Monitoring Coastal Flooding During Storms Irene and Sandy in Long Island Sound, 2011 and
2012
Mullaney, J.R., and Morrison, J.
U.S. Geological Survey, New England Water Science Center, Connecticut Office, 101 Pitkin
Street, East Hartford, CT 06108
Contact email jmullane@usgs.gov data at http://water.usgs.gov/floods/events/2012/sandy/
For oral presentation
Abstract
The U.S. Geological Survey (USGS) used temporary networks of water-level sensors to record
the timing, areal extent, and height of inland hurricane storm tide and coastal flooding generated
by Storms Irene and Sandy. Water-level sensors were deployed at 21 sites along the Connecticut
Coast during Tropical Storm Irene; 28 water-level sensors also were deployed during Hurricane
Sandy. These temporary sensors augmented existing long-term USGS and National Oceanic and
Atmospheric Administration gage networks. Data were used by the Federal Emergency
Management Agency during both storms to direct coordinated Federal response. Data were
collected through the use of submersible pressure transducers that recorded water levels every
10-30 seconds. Maximum storm tides recorded during Irene ranged from 4.4 feet above the
North American Vertical Datum of 1988 (NAVD 88) in the mouth of the Mystic River, to 9.96
feet above NAVD 88 in the Housatonic River in Stratford. Tidal flooding was exacerbated by
riverine flooding on the Housatonic River. The highest storm surge was coincident with high tide
on August 28, 2011, and ranged from about 3.5 to 4.0 feet higher than the high tides predicted
for New London and Bridgeport, respectively. During Hurricane Sandy, the maximum storm
tide ranged from 5.96 feet above NAVD 88 in the mouth of the Mystic River, to 10.3 feet above
NAVD 88 in the Saugatuck River in Westport. Two other high tides were affected by the winds
from Sandy, prior to and following the maximum storm tide. Large waves were measured by
several water-level sensors, including a wave in Niantic that reached 11.7 feet above NAVD 88,
or about 4 feet higher than the maximum storm tide in that area. Maximum storm tides for Sandy
were higher than those determined for the Great Hurricane of 1938 for areas from Stamford to
Clinton, Connecticut.