The Kenton Dune saga
Our two estuaries are the reason Boesmansriviermond and Kenton-on-Sea exist and as Estuary Care (EC), our passion is to manage and enhance this precious asset, ensuring that it can be enjoyed now and preserved for future generations. To accomplish this we need to reduce the impact of human interventions, past and present.
For the past 50 to 60 years we have had an excess of sand building up in the Bushmans estuary due to a historic sand by-pass system being artificially blocked.
Dry Bones Valley (DBV) is a sand by-pass system that has possibly existed for millennia. Shelly Bay headland, like many rocky headlands that jut out into the sea, caused windblown sand to flow behind the headland. The prevailing westerly wind historically carried the sand through the valley towards Middle Beach and onwards.
Inadvertently, what started as a small intrusion into the entrance of DBV ended up closing the sand by-pass. It all started in the 1940s when branches were placed on the beach within Dry Bones Valley (DBV) to protect a water well from sand intrusion. In the 1960s more Port Jackson branches were placed on the beach to protect an ill-placed car park from being covered in sand. As the sand collected the dune formed and the Port Jackson seed started to grow, more branches were placed on top until the artificially vegetated dune contained over a 100 000 m3 of sand and extended from DBV to the river mouth.
Finally, a natural process started, and the fore dune finally shrugged off its vegetation and started rolling back on itself to where it is today. If left to carry on, nature will eventually return to equilibrium but in the meantime, the estuary is drowning in sand. It is estimated that the net gain of sand into the estuary is in the order of 15000 m3 per annum. Throughout 50 to 60 years, one can then see that we have a huge problem and it has to be rectified as soon as possible.
For decades Estuary Care have held the strong opinion that DBV has to be cleared of all vegetation and that some of the huge sand budget has to be physically moved toward Middle Beach. We have attempted, with a very small budget, to have the authorities allow us to do this but with no eventual success. This changed when Robert Rose contracted PRDW, a highly reputable and internationally renowned consulting marine engineers, to formulate a scientific plan to solve this dune problem. This PRDW Team report, which included Ted Avis (MD of CES), was published on the 30th of October 2015. This report fully endorsed the EC long help opinion.
To quote directly from this report:
“We therefore believe that the only option to alleviate the accumulation of sand at the WRCP is to re-instate the DBV headland bypass dune system (DBV-HBDS) and in so doing, encourage the speed up of the natural movement of sand eastwards from the WRCP (Westbourne Road Car Park) dune-field, across the DBV headland bypass dune-field, and from there to Middle Beach. In the past, any sand accumulating on the east bank of the river moved down DBV and finally onto Middle Beach”.
Their recommendation continued:
Restoring the functionality of the DBV-HBDS would involve the following steps:
- Establishing the outline of the baseline/historical DBV dune field from old photographs and establish and peg the boundaries of the DBV-HBDS ( Headland By-pass Dune System)on the ground
- Bring the surface of the DBV-HBDS down to the original level by removing all the vegetation.
- Physically move a portion of the sand retained in the WRCP dune-field through the DBV-HBDS along a road to Middle Beach.
- Arrive at a situation where the sand dunes of the WRCP dune-field would be at a low enough level to allow sand to migrate naturally as windblown sand at a more rapid rate (unhindered by vegetation cover) through DBV-HBDS, due to the Venturi effect (of the hills on either side).
Unfortunately, that was not acceptable to Mr. Rose so he eventually contracted CES with the mandate:
“Dr. Ted Avis was requested to develop a rehabilitation and revegetation plan for the relocated dune. The overall objective is to eliminate the nuisance factor associated with windblown sand, improve access to the river and beach, improve recreational amenities and create a vegetated dune ecosystem that attracts wildlife and is both aesthetically pleasing and stable”.
This mandate does not consider the wellbeing of the estuary at all and nor does the subsequent report. All the planned interventions by Ndlambe of bulldozing the sand towards the river again, as suggested by CES and the re-vegetation of it does not consider the being of a national asset.
As we have in the past, EC are very willing to engage with the KSDNA, their consultants (CES) and Ndlambe to work out a solution that will reduce the sand budget within the Estuary.
Chester Wilmot
Chairman,
Kenton Boesmans Estuary Care Forum