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San Francisco District Coastal Activities. Frank Wu CERB Meeting June 4, 2009. Open Coast Ocean Beach Humboldt Bay Santa Cruz Harbor In-Bay Sacramento DWSC SF Bay to Stockton DWSC South SF Bay Shoreline. - PowerPoint PPT Presentation
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San Francisco District
San Francisco District Coastal Activities
Frank WuCERB MeetingJune 4, 2009
San Francisco District
• Open Coast– Ocean Beach– Humboldt Bay– Santa Cruz Harbor
• In-Bay– Sacramento DWSC– SF Bay to Stockton
DWSC– South SF Bay
Shoreline
San Francisco District
• Beneficial reuse of dredged material for beach nourishment at Ocean Beach and Humboldt Bay
• Background info / controlling parameters / beach erosion• O&M dredge disposal activities / available sediment• Nearshore placement demo projects• Monitoring programs• Future nearshore/onshore placement layout
development• Proposed numerical approaches• Conclusions and recommendations
San Francisco District
Ocean Beach Onshore Placement Demo Project
• Tidal range (4’ ~ 6’)
• El Niño and storm surge (1.5’ ~ 2.5’)
• Tidal currents (0.1 ~ 1 m/s)
• NW and SW waves (1 ~ 3 m)
• Sea level rise (0.2 m/100 yr)
San Francisco District
1983-01-26 to 1983-01-28, SF gage (hourly data)
-4
-2
0
2
4
6
8
10
1/24/830:00
1/25/830:00
1/26/830:00
1/27/830:00
1/28/830:00
1/29/830:00
1/30/830:00
1/31/830:00
Time
Ve
rifi
ed
an
d P
red
icte
d D
ata
: H
eig
ht
ab
ov
e M
LL
W (
fee
t)R
es
idu
al D
ata
: D
iffe
ren
ce
(fe
et)
Pred (ft)
Vrfy (ft)
Vrfy - Pred (ft)
1983-12-03, SF gage (hourly data)
-2
0
2
4
6
8
10
12/1/8312:00
12/2/830:00
12/2/8312:00
12/3/830:00
12/3/8312:00
12/4/830:00
12/4/8312:00
12/5/830:00
12/5/8312:00
Time
Ver
ifie
d a
nd
Pre
dic
ted
Dat
a: H
eig
ht
abo
ve M
LL
W (
feet
)R
esid
ual
Dat
a: D
iffe
ren
ce (
feet
)
Pred (ft)
Vrfy (ft)
Vrfy - Pred (ft)
San Francisco District
Weibull Distribution of Annual Peak Hourly Predicted Data, SF Gage (1901-2005, 105 years)
0
1
2
3
4
5
6
6.85 6.9 6.95 7 7.05 7.1 7.15 7.2 7.25 7.3
Height above MLLW (feet)
Pro
ba
bili
ty D
en
sit
y
Weibull Distribution of Annual Peak Hourly Residual Data, SF Gage (1901-2005, 105 years)
0
0.2
0.4
0.6
0.8
1
0 0.5 1 1.5 2 2.5 3 3.5 4
Difference (feet)
Pro
ba
bili
ty D
en
sit
y
San Francisco District
North Reach, Accretion: + 0 ~ 6 m/yrSouth Reach, Erosion: -1 ~ 2 m/yr
San Francisco District
Erosion Spot
San Francisco District
• Available sediment distribution
• Beach sand (~ >0.25 mm)
San Francisco District
USACE Nearshore Placement Demo Project
• 2005, 2006, 2007 (May)
• 300,000 cy x 3
• 750 m offshore, 9 ~ 14 m depth
• Expect sediment onshore movement
• Protect beach and outfall
San Francisco District
USGS Monitoring Results
• Pre and post sediment placement• 2005, 2006, 2007 (summer and winter)• Bathymetry, beach profile, wave, current• 50% sediment remained at disposal site• Confirm sediment onshore movement• Recommend future placement depth < 5 m,
including nearshore and onshore placements
San Francisco District
Pre-Project Shoreline Changes
San Francisco District
Comparisons / Shoreline Changes
San Francisco District
Comparisons / Elevation Changes
San Francisco District
Monitoring Results / Sediment Movement
San Francisco District
Conceptual Beach Nourishment Layout Development
• 300,000 ~ 1,000,000 cy onshore placement
• 3,000’ length, 30’ height, 150’ ~ 250’ width
• Fine sand dune (1:3 slope)
• Coarse sand berm (water front slope 1:25)
San Francisco District
Conclusions and Recommendations for Ocean Beach
• Plan onshore placement demo project
• Prepare a draft report (9/30/09)
• Target construction timeline (summer 2011)
• Numerical modeling (ERDC, CMS-FLOW & CMS-WAVE, tide, wave, longshore and onshore-offshore sediment transport, 2D/3D), (USGS)
San Francisco District
Humboldt Bay Nearshore Placement Demo Project
• Develop nearshore placement site
• Lessons learned from Ocean Beach
• Beneficial reuse of dredged material
• Establish monitoring plan• Proposed numerical
approaches
San Francisco District
High Energy System
• Swell (NW, winter and summer)
• Wind wave (SW, winter; N summer) (H: 3 ~ 13 ft; T: 12 ~ 16 s)
• Tidal range (5’ ~ 7’)• Tidal current
(1.5 ~ 2.5 ft/s)
San Francisco District
Beach Erosion
• USACE aerial photo (1992-2005)
• Erosion of North Spit• Accretion of South Spit
San Francisco District
Entrance Channel Maintenance
• USACE Maintained 1881• Northern, CA
– 225 mi. N of SF Bay
– 156 mi. S of Coos Bay, OR
• Deep draft harbor (-48 ft MLLW)
• Annually 1,000,000 cy (>95% sand)
San Francisco District
Dredge Disposal Sites Map
• SF-3 1940 ~ 1988 60’ ~ 90’ depth
• NDS 1988 and 1989 50’ ~ 60’ depth
• HOODS > 1989 160~ 180’ depth non-dispersive 50 x 106 cy capacity (60% left)
San Francisco District
Nearshore Project Benefits
• Nourish north spit
• Increase wave protection
• Reduce dredge disposal at HOODS– Maintain littoral cell– Reduce maintenance costs
• Improve recreation (surf, beach)
• Restore Habitat (snowy plover)
San Francisco District
Proposed Nearshore Demo Project
• Preliminary development (800,000 ~ 1,000,000 cy placement)
• Area: 3 mi x ¼ mi• Sediment deposition:
~ 1.0 ft• 2 control cells (N & S)• Hopper dredge Essayons
(USACE)
San Francisco District
Demo Project Monitoring/Modeling• Control Cells
– Sediment samples pre and post placement– Biological Survey (crabs)
• Bathymetric Survey
Suggested Future Activities• Field monitoring program (USGS / local university)
– Beach response and sediment transport
• Numerical modeling (ERDC)– CMS-FLOW and CMS-WAVE
San Francisco District
Conclusions and Recommendations for Humboldt Bay
• Lessons learned from Ocean Beach
• Develop field measurement programs / bathymetry survey / monitoring
• Perform numerical analysis / simulation
• Design nearshore placement scheme
San Francisco District
Acknowledgements
• USACE-SPN PDT
• USGS / M&N
• USACE-SPD
Thank You