Noosa Spit just slipping sliding away
NOOSA Spit has been eroding at a rate of 27,000 cubic metres a year and preparing a council management plan along its shoreline to help fix severe erosion at areas like Dog Beach will cost more than $280,000.
That annual rate of loss reported to council after a detailed study equates to almost 11 Olympic size swimming pools and concerns are that a repeat of severe weather conditions could hasten a breakthrough.
Council has previously held talks with the Department of Environment and Heritage Protection about recommencing dredging and beach nourishment within the Noosa Spit at a site where its permit lapsed in 2009.
This would enable the council to dredge up to 100,000sqm of sand per year, well above current estimated requirements. A council study of the erosion earlier this year using a three-dimensional survey analysis found that 18,000sq m of sand was lost between November 2016 and July 2017 and further measuring will be repeated in July this year.
"It is difficult to predict with absolute certainty what rate of erosion will occur in the future,” the report said.
"This is affected by the impact of existing vegetation which could slow the previous rate of erosion but could also be accelerated by extreme weather events.
"What is certain is that the council would need to intervene to ensure that no break-through would occur to protect the overall purpose of the Noosa Spit, i.e. protecting Hayes Island.”
The report said if the current rate of erosion continues then by December 2018, the risk of break-through is low.
"If it continues at the same rate in 2019 and 2020, then the risk increases substantially,” the report said.
"The impact of extreme weather events is also an unknown in terms of the rate of erosion. The Noosa Spit has worked effectively as a defence for Noosa Sound since its creation nearly 50 years ago until 2010 when the Sunshine Coast Regional Council responded to severe erosion that was occurring at the north-facing beach of Noosa Spit known as Dog Beach.”
The report noted the council constructed both a geotextile sand container groyne and a submerged training wall in 2012.
A second stage of these works were designed and partially deployed and while these works included an investigation of the potential solutions at the time, the project scope was limited to the rehabilitation of these critical areas of erosion.
"The investigations that were undertaken at the time of this project were never developed into a formalised shoreline erosion management plan.”