CASE STUDY: STABILISATION OF A RAPIDLY ERODING POINT USING AN INSITU-FILLED GEOTEXTILE CONTAINER GROYNE FIELD

Abstract

Munna Point is a premiere recreational beach in the Noosa River which has been maintained by regular nourishment for over 20 years. As longevity of each nourishment was less than 6 months, the long-term costs were high and efforts were eventually suspended resulting in loss of the beach. In an effort to reinstate the amenity and provide a more stable beach, a groyne field accompanied by nourishment was proposed. To provide a low-impact, low-risk and low-cost solution, the groynes were designed with a low crest using sand-filled geotextile containers. To achieve the design, containers and scour mattresses were filled in-situ using a dredge, which was an innovative application of a methodology typically adopted for much larger containers. The first 3 groynes have successfully been installed as part of the first stage and 12 months of monitoring subsequently undertaken. The groynes have clearly been effective at extending the longevity of the nourishment and the wider intertidal profile has remained very stable. The beach is now successfully enhancing the amenity of the community and experiencing a high level of usage.