Guernsey Electricity Ltd and Réseau de Transport d’Électricité sought to develop electrical links between Guernsey and France, and Guernsey and Jersey. To support the design and installation planning of 100km of cables, the project required robust metocean information.
The bathymetry and current flow around Guernsey and the Channel Islands are highly complex; a bespoke modelling approach was required to resolve local conditions and underpin the analysis tools.
To build a 40-year hydrodynamic hindcast model for the analysis, our modellers extended the existing SEASTATES tide and surge model, enhancing the spatial resolution around the Channel Islands and the Normandy coast.
This nested approach enabled us to retain the relatively wide model extents to the west of the North West European Continental Shelf, which allowed the development and propagation of storm events from the model boundaries through the model domain onto the continental shelf. Tidal dynamics were also better simulated by allowing this wide model domain, instead of a smaller ‘on-shelf’ boundary.
This bespoke local model was validated using survey data.
Metocean analyses were undertaken using the HD hindcast along with the 40-year wave hindcast and publicly available wind data.
Outputs included characterisation of the metocean conditions, and operational and extreme parameters along the routes.
Further analysis was provided as a weather downtime assessment, assessing the data for environmental thresholds and working weather windows, supporting the planning of construction activities.