Future Projections of Recurrent Tidal Flooding

NOAA Science DaysMarch 9, 2016

Dr. William Sweet NOAA Oceanographer

Coastal communities need to know what to expect

Tidal flood projections can assist community planning (e.g., budgeting for short/long term solutions).

Annual tidal-flood projections (this work) recognize:• long trends (linear or accelerating) from local sea level rise• compounding El Niño Southern Oscillation (ENSO) patterns

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“Nuisance” Tidal Flood

ing

(Days p

er Year)

Sweet et al. (2014)

Nuisance Tidal Flood Trends: 300-900% increase since 1960

NOAA gauges since 1950 reveal concerning trends (linear and accelerating) in tidal flooding.

El Niño Pattern: More West & East Coast Tidal Flooding

West Coast: High sea levels for months increase the reach of storms and tides

East Coast:More NE winds, storms and surges

Eastern Region El Niño Impacts &Outlook: October 2015

2015 El Nino Pattern: 33-200% Tidal Flood Increase Projected

0

5

10

15

20

Nui

sanc

e Ti

dal F

lood

s(D

ays

per Y

ear)

Location 14: Norfolk, VA

Historic

1982/821986/87

1991/92

1997/98 2009/10

0

5

10

15

20

Nui

sanc

e Ti

dal F

lood

s(D

ays

per Y

ear)

Location 14: Norfolk, VA

Historic Poly. (Historic)Trend (Quadratic)

1982/821986/87

1991/92

1997/98 2009/10 2015 Projection

125% increase

2015 Outlook: Number of Days with a Nuisance Tidal FloodBased upon trend (and % increase from El Nino pattern)

Montauk(100%)

Sandy Hook (48%)

Atlantic City (33%)Lewes

(71%)

Baltimore(47%)

Washington D.C.(66%)

Norfolk (125%)

Wilmington(44%)

La Jolla(67%)

San Francisco(75%)

San Diego(44%)

Los Angeles(70%)

Monterey(106%)

Alameda(200%)

Sweet and Marra (2015)

2015 Outlook (May 2015 – April 2016) issued in summer of 2015

2015 Nuisance Tidal Flood Days To Date(May 2015 – Feb 29, 2016)

Below “Trend/El Niño” Projection

Above “Trend/Niño” Projection

All time record

Sweet et al. (In Prep)

All time record (no Trend/ENSO projection)

• Tidal flooding during the 2015/16 El Niño has already surpassed projections and broke records.

• El Niño will likely become more frequent in the future, compounding impacts (in addition to sea level rise).

• NOAA is advancing a national recurrent-flood information system and local dashboards to:

deliver flood-frequency projections track impact indicators & their frequency changes

to enhance resiliency within coastal communities.

In Summary: