New moorings: wave data and engineering design

A new mooring design (Martini et al. 2021) has been developed and is being used with lightweight wave buoys to provide live verification data for coastal wave models.

The Waves and Littoral team of CSIRO Bluelink, in collaboration with UWA, have recently deployed 4 Sofar Spotter wave buoys and 3 acoustic wave and current profilers (AWACs) off the coast of Mandurah, south of Perth. The intent is to collect observation data for the verification of high-resolution littoral and wave modelling; a lack of observations is one of the biggest hurdles in studying the nearshore environment.

The Mandurah site was chosen due to the co-location of other instruments from a UWA coastal erosion study. The exact locations were further refined based on analysis of LiDAR bathymetry available from the WA Department of Transport and publicly available Sentinel 2 satellite imagery.

 

Sofar Spotter buoys are an exciting new tool in the wave measurement field. They are relatively cheap, and can be used as either drifting or moored buoys. They are even deployable from aircraft. In Mandurah, the buoys are moored using an innovative and economical engineering design.

Building and deploying moorings to suit the new lightweight wave buoys was a unique challenge. The CSIRO Engineering & Technology Program worked to reduce the overall mooring hardware to an absolute minimum, which led to simplified operational aspects and reduced cost. The recent publication Martini et al. (2021) describes this approach, and provides guidance and design ideas for future lightweight wave buoy installations.

To evaluate the output of the Sofar Spotter buoys, AWACs have been deployed nearby. These will provide independent measurements for verification, and the combined observations will contribute to scientific study of alongshore and cross shore gradients in wave energy.

Additional instrumentation will be deployed in future to examine the surf zone.