The City That Plans to be Flooded
A guest post by Douglas Hill, a consulting engineer and an adjunct lecturer at the School of Marine and Atmospheric Sciences at Stony Brook University in New York.
Hurricane Irene, remember? Irene, diminished to a mere tropical storm when it struck New York City, came and went, soon disappearing from the news. But think back to August 26 when Irene, a Category 3 hurricane with winds of more than 110 miles per hour, was approaching the North Carolina coast and headed directly for New York City. Mayor Michael R. Bloomberg called a news conference to order 370,000 people to evacuate their homes. Then he stepped aside, and MTA chairman Jay Walder stepped to the microphone and announced that public transportation--buses as well as trains--was being shut down.
Figure 1. GOES-East visible satellite image of Irene taken at 7:45 am EDT on Sunday, August 28, 2011. At the time, Irene was a tropical storm with 65 mph winds, making landfall on Long Island, New York. Image credit: NOAA Environmental Visualization laboratory.
Evacuation without transportation: a novel concept that the mayor described as "preparing for the worst and hoping for the best." Fortunately, hoping for the best worked.
Unfortunately, the City is still hoping for the best, and it is not preparing for the worst. The coastal storm plan of the Office of Emergency Management (OEM) includes strategies for storm tracking, public information, evacuation procedures, people with special needs, recovery, and restoration, but nothing to prevent flooding.
In other words, New York City is planning to be flooded--and according to the National Hurricane Center, it will be. Based on the historical record, hurricanes of Categories 1, 2 and 3 will strike the New York region on an average of every 17, 39 and 68 years, respectively. The City has been overdue for a Category 1 hurricane--Irene should have been no surprise--and we may expect hurricanes of Categories 2 and 3 within the next decade or two. In testimony to a U.S. Senate committee, Max Mayfield, the former director of the National Hurricane Center, said, "It is not a question of if a major hurricane will strike the New York area, but when" (his emphasis.)
The greatest potential for loss of life from a hurricane has historically been from the storm surge. If the eye of a Category 3 hurricane crossed the New Jersey shore, the surge could reach 24 feet--compared with 4.5 feet in Hurricane Irene's--flooding the World Trade Center site and Wall Street, with City Hall resting on a separate island south of the rest of Manhattan. The ripples from a crippled financial district in lower Manhattan would be felt worldwide. In a severe hurricane, the OEM has estimated that up to three million people would have to evacuate, if that can be imagined.
Figure 2. The height above ground that a mid-strength Category 2 hurricane with 100 mph winds would push a storm surge into New York City in a worst-case scenario. The image was generated using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. This "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of ten feet above mean sea level, and the combined storm surge and tide (the "storm tide") is fifteen feet at your location, the water depth image will show five feet of inundation. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide and is a composite of the maximum storm surge found for dozens of individual runs of different Category 2 storms with different tracks. Thus, no single storm will be able to cause the level of flooding depicted in this SLOSH storm surge image. Consult wunderground's Storm Surge Inundation Maps page for more storm surge images of the U.S. coast.
Other major ports have taken measures to prevent being flooded. After the 1938 hurricane, storm surge barriers were built in New England to protect New Bedford, Providence and Stamford. After a disastrous storm in the North Sea in 1953, the Thames Barrier was built to protect London, and the Delta Plan was started in the Netherlands which includes three such barriers, one protecting Rotterdam, Europe's busiest port. Following Hurricane Katrina, a long-disputed barrier was constructed at the entrance to Lake Pontchartrain along with several others, which are now considered to make New Orleans hurricane-proof to Category 3 storms. Barriers are being completed to protect St. Petersburg, Russia, and Venice, Italy.
The heart of New York City could be protected in the same way. Moveable barriers, closed only when the city is threatened with major coastal flooding, could be placed at the upper end of the East River, across the Narrows and at the mouth of the Arthur Kill. Possibly, the latter two could be replaced with a single, longer barrier extending from Sandy Hook to the Rockaway peninsula. Modeling studies have demonstrated that the barriers would work. Four major engineering firms have presented conceptual designs and cost estimates for barriers at these locations. The estimated costs for these individual barriers range from $1 billion to $4.6 billion, with the total of the two or three needed less than $10 billion, comparable to other major infrastructure projects planned or underway.
Figure 3. Proposed hurricane storm surge barrier for New York City near the Verrazano Narrows Bridge. Image credit: Arcadis, Inc.
But unlike the original, the 2010 revision of plaNYC, the City's principal planning document, makes no reference to storm surge barriers. The City's latest plans are seen in the March 2011 Vision 2020: NYC Comprehensive Waterfront Plan, which calls not for protecting the waterfront, but for climate "resilience," the ability to withstand and recover from the disaster. Unfortunately, this may be the best that can be done for those living in the coastal sections of the boroughs that face the Atlantic Ocean.
So the Great Evacuation of August 2011 is a test. In its postmortem on the storm on September 5, the New York Times concluded that "by almost any measure, the evacuation was a success," but it did not report on the principal measure. How many people were left behind? Unlike New Orleans after Katrina, we won't know by counting the bodies. Not this time, anyway.
Douglas Hill, EngScD, P.E., Stony Brook University
Other posts in this series
Storm surge barriers: the New England Experience
Hurricane Irene: New York City's close call
Reader Comments
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Kenneth is definitely a once in a lifetime storm.
Think we're getting a little overly dramatic there...
Irene was a hurricane when it hit North Carolina.
What are you talking about? Irene made landfall here in North Carolina with winds of 85 mph.
Uhh.. what? Irene made landfall in North Carolina as a Category 1 hurricane, causing significant surge and flooding damages.
That was the Eastern Pacific..
^
Just somebody trying to start trouble, nevermind. CybrTeddy, don't you dare go off on a rant, and ignore. (:
Maybe because your facts are wrong.
major hurricane Buy, there were gustav and ike that were also hurricanes but if you mean major than youd be right... and as for mean irene being a tropical storm at US landfall, thats just plain false :)
Oh, dear. Please allow me to correct a few inaccurate details:
As of December 4 the US will pass 99 days without a hurricane making landfall in the US (Irene was a hurricane when it hit this summer). This is the longest such period since 2011.
There. All better. ;-)
LOL
lol.
lee
dos any one think Allison and lee look the same two you?
LOL
"Everything indicates another above-normal season in 2012," Erickson said."
Colorado State University (CSU) releases their 2012 Atlantic hurricane season forecast in three days (12-7-2012). However, I do not believe numbers will be involved, I think it is just the factors that will go into play next hurricane season.
Regardless, an above average hurricane season appears likely next year.
Very similar.
Funny...I remember Irene making landfall as a hurricane in both North Carolina and New Jersey in the summertime...
Nah, that was just a nightmare.
lol.
It was just an illusion...
lol.
Workers discovered today that a previously hidden 45 tons of extremely radioactive water has leaked from the earthquake/tsunami-stricken plant directly into the Pacific Ocean. The water contained about 300 times as much radioactive cesium as the maximum safe level--and up to a million times more radioactive strontium.
It's estimated that between March and July, the amount of radioactive cesium 137 that had leaked into the Pacific from the Fukushima Daiichi plant amounted to 27.1 petabecquerels, making it the largest amount ever released in a single episode. (A becquerel is a frequently used measure of radiation, and a petabecquerel is a million billion becquerels.)
Well, Dr. Gray gives actual numbers in his early-December forecast; last year, for instance, he called for 17-9-5, with an ACE of 165.
(For what its worth, he called for 85 named storm days, 40 hurricane days, and 10 major hurricane days; the count turned out to be 79, 30, and 7.)
Just a thought that crossed my mind today.
And BTW, my prediction of no rain was 100% wrong.... lol
I live in an area extremely vulnerable to storm surge if a storm hits the area just the right way. But it's been such a long time since there's actually been a storm with surge that people around here for the most part are only worried about the wind when one hits. I try and explain to people I know about the surge danger here, and it just doesn't sink in. We have no shelters in this county that are red cross approved in a Cat 3 or higher because there aren't any where the elevation is high enough. Almost everything in the county is less than 20 ft. I guess it takes a bad one for people to realize how bad it can be. I know a lady who lived here in the 40's and they had a weak 3 that hit the area. And from what she told me how far the water came in during that, I wouldn't wanna be here for a storm land falling north of the harbor here.
I'll save it for one of the lulls between major hurricanes next year in August,
By then I'll be all charged up.
Some still develop a Subtropical cyclone, but to the south and west of this low.
They do look very similar. But couldn't have had a more opposite effect on the Lone Star State.
Odd. In the past 1,600 days the USA has been hit by hurricanes Humberto, Dolly, Gustav, Ike, and Irene. Maybe even more, but those storms spring to mind immediately. Irene was a hurricane when she made landfall in North Carolina, as other have said.
JupiterKen is completely wrong here. was flat out wrong on every level.
Until this day, I had gone 2 months without ignoring someone..... This is the longest period ever in my Wunderblogging history.
Same thing happened in my county, Orange. The highest elevation in the county is 13 feet. Apparently in 1975 Army Corp had drawn up plans for a levee or proposed one? Not sure who decided, Nah, we'll pass. Lol. Great move. In 2008 Ike put us under. And I mean hack out of your attic with an ax - you aint getting back into the county no matter who you are or what's on your driver's license - under! Unbelievable! And even more so when you consider Ike was the third hurricane to affect our county in as many years. He didn't go directly over us but there was sustained hurricane winds and surge over us none the less. Rita plowed right through us. Humberto plowed right through us. Eduoard made a pass at us. And about 10 days before Ike we were under an evac order for Gustav. This definitely wasn't our first rodeo. Not even close. And still people stayed. And Rita was a bad one for us. Very bad! So it's kinda scary to wonder what would get people's attention. I guess the best you can do for your loved ones and your community is to keep up with the tropics and try to keep drilling it into their heads. All this about Ike in my county didn't make a lot of headlines. But what if it had been NYC. It happened here. It can happen anywhere.
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE 01S (ONE) WARNING NR 001//
RMKS/
1. TROPICAL CYCLONE 01S (ONE) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN SOUTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
050000Z --- NEAR 12.3S 87.9E
MOVEMENT PAST SIX HOURS - 285 DEGREES AT 11 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
REPEAT POSIT: 12.3S 87.9E
---
FORECASTS:
12 HRS, VALID AT:
051200Z --- 12.6S 86.8E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 225 DEG/ 03 KTS
---
24 HRS, VALID AT:
060000Z --- 13.0S 86.4E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 095 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
105 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 130 DEG/ 05 KTS
---
36 HRS, VALID AT:
061200Z --- 13.6S 87.1E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
115 NM SOUTHEAST QUADRANT
100 NM SOUTHWEST QUADRANT
115 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 120 DEG/ 08 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
070000Z --- 14.4S 88.5E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
120 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 115 DEG/ 13 KTS
---
72 HRS, VALID AT:
080000Z --- 16.6S 93.3E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT
120 NM SOUTHEAST QUADRANT
105 NM SOUTHWEST QUADRANT
120 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 120 DEG/ 13 KTS
---
LONG RANGE OUTLOOK:
---
96 HRS, VALID AT:
090000Z --- 19.1S 98.3E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
---
REMARKS:
050300Z POSITION NEAR 12.4S 87.6E.
TROPICAL CYCLONE (TC) 01S, LOCATED APPROXIMATELY 525 NM WEST OF THE
COCOS ISLANDS, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A RAPIDLY
CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CENTRAL
CONVECTION. A 042325Z SSMIS 37 GHZ MICROWAVE PASS SHOWS A FORMATIVE
MICROWAVE EYE AND TIGHTLY CURVED BANDING WRAPPING INTO THE LLCC. THE
CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES FROM PGTW AND KNES
RANGING FROM 35 TO 45 KNOTS. THE CURRENT POSITION IS BASED ON THE
AFOREMENTIONED MICROWAVE IMAGE AND THE 04/2332Z PGTW SATELLITE FIX
WITH GOOD CONFIDENCE. UPPER LEVEL ANALYSIS INDICATES THAT TC 01S IS
LOCATED UNDER THE RIDGE AXIS IN A REGION OF STRONG DIFFLUENT FLOW
ALOFT AND LOW VERTICAL WIND SHEAR. ANIMATED WATER VAPOR IMAGERY
SHOWS GOOD OUTFLOW IN THE WESTERN AND SOUTHERN SEMI-CIRCLES, BUT
OUTFLOW ALONG THE EASTERN PERIPHERY IS SOMEWHAT INHIBITED BY
EASTERLY FLOW ALOFT. THE SYSTEM IS CURRENTLY TRACKING ALONG THE
NORTHWESTERN PERIPHERY OF A FINGER OF THE SUBTROPICAL RIDGE
EXTENDING FROM SOUTH OF JAKARTA INDONESIA. TC 01 IS EXPECTED TO
CONTINUE TRACKING GENERALLY WESTWARD FOR THE NEXT 12 TO 24 HOURS
BEFORE AN APPROACHING MID-LATITUDE TROUGH WEAKENS THE RIDGE AND
ALLOWS THE SYSTEM TO RECURVE AHEAD OF THE TROUGH AND BEGIN EXTRA-
TROPICAL TRANSITION (ET). THE SYSTEM IS EXPECTED TO GRADUALLY
INTENSIFY AS THE UPPER LEVEL ENVIRONMENT AND SEA SURFACE
TEMPERATURES REMAIN FAVORABLE THROUGH THE FIRST 48 TO 72 HOURS OF
THE FORECAST. TC 01S IS FORECAST TO COMPLETE ET BY TAU 96.
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE TIMING OF
RECURVATURE AND OVERALL FORECAST TRACK, THEREFORE THIS FORECAST
REMAINS CLOSE TO MODEL CONSENSUS. THIS WARNING SUPERSEDES AND
CANCELS REF A, NAVMARFCSTCEN 042021Z DEC 11 TROPICAL CYCLONE
FORMATION ALERT (WTXS22 PGTW 042030) MAXIMUM SIGNIFICANT WAVE HEIGHT
AT 050000Z IS 12 FEET. NEXT WARNINGS AT 051500Z AND 060300Z.//
NNNN
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