Hurricane Sandy Storm Surge Map Animations

Hurricane Sandy was a wild beast, with a powerful high pressure system, a hurricane, a nor’easter and a high tide all meeting simultaneously to cause the highest flood in NYC history.  As a result the peak flood height was poorly forecast by federal and academic scientists.  One of our main pursuits at Stevens Institute’s Davidson Laboratory (aka Center for Maritime Systems) has thus been “capturing Sandy” — creating a reproduction that is as accurate as possible.

Click to see an animation of Hurricane Sandy modeled wind and pressure driven storm surge (color shading) from Hatteras to Nova Scotia. Arrows are wind velocity vectors (see the scale arrow for a 33 m/s or 74 mph hurricane strength wind), contours are isobars - lines of constant atmospheric pressure. An inset panel shows the four day time-history of modeled surge near NYC's shoreline at Sandy Hook.

Click to see an animation of Hurricane Sandy modeled wind and pressure driven storm surge (color shading) from Hatteras to Nova Scotia. Arrows are wind velocity vectors (see the scale arrow for a 33 m/s or 74 mph hurricane strength wind), contours are isobars – lines of constant atmospheric pressure. An inset panel shows the four day time-history of modeled surge near NYC’s shoreline at Sandy Hook.

In order to do this, we needed to find the best representation available of Sandy’s winds and pressure, and accurately simulate Sandy’s storm surge using our ocean model.   We also then needed to compare the resulting flood heights around the region to verify that they are accurate (they are, to an average across several tide gauge stations of 15 cm rms error for the animation above, 16 cm rms error for the animation below).  

Above is an animation of Sandy’s winds, barometric pressure, and storm surge, which is just the wind- and pressure-driven water elevation.  Credits for our ocean modeling also go out to my colleagues Alan Blumberg and Nickitas Georgas.  It is based on the Stevens Northwest Atlantic Predictions (SNAP) model grid that we built last fall, as forced by atmospheric model forecast data from the NOAA National Center for Environmental Prediction Global Forecast System (GFS).  I also have made a 3-minute version with voice-over descriptions of what is occurring.

Note how the winds blew from the northeast across the coastal Atlantic Ocean during the three days leading up to Sandy’s landfall, and this started to pile water up against the mid-Atlantic coast.  This is due to Earth’s rotation (and the “Coriolis Effect”), which causes the net flux of water to move to the right of the wind direction.  As Sandy itself approached the New Jersey coast, higher atmospheric pressure (black lines) pushing down outside the circular center of the storm helped force water to rise under the center of the storm, where the pressure is lower. This is the “inverse barometer” effect.

Next up is an animation of Sandy’s winds, pressure and total water elevation, which is the storm surge plus the tides and plus anything else such as rainfall or river-driven freshwater flooding.  This surge modeling is on a nested smaller grid that receives inputs from the larger scale grid at its boundaries.  The smaller grid is the NYHOPS grid, used for our regular regional forecasts of storm surges and ocean conditions.  The simulation is based partly on GFS atmospheric forcing, but mainly on the best forecast we could find – a Rutgers WRF model forecast (by Greg Seroka and Louis Bowers).

Click to see an anmation of water elevation (color shading) in the New York City, New Jersey and Long Island region. Also shown are wind velocity vectors (arrow) and isobars.  The right panel shows a zoom to the NYC region.  The axes on the top right show water elevation at The Battery over four days.

Click to see an animation of water elevation (color shading) in the New York City, New Jersey and Long Island region. This simulation includes both storm surge plus tides.  (NOTE: Time is in GMT here, four hours later times than EDT. Fixing that …)  Also shown are wind velocity vectors (arrows) and white lines are isobars. The right panel shows a zoom to the NYC region. The axes on the top right show water elevation at The Battery over four days.  The methods used for this simulation are very similar to a recent peer-reviewed published paper.

Now that we have created simulations with good accuracy, we can show people a new perspective on what happened, and we can also do experiments on Sandy to better understand hurricane storm surges and better forecast them in the future.  Beyond that we can even use the storm surge modeling to test out adaptations that reduce or prevent flooding, as we’re doing for the federal HUD’s Rebuild by Design competition.

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Next Mayor: Continue to Lead on Climate

This is an Op-Ed published in the New York Times Room for Debate forum .  It was solicited by the RfD editor, with the topic being “transportation challenges for the next mayor”. It was eventually published under a somewhat different debate topic, without my permission or consultation (strange!):

How to make New York City More Livable

The next mayor of New York faces some tough challenges that go to the core of what keeps the city livable. Challenges that he or she will have to address include basic infrastructural issues like electricity, water, flooding, waste management, housing and development, to name a few. What should be the new mayor’s priorities?

Continue to Lead on Climate

The next mayor’s biggest challenge will be to expand upon Bloomberg’s efforts to reduce our climate footprint. After Sandy, flood adaptation will take center stage, and now we’ll have the will to tackle all the sensible, efficient defense measures we’ve been neglecting. Yet, protections against ever-rising seas are not enough, and they must be paired with aggressive efforts to stop the root of the problem – carbon emissions.

The New York City Panel on Climate Change (NPCC) projects our local sea level to rise by 7-31 inches by the 2050s, bringing regular monthly tidal flooding to some low-lying neighborhoods and making extreme floods like Sandy as much as five times more likely to occur. These sea level changes will be a challenge for NYC, yet they will be a humanitarian crisis for low-lying nations of the world such as Bangladesh, and other climate change effects like drought could lead to global food shortages.

It is crucial that we continue to take steps to limit our impact on our climate by reducing carbon emissions, even if these changes are often initially unpopular or difficult. In the transportation sector, examples already underway include the Second Avenue Subway, Select Bus Service, the bike share program, and increased use of energy efficient marine transportation, all of which should be continued or expanded in the next mayor’s tenure. Also, new strategies are needed to help fund improved public transit, such as the Schwartz Tolling Plan.

Lastly, the next mayor needs to continue to partner with other cities worldwide, particularly now that China has overtaken the United States in carbon emissions – Bloomberg is the chair of a coalition of 58 major global cities taking action as the Cities Climate Leadership Group. As has often been the case before, the steps we’re taking in NYC are having a much broader, global influence.

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Not a Priority: Federal Funding to Improve Flood Forecasting

Dear Dr. Orton:

Thank you for your submission of the proposal [(censored) title relating to improving our Storm Surge Warning System's forecasting of storm surges] to the [(censored) federal program].

Although your proposal ranked in the top group and was very highly regarded by the review panel, we do not have the funds available this year to fund the project. Since we did not receive the increase from the President’s Budget request, we can only fund a couple of proposals from the [other environmental disaster] priority through [same federal program] [other sub-program] funds.

We are carrying over into fiscal year 2014 the top ranked proposals, including yours, with the expectation that we will fund your proposal in the late summer of 2014 pending the availability of funds. We are likely not going to know what the [federal program] budget is for 2014 until spring of 2014, and all funds are subject to Congressional appropriations. However, we do view this proposal and project to be a strong one that would benefit [federal program] and our federal partners. Thus, we will do our best to honor our commitment in 2014.

A panel of experts reviewed your proposal based on the criteria listed in the Federal Funding Opportunity. I will be sending to you a summary of the comments from the panel when I return to the office in a few weeks.

Thank you for your patience during what is a very busy time of year for us.

Regards,

[program manger]

****************************

Was this a result of the sequester, or did they actually (as implied) plan a funding opportunity purely around the President’s budget request?

This proposal took a week of my time, and several days for several other scientists, all likely for naught. It is very difficult to find funding for academic flood forecasting, especially in the era of the sequester, when little or no judgement is utilized on what is worthy of funding.

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Sandy’s Staten Island Flooding Deaths: A Man-Made Disaster?

Ask people how fast the water came into New York Harbor with Hurricane Sandy, or how fast it rose, and you get a wide range of answers. Many people think it was like a tsunami that came in quickly, with dangerous currents. In some cases it was violent, particularly at the beaches where waves brought it on in abrupt fronts. However, in the harbor, the waves were small and the water rose at a maximum of only 2.1 feet per hour, with maximum currents in most places below 5 miles per hour. You would need a fair amount of patience to detect water rising at 2.1 feet per hour (about an inch every two minutes) if you were to stand and watch, and it is not a dangerous rise rate if there are areas of high ground or higher levels to your home or building.

So where did the most people die from Sandy’s floodwaters? New York Times published a map showing this information across the region. from which this zoom image is taken:

Map showing the south-east shore of Staten Island, fatalities (dots), and descriptions of cause-for-death.

Map showing the south-east shore of Staten Island, fatalities (dots), and descriptions of cause-for-death.

The Times map tool shows that the regions with the strongest spatial clustering of fatalities anywhere in Sandy’s path were (1) Staten Island’s southeast shore, shown above, and (2) Rockaway Beach.

I discussed this extensively with Matthew Schuerman, a reporter from WNYC, and his story is a very good and detailed study of one of the neighborhoods on Staten Island, complete with interviews, audio, and maps. The story I explained to him is one of topography, and I could never put it into as good words, so here is his text:

The square mile bounded by Midland Avenue, Father Capodanno Boulevard, Seaview Avenue and Hylan Boulevard turned out to be the most dangerous place to be in New York City the night of Sandy, in terms of deaths.

It also is a topographical “bowl”: the streets are several feet below Father Capodanno Boulevard, the thoroughfare that separates the neighborhood from the Atlantic Ocean.

Sandy brought with it an exceptionally high storm tide that reached almost 14 feet at Manhattan’s Battery. But it was a relatively slow-moving storm, and the water level rose gradually.

Phil Orton, a research scientist at Stevens Institute of Technology in Hoboken, analyzed U.S. Geological Survey data and found that even at the peak of the storm, the water at the edge of Staten Island rose by just about 2 feet an hour.

But that surge would not have reached the streets of Midland Beach until after the water exceeded the level of Father Capodanno Boulevard. Only when the water overtopped the boulevard, as it did at about 6:30 p.m. Oct. 29—the night of Sandy—would people notice it. And, while it is difficult to know exactly what led to any individual victim’s death, the rush of water appears to have caught people off guard.

“Then you have a whole ocean pouring into your neighborhood in minutes,” Orton said, “and it can be much more dangerous.”

If you are having trouble imagining what happened, take a heavy mixing bowl from your kitchen and put it in your bathtub. Fill up the bathtub while holding down the bowl, so it doesn’t float away. The water rises gradually outside the bowl, while the inside stays dry. But once the water level reaches the lip, it will come rushing into the bowl.

Once the water overtopped the shoreline berm, it filled in neighborhoods like Midland Beach with water very quickly, within tens of minutes, much like what happened in New Orleans and has since been labeled part natural disaster and part “man-made disaster”.

Looking back at how this dangerous topography could have come to exist, one has to look back to the 1950s. Due to susceptibility to flooding during moderate storms, likely two severe nor’easters that occurred in 1950 and 1953, the waterfront berm was raised in the 1950s to better protect the neighborhood from flooding. This protection was good enough to stop a moderate storm surge like Hurricane Irene’s, and that recent storm likely contributed to the sense of people in this neighborhood that they were adequately protected from the ocean’s waters.  Unfortunately, the insufficient level of protection also transformed Sandy’s flood rise from an inch every few minutes to 6-8 feet in a few tens of minutes, making it deadly.

Building permanent walls or berms 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 (see New Orleans). Choosing a design height for barriers becomes especially problematic when sea level rise is accelerating, as we know they are now doing.

This relates to the recent term coined by Nassim Taleb, antifragile. Our great challenge is to create antifragile floodwater protections that bend but don’t break. Or put more directly, that help stop or reduce flooding, but when they fail they don’t make a more deadly hazard such as rapid-rising waters.

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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?

caption

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?

Creek

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!

https://boxoffice.mcny.org/public/show.asp?shcode=483

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.)

http://www.dailymotion.com/video/xwvdta_general-assembly-panel-discussion_news

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).

http://www.wnyc.org/articles/wnyc-news/2013/jan/30/salt-marshes-sea-barriers-preparing-next-sandy-defense/

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).

http://nystateassembly.granicus.com/MediaPlayer.php?view_id=2&clip_id=173

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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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