Kinka Beach erosion again making waves
EROSION at the northern end of Kinka Beach has become a concern for Capricorn Coast residents once again, almost 30 years after major revetment work to resolve a massive erosion event that threatened to cut the Scenic Highway.
Livingstone Shire Mayor Bill Ludwig said in 1988-89 the State Government provided funding to put in place a hard rock revetment barrier as a measure of last resort to protect the Scenic Highway.
"Along with the rock wall barrier, which was buried under restored and revegetated dunes, a range of other mitigation measures were put in place to assist sand to accrete and replenish the heavily eroded beach," Cr Ludwig said.
"These measures included the establishment of an artificial groyne created by filling geotextile bags with sand harvested from below the high-water mark. The geotextile groyne assisted to mitigate the erosion and encourage sand accretion."
For three decades, these combined works have provided storage of tidal water to maintain the opening to the Causeway Lake. During that time, the inlet channel has once again moved south and west along the beach, causing erosion of the beach again.
Cr Ludwig said while coastal protection was predominately a state- controlled matter, the council had already begun an assessment and identified the matter in its Environment Taskforce Action Plan and listed it as a potential Coastal Hazards Adaption Strategy project.
"On the matter of the perished geotextile bag groyne, council has been progressively removing the perished bags and will continue to undertake tidy-up works to remove degraded material," he said.
"Survey teams are also currently shooting levels to ensure council has all the information, statistics and data required to find a sustainable long-term solution."
Deputy Mayor Nigel Hutton, who has personally inspected the site, said reinstatement of the tidal lagoon was a major project and any work would need to be well considered to ensure we got the best long-term environmentally sustainable solution.
"It is possible that joint remediation works could be simultaneously undertaken in conjunction with the proposed Causeway Lakes dredging," Cr Hutton said.
"This could create an opportunity to return sand that has been deposited into Causeway Lake from the ocean side back to the Kinka Beach to help replenish the newly eroding areas.
"This would be a real win- win environmentally in both addressing the Kinka Beach erosion while at the same time restoring Causeway Lake to its former glory as a major tourist attraction and water sports recreation area.
"The studies currently being undertaken in both locations will hopefully assist council in attracting the necessary state and federal assistance needed for funding."
While the council endeavours to rectify work on the erosion at Kinka Beach, Yeppoon resident Flavia Santamaria has raised concerns about the use of geotextile bags at both Kinka Beach and Great Keppel Island.
Ms Santamaria said few people were aware those same bags used on GKI, Kinka Beach and many other areas along the coast to halt erosion were made of plastic polymers and susceptible to degradation.
"They were designed for use on dry land during engineering works and are claimed to have a 25-year lifespan based on their intended use on dry land conditions," she said.
"Their use in coastal revetment projects is relatively recent and, with degradation accelerated by salinity, UV radiation, temperature and pH, sand abrasion, tidal undulation and variable currents, the potential for geotextile material to pollute the marine environment is of primary concern."
Ms Santamaria said existing reports on the benefits of geotextiles focussed on cost effectiveness, erosion control, wave mitigation and aesthetic appeal while denoting vandalism as a degrading factor.
"Reports do not appear to have deliberated on leaching and both natural and enhanced degradation," she said.
"Geotextile bags often need patching up and other substances are added when ruptures occur. Studies have found that when the synthetic materials were put under the influence of heat, sunlight and UV radiation, the materials became weak and brittle, leading to cracks whereby various phenolic phosphites, metallic sulphurous compounds, formed resulting in contamination and environmental pollution.
"These are dangerous chemicals that are being released in the Great Barrier Reef Marine Park and in the wider ocean.
"Since the installation of these bags on GKI and Kinka Beach, large and small debris have been found on beaches, on corals and floating in the water, causing grave concerns for the safety and integrity of the Keppel Bay waters and marine life," Ms Santamaria said.