Fig. 2 Two years of online monitoring data showing variation of (a) wind
speeds, (b) wave heights
The variation of the wave speed along the depth of the sea was also
monitored by taking measurements every 3 m from the free surface of
seawater, up to a depth of 33 m below the sea level. Fig. 3 shows that
the wave speed below the sea level remains fairly constant with
increasing depth and undergoes a rapid drop as the depth reaches 24 m.
This value corresponds to a region within few meters of sea floor and
the fall in wave speed can be explained by the obstruction offered by
the sea-bed. It is worth mentioning that this measurement indicates that
the sea waves at the sea-level would have maximum contribution towards
wave loads, therefore the present study uses the height of sea waves at
the surface to compute the wave loads on the monopile foundation.