Tidal Resource Modelling for the Territorial Waters of Guernsey

Part of understanding the marine environment is gaining knowledge of the marine processes that are constantly happening, including the tides, waves and sediment transport. As an appendix (C) to the REA, the RET commissioned Dr Alan Owen of Robert Gordon University to undertake a tidal resource mapping study for the 3nm territorial waters of Guernsey and Sark.

The report was based on work previously undertaken by Robert Gordon University for Black & Veatch Consulting Limited entitled “Tidal Stream Resource Assessment for The Channel Islands area”. The model used in this report formed the basis for the work undertaken by Dr Alan Owen for RET looking at the tidal stream resource in Guernsey waters. The report for RET is a refinement of the model, using a smaller scale grid system and improved data for the specific area.

The initial stage in forming the report was to gather all of the publicly available information on tidal movements in Bailiwick including admiralty chart data from tidal diamonds and other sources from studies undertaken in Bailiwick waters. As well as this, local expertise was sought to verify the data and to outline local anomalies, such as eddies, that are not picked up on other studies. Bathymetry data was also important for the study to understand where there is likely to be laminar flow and where turbulent flow would be expected.

The publicly available information was then fed into a computerised software algorithm, or model, which mapped the data and produced realistic values for where data was missing. The outputs from the algorithm are in the form of coloured graphics with arrows indicating strength and direction of flows.

This first stage was used to inform the REA as to the potential areas of interest in Guernsey’s territorial waters. Subsequent to the REA being completed, further empirical data has been acquired with the aim of validating the model outputs, so as to give RET a better understanding of the resource and its potentially exploitable magnitude in terms of energy generated. The report is available to download from the Downloads Page.