Argus at North Head, WA USAScience for Decision Making

Joan Oltman-Shay

Chad BudworthSponsored by: USACE Portland District

Presentation Overview

• Background on Location and View Orientation

• Directed-Science Objectives and Results

• Other Argus Services

– Derivative products

Argus at the North Head LighthouseMouth of the Columbia River

Washington State USA

Eight cameras looking south

50mm lenses

Jetties, MCR, and the great state of Oregon in the distance

Site E

2 miles; 3.22 km

1km

4km

MCR

North HeadLighthouse

North Head Panorama – 26 Feb 2005

Panoramic to Plan Views – 26 Sept 04

250m

400m

670m

Directed-Science Objectives• Strategic Objective

– Obtain environmental information to aid in decision-making for placement of Columbia River dredge material

– Obtain environmental information relevant to the health of the north jetty

• Operational Objective for Argus– Monitor erosion rates at Benson Beach– Map sediment features near the jetty– Develop a conceptual model of sediment processes

on Benson Beach (adjacent to the north jetty)– Monitor wave activity near the SWS (Site E)

Approach

Analyze Argus data for:2.0m NAVD88 (MHW) shoreline locationOffshore bar movementsDry-beach acreage change

• Between MHW and an onshore baseline Intertidal sand volume change

• Between 0.69 (MLW+.3) and 2.26m (MHHW)

– Run-up• Kent Hathaway: 3 locations along the 3km of beach

– Longshore surface currents• Kent Hathaway: can’t use pixels – Tom Lippmann is trying

PIV– Integrate offshore wave periods and direction

• Either Argus derived, NDBC buoy, or models

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2004_02_21504376 +/- 54 m2

2004_03_20509256 +/- 34 m2

2004_04_25511177 +/- 27 m2

2004_05_28510304 +/- 22 m2

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2004_06_22517009 +/- 20 m2

2004_07_25548898 +/- 80 m2

2004_08_21550669 +/- 31 m2

2004_09_23549976 +/- 17 m2

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2004_10_11563435 +/- 35 m2

2004_11_21552221 +/- 20 m2

2004_12_22541959 +/- 111 m2

2005_01_26525304 +/- 18 m2

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2005_02_27511243 +/- 36 m2

2005_03_23508534 +/- 63 m2

2005_04_20509300 +/- 19 m2

2005_05_25521515 +/- 17 m2

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2005_06_25514258 +/- 30 m22005_06_25514258 +/- 30 m22005_06_25514258 +/- 30 m2

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2005_07_24536571 +/- 242 m22005_07_24536571 +/- 242 m2

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2005_08_21543952 +/- 134 m22005_08_21543952 +/- 134 m2

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2005_09_17554719 +/- 12 m22005_09_17554719 +/- 12 m2

Time increasingFeb 2004 May 2004

June 2005 Sept 2005MHW Shoreline Shape

Thu.Mar.03.18.20.00.GMT.2005

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Sat.Apr.16.18.20.00.GMT.2005

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Mon.May.16.23.20.00.GMT.2005

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Outer

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NorthHead 2.0m NAVD88 Shoreline Contours01Feb04 - 30Sep05

Dis

tanc

e fr

omba

selin

e (m

)

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Mea

n, m

ax,

min

(m

)

maxminmean

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30Stn

drd

Dev

(m

)C

ross

-sho

re (

m)

Alongshore (m)500 1000 1500 2000 2500 3000 3500

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01Feb04 01Apr04 01June04 01Aug04 01Oct04 01Dec04 01Feb05 01Apr05 01June05 01Aug05 01Oct05

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rosi

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Intertidal Volume Change

NMSN CumM CumS Cum

01Feb04 01Apr04 01June04 01Aug04 01Oct04 01Dec04 01Feb05 01Apr05 01June05 01Aug05 01Oct05-20000

0

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60000NorthHead 2.0m NAVD88 Acreage

Dry

Be

ach

Acr

ea

ge

Ch

an

ge

[m2 ]

Date

NMSN CumM CumS Cum

Winter Season 04/05

SWS Material Added

North Jetty Repair

05/06 03/04

Sand Bar

Wave Direction Hsig >4m

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sep03-apr04 may04-aug04 sep04-apr05 may05-aug05 sep03-aug04 sep04-aug05

Time Period

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f o

ccu

ran

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211-240 >4m

241-270 >4m

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Seasonal Comparison Annual Comparison

Occurrence of Eroding Waves: Hsig > 4m

Wave Direction Hsig <2m

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sep03-apr04 may04-aug04 sep04-apr05 may05-aug05 sep03-aug04 sep04-aug05

Time Period

# o

f O

ccu

ran

ces

180-210 <2m

211-240 <2m

241-270 <2m

271-300 <2m

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331-360 <2m

Seasonal Comparison

Annual Comparison

Occurrence of Accreting Waves: Hsig < 2m

Beach normal

Towards a Conceptual Understanding:Nascent Musings

• Acreage and Sand volume changes– North and South ends of the beach behaving differently

• North side shows no net change after two years– Cumulative accretion and erosion close to zero in the second year

• South side shows significant accretion in the 2nd summer– Less erosion at the end of the 2nd winter

• Sand bar accretion to the shoreface began before dredge material placement and jetty repair– Argus temporal resolution shows its value here!

• Offshore wave conditions different in first and second years– Fewer eroding waves (>4m) in the second year– More accreting waves (<2m) out of the extreme north-west in

second year • North side in the shadow of the headland?

Derivative Argus Products

• Are waves breaking offshore of the jetty?– Is it safe for boaters?

• Snapshot images on the web every 20 minutes – Where are they breaking? Dale Beasley, CRCFA

– Why are the waves breaking there? Rod Moritz, USACE

• What was the effect of the Dec 05/Jan 06 storms? – Did some of the nose of the jetty falling off? Rod Moritz,

USACE

– Was there beach erosion?• Can I once again use the south end of Benson Beach for

training? George Vassaur, US Coast Guard

Where are the waves breaking?

Tue.Oct.11.21.20.00.GMT.2005

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Why are the waves breaking there?

October 2005 – end of SWS material placement

5 FEB 2006 at 18:20 PST North Jetty foreground and south jetty back ground

Quick analysis by Rod Moritz using Argus products available on the web site

31 JUL 2005 31 JUL 2005

Dec05/Jan06 Storms: NORTH JETTY FEB 06 vs JUL 05

Head of north jetty has receded 30-60 ft shoreward during Jul 05 and Feb 06

Preliminary NWRA analysis: 12m loss between 26 Dec 05 and 7 Jan 06

Dec05/Jan06 Storms: Benson Beach affected?2.0m NAVD88 Shoreline Contours

Local Argus Coordinates (m)500 1000 1500 2000 2500 3000 3500

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2006_01_112005_12_142005_11_072005_01_06

YES.

MHW shoreline retreated 20 to 90m

Greatest retreat on the south side

Argus at North Head Lighthouse would not have been possible with out the joint cooperation of Washington State Parks, Coast

Guard, and USACE

NorthWest Research Associates (NWRA)

Bellevue, WA

NWRA is a scientific

research group, owned

and operated by its

Principal Investigators,

with expertise in the

geophysical and related

sciences.