Bob West, in his letter (NCE 1 May), is mistaken in assuming that the Venice barrier flood defence gates are similar to the bottom hinged flap gates evaluated during the feasibility study carried out by Rendel, Palmer and Tritton for the Thames Barrier.
The Venice gates are buoyant. Their mass and buoyancy resist the differential head between the Adriatic and the Venice Lagoon during a flood surge. This was not a feasible solution for the Thames Barrier because early elevation of the gates during the tidal cycle would not be possible.
Also, low upriver level during a flood surge would not result in the required buoyancy to resist the downriver surge.
Apart from the identification of both types of gate as bottom hinged flap gates, they are fundamentally different. The Venice gates were devised by an Italian Engineer, Ludovico Solinas, who has not received sufficient credit for his invention.
Professor Jack Lewin (F), 2 Beechrow, Ham Common, Richmond, Surrey, TW10 5HE