aquifer has been supplying about 12 million litres per day for the past week, and we expect this to increase to around 30 million litres per day over the period 2018 to 2020 once the project is complete. Likewise, boreholes being drilled into the Cape Flats Aquifer should start adding a further 80 million litres per day and those into the Table Mountain Aquifer roughly 40 million litres per day from June, over the period 2018 to 2020. The City recognizes that groundwater extraction must be approached with great sensitivity, as aquifer water is a finite resource. The City intends to allow the natural recharge of aquifers in the medium term and ensure that any long term extraction is conducted sustainably.

Three temporary desalination plants are coming online soon. The Strandfontein plant is expected to produce a total of 7 million litres per day once it is fully up and running, with 2 million litres per day from March and the additional 5 million litres per day coming online in May. The V&A Waterfront plant is expected to start producing an additional 2 million litres from March. And the plant at Monwabisi is expected to provide 2 million litres per day from April and will be providing 7 million litres per day by May, once it is at full capacity.

Legal responsibilities

These projects appear to imply that it is the City’s legal responsibility to provide bulk water. It is not. Almost everything the City and Western Cape Province are currently doing to augment water supplies is technically outside their legal mandate.

The budget and responsibility for bulk water supply and storage resides 100% with the national Department of Water and Sanitation (DWS). Section 3 of the National Water Act states:

(1) As the public trustee of the nation’s water resources, the National Government, acting through the Minister, must ensure that water is protected, used, developed, conserved, managed and controlled in a sustainable and equitable manner, for the benefit of all persons, and in accordance with its constitutional mandate.

(2) Without limiting sub-section (1), the Minister is ultimately responsible to ensure that water is allocated equitably and used beneficially in the public interest, while promoting environmental values.

(3) The National Government, acting through the Minister, as the power to regulate the use, flow and control of all water in the Republic.

DWS’s infrastructural budget for the year 2017/18 was R12.2 billion. The DWS has only spent R5 million of this in the Western Cape over the past 3 financial years – on clearing a build-up of silt in the Voelvlei Dam Catchment Area, a project they failed to complete. (The Western Cape government, using budget that was not technically available for that purpose, completed the work of cleaning the water canals.)

Local municipalities are responsible for delivering water from dams to households, with as little wastage as possible. This year, the City of Cape Town has further reduced the volume of water lost to leaks, theft and faulty meters. Our average loss rate is 16% against a national average of 36%.

It is vitally important that South Africans understand the legal distribution of responsibilities, because most of the country faces water shortages in the very near future. Water is already running out in parts of Eastern Cape, KZN, Free State and Limpopo. Lesotho’s dams, which feed parts of the interior, are very low. Many smaller towns have experienced periods of dry taps in the recent past. Last week, the DWS confessed that the taps may run dry across the country within the next few years.

Many more cities will soon be staring down the barrel of a Day Zero gun. We cannot lurch from one local water crisis to the next blaming local and provincial governments each time. And it is reckless for anyone to drive the false narrative that they are responsible.

Blaming local and provincial authorities for water shortages in 2018 is like blaming them for load shedding in 2008. It’s simply irrational. But worse than that, it lets National Government off the hook at a time when we need to be holding them accountable like never before.

If anything good has come out of the Cape drought crisis, it is the loud and clear message that water is the lifeblood of our economy and society. With the realities of rapid population growth, urban migration and climate disruption, we must put water planning and management centre stage. And we must all start treating it as the precious resource it is.

Thank you to all those Day Zero heroes who are already doing so!

Mmusi Maimane DA Leader




Dams – Latest levels: Winelands and Cape Town

Latest report (updated 22nd January 2018) on the main dams serving

Cape Town City and nearby Boland/Overberg towns

 

Water consumption spiked last week to 12.7 M.cuM, 1.4% of total dam capacity; vs the preceding week’s 9.6 M.cuM. Combined dam levels dropped from 28.4% of capacity to 26.9%.

During the same period in 2017, the main dams dropped by a far larger 18.9 M.cuM, with the dams sinking back then by 2.1% to 39.9% of full capacity.

Read More At Toms Blogs

Day Zero Date – a basis of calculation.

Calculation of likely Day Zero date

Using current and likely future water consumption patterns, projected as at end-February 2018.

2018-02-26-5

 

I comprehend the gradually changing water consumption patterns in my model and therefore my predictions of steadily falling weekly water consumption results in the dotted black line curving away to the right and indicating a “Day Zero” date falling around 30th June at point ‘Y’, depending upon how well households further reduce their water consumption over the coming 4-5 months.

 

Going through it step-by-step.

Starting from the 37.5% total storage at beginning November 2017, the business-as-usual consumption expectation indicated a sharply descending fall in dam levels, originally predicting Day Zero as being during week of 13th February 2018 when total storage would drop to the 13.5% level set by CoCT; that point when they would move to stage-2 of the disaster plan.

Then in November 2017 we enjoyed unseasonal rain in the catchments that lifted dam levels and effectively moved the predicted Day Zero out by two weeks to the last week of February.

My information at that time was that the so-called 10% of ‘inaccessible water’ in the dams was in no ways definite and that if necessary, given some extra filtration, more of that last ‘dead water’ could be accessed. In fact, the dams could be drawn down to virtually zero but not easily in all cases. So I assumed that they would be pulled down to, say, 7.5% (line “D”) thereby making more available for consumption. That in turn allowed a corresponding drop in the Day Zero trigger level from 13.5% to 11% of capacity (line “B”) while still retaining the same stage-2 reserve of 3.5% of capacity “E”). This pushed the point where line “A,B” intersects the 11% line out into March. [In the meantime DWS has announced that they are preparing to pull both Voelvlei and Theewaterskloof dams down to zero if necessary. That would make yet more water available.]

The next major change in November was when DWS imposed new limits and cut agricultural water allocations to just 40% of normal. The effect of this massive reduction in overall water consumption is reflected by the blue-striped zone, labelled “F”the current position being where the actual consumption (denoted by the red ‘X’) now lies. Without further savings then the theoretical Day Zero date would be around end-May 2018, on the disaster stage-2 line (point “G”); by then dam levels could have dropped to 11.0% of capacity.

Although they have been drawing their water allocation fast, in fact agriculture has rapidly reached the 40% limit and the irrigation flows were largely cut off by end-January with most of the rest reaching the limit and closing by end-February. The net effect will be that the agricultural sacrifice has extended the communally available water supply out to late May (point “G”). At that stage agriculture’s contribution should be exhausted and “Day Zero” will have arrived for all the farms.

In February 2018 it was announced that the Groenland Water Users Association (Elgin/Grabou) would release their surplus stored water to be pumped through to Steenbras dam. This donation is expected to add 8-10 M.cuM of water to the SW Cape water supplies and help us to reach a point half way between “G” and “I”.

Now, although rain should start by June this is still too tight and the business and household users in the metro and municipalities must save stringently and meet their reduced allocations. In January the CoCT was running at about 586ML/d but has subsequently dropped down to the current level of 510-520 ML/d.

From 1st February level-6B restrictions require consumers to further reduce to 50L/person/day. Residents now must cut usage in order to save that blue zone labelled “H”. This action would make all the difference and enable us to reach “Success Day”, defined as arriving at 30th June 2018 with 100 M.cuM of fresh water still stored in the dams (point “Y”). Average consumption is still up in the area of 75L/p/d  and every effort must be made to encourage that half of the population that is still using too much water to stop doing so (hopefully the new harsh tariffs will help).

As I write, the point red “X” lies at 23.7% of capacity on 26th February – the small yellow circles with ‘x’ mark the previous positions of “X” over the immediate past. Graphically the task is to make sure that, as position red “X” moves along,  it stays on or to the right of the dotted black line, which will show that we are achieving or doing better than our weekly consumption target. At the moment we are doing very well due to the water being donated from the Palmiet system.

If we do reach mid-year with sufficient water in the dams, then nature should start to help with winter rains and low evaporation commencing late-May, but surely in June (yellow zone “I”).

Last but not least, various augmentation initiatives should be starting to make steadily growing contributions (brown striped zone “J”) and, in the final analysis Cape Town should just skim past the lowest point and out of immediate danger. In fact, hopefully the total available water will recover along the heavy dotted red line as the dams recharge, labelled “K”.

In summary, this outcome depends clearly on three main things:

1) the dams will be drawn down at least into the range of 6% – 7.5% of capacity if needed!

2) agriculture is exhausted, so businesses & households must now reduce consumption to 50L/p/d.

3) at least normal rains needs to arrive to start recharging the dams from July onward.

If rains once more fail and Day Zero arrives, then we will at least know we have done our best!

 

Tom Brown,

retired international businessman and fruit farmer in the Klein Karoo.

26th February, 2018.

 

 



Just how severe is the current drought the City of Cape Town is experiencing?

Are we in the middle of an extreme, unusual climate event that caught authorities napping, or is this purely a political machination of some diabolical state-capturers?  There have been a lot of social media posts stating that contrary to what some scientists have said, we are not facing an extreme climate event.  I came across the results of some analysis done by Anton Sparks, a professional engineer at Aurecon, which support the statements that the last 3 years are in fact very likely to be significantly worse than a 1 in 100 year event.

Comparing the combined inflows over the past three years (Preliminarily estimated from the equation “Monthly Inflow” = “Monthly Increase in Storage” + “Monthly Demands on Dams” which can later be refined using evaporation and rainfall on the dam’s surfaces when the data is available) into the 6 dams that feed Cape Town with potable water (note we’re not looking at rainfall, but the inflows into the storage systems that are the main reservoirs we use) and with similar data for the period from 1928 to 2004 (Derived by DWS as part of the study to assess the availability of water in the Berg River (see http://www.dwa.gov.za/Documents/Other/WMA/19/Reports/BergAssess23Jul10.htm), one can note that:

  1. The annual inflows from Nov 2016 – Oct 2017 was about 100 million cubic metres (1 cubic metre of water = 1 kilolitre) LOWER than the LOWEST of any 1 year period during 1928-2004.
  2. The total flows over the TWO consecutive years from Nov 2015 – Oct 2017 were 80 million m3 LOWER than the LOWEST two consecutive year period during 1928-2004.
  3. The total flows over the THREE consecutive years from Nov 2014 – Oct 2017 were 180 million m3 LOWER than the LOWEST three consecutive year period during 1928-2004.

This can be illustrated graphically using a “Percent Exceedance” graph (below).  To produce a percent exceedance graph for say the annual inflows all that is necessary is to rank and plot the annual inflows in descending order, so that the largest annual flow occurs on the left hand side and the smallest annual flow occurs on the right hand side.  None of the flows are greater than the leftmost flow so it has a percent exceedance probability of 0%, while all the flows are greater than the rightmost flow which has a percent exceedance probability of 100%.  Similarly, the middle flow will have an exceedance probability of 50%.  This graph enables one to visually view the distribution of flows and say to pick out the annual flow which is exceeded say 10% of the time, if that was of interest.

Looking at the first graph then, the far left of the red line shows that the very wettest 1 year period had inflows of about 1300 million m3/a (at 0 percent exceedance) and the driest inflow was 380 million m3/a (at 100 percent exceedance).  The red dot representing the inflow from November 2016 to October 2017 only has inflows of 280 million m3/a, 100 million m3/a less than any record in from 1928 to 2004.  Expanding the sample to 2 year and 3 year consecutive periods shows provides data for two and three year long droughts.

What is very interesting is to then look at the values for the periods 2016, 2015 to 2016, & 2014 to 2016.  In all of these cases, there is NOT ONE equivalent period from 1928 to 2004 where the inflows into the 6 CoCT supply dams are lower.

Aurecon then simulated the probabilistic drawdowns on the dams from November 2014, using a stochastic modeling technique developed by Professor Geoff Pegram of UKZN (http://sahg.ukzn.ac.za/people/) and the hydrology data available up until September 2005 and the actual system water demands from November 2014.  The 2nd graph shows the results of the simulations, with the ACTUAL dam levels superimposed as black dots.  The light green line shows how things would have looked if we’d had average inflows to the dams and average drawdowns – everything just fine, thanks very much.  The dark green line shows a 95% exceedance probability (or 1 in 20) risk of lower storage volumes.  Lines for 98%, 99% and 99.75% exceedance probability are shown.  In October 2015, the dam levels were above the 1:20 risk level, in October 2016 at the 1:20 risk level and in October 2017 below the 1:400 risk level.

Again, Aurecon modelled the probability of different storages going forward from November 2017 which are shown in the third graph.  The graphs show what will happen if we cut our usage, in this case Urban use by 45% and Agricultural use by 60%, both with respect to the average consumption from 2011 to 2015.  The “spreadsheet simulation” is based on the worst case annual inflows from November 2016 to October 2017.  If we cut our usage sufficiently, we could make it through and remain above the “Day Zero” storage level when one would have to queue for water.  If we don’t, and the augmentation projects are delayed, or like Beaufort West, do not produce what is predicted, we’re in big trouble.

The red dots track the current storage.  Note that despite the light rains experienced in early summer which have helped to elevate the storages slightly, the storage below the projected storages because the targets are not being achieved.

We have no choice, we HAVE to ensure the City as a whole uses less water.  Given that the severity of the current drought has deepened because of the last winter we should try to reduce our consumption to 50 litres per person per day or less if at all possible.  This means even less/shorter showers or sharing baths, and utilizing grey water to flush!!  50 litres per person per day is still twice the “Day Zero” allowance.

For drought information and tips and advice on water saving methods consider joining the Water Shedding Western Cape Facebook group :
www.facebook.com/groups/watersheddingsa

My thanks to Anton Sparks of Aurecon for patiently taking me through the graphs and answering questions about them.

Dave Gale
Water Shedding Western Cape
2018-01-15