TWO eminent environmental scientists were part of a beach 4×4 drive last week to examine and document the full extent of coastline erosion north of Alkantstrand following an intense storm, tide and wind assault during the month of October.
Courtesy of Ezemvelo KZN Wildlife District conservation manager Frans Mthembu, the Zululand Observer joined Dr Alan Smith, research associate at UKZN and director of Alan Smith Consulting, accompanied by colleague Lisa Guastella to inspect the damage, taking advantage of the spring low tide.
During the drive, it became obvious the worst damage occurred closest to Alkantstrand, becomingly progressively healthier as one mover further northwards.
Similar pattern
‘Richards Bay appears to be going through the same erosion cycle as Thukela mouth,’ said Smith.
‘The latter has lost as much as 200m of land in the last 18 years.
‘Evidence indicates that this has happened before, however we do not know whether this is episodic or cyclic.
‘It seems to be related to a 60 years cycle driven by the Pacific Decadal Oscillation (similar to the El Nino/ La Nina cycle, but longer lived).
‘The more information we can gather on the coast the better our understanding of what is happening will be, and more importantly our ability to forecast.
‘Google earth imagery and GPS waypoints we have taken suggests that the area from Alkantstrand north to 9 Mile has lost about 6 to 12 metres since the last image (28 July, 2016) of this area.’
And while failure to replenish beach sand with dredge spoil has contributed greatly to the sad state of Alkantstrand northwards, Smith says there is more to it.
‘The combination of high swells and tides resulted in erosion and this, on top of the fact we are at the end of a drought – meaning there has been less sand transported by rivers to supply the beaches – meant that the KZN coast was vulnerable to erosion, with some areas more prone than others to attack by the easterly swells and the further high tides on 16-17 October.
Predictions
‘We have been monitoring erosion on KZN beaches since 2006 and in that time it has become evident that change takes place very rapidly,’ said Guastella.
‘With the use of tourist and surf cams we have established a database from which patterns are emerging.
‘These patterns explain ‘erosion events’ to a certain extent.
‘There appear to be several cycles operating: an 18-, a 4.5- and possibly a 60-year cycle.
‘We cannot predict the day that the erosion will happen, but we can predict the year with about a 12 month uncertainty.
‘Severe erosion was expected in 2015, but instead it took place in 2014 and 2016.
‘The more data that we collect will allow a better understanding of what is going on and give us the ability to more accurately forecast coastal erosion.’
Send in your old photos
Dr Alan Smith is keen to get old photographs showing what the coastline looked like in past years.
‘When beach driving was still permitted, many people would have taken photos of outings to the sea.
‘There must have been plenty taken at Alkantstrand, 5 Mile, Dawson’s and other spots along the coast,’ says Smith.
They can be emailed to asconsulting@telkomsa.net and copied to dave@zob.co.za
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