The Richards Bay lighthouse is in danger of collapsing because of serious coastal dune erosion, an environmental expert warned this week.
Transnet Port Authority (TNPA) has approved R10 million for a new lighthouse. Funding had been approved and construction would begin as soon as the land acquisition was finalised, TNPA said.
Durban consultant Dr Alan Smith, who visited the site a few weeks ago and is co-authoring a research paper on the dune erosion there, said: “The coastal erosion seaward of the lighthouse is serious and it won’t take much for the lighthouse to collapse. It must be moved.”
Smith was asked by the Daily News to comment after an aerial photograph taken during a recent flyover of the area revealed the lighthouse’s precarious state.
He said researchers were expecting high rainfall, which could exacerbate the erosion, next year.
“We are beginning to understand the rainfall and long-term tidal patterns that underpin coastal erosion, and we can begin to make forecasts many years in advance,” explained Smith, who is co-authoring the research paper with Dr Maria Ferentinou and Mike Jacobs of the University of KwaZulu-Natal.
He said coastal-erosion researchers had identified an 18-year cycle, which last peaked in 2006.
The next will be 2024.
“However, a shorter 4.4 year cycle (which last peaked in 2011 and with its next peak in 2015) is also present.
“This may be mitigated by river sediment transported to the coast as we are presently in the peak of the Dyer-Tyson wet season cycle, an 18-year cycle in which the annual wet season varies from a relative drought (as in 2006) to very wet.
“As 2015 is situated in the ‘wet’ part of this cycle, sediment may buffer the coast from erosion,” Smith said.
“The Richards Bay lighthouse may or may not withstand 2015, but sooner or later it will fall.”
Smith said that most of the coastal erosion around the lighthouse took place during 2006/7.
“This was a time of very high tides, large waves and little river sediment reaching the coast to buffer it.
“Coastal erosion results from a combination of unusually high tides and marine storms. The 2006/7 period was characterised by unusually high tides and very high waves,” he said.
“Research suggests that this is a part of the natural cycle although the actual climatic connectors are as yet insufficiently well understood. Strong coastal erosion was experienced in 1987-89 and before then in 1970 – dates which all correspond to the dry part of the Dyer-Tyson wet season cycle and the unusually high tides at the peak of the Lunar Nodal Cycle (the 18-year tidal cycle).”
An environmental assessment was done some years ago on moving the Richards Bay lighthouse, “but nothing has happened”, he said.
“Perhaps they have relaxed due to the lack of serious erosion over the past few years. This may change in 2015. The lighthouse will certainly collapse into the sea if nothing is done.”
Said Smith: “Coastal erosion is a fact of life and is exacerbated by the removal of dune vegetation and the dunes themselves.
“Coasts don’t get damaged, but unwisely placed infrastructure does. Consideration should be given to retreat.”
He said that in many cases of really bad dune erosion, the only option was to move the infrastructure.
“Hard structures such as sea walls will protect (for a while) what is behind them, but the problem is simply referred along the coast to the walls’ end, and the problem not solved. Soft defences (such as dunes and vegetation) are better, but they still refer the problem.
“My advice is, do not build too close to the sea, and any infrastructure which has been (built there) should have a phased retreat plan,” Smith said.
“The recent coastal building boom (in the last 25 years) has placed infrastructure at risk. Unfortunately, insufficient attention has been given to aspects of marine risk.”
His comments were supported by fellow researcher Simon Bundy, an ecologist with Sustainable Development Projects, and Coast Watch’s expert on sand dunes.
He said that the present image of the lighthouse, when compared with the 2004 image, showed a marked deterioration.
“The erosion has suddenly got worse,” he said.
“It is in the authorities’ interest to relocate the lighthouse. The dune environment can’t be replenished.”
David Gordon, TNPA senior manager Lighthouse and Navigational Systems, said they had two lighthouses in Richards Bay – Durnford and Richards Bay – situated close to the Port of Richards Bay.
He said the erosion along the east coast, affecting both lighthouses, was as a result of an extreme storm condition that occurred in March 2007.
“The land at Durnford has been fairly stable since that event and recent aerial photographs shows that the vegetation has re-established naturally. TNPA has a 24/7 presence at the Durnford lighthouse and is fairly comfortable that the lighthouse is not under any threat at present,” said Gordan.
“However, the erosion around the Richards Bay lighthouse, north of the port, has continued since the 2007 storm putting the lighthouse at risk.
“A decision to build a new lighthouse 600m to the north of the current site, has been taken at an estimated cost of around R10m.
“The new site is beyond the 100-year coastal setback line.”
He said funding had been approved and construction would begin as soon as the land acquisition was finalised.
“We expect construction of the new Richards Bay lighthouse to begin later this year and to take about four months,” Gordon said.
Umhlathuze spokesman, Vukile Mathabela, last Thursday undertook to respond to questions posed by the Daily News, but had not done so at the time of publication.
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DURNFORD LIGHTHOUSE
Province and nearest town/city: KwaZulu-Natal, Richards Bay.
Location: Latitude 28° 54.9’ S. Longitude: 31° 55.3’ E.
Date commissioned: March 1, 1916.
Architect/builder: The concrete structure was designed by the
Structural Design Office of Transnet;
and constructed by Protekon Construction, a subsidiary of Transnet.
Primary structure material of construction: Original: A 12m steel lattice structure painted white (1916).
Present : Cylindrical concrete tower painted white (March 2005). A red lantern-house will be fitted in the near future.
Original cost: R7 971
Height of tower:12 metres
Height of focal plane:56 metres above sea level.
Optic Original:800mm drum lens with an AGA acetylene gas
flasher.
Present: 178.5mm six-panel Vega VRB-25 rotating beacon with a 12 volt lamp.
Character of light: Composite group flashing four times every 40 seconds.
Intensity of light:50 538 candelas.
Range of light:19 nautical miles.
Other equipment: Racon and solar photovoltaic system.
Heritage status: Not applicable.
Inhabited/manned: No.
Open to public: No.
...
RICHARDS BAY LIGHTHOUSE
Province and nearest town/city: KwaZulu-Natal, Richards Bay.
Location: Latitude 28° 46.5' S. Longitude: 32° 07.7' E.
Date commissioned: May 22, 1979
Architect/builder: The concrete structure was designed by the office of the Chief Civil Engineer, South African Transport Services and constructed by its Harbour New Works Department in Richards Bay.
Primary structure material of construction: Square concrete tower with cylindrical top section, painted white, with white lantern house.
Original cost: R202 515.
Height of tower:11 metres.
Height of focal plane:72m above sea level.
Optic: AGA PRB-21 revolving sealed beam lamp array.
Character of light: Group flashing three times every 15 seconds.
Intensity:660 000 candelas.
Range of light:25 nautical miles.
Other equipment: Mains supply; stand-by diesel generator set. Telemetry monitored from Cape Point.
Heritage status: Not applicable.
Inhabited/manned: No.
Open to public: No.