Application of geomorphic frameworks to Western Australian (WA) government coastal management has been more of an ‘objective’ than a ‘project’. Project studies and components have been funded on an ad hoc basis, opportunistically based on short-term needs of several different agencies. The strategic vision behind development and use of geomorphic frameworks has been led by Dr Ian Eliot.
Several of the team members have been involved in development and implementation of coastal planning policy through the 1980s to early 2000s. Although the incredibly diverse morphology along the enormous WA coast was acknowledged, only one simple method was presented for determining coastal setback allowances. This involved use of a beach profile storm-erosion model and local rates of coastal vegetation line change. Progressive application by bureaucrats and interpretation by consultants became increasingly convergent, largely resulting in limited consideration of either changes in morphology or the influence of the wider coastal setting.
The need for improved integration of locally-relevant coastal science with policy was identified by the State Government. Three pathways for improvement were undertaken:
Refinement of numerical modelling techniques to provide improved simulation of locally-relevant processes, co-ordinated through the Western Australian Marine Science Institute;
Improved description and classification of Western Australian coastal morphology;
Revision of the State Coastal Planning Policy to incorporate greater consideration of the morphologic range.
Almost simultaneous to this process, refinement of marine planning in Western Australia had acknowledged the relationship of geologic and geomorphic settings to the spatial distribution of marine habitats. Mapping of regional and sub-regional geomorphology (i.e. large-scale) was used to support definition of marine planning precincts.
Parallel classification of coastal geomorphology at a range of scales supported synthesis of scale-relationships. Consideration of how geomorphic information is used at different scales highlighted the need for a multi-disciplinary approach between planners, coastal engineers, geomorphologists, ecologists and environmental geologists. This provided a scientific challenge to meaningfully transfer between the modes of thinking used by coastal engineers, geomorphologists and geologists to explain coastal dynamics. The knowledge and intense collaboration of Dr Ian Eliot and Dr Bob Gozzard (Geological Survey WA) were essential to develop of a meaningful approach.
A hierarchical framework based on geomorphology and geology was developed, built around the main applications of planning at different scales. In this regard, the framework deliberately differs from solely spatial-based hierarchies.
Several applications of the geomorphic hierarchy have subsequently been undertaken:
Coastal information has been collated for a number of sub-regions along the Western Australian coast to support strategic planning. Geomorphic classifications within the framework were used to develop large-scale evaluations of coastal vulnerability. The relative sensitivity of each morphologic classification to active drivers (e.g. meteorology and oceanography) was combined with a measure of the relative susceptibility to change (e.g. sea level rise or human coastal interventions), to develop a vulnerability index.
Analysis of physical coastal parameters including geology, sediments, morphology, geometry and energetics was used to define two-dimensional sediment cells along extended parts of the Western Australian coast. The sediment cells provide indication of areas within which sediment exchange may be strongly related, and therefore provide an important contextual basis for evaluation of observed or anticipated coastal change. A three-level hierarchy has been used, broadly related to time scales from years to centuries, within which coherent behaviour is expected to occur.
The geomorphic framework at the scale of tertiary sediment cells has been used to structure a regional coastal monitoring program for the Peron-Naturaliste coast in southwest WA, along a length of approximately 300km. Identified coastal behaviour within sediment cells supports the integration of high resolution monitoring techniques in areas of high development density with more cost-effective use of indicator monitoring in areas of low development density
Regional differences in pathways for coastal response to sea level rise have been presented in the context of geomorphic frameworks. Consideration of existing morphology in the Vlamingh (southwest WA) and Pilbara (north WA) regions has demonstrated the need for improved understanding of sediment dynamics and controls when evaluating sensitivity to change.
The considerable body of work developed to support use of geomorphic frameworks on the Western Australian coast has helped to stimulate national interest and activity. Most States have experienced a similar pathway of coastal policy and science divergence over the last 30 years.
Organisations who have funded studies that contributed to the identification and application of geomorphic frameworks for coastal management include the Western Australian Departments of Planning, Transport and Parks & Wildlife, along with Geoscience Australia and the nine local government bodies who form the Peron-Naturaliste Partnership. Within each of these agencies, we have had in-industry champions, too numerous to list. The contribution of the Geological Survey of Western Australia, through the ongoing involvement of Dr Bob Gozzard, has been immeasurable.
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