In order to log this cache you need to e-mail the answers of the following questions via my profile.
1) Name the three bypass dune fields that moved sand across the Cape Recife headland into Algoa Bay?
2) What is the width of the Noordhoek dune field?
3) If allowed to be re-activated, how long will it take for the Noordhoek dune field to reach Algoa Bay?
4) Standing at ground zero, which two man made structures are visible looking east? If you can't name them, describe them and their positions.
5) Although not a requirement, a selfie with the dune field in the background is always welcome.
Aerial shot of the Noordhoek dune field in 2010. The blue thing between the leading edge & the sea is the sewerage maturation plant
The Noordhoek dune field is located in the Cape Recife Nature Reserve. It is a natural path of sand blowing from the wild side, across the Cape Recife headland, and towards the bay. It’s a fairly narrow dunefield and only about 500m across. It would have most likely entered the bay just south of the SAMREC penguin facility in Cape Recife.
Map showing the dune field systems in 1890. Summerstrand & Humewood were just 1 big sand dune
Historically the Cape Recife area was characterized by 3 main driftsand areas, known as Driftsands, Noordhoek and Cape Recife. These mobile dune systems were separated by naturally stable vegetated dunes.
The main sand bypass known as Dritsands covered the area between Schoenmakerskop and Summerstrand. As these moving dunes threatened the young town of Port Elizabeth, plans were devided in the last 1800's to try and stabalised them. At first a steam train was used to dump the town's garbage on the dunes and you still find areas where pieces of old bottles, plates and other objects can be found. In the beginning of the 1900s the area was stabilised by planting Australian wattles such as Rooikrans and Port Jackson as well as Eucalyptus trees planted in an attempt to start a commercial forest.
When the sewerage maturation ponds were built in Cape Recife back in the 1960’s, they fell into the path of the moving Noordhoek dune field, so the leading edge of the dunes were stabilised by planting vegetation. To avoid the developing residential area of Summerstrand from becoming inundated with sand, both the Driftsands and Noordhoek dune systems were substantially reclaimed from around the 1970’s.
Research showed that the predominant source of sand for the beaches along the Cape Recife to harbor stretch was from these 3 dune fields. Before the reclamation of Driftsands, the bay used to get around 170000m3 of sand a year from the dune systems. Driftsands is actually the dune system that starts in Sardinia Bay, and in those days used to track over the peninsula, right past where the airport is today, and empty into the sea between Happy Valley and Bird Rock. There’s historical evidence of its existence long before the first settlements in the area.
After Driftsands was reclaimed, the sand entering the bay from the remaining 2 dune systems dropped to around 78000m3/yr. Then in the early ‘70’s, after Noordhoek was also reclaimed, it dropped even further to only 26000m3/yr, which was coming from the small dune field at the lighthouse at Cape Recife.
That’s a 75% decrease in the amount of feeder sand the Port Elizabeth beaches are receiving. Little wonder they disappearing!
Aerial photo from 1930 showing Noordhoek dunes going right across Cape Recife
Aerial photo from 1971 showing how dunes had receded
During the first half of the 20th century all the beaches from the harbor to Cape Recife were sandy. However, a report by the Institute for Coastal Research at UPE in 1985 showed that all the beaches except Kings were showing marked erosion. The only way to ensure the beaches not to fully erode away over time would be to re-activate the Noordhoek dune field bypass again.
Re-activating the dune field would essentially entail stopping the prevention of the natural flow of sand through this stabilisation, and let it revert to just following its course. Removing the stabilising vegetation would speed things up even further. In time this would see the Noordhoek dunefield cut right across Cape Recife as it did in the past and feed sand back into the top of Algoa Bay. It’s anticipated that it would add 15% to the current sand volume entering the bay. This would go a long way in helping to replenish the town’s beaches, as it would become a regular supply of feeder sand. Sand fed into the sea from the dunes would drift down towards the Bay’s beaches due to the natural longshore current that sweeps from the tip of Cape Recife into the bay.
It's estimated that it'll take the dunes about 55 years to reach the beach. At the moment they're about 1km away from Algoa Bay and moving at a rate of around 16m a year. This assumption is based on comparison of aerial photographs taken in 2004 and 2007. If an active effort was made to clear a path for them, and remove the stabilizing vegetation at the leading edge of the dune field, then it might speed things up a fair bit.
Comparison btw 2004 and 2007, showing a 16m growth of the dune field. Image courtesy Glendore Sand.
Ironically Sardinia Bay is suffering from too much sand at the moment. The sand got shoved back to make way for roads and amenities that we’re now accustomed to at the Sardinia Bay beach and beyond. Problem is, sand doesn’t respond well to being held back and is relentlessly trying to make its way back along its original track. This has seen the road and ablution blocks totally covered and Sards beach essentially cut off. Interestingly, if you check out the old map near the beginning of the listing, you’ll see that the Driftsand dune system which ran through Summerstrand and Humewood and supplied all the sand into Algoa Bay actually has the Sardinia Bay beach as its start point!
The consequences of letting that dune field return to normal would be pretty challenging so the ideal would be to get Noordhoek going again.
If the Sards dunes were allowed to have their own way, this is where they'd end up again. Just like it was back in the 1800's.
Thanks to Millers Local for the information and photos used as well as Glendore Sand as the original source of some of the pictures used by Millers Local.
