Cape Town Water Outlook 2018

Updated 20 May 2018

Department of Water and Sanitation

City of Cape Town

Dam levels (as at 18 May 2018)

What happened to Day Zero?

The level of water in the dams supplying Cape Town will not drop below 13.5% this year if restrictions are adhered to and assuming rainfall similar to last year.

Monitoring dam levels (inflow, evaporation and withdrawals) and managing withdrawals is key to maintaining the integrity of the system and getting through

the drought.

Day Zero calculation is based on conservative assumptions of consumption beyond the City’s control, including releases to agriculture, urban demand,

evaporation and rainfall. The projected Day Zero date is based on the previous weeks’ average volume extracted from the system, extrapolated into the

future to the intersection point of 13.5% dam level without adjusting for potential rainfall, reduction in demand etc. Unlike previous years, DWS stopped releases

to irrigation boards once allocations were reached late in January onwards thus dramatically reducing drawdown from the system. Furthermore, a sizeable

transfer was made by an adjacent catchment area in February, also reducing the drop in dam level. These two aspects, as well as a reduction in urban

demand led to the Day Zero date moving well beyond the anticipated start of the rainy season in 2018.

22 January 2018 - Projection of 13.5% dam level = 12 April

2018, Weekly drawdown = 1.4%, Agriculture : CCT, 48% : 47%

13 April 2018 - Projection of 13.5% dam level beyond July 2018,

Weekly drawdown = 0.5%, Agriculture : CCT, 15% : 76%

Cape Town’s water is part of an integrated system

Cape Town gets its water from a system of dams that supply agriculture and other urban areas. The current system is heavily dependent on rainfall. This complex system is managed by the national Department

of Water and Sanitation. About a third of the water in this system is used by agriculture and 7% by other urban areas (smaller towns).

2015

2016 2017

The National Department of Water and Sanitation

is responsible for planning and implementing

water resources schemes to meet water demand

for cities, industries, mining and agriculture.

The Department plans at a 1 in 50 year level of

assurance. This means that during droughts with a

severity of 1:50 years or more, restrictions need to

be imposed to reduce demand.

The current drought is much more severe than a 1

in 50 drought event. The best estimate of the

return interval of the meteorological drought in

the region of WCWSS dams is 311 years, with 90%

confidence that it actually falls between 105 and

1280 years1.

The next augmentation scheme for Cape Town

was planned for 2022/3 and is being accelerated

by the national Department. This scheme

(augmentation of Voelvlei Dam) is unlikely to be

ready before 2021.

Why is there a shortage of water in Cape Town?

Cape Town is experiencing an unprecedented multi-year

drought event.

Rainfall in the Cape Town area is variable. Wetter and drier years are common.

16 global climate models predict an overall decline in rainfall for Cape Town in the

future with more dry years and fewer wetter years.

A scenario in which it does not rain the future or in which it only rains at 2017 levels is

unrealistic.

Will it rain again? Yes.

Historical (grey) and predicted (pink) annual rainfall for Cape Town, according to

16 global climate models. Yellow dots below indicate rainfall incidents equal to or

lower than 2017 rainfall.

Sources: 1Facts are few, opinions plenty… on drought severity again (January 2018)

Is Cape Town’s drought the new normal? (1 November 2017)

Why Cape Town’s drought was so hard to predict (19 October 2017)

www.csag.uct.ac.za

284 329 368 361 275 184 125 77 83 94 136 201

1010 1100 1100 1218 1039 979 856 821 764 794 884 917

254 737 983 1028

846 451

55 28 27 27 28 136

0500

10001500200025003000

Nov

-17

Dec

-17

Jan-

18

Feb

-18

Mar

-18

Apr

-18

May

-18

Jun-

18

Jul-1

8

Aug

-18

Sep

-18

Oct

-18

Dai

ly c

on

sum

pti

on

ML

D

Evaporation - Maximum Urban (DWS average of last 5 years) Agriculture unrestricted

284 329 368 361 275 184 125 77 83 94 136 201 556 605 605 670 571 538 471 452 420 437 486 504 102 295 393 411

339 181

22 11 11 11 11 55

0500

10001500200025003000

Nov

-17

Dec

-17

Jan-

18

Feb

-18

Mar

-18

Apr

-18

May

-18

Jun-

18

Jul-1

8

Aug

-18

Sep

-18

Oct

-18

Dai

ly c

on

sum

pti

on

ML

D

Evaporation - Maximum 45% restricted Urban Agriculture 60% restricted

RESTRICT TO

Demand management through DWS restrictions

Demand management: Both the City, other urban and agriculture

must adhere to the restrictions imposed on the system

While Cape Town has significantly reduced its demand (measured here as production from the treatment works),

from a peak of 1200 Ml/day in 2015 down to nearly 500 Ml/day, a further reduction in demand is needed to below

450 Ml/day immediately due to not meeting the 500 Ml/day target since July 2017

For Cape Town, this means that demand must be

managed down to get below 450 Ml/day

Further measures are being put in place to reduce demand, including:

• punitive drought tariffs

• demand management devices & flow restrictors

• more aggressive pressure management

Demand reduction is saving >400 Ml/day Feb 2017 = 900 Ml/day Feb 2018 = 500 Ml/day

Demand management: Cape Town has done really well, but

we have to reduce to 450MLD

-

50

100

150

200

250

300

350

400

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

WaterintonetworkLitresperpersonperday(basedonpopulationinservicearea)

BuffaloCity

NelsonMandelaBay

Mangaung

EkurhuleniMetro

CityOfJohannesburg

CityOfTshwane

eThekwini

CapeTown

(Allmetros)

(based on litres per person per day, population in service area)

The drought affects the city’s finances in two primary ways: 1. Reduced sales means that city income is reduced because tariffs are volume based. 2. Additional expenditure is required to increase availability of water. New sources of water are more costly than the water obtained from the existing dams. This increases both capital and operating costs.

Demand management: Punitive tariff structure

Existing Restriction Water Tariffs 2017/18 (ex VAT)

Level 1 Level 2 Level 3 Level 4 Level 5 Level 6

Step 1 [0-6kl] 4.00 4.00 4.00 4.00 18.75 26.25

Step 2 [6-10.5kl] 15.57 15.57 15.57 15.57 26.25 46.00

Step 3 [10.5-20kl] 18.22 20.04 21.87 22.78 46.00 100.00

Step 4 [20-35kl] 26.99 32.65 36.43 38.32 100.00 300.00

Step 5 [35-50kl] 33.33 45.00 61.66 99.99 300.00 800.00

Step 6 [+50kl] 43.97 97.71 209.29 265.12 800.00 800.00

Commercial 19.63 21.59 23.55 24.54 37.50 50.00

Moving towards a resilient tariff means we need to:

1. Recover full costs including cost of water resilience program and adequate depreciation. It is a legal requirement to balance budget

2. Retain affordability for indigent and less affluent households and improve payment levels

3. Increase resilience of tariff to shocks (greater revenue stability in face of drought conditions)

4. Tariff reflects value of water and supports sustainability

Punitive tariffs discourage high water usage & support a sustainable water service

See Annexure B of Water Outlook for details on 2018/19 Tariff increase

Augmentation - considerations

Augmentation schemes are a far more

expensive source of water than runoff

from rainfall. The volume of runoff

cannot be easily augmented in short

time periods and is dependent on

rainfall patterns. Under poor rainfall

conditions like 2017 we would require

augmentation of ~770 MLD to match the

volume of runoff. Despite all

augmentation efforts, the supply scheme

is vulnerable to poor rainfall.

As can be seen the cost per kl of water

from other sources vary considerably.

The cost of bulk water, waste water and

reticulation is common so the costs can

be compared to the cost of runoff which

is ~R5.20/kl vs temporary desalination at

>R40/kl.

R 0 R 10 R 20 R 30 R 40 R 50

temporary desalination

temporary water re-use

groundwater extraction - TMG

permanent desalination

permanent re-use

groundwater extraction - sandy aquifer

treated surface water- historical Estimated cost ranges for treated water by source (R/kl)

0

200

400

600

800

2018

Pla

nned

augm

enta

tion

2019

Pla

nned

augm

enta

tion

500M

LD

2015

run

off

2016

run

off

2017

run

off

Ave

rage

run

off

Wet

win

ter

runo

ff

Equivalent annual inflow (millions of m3)

Augmentation - Advice from International Review (November 2017)

1. Assuming it will not rain again is not realistic

2. Prioritise ground water (Cape Flats Aquifer and Table Mountain Group Aquifer)

3. Do not pursue temporary desalination and reuse

4. Permanent Re-use is cheaper than desalination and may be quicker to execute

5. Plan and execute permanent desalination at an optimum scale

6. A turnkey approach for desalination with a water purchase agreement will yield

the lowest cost per unit of water

7. Do not delay decisions on permanent reuse and desalination.

Yield, cost, timing inform priorities

Indicativetargettime-framestoimplement

Timetoimplement(monthsfromafirmcommitmenttoproceed)

Yield(millionlitersperday)

0

100

200

300

0 12 24 36 48

Ground(100)

Reuse(70)

Desalination(120)

Surface(60)

0

5

10

15

20

0 100 200 300 400

TargetUnitCostsanduncertainty(Randperthousandliters)

Additionalsupply- Millionliters perday(MLD)

Ground

+100

Re-use

+70

Desalination

+120Surface

+60

+50%

+33%

+25%

+20%

• Surface water is least costly, but not resilient to drought;

• Groundwater is more drought resilient, and quick to provide additional water into the system;

• Permanent Desalination is very costly and cannot be implemented quickly BUT it is the only unlimited

new source of water into the system not reliant on rainfall;

• Re-used water is less costly than desalination, and is necessary to maximize value from the diversified

supply mix which is considerably more expensive than single source surface water.

The New Water Program – long-term plan

• Current existing augmentation includes transfers, springs & rivers, existing groundwater (Atlantis) and temporary desalination; • TMG and CFA are both programmed to provide yield in terms of phase 1 license conditions but over a longer period than

previously reported. Groundwater planned for sustainable yield of more than 100MLD, able to provide ~3x more during drought; • Permanent desalination and re-use in planning, each in the order of 100MLD sustainable yield.

See Annexure A of Water Outlook for details of change in augmentation program

0

20

40

60

80

100

120

140

160

180

0

50

100

150

200

250

300

350

400

450M

ay-1

8

Jun-

18

Jul-1

8

Aug

-18

Sep

-18

Oct

-18

Nov

-18

Dec

-18

Jan-

19

Feb

-19

Mar

-19

Apr

-19

May

-19

Jun-

19

Jul-1

9

Aug

-19

Sep

-19

Oct

-19

Nov

-19

Dec

-19

Jan-

20

Feb

-20

Mar

-20

Apr

-20

May

-20

Jun-

20

Jul-2

0

Aug

-20

Sep

-20

Oct

-20

Nov

-20

Dec

-20

Jan-

21

Feb

-21

Mar

-21

Apr

-21

May

-21

Jun-

21

Jul-2

1

Aug

-21

Sep

-21

Oct

-21

Nov

-21

Dec

-21

Cum

ulat

ive

volu

me

(mill

ions

of c

ubic

met

ers)

Dai

ly a

ugm

enta

tion

(MLD

)

Provisional Future Augmentation Programme May 2018 - December 2021

Cumulative volume Springs & rivers Atlantis Emergency desalination

TMG Ground Water Atlantis & Silverstroom Add Permanent desalination Permanent re-use

BRVAS Cape Flats Aquifer Temporary re-use

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

JA

N-1

8

FE

B-1

8

MA

R-1

8

AP

R-1

8

MA

Y-1

8

JU

N-1

8

JU

L-1

8

AU

G-1

8

SE

P-1

8

OC

T-1

8

NO

V-1

8

DE

C-1

8

JA

N-1

9

FE

B-1

9

MA

R-1

9

AP

R-1

9

DA

M L

EV

EL

MO

DE

LLE

D

Restricted, 100% 2017 Restricted, 50% rainfall Restricted, Average rainfall

Average rainfall

The impact of rainfall is such that other sources are insignificant in the short term

2017 rainfall

50% of 2017 rainfall

Summary

1. Continue demand management to reduce dam drawdown (in line with NDWS restriction 450MLD required);

2. Manage and monitor dam behaviour;

3. Fast-track augmentation:

• Decisions under consideration by the City on optimal augmentation types, volumes, methods;

• Groundwater projects (Atlantis, Cape Flats and TMG Aquifers) have been prioritised;

• Aquifer recharge projects from treated wastewater under development;

• Long-term Permanent Re-use project under development;

• Long-term Permanent Desalination under evaluation in terms of siting, optimum yield & procurement method;

4. Manage financial impacts through appropriate adjustments to the tariff structure and level. There is a high degree of

uncertainty related to future tariff revenues as a result of significant shifts in demand patterns and a steeply inclining block

tariff;

5. Improve coordination and leadership within and between spheres of government;

6. Improve information flows and consistency of messaging; actively engage citizens and stakeholders to encourage

active citizenry and stakeholder partnerships to jointly solve problems.

THANK YOU | ENKOSI | DANKIE

http://www.capetown.gov.za/thinkwater