Some further understanding of the WASPHEAD

The silo as depicted appear to be floating just under the surface. I apologise for this illusion but it was really difficult to demonstrate the water flow beneath the Wasphead without doing that. The silos go to the sea bed but are deeply scalloped to allow flow throughout the footprint of the whole 'island'.
Of course the two lower diagrams in Fig. 8 show cut off sections and the plan view of the circulation of water beneath the 'island'.

The normal running of the hydroelectric generating unit is through the overspill or overflow from the top of the water-head in the silos thus keeping in hand that water-head potential when wind, tide wave and solar are inadequate to the grid's needs.
This allows tide and overspill from the central hydro-electric generating unit and from any overfill of the silos themselves which is not being diverted to this generating unit, to contribute to the tidal effect on the marginal tidal/wave generators.

In the vimeo there is some detailing of the flow of rainwater into the marginal silo

The whole of the 'islands' margin will be contained by these particular silos and the pump action of the tide and waves on the drum turbine in the base of the silos will contribute to the total water-head driving the central generation turbine and of course be separate from the section of silo above it containing the fresh water.

A diagram of the action of the drum turbine is shown in Fig. 9 below.

Some detail as to how the rotary and vertical reciprocation action of the drum pumps water through a cam mechanism is shown below.