HiOOS P.I. - B. Taylor

Waves and Water Levels Component

M. Merrifield & D. Luther - Co-PIs

Waves and Water Levels Objectives

Inundation Product: Warning of extreme high sea levels at least a day in advance around Oahu (in collaboration with Coastal Inundation component of HiOOS).

Harbor Conditions Products (Nowcast & Forecast): Providing real-time information & forecasts of tides, sea/swell, seiches and currents at two high-use, vulnerable harbors: Barber’s Pt., Oahu, and Kaumalapau, Lana’i.

Inundation Problem

High Tide + High Winter Surf (Setup) =

North Shore Coastline Flooding (property damage & road overtopping)

Inundation Problem

High Tide + A Little Extra (due to an eddy)

= Low-Land Flooding

(property damage & business disruption)

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CRAIG T. KOJIMA / CKOJIMA@STARBULLETIN.COMCharles Memminger kayaks at the intersection of Ahua and Kilihau streets in Mapunapuna, which often floods at high tide. July 30, 2006.

Inundation Problem: High Tide + A Little Extra (due to an eddy) = Beach Flooding (increased erosion & tourist discontent)

Ala Moana ParkHonolulu

Inundation Problem: High Tide + A Little Extra (due to an eddy) = Beach Flooding (increased erosion & tourist discontent)

Ala Moana ParkHonolulu

Inundation Problem: High Tide + A Little Extra (due to an eddy) = Beach Flooding (increased erosion & tourist discontent)

Ala Moana ParkHonolulu

Inundation Product Requires:

• accurate tides along Oahu shorelines (spring tide range ~ 1.2m )– provided by G. Carter (SOEST/UH) model validated by NOAA station SL

• sea/swell setup prediction (often reaches 0.5m )– provided by model validated with near-shore wave/SL data funded under HiOOS

• mesoscale eddy SL prediction (range each year ~ 0.3m )– provided by HiOOS modeling component

• SSH annual cycle estimate (Sep-Oct max; often has a range of 0.3m )– provided by HiOOS modeling component

• long-term SL rise estimate (at Honolulu, currently ~ 0.003m/yr)– provided by analyses of NOAA SL gauge data

• storm surge prediction (during hurricane, easily over 2.0m )– defer to NWS

• tsunami (depending on location, expect up to 2.0m )– defer to PTWC

Inundation Product: Sea/swell setup based on HiOOS models of wave amplitude & setup, validated with HiOOS & other NOAA wave & SL obs.

Wave setup at Mokuleia, N. Shore Oahu

Inundation Product: Sea/swell setup varies significantly along shoreline.Where barrier reef is wide, coastal water level unrelated to outside wave activity.

Makapu’uOahu

Inundation Product: Nested models (K-F Cheung, SOEST/HiOOS) bring wave predictions into shallow water (validated with HiOOS & NOAA obs).

Local Boussinesq Model SWAN – Littoral Wave Model

Regional WaveWatch3Global WaveWatch 3

Inundation Product: Mesoscale eddies originate east of the islands and propagate to the islands, often amplifying along the way.

Satellite SSH

Y. Firing, M. Merrifield, Oceanography

High Event

Honolulu Sea Level

Inundation Product: Eddy heights along the shores of Oahu will be determined by high-resolution models validated by NOAA SL gauges & altimetry.

Ocean circulation model comparisons for 17 Sep. 2007. Note:

• Coastline resolution• Channel resolution• Open-ocean and near-shore currents

- Enhanced resolution model captures eddies.- Model output must be evaluated with SL obs.

Harbor Conditions Problem: SL amplitudes of seiches (3-40 minute periods) in some harbors often reach 10’s of cm’s, with concomitant disruptive currents.

Kahului, Maui SL - Jan. 28-29, 1998

Se

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l (m

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Time (day of year - 1998)

40 cm changes in 20 minutes

Time (day of year - 1998)

Harbor Conditions Product: For best results, directional wave buoys are deployed outside target harbors: sea/swell monitoring & seiche prediction.

Kaumalapau Hbr.Lana’i

J. Aucan, M. Merrifield, OceanographyACE, CDIP

Harbor Conditions Product: mock-up of a real-time product that we have on-line for Kaumalapau: tides & seiche surge from our harbor gauge; gravity wave height from our wave buoy.

Harbor Conditions Product: similar product under construction for Barber’s Pt. Hbr., Oahu, but will also have currents in channel per request of pilots.

M. Merrifield, D. Luther, J. Aucan - Oceanography

Important In Situ Assets

All HiOOS W&WL sensors feed into the usual national and international data repositories for SL and surface wave data, e.g.,- CDIP- NOAA CO-OPS- IOC SL Facility

Underway Development Work:

Inundation Product:- refine near-shore sea/swell wave modeling- establish accuracy of eddy SL in regional ocean circulation models

Harbor Conditions Products:- deploy current meter off Barber’s Pt. Harbor- deploy real-time harbor conditions product for Barber’s Pt. Hbr.- establish prediction capability for harbor seiche/surge

Future Expansion:

Hawaii:- acquire SL data from more locations around Oahu to refine wave setup model in terms of reef dimensions - need to acquire and deploy more temporary sea level gauges

- expand inundation product to other vulnerable (low-lying) Hawaii coastlines, such as west Maui - need to evaluate specific contributors to inundation through deployment of wave and SL gauges

- establish harbor conditions products at other vulnerable Hawaiian harbors, e.g., Kahului & Hilo - need to deploy directional wave buoys, sea level sensors and current meters both inside and outside of harbors (some temporary; some permanent)

Future Expansion:

Pacific Islands:- expand/export our wave & water level products and monitoring systems to other islands in the PacIOOS RA

- currently have a directional wave buoy deployed off Guam- NOS & UHSLC network of sea level gauges on Pacific Is.

gives us a jump start on evaluating inundation characteristics at many Pacific Is.- need to evaluate/confirm specific contributors to inundation through

deployment of wave and SL gauges

- need to deploy directional wave buoys, sea level sensors and current meters both inside and outside of harbors (some temporary; some permanent)- need to expand high resolution wave and ocean circulation modeling to target islands

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December 2008Flooding at Majuro