Dissecting and Classifying the Impacts of
Historic Hurricanes on Estuarine
Systems.
J. Court Stevenson
University of Maryland Center for Environmental
Science
Michael S. Kearney
Department of Geography
University of Maryland
Outline
• Impacts of various areas in Maryland and
Virginia from waves and storm surge (déjà
vu all over again)
• Roles played by precipitation, wind, and
waves in Chesapeake hurricanes and
tropical storms
– Wave setup
• Influence of sea level rise
• Classification of storms by track and type
of damage
• Frequency of different types of storms
– 20th century
– Late 19th century
The Great 1667 Hurricane
“Sir having this opportunity, I cannot but acquaint you with the relation of a
very strange tempest which hath been in these parts with us called a hurricane
which had began August 27th and continued with such violence, that it overturned
many houses, burying in the ruines much goods and many people, beating to the
ground such as were any wayes employed in the fields, blowing many cattle that
were near the sea or rivers, into them., whereby unknown numbers have perished,
to the great afflication of all people, few having escaped who have not suffered in
their persons or estates, much corn was blown away, and great quantities of
tobacco have been lost, to the great damage of many, and utter undoing of others.
Neither did it end here, but the trees were torn up by the roots, and in many
places whole woods blown down so that they cannot go from plantation to
plantation. The sea, by the violence of the wind, swelled twelve feet above its
usual height drowning the whole country before it, with many of the inhabitants,
their cattle and goods, the rest being forced to save themselves in the mountains
nearest adjoining, while they were forced to remain many days together in great
want.”[i]
[i] Truit, R.V. 1967. High Winds and Waves: A Chronicle of Maryland’s Coastal
Hurricanes. Natural Resources Institute, University of Maryland Press,
Large waves have historically
been devastating
Galveston Island, Texas, Sept 8 1900 during a Category 4 hurricane
Hurricane Floyd (1999) caused
massive flooding in North Carolina
Impacts on Maryland and
Virginia
Pictures from Annapolis, Maryland
Eastern Shore, Southern Virginia,
and Hog Island
Isabel: surge height and impact
Cambridge tide gauge Data: PSMSL
Photo: Monica Salerno
Cambridge
Photo: Don Merritt
Horn Point
Photo: Don Boesch
Annapolis
NOAA Tide Gauge at
Gloucester Point During Isabel
Damage In Virginia from
Isabel
Isabel and the South Part of Hog Island, Virginia
During
Before
After
Photos: John Porter,
University of Virginia
Classification of Hurricane/Tropical
Storms Relative Impacts on
Chesapeake Bay
• “Backdoor” Storms – originating in the Gulf of
Mexico and Atlantic hurricanes which landfall in
Georgia or South Carolina, having moved
considerably inland before reaching the middle
Atlantic Coast
– Precipitation events with runoff, more likely to produce
Bay-wide if track crosses upper Bay
• Outer Banks Landfall
– Lower Outer Banks – tend to track along lower Virginia
Eastern Shore storm surge and waves affecting lower
Bay
– Upper Outer Banks – tend to track west subparallel of
Chesapeake Bay, storm surge and waves affecting upper
and middle Bay (exception Connie in 1955)
The Role of Precipitation
• Many long-term residents vividly remember
Tropical Storm record holder for the most
inches of rainfall per hour in the upper Bay
•
•
•
Ten Heaviest Rains in Virginia from
Tropical Cyclones and their Remnants
Amount
Dates
Location
27.00"
8/19-20/1969
Nelson County
19.77"
11/02-07/1985
2 NE Montebello
18.13"
9/14-16/1999
Yorktown
16.57"
9/14-16/1999
Newport News
16.00"
6/17-24/1972
Chantilly
14.30"
9/14-16/1999
James City
14.30"
9/05-09/1996
Tom's Branch
14.18"
6/17-24/1972
Centreville
14.17"
9/05-09/1996
Luray 5 SE
13.60"
6/17-24/1972
Big Meadows
The data above suggest that three classes can be used for our hurricane
classification system: P Class #1 = 0-10”, P Class#2 = 10-20” and P Class#3 >
20”
Potomac River During 1933
“Storm King” Hurricane
Flood Damage From Tropical
Storm Agnes in 1972
The Role of Wind
•Storm Tide: winds piling up
water on the shore – more
effective than drop in pressure.
Even a pressure as low as 27.93
inches would only produce a 2.5
foot rise in water level
•In 1928, hurricane blowing
across Lake Okeechobee
produced a surge that killed
1,835 people
Saffir-Simpson Scale
Tropical Storms =
Winds < 74 mph
Category 1
74-95 mph
Class #1= Winds < 95 mph
(119 km hr-1)
= Winds
Category 2 = Winds
96-110 mph
Class #2 = Winds 96-130
mph (154-209 km hr-1)
Category 3 = Winds
111- 130 mph
Category 4 = Winds
131 – 155 mph
Category 5 = Winds >
155 mph
Class #3 = Winds >130 mph
(>209 km hr-1 )
The Role of Waves
• Waves ride on top of the storm surge
– Galveston Hurricane is a classic example
– Increased flooding
• As sea level rises, greater depths of water
increase the potential for generation of
larger waves from the same wind field
– Increases the flood risk
Wave setup can compound the
effect of sea level rise
Large waves moving
directly onshore
Waves from Hurricane Isabel on North Carolina’s coast
Mean sea level has risen 30 cm
(1 foot) over the last century
PSMSL data
Baltimore tide gauge
Temperature and sea level
will continue to rise
Year
Mid-Atlantic
temperature rise
(projected)
Year
Mid-Atlantic
sea level rise
(projected)
2030
2095
1.0 °C – 1.5 °C
2.7 °C – 5.3 °C
2030
2095
109 mm – 310 mm
409 mm – 1029 mm
Projected future rise in global temperature
Projected future rise in global sea level
Data: IPCC and Pennsylvania State University
20th Century
Hurricanes/Tropical Storms
In Chesapeake Bay
Chesapeake Bay
Hurricanes/Tropical
Storms 1926 - 1950
Chesapeake Bay
Hurricanes/Tropical Storms 1951 1975
Hurricanes/Tropical
Storms 1976 - 2000
1851 -1876
1876 - 1900
1900 - 1925
Conclusions
• There are as many 27 different combinations of
storms that can potentially the Chesapeake Bay
based on track, intensity, and precipitation
– However, these large number of variations can be
collapsed down to: 1) “Backdoor Storms; 2) lower Outer
Banks Storms; and 3) Upper Outer Banks Storms
– Backdoor Storms are largely precipitation events
– Lower Outer Bank Storms produce storm surges and
wave setup in the lower Chesapeake Bay
– Upper Outer Banks Storms can produce substantial
“wind-driven” tides (wave setup) that can affect the
whole Chesapeake Bay
• Only 3 storms like this occurred in the 20th Century in the
Chesapeake Bay
FINI
Questions?
Chesapeake Bay islands
are rapidly disappearing
Isabel makes landfall Sept 18, 2003
Photo: NASA/MODIS
Risk of flooding much greater when storm
surge and wave setup are considered
Submergence risk
determined by EPA
Isabel same size and path as 1933 hurricane
1933
hurricane
Min pressure (" Hg)
28.7
Max sustained wind speed
Tidal surge in Potomac River
(feet above MLLW)
Hurricane
Isabel
29.1
70 mph
73 mph
11.1 '
11.3 '
Chesapeake Biological Laboratory after the 1933
hurricane. Photo courtesy Calvert Marine Museum
Historical Category 2
Hurricanes In Chesapeake Bay
Historical Category 3 Hurricanes In
Chesapeake Bay
Historical Category 1 Hurricanes
In Chesapeake Bay
Impact of Sea Level Rise on Storm Waves
•Zone of “saturation” of
wave energy closer to
bank
•Overall penetration of
storms significantly
landwards
Δ
•Wave Decay Occurs
farther in shore
Wave Energy*
*(Airy Wave Theory)
E=
2
1/8ρgH
Small Changes in Wave
Height = Large Changes in
Wave Energy
Re la tive Wave Power
Relative wave power increased
with increasing water depth
4s
wave 16’
2000
1500
2s
wave
1000
500
0
15’
15’
16’
1
2
3
Ca ses
4
Total flood height =
sea level + storm surge + wave setup
Track of the
storm affects
direction of
wave
generation