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Hurricane Irma Storm Surge and Impact on ENP Marine Monitoring Stations(September 9 to 11, 2017)

Prepared byWossenu Abtew, Ph.D, P.E., DWRE.

Principal EngineerWater Quality BureauSeptember 29, 2017

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Hurricane Irma Storm Surge and Impact on ENP Marine Monitoring Stations

Hurricane Irma Storm Surge and Impact on ENP Marine Monitoring Stations

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ENP – Marine Monitoring Network and Hurricane Irma Storm TrackENP – Marine Monitoring Network and Hurricane Irma Storm Track

https://en.wikipedia.org/wiki/Hurricane_Irma#/media/File:Irma_2017_track.png

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Summary – Hurricane Irma Storm Surge

1. Storm surge from Hurricane Irma was lower than expected. According to Henry Fountain and Brad Plummer (NY Times, September 11, 2017), the dreaded storm surge from Hurricane Irma was not as bad as forecasted for coastal Florida. This was due to meteorological favorable conditions that included the path and speed of the hurricane.

2. The location of the stations influenced storm surge; high surge was in western stations (Watson Place, Shark River and Lostmans River).

3. Open water stations also had higher surge (Johnson Key, Garfield Blight, Buoy Key and Duck Key).

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Both storm surge and wind speed require high resolution measurements as frequent as10 times a second (10 Hz) for wind speed. The stage data is hourly and the District wind gust data is sampled once in 10 seconds. The maximum gust speed at SGGEWX (Collier) and S331W (Miami-Dade) 97 and 70 mph, respectively, are lower than reported by others:

• Naples 142 mph gust at 18:00 on 9/10/17 (NHC)

• Top gust in Miami-Dade 99 mph at MIA, Sweetwater 96 mph, Belle Meade 92 mph and Coral Gables 90 mph (Miami Herald 9/12/17)

Summary – Hurricane Irma Storm Surge and Wind Speed Measurements

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Summary – Hurricane Irma Impact onMMN Monitoring Stations

1. 14 out of 33 stations (42%) malfunctioned probably from both wind and storm surge impact.

2. A number of the malfunctioned sites are in open water

3. The design height of marine stage recorders need to account for hurricane storm surge

4. The path, speed of forward movement, and wind speed of hurricanes are important on determining storm surge

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Storm Surge during Hurricane Irma by Group

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Malfunctioned Stations during Hurricane Irma

Broad River Lower Little Blackwater Sound Peterson Key

Buoy Key Lane River Terrapin Bay

Butternut Key Little Rabbit Key Trout Cove

Blackwater Sound Long Sound Willy Willy

Highway Creek Murray Key

Over 40% (14 of 33) Stations Malfunctioned:

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Wind Gust Speed from Hurricane Irma in Collier County (September 9-11, 2017)

Wind Gust Speed from Hurricane Irma in Collier County (September 9-11, 2017)

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Wind Gust Speed from Hurricane Irma in Miami-Dade County (September 9-11, 2017)

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Storm Surge during Hurricane Irma and Storm Impact on ENP Marine Monitoring Stations

https://en.wikipedia.org/wiki/Storm_surge#/media/File:Surge-en.svg

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Bob Allen (3 ft surge)

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Broad River Lower (malfunction)

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Buoy Key (≈ 5 ft surge and malfunction)

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Butternut Key (malfunction)

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Broad River (≈ 1.5 ft surge)

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Blackwater Sound (malfunction)

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Cannon Bay (3.5 ft surge)

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Cane Patch (1 ft surge)

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Clearwater Pass (2 ft surge)

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Duck Key (4.5 ft surge)

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Garfield Bight (5.5 ft surge)

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Gunboat Island (3 ft surge)

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Highway Creek (malfunction)

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Harney River (3.5 ft surge)

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Johnson Key ( 6 ft surge)

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Little Blackwater Sound (malfunction)

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Little Madeira (3.5 ft surge)

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Lane River (malfunction)

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Lostmans River (over 5 ft surge)

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Little Rabbit Key (malfunction)

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Long Sound (malfunction)

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Murray Key (malfunction)

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North River (1.5 ft surge)

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Peterson Key (malfunction)

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Shark River (7 ft surge)

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Terrapin Bay (malfunction)

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Trout Cove (malfunction)

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Tarpon Bay East (2 ft surge)

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Taylor River (2 ft surge needs check)

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Whipray Basin (4 ft surge)

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Whitewater Bay East (2 ft surge)

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Watson Place (6 ft surge)

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Willy Willy (malfunction)