A Penhorn Polder Wildlife Refuge for Hoboken Flood Protection

We hear all the time how The Netherlands is a demonstration of how the New York City and New Jersey metro area can adapt to coastal flooding.  But we have very little in common with The Netherlands … they have 28% of their land below average sea level and evacuation distances can be very long.  We have 0% below average sea level.  We have 0% of our neighborhoods below typical high tide levels (rounded off), for that matter.  Most importantly in terms of human vulnerability, as opposed to property concerns, our region has ample high ground for evacuation.

Building permanent walls or tide gates like the Dutch have done should be seen as a property-protecting solution only.  This approach successfully reduces risk for smaller flood events, leads to temporary safety, additional development in floodplains, and eventually, complacency.  However, it also dramatically raises human risks when “surprise” large events go higher than the design height of the barriers (just ask New Orleans).  Choosing a design height for barriers becomes especially problematic when sea level rise is accelerating, as we know they are now doing.

The Netherlands has one option that we may want to look at more closely, however — the humble polder.  A Polder is a large walled-in tract of land where water (and groundwater) is pumped out to a lower level than surrounding areas.  These areas then can accept flood waters from surrounding urban areas, as a last resort during a storm surge.  This hasn’t been examined in the New York City metropolitan area because we lack large, non-pristine open areas like the Dutch farmland … or do we?


Hoboken and its nearby neighbor to the west, the Penhorn Creek watershed, across the Palisades (The Heights).  The area is bordered on the north by highway 495, west by highway 95, south by County Road and east by highway 1/9.

Hoboken is a square-mile city with a population of 50,000 along the Hudson River with about 50% of its property inside the new (draft) FEMA 100-year flood zones.  Our mayor recently proposed using a combination of retractable and permanent walls to block out flood waters.  She also smartly proposed many additional redundant steps to improve resilience, such as elevating living quarters above base flood elevations.

If you look closely at a map of Hoboken, there is a heavily impacted region just over the bluff, just over one mile away — The Meadowlands.  In particular, the Penhorn Creek area shown above currently has about 50%  areal coverage of parking lots, and is most certainly not a pristine wild area.  What if towns like Hoboken and Jersey City bought up the properties and converted the area to a polder system, with environmental improvements to create something with more ecological value and far more societal value than what exists today?


Zoom-in to Penhorn Creek, just over one mile west of Hoboken

A standard polder protocol would apply — Pumps would lower the average water level in the area, and walls could keep out the tides.  A system like this can be modified and the parking lots removed to simulate a seasonally-flooded habitat instead of a tidal habitat, as long as the “low water season” coincides with storm surge season so it is a useful “escape hatch” for flood waters.  In the event of a 500-year flood that overtops all other protections, gated tunnels at the back of Hoboken could be opened and lead floodwaters away and gently down-slope into the polder.

I’m not sure I would vote for the idea, but it’s worth putting out there.  Cities like Hoboken are our most sustainable communities in many ways because of their urban density.  However, with increasing threats from sea level rise and storm surges, solutions for such a low-lying city with very little high ground are hard to come by.  It’s worth exploring any way to protect the city’s property.

The new FEMA advisory flood maps have 100-year base flood elevations of 14-16 feet, which is ~10 feet above the lower waterfront walls in some parts of town.  The 500-year base flood elevations are 4-5 feet higher … do we want 10 or even 15 foot high walls at the front of Hoboken?  The polder idea may enable us to simply plan for the 100-year flood, use retractable 5-8 foot walls on the waterfront and 10-15 foot high walls at the lowest points on the sides of town, and give us a back-up solution if the flood waters rise higher.

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Perspectives on NY/NJ Coastal Adaptation to Extreme Flooding Events

Jamaica Bay in 1844 - note the different location of the bay's entrance channel (Coney Island is to the far left)

Jamaica Bay in 1844 – note the different location of the bay’s entrance channel (Coney Island is to the far left). Small specks are actually depth values – this was a large map and these are readable in the full-size version.   There are no depths across the bulk of Jamaica Bay because it was too shallow at that time for anything but small boats.

I’ve been busy trying to finish up a bunch of storm surge related research for the past few months, but occasionally speaking on various scientific panels and other public events.  So, below I’m linking a few of these that people may find interesting and informative.

First, I’ll mention that I’ll be at City Museum of New York next Tuesday, participating in the panel discussion “New York After The Storm: Tough Questions”, moderated by NY Times architecture critic Michael Kimmelman.  Come see!


Note that reservations are required.  Click here to register online. For more information or to register by phone, please call 917-492-3395.

Here is a speech I gave and then a three-member panel discussion from the Metropolitan Waterfront Alliance “all hands” meeting back in November, on urban NY/NJ coastal adaptation after Sandy.  (Okay, so he ain’t no Kennedy, but he got some points across.)


Here is a very cool story on coastal adaptation options that was carried last week locally in the morning news on WNYC, relating to my long-time interest in wetlands and storm surges in Jamaica Bay.  (Check out the great map tool!  But note that it’s actually NOT the pristine Jamaica Bay, as there were already some major modifications by 1891, as shown in older maps like the one above).


And here is a more detail-oriented panel discussion with some colleagues for a special session of the NY State Assembly Standing Committee on Environmental Conservation’s public hearing on Extreme Weather.  I start at 0:51:50 into the session, but the entire session is very interesting (our panel ends at 2:06:00).


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Touring Sandy’s Impact on Lower Manhattan

High water mark in the South Street Seaport neighborhood, at South St. and Dover St., just behind (and downhill from) the waterfront. Site is just below the Brooklyn Bridge ramp.

After an interview at Battery Park on Tuesday the day after for ABC News 20/20 Special “The Perfect Storm”, I went on a walk to see the aftermath of Sandy’s visit to lower Manhattan.  My tour took me from Battery Park through the Financial District and then onward to South Street Seaport.

Pre-storm at Battery Park: Will the plywood storm barriers over subway stairwells and air vents be enough? We now know the answer, as six subway lines under East River were filled with water and are only just coming back into service … I don’t know whether these particular plywood boards worked — water could have gotten in through other “holes”.

Soggy plywood after the storm. Seems to have held, but you have to wonder how much water seeps in when there is standing deep water on top for a few hours.

Pumping water out near White Horse, a favorite old bar

The Financial District was a chorus of pumps and generators, lacking power but replete with water.

High water lines of flotsam at the Financial District intersection of Pearl Street and Hanover Square. Bad sign: portable plastic dams in the flotsam line.  Pearl Street used to be paved with oysters, back in the day, which should have been a sign …

“High water marks” such as those shown above will be valuable as we move to improve our storm surge model so that it can predict flooding within the city streets, for forecasts as well as for risk assessment.

Ramp down into underground parking — lots in flood evacuation zones may lose some popularity

Literally thousands of cars were flooded with seawater in the storm, including large lots full of new cars at the Port of Newark/Elizabeth.

South Street Seaport Heartland Brewers — sandbags in front of the door, but water finds a way — water condensation you see is on the inside.

South Street Seaport’s main drag was a mess, with an oily sheen over every surface due to the cars that were “floated” by the deep floodwaters.

Incidentally, we all have a new appreciation for neighborhood names, such as those with “lower”, “bay” and  “seaport”, versus “heights” and “upper”, and for that matter “Canal Street”.

High water mark looking toward South Street and Dover Street (same as top), shown with wet bricks and pink chalk.

With layers of expansion into East River over NYC’s history, the original waterfront street, Pearl Street (initially called “Queen Street”), is actually three blocks inland and was relatively dry.  However, landfill was used to extend the neighborhood seaward, and Pearl Street has been superceded by Front Street, and then by Water Street, and then seaward of that by South Street / FDR Drive and the modern-day waterfront park promenade.   Landfill compresses with time, so it is a downhill path from the seawalls down into this area, and these streets were temporarily re-claimed by the hungry East River during Sandy’s sojourn.

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Tempest-Tossed, Let’s Not Imitate New Orleans

[This opinion piece was published online in the New York Times Room for Debate series on 11/1/12 as part of the debate Should New York Build Sea Gates?  Someone also published an editorial with a similar point to my second paragraph in the Sunday Review this morning, though with detailed consideration of the issue's morality.]


In September, The Times reported that New York City might be “moving too slowly to address the potential for flooding that could paralyze transportation, cripple the low-lying financial district and temporarily drive hundreds of thousands of people from their homes.”

This week, the theory was tested, as Hurricane Sandy flooded parts of all five boroughs. Could sea gates or storm barriers help to prevent future flooding in New York City? Are they cost effective? Or is there a better alternative?


Tempest-Tossed, Let’s Not Imitate New Orleans

Hurricane Sandy has taken a severe toll on New York City, but it’s not likely to be repeated soon – it was an unlucky merger of the city’s worst storm surge since 1821 and a full-moon high tide.  While we should continue to study storm surge barrier options, we should avoid rushing back in time to the dam-building fanaticism of the 1930s-1950s, when rapid common sense actions are available to improve our floodwater resilience.

The original proposal to build three barriers and protect NY Harbor inside Verrazano Narrows does not protect the 300,000 people in Brooklyn and Queens that live around Jamaica Bay within the floodplain of a Category 2-3 hurricane (below 16 feet above sea level).  Worse yet, experiments with our storm surge model show that these barriers would slightly worsen the flood elevations in Jamaica Bay.  So, this plan may be perceived as choosing “winners and losers”, and the area with the greater population (and votes) is in the latter group.

Another barrier proposal is protective of nearly the entire city, but features massive levees over Rockaway Peninsula and other low-lying nearby land areas.  Who really believes that New Yorkers will be interested in taking the “New Orleans approach” to stopping storm surges?

Also, every barrier plan that has been presented would reduce exchanges of our city’s estuarine waters with the ocean, degrading water quality and changing temperature and salinity.  This would have complex effects on our rebounding ecosystems and coastal fisheries, a source of pride for a growing number of New Yorkers.

The silver lining is that now we’ll finally have the political will to tackle all the sensible, efficient defense measures we’ve been neglecting.  A great deal of protection can come from simply making better small-scale and (this time) watertight adaptations to protect subways and electrical infrastructure, such as retractable subway stairwell domes or rubber subway air vent covers.  Let’s leverage the amazing designers and engineers of New York City and have open design competitions.  This could be a 1-year or 2-year process, and we could dramatically improve our resilience in the rare event that seawater comes into our city.

And beyond that, we will now have license to think big.  Large areas like Jamaica Bay and Lower NY Bay have lost wetlands, oyster reefs and other natural systems that could be brought back to enhance our defenses.  These ecosystems can slow and reduce a storm surge, and they would have a wealth of other benefits including absorbing carbon dioxide from the atmosphere.  We can simultaneously work to improve our flood resilience, coastal ecosystems and climate, instead of rushing to pour concrete on the problem.

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Sandy We’re in Misery: Storm Recap

Hoboken taxi lot under water the day after Sandy’s sojourn to NYC and NJ. Credit: Charles Sykes, AP

Now that Sandy has moved on, and some of us are lucky enough to have power and be getting back to “normal life”, I’m finally writing to recap what happened with the coastal flooding and how the forecasts compared to the observed flood.

Coastal water levels in New York Harbor were the highest in all ~300 years of New York City (and New Amsterdam) history.  The water level at The Battery was 13.9 ft above the average daily low tide level (MLLW) at 9:24 pm EDT, with a peak storm surge of ~9.2 ft coming close to high tide.  This storm tide (water level) of 13.9 ft MLLW is about 5.5 ft above many of the area’s lowest sea walls.

Water levels (WL) for the secondary gauge (primary one failed) at The Battery for Hurricane Sandy, relative to MLLW (average daily low tide), from NOAA/NOS.  Obs-Pred is the “storm surge”.

Sandy’s storm tide beat that of Irene by 4.5 ft, the (80 year) tide gauge record of Hurricane Donna (1960), and the estimated all-time record of about ~13.3 ft from the Hurricane of 1821.  (though some estimate it to be more like 11.2 ft).

The flood elevation at Kings Point (Western Long Island Sound) was ~14 ft a few hours later, with a peak storm surge of ~12.3 ft coming near LOW tide – fortunate!

Our NYHOPS/SSWS webpage is offline due to the power loss in Hoboken, but the last graphical forecast of flood elevations that I have on my laptop (Monday at 10:30 am, posted on this blog) at Battery was low by 22%, and our forecast for Kings Point was low by 10%.  Other forecast models also under-estimated the central forecast, likely in part due to the unusual nature of Sandy (aka “Frankenstorm”) and its surprising strengthening on the last day.  The other models include P-Surge, ET-Surge (also shown here), and Stony Brook).  Some other things we will examine as possible factors with our model’s underestimation of the final storm tide are summarized in a recent paper we published on Irene’s storm tide, and include the “sea surface drag coefficient” that helps represent how well momentum from wind is transferred to the ocean, and the high-bias of the NAM atmospheric model in forecasting a tropical cyclone’s low central pressure (thus causing our model to underestimate the inverse barometer effect).

The forecast range given by NOAA’s National Hurricane Center was very valuable for decision-makers and the public, as they have a probability-oriented product that gives percent-likelihood exceedance levels.  They used those results to predict a storm surge 6-11 ft, and the surge was 9.3 ft at The Battery and 12.0 ft at Kings Point.   Stevens Institute doesn’t make probabilistic surge forecasts, but we’ve had preliminary signs that we’ve secured funding with a recent proposal to develop such a product.

(click to see) Animation of GOES infrared satellite data showing cloud top temperatures for Sandy as she made landfall in New Jersey Oct 29, 2012 (Credit: University of Wisconsin).
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Large oil spill in NY harbor delays port opening

A significant oil spill in NY harbor is keeping the critical Arthur Kill closed indefinitely.  The Coast Guard reports that the diesel leak from a fuel terminal was contained November 1.  The rupture occurred as a result of Hurricane Sandy and has been called a “catastrophic failure of tanks” by Rear Adm Abel.  Clean-up continues on the estimated 300,000 gallons of fuel.  NOAA and Coast Guard are responding and the Coast Guard Atlantic Strike Team has been deployed.

The Arthur Kill separates Staten Island from New Jersey and holds crucial oil supply infrastructure.  It is the passageway for container ships to reach Port Newark.  Clean-up of comparable spills has taken 1-2 weeks.  Terminals in the port sustained damage during the storm, including the flooding of the Philips 66 terminal on the Arthur Kill.  The Kill Van Kull was re-opened for vessel traffic today (November 2), but the Arthur Kill remains closed.  Addressing both the damage to the port infrastructure and the oil spill are necessary for fully re-opening the port to all shipments.  (More details on the status of the oil terminals here.) Popular Science today has an overview of the situation.

The Captain of the Port based at the Coast Guard station on Fort Wadsworth, Staten Island closed the Port of New York and New Jersey beginning Monday October 29 at 7 am.  This closure of the port, extending a week, is believed to be the longest.  The port of NY & NJ is the largest oil importing port in the country and the largest container port on the east coast.

NY harbor, normally bustling with vessel traffic, is quiet Friday afternoon. In the distance, vessels are moored awaiting entrance to the harbor.

Incidentally, jet fuel for the 3 NYC area airports is supplied by Buckeye Pipeline through Linden (NJ) Station.  Today that facility is transferring from generator power to main power. (From Department Of Energy Hurricane Sandy Situation Report # 11 November 2, 2012 (3:00 PM EDT))

Riverkeeper has been warning about water quality in the city’s waterways as a result of Hurricane Sandy.


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Upcoming Presentation on Surges, Barriers and Coastal Restoration

I have an oral presentation at the American Geophysical Union Fall Conference in San Francisco, December 4th, 3:25-3:40 pm.  It is particularly timely, given the destruction left by Sandy and the growing discussions about storm surge barriers.  And similarly, don’t forget that there is the Kerry Emanuel NYC hurricane risk lecture Nov 15th at Columbia (public) with attendance by registration only.

CONTROL ID: 1502631
TITLE: Contrasting NYC Coastal Restoration and Storm Surge Barrier Impacts on Flooding
AUTHORS (FIRST NAME, LAST NAME): Philip Mark Orton2, 1, Nickitas Georgas2, Alan F Blumberg2
INSTITUTIONS (ALL): 1. Maritime Security Laboratory, Stevens Institute of Technology, Hoboken, NJ, United States.
2. Center for Maritime Systems, Stevens Institute of Technology, Hoboken, NJ, United States.
ABSTRACT BODY: A detailed and well-validated hydrodynamic model is used to examine the potential effects of storm surge barriers and Jamaica Bay restoration on coastal flooding in New York City (NYC). The most recent flooding episode, the August 2011 tropical cyclone Irene, is utilized as a test case. Two experiments are run: (a) adding three storm surge barriers, and (b) reducing the depths of channels in Jamaica Bay towards their historical levels before extensive dredging took place. Results show that the surge barriers are an effective method for protecting the city center, but have a negative result of raising flood elevations outside the barriers. The rise is ~5% in the Jamaica Bay watershed, where most of NYC’s low-lying vulnerable population is located. Shallowing Jamaica Bay reduces Irene’s peak storm tide elevation by ~12% in the Bay, reduces normal high tide elevations, but also raises low tides and overall mean water levels. The reduction in storm tide flood elevations is enough to offset decades of anticipated sea level rise. In recent decades, tidal marsh islands in the Bay have been rapidly eroding. Further research should examine how the marshes would adapt to a managed long-term shallowing plan, as well as how their re-growth could provide additional flood protection.
KEYWORDS: [4564] OCEANOGRAPHY: PHYSICAL / Tsunamis and storm surges, [4534] OCEANOGRAPHY: PHYSICAL / Hydrodynamic modeling, [4332] NATURAL HAZARDS / Disaster resilience, [1641] GLOBAL CHANGE / Sea level change.
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