Cape Town water outlook 2018 25 January 2018 Department of Water and Sanitation City of Cape Town
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).
Why is there a shortage of water in Cape Town? Cape Town is experiencing an unprecedented multi-year drought event. 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 that a 1 in 50 drought event. 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.
Will it rain again? Yes. Historical (grey) and predicted (pink) annual rainfall for Cape Town, according to 16 global climate models. Yellow dots indicate rainfall incidents equal to or lower than 2017 rainfall. 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. Sources: 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
Overall level of the Dams Cape Town will get through the drought IF restrictions on dam withdrawals are enforced The level of water in the dams supplying Cape Town will not drop below 10% this year if restrictions are adhered to and assuming another low rainfall year. Monitoring dam levels (inflow, evaporation and withdrawals) and managing dam withdrawals is a key to maintaining the integrity of the system and getting through the drought.
Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Jul-18 Aug-18 Sep-18 Oct-18 Daily consumption MLD Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Jul-18 Aug-18 Sep-18 Oct-18 Daily consumption MLD 3000 2500 2000 1028 983 737 846 1500 254 451 1000 1010 1100 1100 1218 55 28 28 1039 27 27 979 500 856 821 764 794 884 284 329 368 361 275 0 184 125 77 83 94 136 136 917 201 Evaporation - Maximum Urban (DWS average of last 5 years) Agriculture unrestricted RESTRICT TO 3000 2500 2000 1500 295 393 411 1000 339 102 181 556 605 605 670 571 22 538 11 11 11 11 500 471 452 420 437 486 284 329 368 361 275 0 184 125 77 83 94 136 55 504 201 Evaporation - Maximum 45% restricted Urban Agriculture 60% restricted
Both the City and agriculture MUST adhere to the restrictions imposed on the system. Cape Town is not yet meeting its target. Over abstraction by agriculture is a key risk to the system.
For Cape Town, this means that demand must now be managed down to below 450 Ml/day 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 below 600 Ml/day, a further reduction in demand is needed to below 450 Ml/day immediately due to not meeting the 500 Ml/day target. Further measures are being put in place to reduce demand, including: punitive drought tariffs demand management devices & flow restrictors more aggressive pressure management
For agriculture, this means that releases from the dams will need to be curtailed By 1 January, agriculture had already used 40 million kl out of its total allocation for the year of 60 million kl. It is imperative that agricultural use is restricted to the allocated amount. This requires urgent attention on the part of the Department of Water and Sanitation to enforce the restrictions by managing, reducing and cutting releases from the dams.
What about new water supplies? AUGMENTATION 900 800 700 600 500 400 Equivalent annual inflow (millions of m 3 ) 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 ~720MLD to match the volume of runoff. Despite all augmentation efforts, the supply scheme is vulnerable to poor rainfall. 300 200 100 0 Planned augmentation 300MLD 500MLD 2017 runoff Average runoff Wet winter runoff As can be seen below 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 below can be compared to the cost of runoff which is R5.20/kl.
MLD Augmentation programme Cape Town is actively pursuing opportunities to increase the supply of water available to Cape Town including ground water, reuse, desalination (temporary and permanent), swaps/purchase of water from agriculture and other (typically) small sources such as springs. (Program subject to change as new information comes to light and due to contingencies) 500 400 300 200 100 Permanent desalination Emergency desalination Water Reclamation Ground Water Abstraction (TMG) Ground Water Abstraction (sandy) Springs Temporary transfers 0 Dec-17 Mar-18 Jun-18 Sep-18 Dec-18 Mar-19 Jun-19 Sep-19 Dec-19 Mar-20 Jun-20 Sep-20 Dec-20 Mar-21 Jun-21 Sep-21 Dec-21 Mar-22 Jun-22
New water supplies are important for water security going forward but these will have little impact this summer. 60% 50% New supplies have a small impact this summer. But are very important for 2019 if winter rainfall is low DAM LEVEL 40% 30% 35.1% 30.5% 25.4% 27.2% 31.4% 28.8% 25.1% 25.4% 29.7% 27.1% with augmentation 20% 10% 20.8% 16.3% 13.2% 11.8% 11.2% 13.3% 19.3% 20.8% 16.9% 13.1% 10.6% 9.7% 9.4% 11.6% 17.6% 0% Nov-17 Dec-17 Jan-18 Feb-18 Mar-18 Apr-18 May-18 Jun-18 Jul-18 Aug-18 Sep-18 Oct-18 Nov-18 Dec-18 Jan-19 Feb-19 Mar-19 Apr-19 May-19 Jun-19 Jul-19 Aug-19 Sep-19 Oct-19 Nov-19 very conservative scenarios Status quo (no additional) +CFA60 With water trading With return effluent Ph1 236
Financial implications of the drought 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. (The increase to level 4 tariffs have not compensated for the reduction in sales because required reductions in sales have been larger than anticipated in the tariff design.) 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. treated surface water- historical groundwater extraction - sandy aquifer permanent re-use permanent desalination groundwater extraction - TMG temporary water re-use temporary desalination Estimated cost ranges for treated water by source (R/kl) R 0 R 5 R 10 R 15 R 20 R 25 R 30 R 35 R 40 R 45 R 50
Responses to financial challenges Primary goals: 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 poor people and improve payment levels 3. Increase resilience of tariff to shocks (greater revenue stability in face of drought conditions which the city is currently facing and is likely to face again in the future) 4. Tariff reflects value of water and supports sustainability (including adequate cashbacked depreciation to replace assets) Mechanisms to achieve goals: 1. In-year tariff revision for 2017/18 establish level 5 and 6 restrictions tariffs to increase incentives to reduce demand. 2. Implement a drought charge to assist with the major financial challenges of creating a water resilient city with diverse sources of supply. 3. Include structural changes in the 2018/19 tariff to make the tariff more resilient. Existing Restriction tariffs (Water) 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
Summary 1. Day zero can be avoided by reducing demand 2. For City of Cape Town, move to level 6B restrictions and introduce punitive drought tariffs (level 6) from 1 February to comply with NDWS restriction Continue all demand management initiatives Physically restrict demand to Cape Town Weekly Water Budget of 450 Ml/day (water-rationing) 3. Influence agricultural restrictions to stay within allocation as agreed to in line with NDWS restriction 4. Improve communications and have consistent messaging across government 5. Engage stakeholders into active citizenry City can t do it alone