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Argus at North Head, WA USA Science for Decision Making. Joan Oltman-Shay Chad Budworth Sponsored by: USACE Portland District. Presentation Overview. Background on Location and View Orientation Directed-Science Objectives and Results Other Argus Services Derivative products. - PowerPoint PPT Presentation
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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
200
400
600
2004_02_21504376 +/- 54 m2
2004_03_20509256 +/- 34 m2
2004_04_25511177 +/- 27 m2
2004_05_28510304 +/- 22 m2
200
400
600
2004_06_22517009 +/- 20 m2
2004_07_25548898 +/- 80 m2
2004_08_21550669 +/- 31 m2
2004_09_23549976 +/- 17 m2
200
400
600
2004_10_11563435 +/- 35 m2
2004_11_21552221 +/- 20 m2
2004_12_22541959 +/- 111 m2
2005_01_26525304 +/- 18 m2
200
400
600
2005_02_27511243 +/- 36 m2
2005_03_23508534 +/- 63 m2
2005_04_20509300 +/- 19 m2
2005_05_25521515 +/- 17 m2
1000 2000 3000
200
400
600
2005_06_25514258 +/- 30 m22005_06_25514258 +/- 30 m22005_06_25514258 +/- 30 m2
1000 2000 3000
2005_07_24536571 +/- 242 m22005_07_24536571 +/- 242 m2
1000 2000 3000
2005_08_21543952 +/- 134 m22005_08_21543952 +/- 134 m2
1000 2000 3000
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
1000 1500 2000 2500 3000 3500 4000 4500
-200
0
200
400
600
800
1000
1200
1400
1600
Sat.Apr.16.18.20.00.GMT.2005
1000 1500 2000 2500 3000 3500 4000 4500
-200
0
200
400
600
800
1000
1200
1400
1600
Mon.May.16.23.20.00.GMT.2005
1000 1500 2000 2500 3000 3500 4000 4500
-200
0
200
400
600
800
1000
1200
1400
1600
Outer
500 1000 1500 2000 2500 3000 3500
100
200
300
400
NorthHead 2.0m NAVD88 Shoreline Contours01Feb04 - 30Sep05
Dis
tanc
e fr
omba
selin
e (m
)
500 1000 1500 2000 2500 3000 3500
100
200
300
400
Mea
n, m
ax,
min
(m
)
maxminmean
500 1000 1500 2000 2500 3000 3500
0
10
20
30Stn
drd
Dev
(m
)C
ross
-sho
re (
m)
Alongshore (m)500 1000 1500 2000 2500 3000 3500
200
400
600
800
01Feb04 01Apr04 01June04 01Aug04 01Oct04 01Dec04 01Feb05 01Apr05 01June05 01Aug05 01Oct05
-50000
0
50000
100000
150000E
rosi
on
-Acc
retio
n [m
3 ]
Intertidal Volume Change
NMSN CumM CumS Cum
01Feb04 01Apr04 01June04 01Aug04 01Oct04 01Dec04 01Feb05 01Apr05 01June05 01Aug05 01Oct05-20000
0
20000
40000
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
0
50
100
150
200
250
300
350
400
sep03-apr04 may04-aug04 sep04-apr05 may05-aug05 sep03-aug04 sep04-aug05
Time Period
# o
f o
ccu
ran
ces
180-210 >4m
211-240 >4m
241-270 >4m
271-300 >4m
301-330 >4m
331-360 >4m
Seasonal Comparison Annual Comparison
Occurrence of Eroding Waves: Hsig > 4m
Wave Direction Hsig <2m
0
500
1000
1500
2000
2500
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
301-330 <2m
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
1000 1500 2000 2500 3000 3500 4000 4500
-200
0
200
400
600
800
1000
1200
1400
1600
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
100
200
300
400
500
600
700
800
900
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.