THE SANDY beaches ofAustralia's Gold Coast - or Surfers'Paradise as it is known across the world - play an important role in the country's tourism and the economy.
The beaches lose large volumes ofmaterial to coastal erosion. To control the sand erosion and assure the future of the region's tourism, local authorities have instigated a long-term coastal protection programme.
Besides conventional beach stabilising measures, The Gold Coast Beach Protection Strategy includes construction of a near-shore submerged artificial reef, designed to minimise the destructive effects of the waves upon the beaches and to improve the surfing conditions.
The reef has been built at Narrowneck, using more than 350 individually and accurately placed Terrafix Soft Rock 'mega sand containers'supplied and manufactured by Soil Filters Australia, a subsidiary company of German geosynthetics manufacturer Naue Fasertechnik which also provided technical advice and support.
The cross-section profile of the 350m x 600m, V-shaped artificial reef ranges between 1m and 10m below mean sea level and is positioned 200m offshore, producing left and right surf breaks.
By using mechanically bonded nonwoven geotextile sand containers as construction elements, a cost saving of 50% was achieved compared with conventional reef/ breakwater construction methods using rock or concrete.
Each of the 20m long sand containers was manufactured with diameters between 3. 0m to 4. 8m, resulting in filled weights of up to 500t.
Offshore installation was undertaken by local company McQuade Marine Dredging using its split hull hopper Faucon. During installation the pre-fabricated sand containers were opened out in the load area of the hopper, then filled with dredgings delivered by a trailing arm suction device.
After positioning using GPS, the sand container was dropped to the sea-bed by opening the split hull hopper in the ship's longitudinal direction. Up to 10 sand containers could be installed per day.
Construction work started in August 1999 and was completed in middle of this year.
Since then, considerable marine life - fish, algae, seaweed and surfers - have been observed settling on the reef after only a few months.