A perched beach is a beach that either overlies a hard substrate; or has a hard substrate seaward, but that is landward of the depth of closure. Naturally-formed perched beaches are due to coral and rock formations that are present along much of the world's coastline. In addition, many beaches with engineered structures such as shore-parallel breakwaters and artificial reefs may also be considered as perched. The goal of this thesis was to investigate how coastal reefs influence spatial and temporal variability in coastal erosion and accretion, over nested temporal and spatial scales. To provide a framework for this process-based research, the first fully-comprehensive classification was developed of morphotypes of rock and coral formations supporting perched beaches. A novel feature of this classification is its universality and flexibility. It is based on four morphological elements (reefs, pavement, horizontal platforms and ramps) that can have common morphologies regardless of what substance the structure is made of (limestone, coral, beachrock, etc.). These elements can vary morphologically within 8 attributes, such as roughness, elevation relative to tidal range, alongshore porosity and cross-shore width. The influence of the reefs on coastal morphodynamics from hours to decades was investigated in detail at one type of perched beach: a sandy beach with reefs at Yanchep Lagoon in southwest Australia. This was based on multi-scale field deployments during sea breezes and storms, and monthly to seasonal time scales.
|Qualification||Doctor of Philosophy|
|Award date||30 Aug 2013|
|Publication status||Unpublished - 2013|