Tide Gage Observations of Coastal Inundation in the Delaware Inland ...
Tide Gage Observations of Coastal Inundation in the Delaware Inland Bays John Callahan Delaware Geological Survey Delaware Estuary Science and Environmental Summit January 26-28, 2015 Cape May, NJ
Outline ∗ ∗ ∗ ∗ ∗
Delaware Inland Bays Tide gage general timing and historical peaks Tidal datums for period of study (2001 – 2014) Changes over time of MSL and nuisance flooding Ongoing work
Delaware Inland Bays ∗ Rehoboth Bay, Indian River Bay, Little Assawoman Day ∗ Lewes-Rehoboth Canal ∗ Assawoman Canal
∗ Average depth 3-8 feet ∗ 320 square mile watershed ∗ Canals, ditches, winding creeks, salt marshes, tidal flats… ∗ Agriculture: 32%, Developed: 22%, Forest: 17%, Wetlands: 16%, Water: 12% Source: 2011 State of the Bays
Delaware Inland Bays ∗ Important to Delaware’s economy (recreation, fishing, tourism), natural habitat (white cedar swamp, fish, waterfowl), migratory birds, ecosystem services (filtering nutrients), etc… ∗ However, they are poorly flushed (slight changes can upset the balance), heavily developed, extremely vulnerable to coastal flooding
USACE 2014 study on vulnerability to coastal flooding
Hurricane Sandy 10/29/2012
Indian River Bay Inlet
Fenwick Island
Delaware Coastal Storm Frequency 1945 - 2013
Source: Delaware Storm Climatology, Delaware Environmental Observing System
Sea-Level Rise (SLR)
Source: NOAA National Ocean Service, 2014 Source: Hay et al, 2014
Which Way Is Up?
Source: National Climate Assessment 2014
NOAA National Ocean Service ∗ Lewes Breakwater (1919) ∗ Ocean City Inlet (1997) United States Geological Survey ∗ Rehoboth Beach (1985) ∗ Indian River Bay Inlet (1989) ∗ IRB Rosedale (1992) ∗ South Bethany (1999) ∗ Fenwick Island (1999)
Water Level Monitoring Locations Delaware Inland Bays
Delaware Environmental Observing System (DEOS) ∗ Research monitoring sites ∗ Meteorological stations
Full moon - Aug 20/21
T2 – 1:00
T6 – 3:30 T4 – 2:18
T3 – 1:18
T7 – 4:48 T5 – 3:12 T1 – 0:00
Last quarter - Aug 28
Source: Jeff Gebert, USACE Philadelphia District, 2013 presentation
Top Observed Storm Tides Notable Storms 10/29/2012 – Sandy 11/13/2009 – Nor’Ida 5/12/2008 – Mother’sDay 1/28/1998 – Nor’easter 2/5/1998 – Nor’easter 9/19/2003 - Isabel
Lewes
WL (ft)
IRB Inlet
WL (ft)
Rosedale
WL (ft)
3/6/1962
6.59
10/29/2012
5.72
2/5/1998
6.21
1/4/1992
6.12
2/5/1998
5.07
1/28/1998
5.77
10/29/2012
6.06
11/13/2009
5.05
10/29/2012
5.45
1/28/1998
5.99
5/12/2008
5.00
11/12/2009
5.26
2/5/1998
5.86
1/25/2000
4.87
3/6/2013
4.98
Rehoboth
WL (ft)
S.Bethany
WL (ft)
FenwickIsl
WL (ft)
OceanCity
WL (ft)
10/29/2012
4.56
10/29/2012
4.66
10/29/2012
4.04
10/29/2012
4.41
10/31/1991
3.67
9/19/2003
2.74
10/25/2005
2.35
11/22/2006
3.88
11/13/2009
3.62
10/25/2005
2.59
9/19/2003
2.23
11/13/2009
3.84
5/12/2008
3.4
9/2/2006
2.38
11/8/2012
2.22
3/6/2013
3.21
11/8/2012
2.35
11/13/2009
2.21
10/18/2009
3.13
10/25/2005 3.28
Water Level Analysis Study Period 2000 - 2014 Gage
Source
Install Date
Study Period
Years
Hourly Data %
Lewes
NOS
1919
5/1/2000 – 4/30/2014
14
99.6%
Rehoboth/Dewey
USGS
1985
5/1/2000 – 4/30/2014
14
93.0%
IRB Inlet
USGS
1988
5/1/2000 – 4/30/2014
14
89.4%*
Rosedale
USGS
1992
5/1/2000 – 4/30/2014
14
97.2%
South Bethany
USGS
1999
5/1/2000 – 4/30/2014
14
99.4%
Fenwick Island
USGS
1999
5/1/2000 – 4/30/2014
14
99.5%
Ocean City
NOS
1997
5/1/2003 – 4/30/2014
11
99.5%
*NOS also had IRB Inlet gage from 1972 – 1986; USGS gage down due to maintenance 12/2010-11/2011 All years based on meteorological year, May through April, as to not split winter storm season (Sweet 2014)
Comparison of Tidal Datums 2000 - 2014 MSL (feet)
MHHW
MLLW
GT/Range
Lewes
-0.18
2.19
-2.37
4.56
Rehoboth
-0.01
0.92
-0.70
1.63
IRB Inlet
0.27
1.75
-1.16
2.92
Rosedale
0.40
1.81
-0.84
2.65
South Bethany
0.09
0.55
-0.31
0.86
Fenwick Island
-0.04
0.42
-0.35
0.77
Ocean City
-0.10
1.07
-1.33
2.39
All values relative to NAVD88 feet, calculated over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, which is for 11 years, 5/1/2003 – 4/30/2014
Tidal Datums to Geodetic 3.00 2.00 1.00
MSL
0.00
MHHW MLLW
-1.00 -2.00 -3.00
North
South
Based over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, at 11 years, 5/1/2003 – 4/30/2014
Comparison to NTDE 1983-2001 MSL (feet)
MHHW
MLLW
GT/Range
-0.18
2.19
-2.37
4.56
Rehoboth NTDE 83-01
-0.01 -0.40
0.925 2.02
-0.70 -2.63
1.63 4.65
Rosedale
0.40
1.81
-0.84
2.65
South Bethany
0.09
0.55
-0.31
0.86
Fenwick Island
-0.04
0.42
-0.35
0.77
Ocean City
-0.10
1.07
-1.33
2.39
Lewes IRB Inlet
0.27
1.75
-1.16
2.92
NTDE -0.36 0.83 -1.64 2.46 All values83-01 relative to NAVD88 feet, calculated over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, which is for 11 years, 5/1/2003 – 4/30/2014
MLLW -2.37 ft
MHHW 2.19 ft
Water Level Frequency Distribution
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
Delaware Inland Bays Annual Mean Sea Level, 2000 - 2014
Delaware Inland Bays Annual Mean Sea Level, 2000 - 2014
Nuisance Flooding ∗ Lesser extremes; analogous to NWS “minor” flooding ∗ Sweet (2014) report by NOAA found a significant increase in nuisance flooding through time at numerous US East and Gulf Coasts tide gages. ∗ Used NWS minor flooding category, 6 ft MLLW ∗ Most often occurring in the Fall months in southern Delaware.
Nuisance Flooding ∗ Sweet (2014) Sweet and Park (2014) found a significant increase in nuisance flooding through time at numerous US East and Gulf Coasts tide gages. ∗ Used NWS minor flooding category, 6 ft MLLW ∗ Most often occurring in the Fall months in southern Delaware.
Hours/Year > MHHW + 1.0 and 2.0 ft Lewes, Ocean City
Hours/Year > MHHW + 1.0 and 2.0 ft IRB Inlet, Rosedale
Hours/Year > MHHW + 1.0 and 2.0 ft Rehoboth, S. Bethany
Hours/Year > MHHW + 1.0 and 2.0 ft LAB/Fenwick Island
General observations…so far ∗ Inlet and Rosedale: ∗ similar magnitude and behavior, under tidal-only and non-tidal influences, and highest MSL
∗ Lewes and Ocean City: ∗ strong tidal signal in all conditions; lowest MSL
∗ Rehoboth, Bethany and Fenwick: ∗ significantly lagged and diminished high tides; no low tide/cycle during storms, very small range
∗ All gages show increases over time: ∗ MSL ∗ MHHW and MLLW (Lewes and Ocean City) ∗ minor/nuisance flooding.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels/surge along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
∗ Use with NWS and NOS forecasts to integrate with Delaware Coastal Flood Warning System.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
∗ Use with NWS and NOS forecasts to integrate with Delaware Coastal Flood Warning System. ∗ Expand spatial coverage within Inland Bays
Possible monitoring locations for water level analysis study
Thank You!
John Callahan Delaware Geological Survey [email protected]
Kevin Brinson Delaware Environmental Observing System
Seasonal Variation of Coastal Storms
Source: Delaware Storm Climatology, Delaware Environmental Observing System
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
NCA 2012
Historical Sea Levels
Coastal Inundation Study of the Delaware Inland Bays ∗ General behavior of all tidal gages in Inland Bays ∗ Timing and amplitude, under spring/neap/storm conditions
∗ “Water level” analysis ∗ Comparison of tidal datums ∗ Seasonal and annual frequency and duration of flooding (nuisance flooding, extreme events)
∗ Correlation of water levels and/or storm surge along coast to gages within Inland Bays ∗ Including time lag/duration and weather (winds, precip)
∗ Integration into Delaware CFMS for early warning
Outline ∗ ∗ ∗ ∗ ∗
Delaware Inland Bays Tide gage general timing and historical peaks Tidal datums for period of study (2001 – 2014) Changes over time of MSL and nuisance flooding Ongoing work
Delaware Inland Bays ∗ Rehoboth Bay, Indian River Bay, Little Assawoman Day ∗ Lewes-Rehoboth Canal ∗ Assawoman Canal
∗ Average depth 3-8 feet ∗ 320 square mile watershed ∗ Canals, ditches, winding creeks, salt marshes, tidal flats… ∗ Agriculture: 32%, Developed: 22%, Forest: 17%, Wetlands: 16%, Water: 12% Source: 2011 State of the Bays
Delaware Inland Bays ∗ Important to Delaware’s economy (recreation, fishing, tourism), natural habitat (white cedar swamp, fish, waterfowl), migratory birds, ecosystem services (filtering nutrients), etc… ∗ However, they are poorly flushed (slight changes can upset the balance), heavily developed, extremely vulnerable to coastal flooding
USACE 2014 study on vulnerability to coastal flooding
Hurricane Sandy 10/29/2012
Indian River Bay Inlet
Fenwick Island
Delaware Coastal Storm Frequency 1945 - 2013
Source: Delaware Storm Climatology, Delaware Environmental Observing System
Sea-Level Rise (SLR)
Source: NOAA National Ocean Service, 2014 Source: Hay et al, 2014
Which Way Is Up?
Source: National Climate Assessment 2014
NOAA National Ocean Service ∗ Lewes Breakwater (1919) ∗ Ocean City Inlet (1997) United States Geological Survey ∗ Rehoboth Beach (1985) ∗ Indian River Bay Inlet (1989) ∗ IRB Rosedale (1992) ∗ South Bethany (1999) ∗ Fenwick Island (1999)
Water Level Monitoring Locations Delaware Inland Bays
Delaware Environmental Observing System (DEOS) ∗ Research monitoring sites ∗ Meteorological stations
Full moon - Aug 20/21
T2 – 1:00
T6 – 3:30 T4 – 2:18
T3 – 1:18
T7 – 4:48 T5 – 3:12 T1 – 0:00
Last quarter - Aug 28
Source: Jeff Gebert, USACE Philadelphia District, 2013 presentation
Top Observed Storm Tides Notable Storms 10/29/2012 – Sandy 11/13/2009 – Nor’Ida 5/12/2008 – Mother’sDay 1/28/1998 – Nor’easter 2/5/1998 – Nor’easter 9/19/2003 - Isabel
Lewes
WL (ft)
IRB Inlet
WL (ft)
Rosedale
WL (ft)
3/6/1962
6.59
10/29/2012
5.72
2/5/1998
6.21
1/4/1992
6.12
2/5/1998
5.07
1/28/1998
5.77
10/29/2012
6.06
11/13/2009
5.05
10/29/2012
5.45
1/28/1998
5.99
5/12/2008
5.00
11/12/2009
5.26
2/5/1998
5.86
1/25/2000
4.87
3/6/2013
4.98
Rehoboth
WL (ft)
S.Bethany
WL (ft)
FenwickIsl
WL (ft)
OceanCity
WL (ft)
10/29/2012
4.56
10/29/2012
4.66
10/29/2012
4.04
10/29/2012
4.41
10/31/1991
3.67
9/19/2003
2.74
10/25/2005
2.35
11/22/2006
3.88
11/13/2009
3.62
10/25/2005
2.59
9/19/2003
2.23
11/13/2009
3.84
5/12/2008
3.4
9/2/2006
2.38
11/8/2012
2.22
3/6/2013
3.21
11/8/2012
2.35
11/13/2009
2.21
10/18/2009
3.13
10/25/2005 3.28
Water Level Analysis Study Period 2000 - 2014 Gage
Source
Install Date
Study Period
Years
Hourly Data %
Lewes
NOS
1919
5/1/2000 – 4/30/2014
14
99.6%
Rehoboth/Dewey
USGS
1985
5/1/2000 – 4/30/2014
14
93.0%
IRB Inlet
USGS
1988
5/1/2000 – 4/30/2014
14
89.4%*
Rosedale
USGS
1992
5/1/2000 – 4/30/2014
14
97.2%
South Bethany
USGS
1999
5/1/2000 – 4/30/2014
14
99.4%
Fenwick Island
USGS
1999
5/1/2000 – 4/30/2014
14
99.5%
Ocean City
NOS
1997
5/1/2003 – 4/30/2014
11
99.5%
*NOS also had IRB Inlet gage from 1972 – 1986; USGS gage down due to maintenance 12/2010-11/2011 All years based on meteorological year, May through April, as to not split winter storm season (Sweet 2014)
Comparison of Tidal Datums 2000 - 2014 MSL (feet)
MHHW
MLLW
GT/Range
Lewes
-0.18
2.19
-2.37
4.56
Rehoboth
-0.01
0.92
-0.70
1.63
IRB Inlet
0.27
1.75
-1.16
2.92
Rosedale
0.40
1.81
-0.84
2.65
South Bethany
0.09
0.55
-0.31
0.86
Fenwick Island
-0.04
0.42
-0.35
0.77
Ocean City
-0.10
1.07
-1.33
2.39
All values relative to NAVD88 feet, calculated over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, which is for 11 years, 5/1/2003 – 4/30/2014
Tidal Datums to Geodetic 3.00 2.00 1.00
MSL
0.00
MHHW MLLW
-1.00 -2.00 -3.00
North
South
Based over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, at 11 years, 5/1/2003 – 4/30/2014
Comparison to NTDE 1983-2001 MSL (feet)
MHHW
MLLW
GT/Range
-0.18
2.19
-2.37
4.56
Rehoboth NTDE 83-01
-0.01 -0.40
0.925 2.02
-0.70 -2.63
1.63 4.65
Rosedale
0.40
1.81
-0.84
2.65
South Bethany
0.09
0.55
-0.31
0.86
Fenwick Island
-0.04
0.42
-0.35
0.77
Ocean City
-0.10
1.07
-1.33
2.39
Lewes IRB Inlet
0.27
1.75
-1.16
2.92
NTDE -0.36 0.83 -1.64 2.46 All values83-01 relative to NAVD88 feet, calculated over 14 year period, 5/1/2000 - 4/30/2014, except Ocean City, which is for 11 years, 5/1/2003 – 4/30/2014
MLLW -2.37 ft
MHHW 2.19 ft
Water Level Frequency Distribution
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
Delaware Inland Bays Annual Mean Sea Level, 2000 - 2014
Delaware Inland Bays Annual Mean Sea Level, 2000 - 2014
Nuisance Flooding ∗ Lesser extremes; analogous to NWS “minor” flooding ∗ Sweet (2014) report by NOAA found a significant increase in nuisance flooding through time at numerous US East and Gulf Coasts tide gages. ∗ Used NWS minor flooding category, 6 ft MLLW ∗ Most often occurring in the Fall months in southern Delaware.
Nuisance Flooding ∗ Sweet (2014) Sweet and Park (2014) found a significant increase in nuisance flooding through time at numerous US East and Gulf Coasts tide gages. ∗ Used NWS minor flooding category, 6 ft MLLW ∗ Most often occurring in the Fall months in southern Delaware.
Hours/Year > MHHW + 1.0 and 2.0 ft Lewes, Ocean City
Hours/Year > MHHW + 1.0 and 2.0 ft IRB Inlet, Rosedale
Hours/Year > MHHW + 1.0 and 2.0 ft Rehoboth, S. Bethany
Hours/Year > MHHW + 1.0 and 2.0 ft LAB/Fenwick Island
General observations…so far ∗ Inlet and Rosedale: ∗ similar magnitude and behavior, under tidal-only and non-tidal influences, and highest MSL
∗ Lewes and Ocean City: ∗ strong tidal signal in all conditions; lowest MSL
∗ Rehoboth, Bethany and Fenwick: ∗ significantly lagged and diminished high tides; no low tide/cycle during storms, very small range
∗ All gages show increases over time: ∗ MSL ∗ MHHW and MLLW (Lewes and Ocean City) ∗ minor/nuisance flooding.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels/surge along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
∗ Use with NWS and NOS forecasts to integrate with Delaware Coastal Flood Warning System.
In Progress…. ∗ Explore full POR per station for flooding frequency, duration and exceedance probabilities. ∗ Separate tidal vs non-tidal (surge) ∗ Harmonic analysis (M2, S2, K1, O2, M4, …)
∗ Develop statistical relationships between water levels along coast to locations within Inland Bays ∗ include time and weather (wind, precip)
∗ Use with NWS and NOS forecasts to integrate with Delaware Coastal Flood Warning System. ∗ Expand spatial coverage within Inland Bays
Possible monitoring locations for water level analysis study
Thank You!
John Callahan Delaware Geological Survey [email protected]
Kevin Brinson Delaware Environmental Observing System
Seasonal Variation of Coastal Storms
Source: Delaware Storm Climatology, Delaware Environmental Observing System
Delaware Inland Bays Seasonal Variation MSL, 2000 - 2014
NCA 2012
Historical Sea Levels
Coastal Inundation Study of the Delaware Inland Bays ∗ General behavior of all tidal gages in Inland Bays ∗ Timing and amplitude, under spring/neap/storm conditions
∗ “Water level” analysis ∗ Comparison of tidal datums ∗ Seasonal and annual frequency and duration of flooding (nuisance flooding, extreme events)
∗ Correlation of water levels and/or storm surge along coast to gages within Inland Bays ∗ Including time lag/duration and weather (winds, precip)
∗ Integration into Delaware CFMS for early warning
