Gardline purchases 25 AWACs for deployment along the UK coast

The initial purpose of Gardline Environmental’s project is to accurately calibrate the transformation of wave energy reaching the Anglian coast. A network of Datawell Directional Waverider buoys will also be maintained in deeper water offshore and transmitting data in real time. After several years of comparative measurements, the calibration of the wave transformation model between offshore and inshore directional wave energy spectra will be verified for all normal conditions with a large statistical dataset available for forecasting of extremes.

Tidal harmonics and surge heights are also extracted from the AWAC data to be related to the range of wave states between calms and storms. The cotidal model for the Anglian coast can be refined with surge variation studied between the existing Data ring sites maintained as part of the National Surge Monitoring Service.

Internal recording by the AWACs will provide accumulating blocks of data for the wave/tide/current model calibrations being numerically modeled by Consultant Engineers as a post-processing exercise. The eventual aim is to develop a precise, comprehensive model for the long coastal region which will run in real time with on-line wave readings being fed into the model from the permanent offshore wave buoy network alone. The Datawell buoys already feed continuous wave measurements ashore by HF radio links to receivers linked to Broadband internet connections. Wave spectral processing and quality control can then be performed at Gardline's base in Gt Yarmouth. Back-up, compressed spectra are also prepared by the buoy's microprocessor and transmitted by the Orbcomm satellite link. When proven, the whole system will be available as a national resource.

The Anglian coastline is constantly changing with mobile sandbanks under strong currents, beach erosion in storms, seasonal accretion during calmer periods and mudflat areas being threatened by rising sea levels. A parallel project will seek to calibrate bed-load transport levels by utilizing AWAC acoustic backscatter intensity collected in the lowest data bins at each site. Recording laser particle-sizers (LISST-25) instruments will be deployed alongside AWACs in this research calibration phase.

The profiled currents will be used in studying the phase of suspended sediment levels combined with the periodic amplification by wave-induced disturbances being monitored.

In order to provide a comprehensive calibration of the wave transformations between the permanent offshore monitoring buoys and the coast, it is anticipated that several annual periods will be studied. Initial modeling results are expected to highlight certain complex coastal areas where more measurement sites are required. The multi-function capabilities of the AWAC instrument suggest it will remain a useful tool for ongoing wave/current/tide/sediment studies in the southern North Sea for as long as serious concerns remain for the low-lying coastal reaches.

This is another example demonstrating that the AWAC has become the state-of-the-art sensor in bottom-mounted current profile and wave measurements. Now not only researchers and scientific personnel are acknowledging the uniqueness and superiority of the AWAC, but also the commercial part of the business.

For more information, please contact Greg Brown at Gardline Environmental Ltd. (Greg.Brown@gardline.co.uk)