The Zandvlei estuary mouth is manually managed to support flushing of nutrients and sediment out of the system and to manage the salinity levels. This is in compliance with conditions of the Zandvlei Estuary Mouth Maintenance Management Plan: DEADP Reference E12/2/4/7 – A5/328 – CJ2142/11.
Schedule of PROVISIONAL DATES for mouth management.
- Note that these provisional dates have been compiled using the tide tables.
However they are subject to weather conditions which may necessitate adjustments to these dates or the introduction of additional dates.
This screenshot shows the opening and closings for 2108 – 2 March is closing, 26 March opening, 2 April closing, etc.
(while this is being reworked, have a look at a relevant old page from the Zandvlei Trust)
Getting hold of the information of when the mouth is opened is tricky, but roughly corresponds to spring tides.
The above information are supplied by City of Cape Town – Stormwater Catchment Management and are planned dates for opening and closing the mouth. Note – these are planned dates and may change with weather conditions and other factors.
The vlei mouth is opened and closed mechanically at full moon and spring tides where the tide is generally in excess of 1,8 meters.This is to get as much sea water into the estuary as possible. The rainfall in the catchment is monitored electronically. With telemetry the responsible Managers are notified of the rising and falling water levels in the catchment rivers.
Mouth will remain open in the winter months, unless there is very little rainfall. Officials monitor the forecasts daily.
The Zandvlei Catchment Forum and Zandvlei Protected Areas Advisory Committee (City of Cape Town, Provincial and National government officials and other interested stakeholders) regularly review in and out flows of Zandvlei, as there are a number of critical factors which have to be maintained. ie. water levels for flood management for the residents and waterbody user groups, also the salintity levels need to be maintained so that the estuary may function to an optimum for aquatic fauna and flora.
Martin Thompson has produced a pamphlet;
Zandvlei – Factors concerning Water Level Management. (link pending)
- This pamphlet sets out the background information in priority order for;
Revetment stability (concrete walls around the vleis edge)