oa Analysis of Geophysical Datasets for Coastal Vulnerability and Asset Management

As part of Western Australia’s State and Coastal Planning Policies, local councils are formulating Coastal Hazard Risk Management and Adaptation Plans (CHRMAP) with the aim of rating areas of concern with a risk level and to assist in future planning of land use and infrastructure.

To assist with geological modelling of future coastal erosion a suite of geophysical methods was utilised to model current sand thickness and depth and condition of underlying limestone bedrock. Seismic Refraction, Multichannel Analysis of Surface Waves (MASW) and Ground Penetrating Radar (GPR) were utilises and all proved to provide reliable data in suitable conditions. However, all methods showed limitations which were noted to improve productivity and planning of future coastal geophysical investigations. These limitations included dealing with loss of useable data due to interaction with saline, saturated sands, inaccessibility due to topography or local scrub, and data resolution.

A combination of Seismic Refraction and MASW proved to be the most robust and reliable combination of geophysical methods with GPR utilised only when well above mean sea level and where high resolution modelling of karst and pinnacles was required. When combined with Cone Penetrometer Tests (CPT), selected methods showed to provide significant value to CHRMAP.