Clearly the solution to free the Thames Valley of flooding in the future will be a substantial project(s).
Present solutions appear to be at ground level and will result in considerable disruption and dare I say controversy.
Would a tunnel from the river to the south coast provide the necessary relief? The parameters could be a distance of 80km, and a head differential of 35m.
From the Lee Tunnel, it would seem that a substantial tunnel may cost £20M/ km; so for £1.6bn we may have a solution. I trust that a hydraulics expert will provide the basic answer.
Spoil, certainly from the south end, could be used to secure vulnerable coastline. Also, a hydroelectric facility could be incorporated into the design which would operate in a flow range from, say, normal to excessive.
George Muir, email@example.com