Our Quarries Sardinia Bay beach
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SARDINIA BAY BEACH SAND Glendore Sand and Stone is actively involved in the "Save the Beach" campaign. This has included assisting to remove sand to help keep the lower car park open. Background Over the last twenty years, the vegetation on the foredune ridge, which serves to protect the hinterland from erosion by waves during severe storms, and also prevents the sand on the beach from progressing inland, has been damaged to such an extent that it has basically ceased to exist. This has resulted in the advancement of windblown sand from the high water mark, over the remains of the foredune, and towards the carpark. If left unchecked, this will result in the sand continually advancing inland. Where does the beach sand come from? Sediments on beaches are transported by wave driven littoral drift. In the region of Sardinia Bay, the sediment is transported parallel to the coast, in an easterly direction from Tsitsikamma to Woody Cape. When a half heart shape bay occurs, the sand is deposited onto the north eastern shore. This occurs at Sardinia Bay, Cape Receife, Seal Point, Oyster Bay and in the Van Stadens/ Maitland area. Tthe Agulhas current runs south-westward down the Eastern Cape coast in the deep water, and when it hits the Agulhas bank, it creates a counter current, which swings back along the south coast in an easterly direction. It is this counter current that carries the sand sediment which gets deposited along our beaches.
Function of the foredune Under normal wave conditions there is a nett onshore movement of sediment which is transported by the wind and is deposited ashore as coastal dunes. During storm events, there tends to be a net offshore movement of sediment and the beaches are temporarily eroded. The foredune ridge serves to protect the hinterland from erosion by waves during severe storms and supplies sand to replenish the beach-line afterwards. if the foredune is removed for any reason, or damaged, the beachline may not be re-established naturally. This has happenned at Sardinia Bay beach - the flora on the foredune is very hardy, and is able to survive natures wrath, but is completely unable to survive man's interferance, and man's mark has been made in no uncertain way at Sardinia Bay over the last 20 years. The dunes adjacent to the coast at Sardinia Bay can be divided into two components. the first is a belt of mobile dunes moving along the coast, and the second is what should be a relativly fixed vegetated foredune ridge. In its natural state, the foredune ridge tends to be apporximatly 40% vegetated. Blowouts occur at regularly spaced intervals in the half heart bays between Port Elizabeth and Cape Town. Under certain conditions, blowouts develop. these are long strips of bare sand that run between the beach and the vegetation behind the foredune. Under certain conditions these can enlarge. Natural landward movement of sand in other areas, such as Joorst park and in the Alexandria Dunefield, is minimal, ranging between 025 and 1m per year. (Illenberger & Burkinshaw 1996) Movement at Cape Receife and Sardinia Bay is vastly different, and is about 16 metres per year. (see photographs below) How do Sand Dunes Move? Posted by: strandloper on www.sardiniabay.co.za Sand can only be moved by strong, steady winds. The air must be moving at least 15 miles per hour (about 24km/per hour) to be able to pick up sand grains. These winds are called unidirectional winds because they always move in the same direction, from the southwest to the northeast. As the wind blows, it pushes the sand ahead of it, so individual dunes are slowly moving to the northeast. Sand is not as easy to move as you might think. Even very strong winds can’t lift the sand any higher than three feet above the ground. As the wind blows, it lifts small sand grains a few feet off the ground, then drops them. When they hit the ground, they bump into other sand grains and cause them to jump up and be caught by the wind. It’s almost as if the sand is playing leap-frog, jumping and bumping along. This kind of jumping movement is called saltation. You can see this kind of movement on the windward side of the dune, or the side facing the oncoming wind. But what about the leeward side of the dune, protected from blowing wind? What causes the sand to move on that side? As the tiny sand grains slowly work their way up the windward dune face, they finally reach the crest, or top of the dune. They fall over the crest and start to pile up because they are protected from the wind. Now gravity steps in to move the dune. As more and more sand grains pile up, the angle of the leeward face becomes steeper and steeper. A pile of loose material, like sand, can only hold a slope of about 34 degrees. When the slope gets greater than 34 degrees, gravity pulls the loose sand down. Small avalanches occur. The sand might run down the leeward face like a waterfall, or the whole side might slip at once. When the entire face of the dune slips, it’s called slumping. How fast a sand dune moves depends on a number of things. Of course, the speed of the wind is a big factor. Wind that is blowing 45 miles per hour(about 24km/per hour) will move more sand than at 15 miles per hour(about 72km/per hour). The size of the dune is also important. Smaller dunes with less sand move much more quickly than large ones. The vegetation also plays an important role. The dunes get caught on the plants that grow in the basin, and that slows them down. There are 4 types of dunes.The first ones to form, the “baby” dunes, are called embryonic dunes. They are usually not more than 20 feet. high.Transverse dunes form long ridges of sand, and can be very tall. They move much more slowly - usually between 8 to 12 feet a year. Barchan dunes are crescent shaped. This dune looks like a new moon. The arms or horns of the barchan dune always point in the direction the wind is blowing. Barchan dunes are also very large, and move between 8 and 12 feet per year. The last type is called a parabolic dune, and looks like an inside out barchan dune. The movement of this dune has been slowed down by vegetation, and rarely moves more than 5 feet per year. The road becomes blocked by sand and is re-opened
The entrance road to Sardinia Bay Beach first became blocked by sand during late 2007, and Glendore Sand becamed involved at that stage. After much negotiating with varius stakeholders, the NMMM put out a tender for the removal of the sand. Glendore Sand and Stone was awarded the tender and commenced work immediatly. By December, the road was open again, and over 11000 cubic metres, or about 15000 tons had been removed!
2007-12-14 After the sand had been removed 2008-01-22 the sand is on the move again! The road to the lower car park once again became completely blocked by windblown sand during the Great Storm of June 2009. This proves that the foredune has ceased to function naturally, and is no longer able to hold back the sediment deposited onto the beach. If left unchecked, this sand would continue advancing!
2009-06-24 The start of the storm The shape of the beach had completely changed after e. the storm
2007-12-14 - After the sand had been removed By 2009-07-03 the road had been completely closed - Glendore assisted to re-open it On Friday 03 July 2009, Glendore Sand & Stone, in conjunction with the Sardinia Bay Action Group started removing Sand from the sand dunes adjacent to the entrance road of Sardinia Bay Beach, to enable traffic to once again use the lower car park. This was done free of charge, as a goodwill gesture by the company.
Various stakeholders are being engaged to discuss long term solutions, and the public will be advised as regards developments. More information can be found on www.sardiniabay.co.za. Proposals for solutions One of the current proposals being considered ( by Arcus Gibb (Pty) Ltd and others) is as follows:
The proposed development activities were formulated to reach an integrated solution to the problem of moving dunesobstructing public access to Sardinia Bay beach that is future proof for many years to come. Specific activities consist of: Many persons feel that this is not a suitable solution. A particular concern is that if an emergency occurs, there will not be access to the beach for NSRI, emergency services etc.
The view of Glendore Sand and Stone is that the foredune should be rehabilitated to prevent the movement of the sand dunes. This would also enable locals and tourists to continue to use the beach. Our response to the basic Environmental Assessment was as follows "The public, including the disabled, old and infirm, and those with young children have been enjoying access to Sardinia Bay by means of the existing road for the last 60 years at least. Why should it now be closed? It is quite obvious that the problem is being caused by the destabilization of the foredune through the activities of the public. This area should be fenced off as it was a number of years ago and the re-establishment of the foredune made a priority. This should be done by the metro with the assistance of the Lifesaving Club and security firms. The costs could be covered by charging an entrance fee at week ends and during school holidays. Glendore Sand, removed approximately 11000m^3 of sand from the access to the car park at NO COST to the NMMM (yes, we removed it at no charge in exchange for the sand). We would be prepared to continue this arrangement provided the necessary permissions were obtained by the Metro, until such time as the foredune is once again established. The previous boardwalk disappeared – why will this one be any different. While I absolutely agree that the environment should be protected, it should not be at the expense of one of our most pristine and unspoilt beaches becoming inaccessible to about 50% of it’s regular users, particularly if this access can be maintained by reversing the adverse impact caused to the environment by undisciplined members of the public." Latest Updates
A Stakeholders meeting was held on 09 July 2009, and the outcome was while many are extremely appreciative of Glendore's input with regards to the clearing and opening of the road, no one is currently able to actually take responsibility for the area, nor is anyone able to grant permission for the removal of sand! The opinion of the Sardinia Bay Stakeholders group is that if Glendore makes contact with the appropriate Authorities & permission is given, then perhaps the road clearing could continue until such time as an alternative is established. Glendore remains committed to trying to keep the beach accessible for all persons, and will continue to engage the stakeholders in this regards. Once of the sticking points seem to be the NEMA, or the National Environmental Management Act, which states that natural processes may not be interfered with, especially in the coastal zone. But consideration must given to the fact that if the dune movement is not controlled, the sand WILL eventually reach Algoa Bay, and in the process pass through the airport and through Summerstrand.
The map below shows the source of the Lovemore Park Dunes and the Summerstrand Dunes, and areas that the current Sardinia Bay Dune Movements could impact if left unchecked. it can be clearly seen that the "Driftsands" of Summerstrand originally came from the Sardinia Bay Area. The sand dunes that Glendore Sand and Stone have been mining for the last 20 years, in Lovemore Park, also originated from this shoreline! The argument by certain environmentalists is that nature must be left to take it's course - but the problem here is that if this is done, it will not only mean that the existing Sardinia Bay beach carparks (Upper and Lower) will be covered with sand, but eventually, the sand will spread right through to the Airport, possibly covering the runways, and then procede through Summerstrand, (possibly inundating hundreds of houses with sand dunes), and end up blowing into the sea at Hobie Beach - an interesting consideration! The following photo shows the advancement of the dunes at Sardinia Bay over the last 5 years.
The following photo has been edited to display what the Sardinia Bay Beach might look like within 2 years if the dunes are left to run their course.
The dune advancement on a similar Dunefield at Cape Receife has been about 16 metres per year - and consider that these dunes are between 3 and 5 metres high! It is amazing what quantity of sand the wind can move in a short space of time.
Keep checking this page - more updates coming..... |
