Cape Dams Levels – weekly report (006)
ShowMe Winelands
Cape Dams Levels – weekly report nr. 006
as at 3rd December 2018
[Wemmershoek Dam. Currently 85% full. Photo: DWS]
Net outflows from the six main dams rose slightly week-on-week to 10.1 M.cuM, 1.1% of capacity while total stored water fell to 619.7 M.cuM; i.e. from 70.8% to 69.7% of overall capacity. Last year during the same week the total volume stored fell by a very similar 10.6 M.cuM (1.1%).
Use of water from the dams by the Metro residential and business users also rose fractionally (555 ML/d rising to 563 ML/d). It appears that consumption by domestic as well as by business and agriculture is tracking smoothly as the irrigation and tourism seasons builds up.
Here are the levels of the 6 main dams in SW cape.
The following graph charts the progress of the weekly water consumption as evidenced by the net change in the water stored collectively in the main dams. This continues to be as expected with spring 2018 usage lying between the 2017/18 (green) and 2016/17 (black/grey) levels.
Unusually there was no spike in rainfall during November so no recharge of the dams took place. However, it now seems that a coastal low may develop next weekend, 6th-7th December, bringing a burst of rain in the catchments that may run-off to boost the stored water reserves.
[click on the graph to see an enlarged version]Last week, the municipalities reached agreement with DWS and announced new level-3 restrictions and tariffs that will likely now apply from 1st December 2018 until November 2019.
In terms of this arrangement, munis are required to reduce consumption to 80% or less of ‘normal’ levels. In the case of the Metro this amounts to an allocation of 243 M.cuM of water for the coming 12 months, which would equate to some 675 ML/day. However CoCT has decided to impose a tighter overall limit of 650 ML/day in order to be cautious in the consumption of available stored water. Within this overall target it has decided to constrain domestic users to just 105 L/p/d while removing all water usage limits on business and tourism, all in the interests of job creation and boosting economic activity.
Read a summary of the revised Cape Town level-3 water restrictions here.
Drakenstein municipality has decided to allow a nominally higher 120 L/p/d to its residents
As predicted last week, the allocation to agricultural irrigation schemes by DWS will be 90% of normal. Since the various irrigation schemes commenced distributing water to farmers at the end of October, agricultural consumption has risen quickly to full normal levels and should continue at this rate for the balance of the summer season.
Although it is early days, it seems that domestic users are following their previous water savings practices, so overall consumption in the City has shown only a small increase over the past 60 days.
Prevailing uncertain weather prospects are proving hard for forecasters to pin down at this volatile time of changing seasons. While this week was originally predicted to be dry, projections are now starting to show development of a coastal low that will move over the SW Cape coming Friday into the weekend, and possibly bring useful sustained rain in the catchment areas. Importantly, it is also expected to include a few thunderstorms that may bring relief to the Klein Karoo. Here is the NOAA CPC projection for rainfall on Saturday 7th December.
Many months ago, at the height of the water crisis I wrote that I believed we would get through the water shortage but that the “elephant in the room” was Eskom, which even back then was starting to exhibit worrying signs of potential failure. And the primary issue is, of course, that while water shortages will usually be local or regional in their extent, a failure of the electricity supply would have national ramifications. Sadly the decline in Eskom has since followed its foreseen path and we are now faced with a possibly lengthy period of load-shedding and potential partial black-outs, which in some areas may also impact negatively on water distribution – a nasty “double whammy”.
To remain fully informed you may like to check the following items weekly
- City of Cape Town weekly “Water Dashboard“, to be found here.
- Our 7-day & 24-hour weather report here shows probable rain in Boland dam catchments.
- SA Weather Services current Synoptic Chart here showing the currently developing weather.
- Look at our supporting current monthly report here.
Tom Brown. Retired international businessman with a background in Finance and IT; and now a fruit farmer, with a passion for the weather and climate. Views expressed in this article, and comments in response, are those of the writer and commenters alone and do not necessarily reflect the views and opinions of ShowMe, nor is any warranty hereby given as to suitability for any purpose of a reviewed enterprise or as to the quality of offered advice, products, services or value. Copyright ShowMe Paarl. All rights reserved. Copy only with prior permission.