Hebridean Marine Energy Futures (HMEF)

WP1: The produced model yields area maps of wave parameters, including significant wave height, directional peaks, means and spreads, mean wave period, and power flux. Time varying directional spectra were also generated for all the sensor locations.

The model will produce area maps of various wave parameters, and directional spectra at the locations of the wave sensors. Validation data and error estimations will be available following the end of the model run. Software tools for generating and post-processing simulations for multiple parameters and times have also been produced.

WP2: The data acquisition activities have returned wave datasets in displacement time series format, and also fully spectrally resolved, of durations and wave situations sufficient to support detailed and credible numerical wave resource modelling studies. The wave buoy data has already been used as boundary condition in DHI Mike21 SW models, with model calibration carried out against the nearshore ADCPs.

The wave buoy data has also been used by Open Ocean to calibrate an Outer Hebrides boundary model, with model outputs driving another DHI Mike21 SW model under the HebMEF WP1. This latter model covers the entire west coast of the Outer Hebrides island chain and has been calibrated and validated against both buoy and ADCP data for white-capping at the buoy locations and additional calibration parameters such as bottom friction and wave breaking applied against the nearshore measured data with results showing high similarity.

WP4:Differences were observed in Kernel Density Estimation area and distance from the mooring points, however it is currently impossible to say if these differences are due to the presence of a device or to other patterns of habitat use.

A combination of seasonality in device deployments, and varying detection rates in differing sea conditions and distances from shore could lead to spurious relationships between device presence and bird abundance and could explain the significance of device presence in the Generalised Additive Mixed Models Analysis. These issues cannot be meaningfully resolved until device deployments increase in length and cover periods in all seasons, including winter when there are fewer birds near the coast. It is also possible that there is a genuine effect correctly selected for by the model.

There are many possible ways in which changes in the marine environment could impact red-throated diver populations (mortality of different age classes due to collision or entanglement, non-fatal impacts such as disturbance or displacement, changes in prey distribution or availability) and the magnitude of these impacts on populations is not always clear. A direct mortality event may be less likely than a possible change in the prey distribution or repeated disturbance events, however if the risk of this is prolonged there could be a large impact on the population growth rate.