New York City and Hurricane Sandy's Storm SurgeDavid W. Kobilka, Geoscience, Central Lakes College-Brainerd
SummaryMuch has been written about how Hurricane Sandy's storm surge made landfall at high tide. Certainly everyone has an intuitive sense for what that means. What is less well understood by the general public and certainly by non-coastal dwelling students is how inextricably tied hurricane damage can be with the tidal phase at the time of the storm's arrival, especially at higher latitudes where tidal ranges can be greater. The magnitude of a storm surge, and the damage it causes can vary wildly depending on the hour of the storm surge arrival. Vary the time by just a couple of hours, and conditions can be completely different.
This effect was demonstrated with remarkable clarity by Hurricane Sandy's storm surge, that arrived at high tide of a full moon. While the storm surge itself was impressive (in a horrible way), it could have been higher. The peak of the storm surge arrived close to high tide, but not exactly, and at the lower of the two tides for that day. Furthermore, had the storm arrived a couple of weeks earlier or later, at new moon rather than full moon, the tide then might have made things even worse. And tide is not the only factor. Coastal development, sea level rise, the shape of the seabed, etc. also adds to the calculus of storm surge height predictions and makes the entire process extraordinarily challenging.
That challenge all becomes focused on the day the event makes landfall, when emergency management, law enforcement, transit authorities, public utilities, and every other agency of coastal communities struggle to send out accurate warnings to a populace that hang life-or-death decisions on storm surge predictions.
Individuals with expertise/responsibilities in the following areas have helped create the case study:
- National Center for Atmospheric Research
- New York Mass Transit Authority: http://wagner.nyu.edu/files/rudincenter/sandytransportation.pdf
- New York City Office of Emergency Management: http://www1.nyc.gov/site/em/index.page
Key teaching points:
- Storm surge is extremely damaging.
- Storm surge height, and subsequent flooding and damage is extremely difficult to predict, especially in places where tidal ranges are high.
- Enormous resources are poured into trying to reduce loss of life and property due to storm surge.
How this example is used in the classroom:
I use this case in introductory courses on Natural Disasters and Oceanography. It comes at the end of a section about hurricanes with specific focus on comparing hurricanes Sandy and Katrina. We use this as an activity where students use tidal data to reveal how the storm surge could have been much higher, or lower depending on the small variations in timing.Note: This case study wants for resources that will help students understand how flood maps are developed. An activity in which students can create their own flood map, especially for the area in question would make this case more complete.
ReferencesNCAR/UCAR Atmos News: Sandy's Stunning Surge. https://www2.ucar.edu/atmosnews/perspective/8584/phenomenon-year-sandy-s-stunning-surge
NOAA tides and currents: http://tidesandcurrents.noaa.gov/noaatidepredictions/NOAATidesFacade.jsp?Stationid=8518750&&bmon=04&bday=12&byear=2014&edate=&timelength=daily
Flooding and Flood Zone interactive map for NY and NJ coastlines: http://project.wnyc.org/flooding-sandy-new/#12.00/40.5837/-73.9663