Quinns Beach is situated within the City of Wanneroo on the south western Australian coast, approximately 40km north of Perth. The beach is fronted by a series of three limestone barrier reefs, which in contrast to coral reefs, are highly perforated resulting in a strongly modified nearshore wave climate that is responsible for the undulating planform character of the beaches in the City of Wanneroo; with numerous salients and cuspate forelands. Quinns Beach is situated on one such large cuspate foreland and has been experiencing ongoing erosion since at least the 1940's. Despite several engineering interventions over the past 30 years erosion is continuing at Quinns Beach. The present best estimate is that the 4 km length of beach has an average annual sediment deficit of approximately 20,000 m3. From an engineering perspective, Quinns Beach presents a challenging problem due to the importance of both longshore and cross shore transport at both seasonal and individual storm timescales. This, combined with existing coastal structures, results in a particular sensitivity to antecedent conditions that causes the locations of erosion to change between storms and seasons. In an effort to better understand the sediment transport pathways and support the assessment of options to improve management of the erosion issue, the XBeach model was set-up and calibrated to observed nearshore currents and morphological changes for a storm in September 2014. The extensive reefs (the furthest located 5km offshore) presented a significant challenge for developing a model domain that successfully resolved beach morphological changes around coastal structures and had sufficient spatial extent to suitably capture important areas of wind and wave set-up on reefs that drive the nearshore circulation. Modelling this complex environment provides important lessons for future coastal engineering on coasts with fringing reefs more generally.
|Number of pages||7|
|Publication status||Published - 1 Jan 2015|
|Event||Australian Coasts and Ports 2015 Conference - Auckland, New Zealand, Auckland, New Zealand|
Duration: 15 Sep 2015 → 18 Sep 2015
|Conference||Australian Coasts and Ports 2015 Conference|
|Period||15/09/15 → 18/09/15|