Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan...
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![Page 1: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/1.jpg)
Argus as an Coastal Engineering Tool -
Validation through Comparisons with Traditional Methods
Joan Oltman-Shay,
Matt Pruis, and Dave BerlinerSponsored (Requested) by: USACE Portland District
![Page 2: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/2.jpg)
Background: Argus Monitoring at North Head
• Sponsor: US Army Corps of Engineers – Portland District
• Project Objectives:
• Survey the intertidal zone of Benson Beach, north of the Mouth of the Columbia River
• Develop a process understanding of sediment transport on Benson Beach
• Provide an “informed” opinion of best location(s) for dredge material disposal within the littoral cell (beneficial use of dredged sands)
![Page 3: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/3.jpg)
Eight cameras looking south
50mm lenses
Jetties, MCR, and the great state of Oregon in the distance
![Page 4: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/4.jpg)
Site E
2 miles; 3.22 km
1km
4km
MCR
North HeadLighthouse
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USACE District Experience with Argus
• The bosses of Corps project engineers do not “know” Argus from Adam
• Proof of Argus methods is therefore needed
– e.g., comparison with “traditional” survey methods like RTK GPS
• Comparison #1: Where is the painted rock?
• Comparison #2: Intertidal bathmetry comparision with RTK GPS
– Result: Identification of “best-use” images and parameters for intertidal bathymetry mapping
• Only use images collected during flood tides
• “Measure” foreshore beach slope for each survey day
![Page 6: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/6.jpg)
Comparison #1:GPS vs Argus:
Location of the White Rocks 2005 Request: Location ofPainted Stones ?
Argus Answer:
A creative X,Y, Z solution
Results:
The contract has continued.
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Comparison #2: Traditional vs ArgusIntertidal Bathymetry Surveys
• RTK GPS “Traditional” Surveys– Peter Ruggiero and George
Kaminsky • USACE Portand District funding
– Bi-annual surveys of Benson Beach and the larger Columbia River Littoral Cell
• 6 surveys between Feb 2004 and Nov 2005 coincide with Argus acquisition of good images– No fog, Hrms < 2m, large tidal
range
![Page 8: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/8.jpg)
Argus intertidal bathymetry surveys:• Tools from Delft’s ARE
Shoreline Detection: Pixel Intensity Clustering Method of Aarninkof and Roelvink (1999)
Shoreline Elevation:
Zwl = Ztide + Zwvsetup + (Kosc)Zswash
(Battjes&Jannsen, 1978; Svendsen, 1984; Stive and DeVriend, 1994; Aarninkof&Roelvink, 1999)
Note: Zwvsetup and Zswash are a function of Hrms, Tpk, and foreshore beach slope)
Contours span 4m elevation
Sept 2005
Sept 2006
![Page 9: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/9.jpg)
Warning: Foreshore beach slope can changea lot…and often
Date Intertidal Beach Slope Comments
20 February 2004 0.044 0.053 slope for 1.5-2.5m elev
30 July 2004 0.016 0.042 slope for 1.5-2.5m elev
20 September 2004 0.026 0.028 slope for 1.5-2.5m elev
20 February 2005 0.022 0.026 slope for 1.5-2.5m elev
23 August 2005 0.01 0.015 slope for 1.5-2.5m elev
15 November 2005 0.042 0.042 slope for 1.5-2.5m elev
The alongshore average (2km) intertidal (0.5-1.5m NAVD88) beach slope determined from an initial (beach slope fixed at 0.025) Argus intertidal bathymetry
![Page 10: Argus as an Coastal Engineering Tool - Validation through Comparisons with Traditional Methods Joan Oltman-Shay, Matt Pruis, and Dave Berliner Sponsored.](https://reader036.fdocuments.us/reader036/viewer/2022062716/56649e005503460f94ae9bff/html5/thumbnails/10.jpg)
Argus and RTK GPS Comparisons: Flood vs Flood & Ebb Tide Images
Flood & ebb images
Flood only images
Argus contour elevations compared with the average elevation of the interpolated GPS-Buggy data along each of the Argus x,y contours (Aarninkhof method).
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Argus and RTK GPS Comparisons: Flood vs Flood & Ebb Tide Images
DATE FLOOD TIDE ONLY FLOOD & EBB TIDE
Mean Error (cm)
RMS Error (cm)
Mean Error (cm)
RMS Error (cm)
20 Feb 2004 -1.4 10.6 11.7 30.6
30 July 2004 -3.4 8.9 -10 18.8
20Sep 2004 -5.2 9.3 -21.2 26.7
20 Feb 2005 8.9 11.5 10.1 14
23Aug 2005 0.2 9.3 -11.3 20
15Nov 2005 -7.3 10.9 -10.2 30.6
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Argus and RTK GPS Comparisons: Fixed vs “Measured” Foreshore Slope
DATE MEASURED BEACH SLOPE FIXED 0.025 BEACH SLOPE
Mean Error (cm)
RMS Error (cm)
Mean Error (cm)
RMS Error (cm)
20 Feb 2004 -1.4 10.6 25.2 26.5
30 July 2004 -3.4 8.9 -20.6 22
20 Sep 2004 -5.2 9.3 -4.1 8.6
20 Feb 2005 8.9 11.5 5.3 8.9
23 Aug 2005 0.2 9.3 -24.8 26.4
15 Nov 2005 -7.3 10.9 -6.3 10.8
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A Picture is Worth A Thousand Words
Alongshore (m)
Cro
ss-s
hore
(m
)
Feb. 21, 2004
1000 1500 2000 2500 3000
300
350
400
450
500
550
Buggy
Argus
MHW Shoreline
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Alongshore (m)
Cro
ss-s
hore
(m
)
Jul. 28, 2004
1000 1500 2000 2500 3000
300
350
400
450
500
550
Buggy
Argus
Alongshore (m)
Cro
ss-s
hore
(m
)
Feb. 20, 2004
1000 1500 2000 2500 3000
300
350
400
450
500
550
Buggy
Argus
Alongshore (m)
Cro
ss-s
hore
(m
)
Aug. 23, 2005
1000 1500 2000 2500 3000
300
350
400
450
500
550
Buggy
Argus
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Summary
• RMS errors of O(10cm) between RTK GPS and Argus surveys at North Head can be achieved if:– Argus uses only images acquired during flood tides
• rms errors reduced by as much as 20cm
– the Argus waterline elevation model uses a timely “measured” foreshore slope
• An one-step, iterative method of first estimating foreshore slope from Argus contour elevations estimated with a fixed beach slope and then corrected with the “measured” foreshore slope improved comparisons
– rms errors reduced by as much as 15cm
– you don’t have to re-pick contours to do this
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Reprocessing North Head Contour Data
• We’re going back through 30+ months of Argus images and constraining (“filtering”) our contour for:– Flood tide images– Flood tidal ranges spanning nominally 1 to 3m NAVD88– Hrms < nominally 2m*– Tpk < nominally 15sec*
• We use autogeom to also help us identify and filter good quality images (good geometry solutions = good images … no fog at North Head)– This is a critically important time saver
* Minimizing Hrms and Tpk reduces the magnitude of wave setup and swash (model error); we presently use Hrms < 1m in summer, < 2.5m in winter and do not constrainTpk.
This exercise has given us great confidence in the ARE waterline elevation model
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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.