9 March, 2010 – New York's Outer Harbour Gateway - a concept for Flood Surge Defence

Graeme Forsyth

New York is one of the world's major cities and is vulnerable to surge flooding.

As background to the discussions on this potential risk, the mechanism for surge flooding is described and examples of past floods and their outcomes are presented. The potential risk to the city of New York is examined using historical data and analysis by US federal, state and academic specialists.

The threat to New York has caused concern among the local engineering community, which led to an ASCE backed conference of researchers and engineers to examine the issues and the potential for solutions. Invited to participate, Halcrow developed and presented a concept design of a flood defence barrier, based on their work on the St Petersburg Barrier.

The concept design for the New York Outer Harbor Gateway is described. In providing protection, it crosses a 5 mile length of the harbour as a causeway, utilizes berms to reinforce existing land features and incorporates a number of large gates and sluices to accommodate ship navigation and water movements. The design requirements, options and selection of the gates, sluices, causeway and berms are discussed. Images of the St Petersburg Barrier are used to illustrate the scale and operation of the New York Barrier.

Comparative costs and timescales for barrier construction are presented.