Whilst groundwater can be the answer to Cape Town’s water supply issues, there are some key points that I would like to point out about the articles on the springs in the City Bowl:
- Freshwater flowing out to see is NOT wasted
Although the Table Mountain Marine Protected area only starts at Mouille Point, I would imagine that the springs play an important role in diluting the pollutants from the harbour in Duncan Dock and Table Bay. Take a read of the first guideline of freshwater conservation planning from the Freshwater Ecosystem Priority Areas project:
“Freshwater inputs to estuaries and the sea are necessary to maintain important ecological processes that keep our marine resources healthy. For example, fresh water provides an important environmental cue that helps fish and other marine animals find their way to estuary mouths to breed. Nutrients in fresh water also form the foundation of marine food webs. These ecological processes are vital for maintaining commercial and recreational fish stocks, as well as for providing a source of food to poor coastal communities that depend directly on marine resources for food. A certain amount of water is also required to flush and scour the mouth of most estuaries. Without the scouring effect, sediments build up at the mouth and the risk of back-flooding during storms increases. Artificial breaching of an estuary mouth to minimise this risk is expensive and damages estuarine ecosystems. Apart from the scouring effect, fresh water helps to flush estuaries of organic matter and other pollutants, which otherwise smell unpleasant. If too much water is taken out of a river along its length, not enough fresh water reaches the estuary and the sea to maintain these vital ecological processes.” Available from http://bgis.sanbi.org/NFEPA.
- A combined spring system of 40 Litres/second is only able to supply 1382 people with the average water consumption (based on 250 L/day).
Oranjezicht springs are 28 litres/second, and combined with formal springs increase to 40 L/s (http://www.dwaf.gov.za/…/…/WMA/19/WCWRSNewsletterMarch09.pdf). 40 L/s is equal to 3,456,600 litres/day and 1.262 million cubic metres (mcm) per annum (http://www.convert-me.com/…/…/flow_rate_volume/liter_s.html…) . Assuming the water could be treated to drinking water quality, the average daily consumption for South Africa is 250 l/day, which means the springs would be able to supply 1382.4 people with 250 l/day. And that’s 1382 people in Gardens or Oranjezicht, not on the informal settlements on the cape flats where it is needed (like the Huffington post comments. I doubt he would be driving through oranjezicht and kloof nek thinking that these wealthy residents need more water…)
- The Western Cape Water Supply Scheme has a gross capacity of 904 mcm (million cubic metres) while City of Cape Town has a demand of 399 mcm, compared to the spring supply of 1.262 mcm per year.
The Berg River Dam is 127 mcm, Theewaterskloof is 480 mcm, Voelvlei is 172 mcm and Wemmershoek is 59 mcm. So the springs are insignificant compared to the volume of water required for City of Cape Town. However, for the city bowl, Woodhead Reservoir has a capacity of 0.927 mcm and the Hely-Hutchinson Dam is 0.95 mcm so it is locally important water resource, but again do the residents of Oranjezicht and Gardens need more water?
- The Springs cannot be used for domestic drinking water.
The springs have been polluted and are not drinking water quality and haven’t been since the 1890s when it was diverted into the sea for that very reason. The water would need to be treated before it can be used, which would increase the cost of using it, making it unviable.
- Springs can be used for irrigation rather than irrigating with drinking water.
The studies 2008 studies note that the volume is “more than sufficient to meet the annual irrigation needs of the Common, Green Point Stadium, the Metropolitan Golf Course and Mouille Point Beachfront. And so, the city could, once again, to some extent at least, be connected to the sweet waters of Camissa.” Greenpoint urban park uses the water from the springs. The park has an annual requirement of 0.58 mcm. As far as I remember when they designed Cape Town Stadium they designed it to use City of Cape Town water, so there would be a cost involved in diverting water and redesigning their system.
- Most of the irrigated areas in the City Bowl and the Southern Suburbs use existing cheap sources of water (like boreholes)
There are not many areas under irrigation in the city that use drinking water. Most of the schools use borehole water (groundwater) to irrigate, which at the moment is free (in terms of volume) with the main cost being the drilling of the borehole. There are some schools with green fields, but it is not financially feasible to pipe this water to school fields and then to charge schools for the water while they are now getting it for free. Also the schools aren’t income generating so it isn’t socially fair to burden schools with additional expense. This is especially true for the Southern Suburbs and the Albion/Newlands spring. That spring has a much higher yield but there isn’t a need. City of CT is looking at reconnecting the Albion spring to the water supply network. Although currently this spring is diluting the pollution in the liesbeck river so removing it could cause huge pollution problems for the Liesbeck.
So overall I feel that Camissa has become an emotional issue rather than fact based.
City of Cape Town is award winning in terms of its water management (The City of Cape Town was presented with the C40 Cities Award for “Adaptation Implementation”, recognising the City’s Water Conservation and Demand Management [WCWDM] Programme, ) and has been proactive in looking at additional water resources to augment future water supply.
Because of the Water Conservation and Demand Management programme, Water Demand peaked in 1999 at 335 mcm. The 2014 water demand was 318 mcm. So since 1999 CoCT has been able to reduce its water consumption despite massive population growth and better water service delivery. (http://www.watersummit.co.za/…/24June2015_6b_Paul%20Rhode.p… )
Future interventions planned: (a big and easy one is water reuse, which currently isn’t happening)
Photo from News24.com