Dam level statistics

CM Pickering, Helderberg

On the issue of water saving and the implementation of restrictions imposed by the City of Cape Town, I think it is necessary for any councillor mouthpiece for this to make public the water savings that are presently being achieved, on a weekly basis, other than just announcing last week’s total consumption = 890 m cu l or whatever.

Prior to the City taking off access on the internet to its weekly dam readings, which happened during November and December, it was possible to calculate how much water was being extracted each week from the six principal dams as against the comparable readings in 2015/2016, from the City’s own site.

However, when the information was not available directly from the City’s internet site, it could be accessed from Elsenburg agricultural college’s weekly publication of dam levels for the whole Western Cape.

This has always been available on their internet site.

For the public’s interest, for example, I therefore submit my calculations for the amount of water saved for the past seven weeks ending on January 23.

It averages 14.9 percent less water being taken out of the six principal dams each week as against the identical seven week period in the previous year. That amounts to a saving of 19.65 m. cu m. during seven weeks, and 112.02 in total out of the dams in 2016/7 versus 131.67 in 2015/6.

It is my contention that were there a minimum saving of 15 percent of the six dams’ capacity for the next 130 days (versus the comparable percentage in the dams in the same period in 2016) bringing us to the end of May, the dams will hold very close to the same capacity reading they had last year at the same time.

That idea necessarily is based on an estimate of a similar run-off from rainfall into the dams as occurred last year.