The Sandy-affected region is a long coastline with many assets, and as we now know, at risk. A fully comprehensive solution is beyond our means, so we will need to prioritize, build smart, and recognize where best to focus our resources. Integrated into our built environments our investments in risk reduction should also empower our communities and our economy, allowing us to grow resiliently.

The approach of team OMA is framed by a desire to understand and quantify flood risk. In doing so, we are better positioned to identify those opportunities that present the greatest impact, the best value, and the highest potential—our areas of focus.

Within the Sandy-affected region, New Jersey’s communities of Jersey City, Hoboken, and Weehawken are susceptible to both flash flood and storm surge. As integrated urban environments, discreet one-house-at-a-time solutions do not make sense. What is required is a comprehensive approach that acknowledges the density and complexity of the context, galvanizes a diverse community of beneficiaries, and defends the entire city, its assets and citizens.

Two-thirds of Hoboken lies within the FEMA 100-year flood zone—Sandy clearly demonstrated the consequence of such vulnerabilities to flood risk; Hoboken is the 4th densest city in the country, and represents a sizeable concentration of value; The NJT / PANYNJ transit complex at Hoboken station, and NHSA sewage works, are examples of exposed infrastructure with significant regional impact. It is the combination of these factors, and others, that warrant such significant investment in flood defense. Engaged citizenry, and leadership with the capacity to move quickly, provides the conditions for a swift political process.

Our comprehensive urban water strategy deploys programmed hard infrastructure and soft landscape for coastal defense (resist); policy recommendations, guidelines, and urban infrastructure to slow rainwater runoff (delay); a circuit of interconnected green infrastructure to store and direct excess rainwater (store); and water pumps and alternative routes to support drainage (discharge).

The objectives of this manifold strategy are to manage water, for both disaster and for long-term growth; to mitigate the financial pressures of flood insurance―enabling reasonable premiums, or exemption from the Federal flood insurance program, through the redrawing of the FEMA flood maps; and the delivery of co-benefits―including: civic, cultural, recreational, and commercial amenities―that enhance the quality of the built environment.

The net benefits are considerable. A robust flood defense will avert losses to assets and disruption of activities (preserve); in turn, this will lead to considerable savings on the ongoing cost of defensive measures and emergency response (reduce); the defensive infrastructure will serve as the catalyst for community amenities (enhance); while the certainty afforded by these measures will provide a sound basis for growth (sustain).

Our strategy is predicated on a series of innovations: a comprehensive approach to flood risk; a coalition of stakeholders and collaborative funding framework; an umbrella of communication and education; and integrated multi-faceted design solutions. Inherent to each innovation is the opportunity for replication across the region—insuring positive impact from both the built solution and the propagation of its underlying ideas.

Implementation of our strategy will be carried out over a number of years and leverage a broad program of funds across government, philanthropy, business, and community sources—including the keystone investment of $230m in HUD CDBG-DR funding.

Fig. 1 A four part comprehensive urban water strategy. Photo courtesy of OMA.

Fig. 2 How it works—water graphs. Photo courtesy of OMA.

Resist:

• Defense against storm surge is primarily a question of elevation. The height of flood defense measures is determined by an extreme water level analysis, which is based on storm surge water levels to defend against – in this case, a one-in-five hundred year storm surge water level – and expected sea-level rise.

Delay, Store, Discharge:

• Flash flooding from rainfall occurs when rainwater overwhelms the capacity of the drainage system—water goes in faster than it can come out—the intended level of defense against this systemic seasonal flooding is a one-in-ten year flood level.
• Delay strategies act like a sponge by slowing rainwater down. This slower rate of flow gives more time for the drainage to do its job.
• Store strategies temporarily take excess water out of the drainage system. This water can later be returned once the system has recovered capacity.
• While Delay and Store address water going in, Discharge strategies address water going out—removing water from the system. Additional pumps, and alternative drainage routes, increase the rate in which this can occur. 

Together, these complementary strategies provide a robust, cost effective, system of defense that no single strategy can deliver.

Fig. 3 Hoboken Waterfront (aerial). Photo courtesy of OMA.

Fig. 4 Hoboken Waterfront. Photo courtesy of OMA.