Due to a decline in agricultural water usage, Day Zero has been pushed back to mid-May 2018. Agricultural usage is likely to drop significantly over the next few weeks as many of the agricultural users in the Western Cape Supply System, where the city also draws its water from, have used up their water allocation as per agreement with the National Department of Water and Sanitation.
China Crisis via Wikimedia Commons - The Berg River Dam, located near Franschhoek, is one of the principal dams in the Western Cape Water Supply System.
Currently, the agriculture sector is drawing about 30% of the water in the supply scheme. This should fall to approximately 15% in March and 10% in April. It must be noted that the city does not have any control over agricultural releases, so this is the best estimate we can make with the information at hand.
All preparations for Day Zero must continue in earnest
This is a welcome decline in water usage and gives Cape Town and some of the other municipalities hope but importantly, we need to get our consumption down to 450 million litres per day to prevent the remaining water supplies running out before the arrival of winter rains. We cannot accurately predict the volume of rainfall still to come, or when it will come.
Capetonians must continue reducing consumption if we are to avoid Day Zero. There has not been any significant decline in urban usage. All Capetonians must, therefore, continue to use no more than 50 litres per person per day to help stretch our dwindling supplies.
Last year, we had abnormally low winter rainfall, and we cannot assume that this year will be any different. Even if we have been given a slight reprieve at this stage, we are likely to be facing a late and dry winter. All preparations for the possibility of reaching Day Zero continue in earnest. The city also continues with the roll-out of aggressive pressure management initiatives in an effort to stretch our supplies.
With the hot weather predicted over the week ahead and expected high evaporation rates, coupled with an expected increase in water use by our residents as a result of the weather, we dare not rest on our laurels now. It will be to the detriment of our efforts as Team Cape Town.
Calculating Day Zero
In calculating Day Zero, we have consistently taken a conservative approach (based on what we have experienced before, especially in relation to agricultural usage) to water management and demand. We’ve taken into account:
• Evaporation: The model assumes maximum calculated evaporation rates, based on historical calculations adjusted for increases in temperature and wind.
• Agricultural releases: The city extrapolated the National Department of Water and Sanitation’s (NDWS) unverified release data as read from the NDWS hydrology website. In the previous season, agriculture exceeded its unrestricted allocation by a small percentage. The city thus had no historical evidence base to assume that agriculture would remain within their allocation. However, the national department has now shut off supply to two irrigation boards that utilised their full allocation by the end of January 2018. The city, therefore, feels more confident that agriculture will stay within their allocation this year, as opposed to the previous year. Had agricultural releases not slowed down, the threat of Day Zero would have moved closer.
• Urban usage: While the city has worked tirelessly on fixing bursts and leaks, installing water management devices and implementing advanced pressure management to drive down consumption and minimise leaks and bursts, urban demand is very much reliant on the behaviour of water users. For this reason, the model assumes that consumption will remain at the previous weeks’ average usage levels.
As of 1 February 2018, level 6B water restrictions and tariffs have come into effect to help finance water services and to reduce usage. To cover the costs of water and sanitation provision, and to assist in driving down demand further, the water and sanitation tariffs have been increased. The tariffs remain based on usage. The more you use, the more you pay. High users will be hit especially hard. The city does not make a profit on income from the sale of water.
"We have reached a point of no return," advised City of Cape Town Mayor Patricia de Lille during a media briefing ahead of a special council meeting set for Friday, 19 January...
18 Jan 2018
This is part of the city’s efforts to avoid Day Zero and to create financial stability for the provision of water services. Although we have brought usage down from 1.1 billion litres per day to just under 600 million litres per day, we need to get to 450 million litres of collective usage per day.
• Day Zero: 11 May 2018 (was 16 April 2018) • Dam Levels: 25.5% (decline of 0.8%) • Total consumption: 547 million litres per day (97 million litres above the target of 450 million litres per day) • % of Capetonians saving: *note, due to the implementation of 50-litre targets, this calculation is under review
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