Transcript San Francisco Bay Re..

San Francisco Bay
“Its All About the Sediment”
Brenda Goeden
San Francisco Bay Conservation and Development Commission
San Francisco
Bay
Approximately 54
Square Miles Today
• Two Major Fresh Water
Rivers to the East:
Sacramento and San Joaquin
• Drain 40% of the state
1849
2100
Changed Situation
The New World:
Sea Level Rise
Area subject to high
tide with 16 inches
of sea level rise
Current 100-year
flood plain
Floods
Storm Surge
Shoreline and Beach Erosion
Changed
Situation
The New World: Sediment Deficit
1600
1400
SSC, mg/L
1200
1000
800
600
400
200
0
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Point San Pablo, mid-depth, Dave Schoellhamer,
USGS
Why Do We Care?
Shorelines
Levees
Habitat
Sea Level Rise
What’s Changed?
The System?
Our Understanding of the System?
Sediment Rich
Sediment Poor
1990/2011 San Francisco Bay
 Historic marshes diked off
 Historic beaches no longer connected
 Watersheds channelized
 Watersheds clogged with fine grain sediment
 Sediment trapped behind dams
 Shoreline developed
 Water from Delta controlled
Changed Situation
Sediment Supply
Shift: from the
Delta to local
tributaries
Oakland Museum Creek
A Large Water and
Sediment-shed
Local Tributaries are Becoming
Increasingly Important
Clemson University
Embayments: Erosional & Depositional
San Pablo Bay Erosional
Central Bay - Erosional
South Bay Depositional
Fregoso, Jaffe, Foxgrover, USGS
Ebb-Tide Delta Erosion
• Sediment Removal from system
• Changed wave refraction
• Erosion along outer coast
Dallas & Barnard, USGS
Sand mining
removing
sand
Sand appears
slow to
replenish
Patrick Barnard & Rikk
Dredging
Projects
✳ Federal Channels
✳ Ports
✳ Refineries
✳ Marinas
In-Bay Disposal Sites
✳ Alcatraz
✳ San Pablo Bay
✳ Carquinez Strait
✳ Suisun Channel
Ocean Disposal Site
Dispersive In Bay sites
Carquinez
San Pablo
Alcatraz
LTMS EIS/EIR
Ocean Disposal Removes Sediment from
the System
FINAL EIS/EIR
LTMS MANAGEMENT STRATEGY FOR THE
Percent of all Disposal
PLACEMENT OF DREDGED SEDIMENT IN THE BAY AREA
MONTEZUMA
WETLANDS
HAMILTON WETLANDS WITH
BEL MARIN KEYS PARCEL V
ADDITION
SONOMA BAYLANDS
In An Ever Changing World “New”
Issues to Contend With…
Watershed
Management
Climate
Change
Sediment
Supply and
Demand
Shoreline
Protection
Habitat
Restoration
and
Maintenance
Dredging and
Aggregate
Mining
Regional Sediment Management Is…
The integrated management of littoral, estuarine, and
riverine sediments to achieve balanced and
sustainable solutions to sediment related needs.”
Regional sediment management recognizes sediment
as a resource.
Sediment processes are important components of
coastal and riverine systems that are integral to
environmental and economic vitality.
Shorelines, Marshes and Beaches need
sediment to keep up with sea level rise
PWA & PRBO in review
Need
Flood Protection is
a Key Component in
Regional Sediment
Management
Walnut Creek
Need to Find New Ways
to Protect From Flooding
and Support Sediment
Supply to Wetlands and
the Bay
Ballona Creek
To Respond to a Changing Bay, A New
Approach and Much Coordination is
Needed
Scientific Inputs
Management
Considerations and
Planning
Optimized
Management
of Programs
Affecting
Sediment Supply
and Demand
New Areas to Consider
Sediment Sources and Sinks
 Flood Protection
 Aggregate Mining
 Dredging
 Wetland Restoration
 Beach Nourishment
 Shoreline Protection
Local Tributaries Sediment
Flow Analysis
Quantify local tributaries contribution to Bay
sediment budget
 Corte Madera & Alameda Creeks
 Sediment gauges at head of tide and creek mouth
 Sediment flow and flux between creek and Bay
 Short term study – need funding to continue
 First step in developing a predictive numerical
model for local tributaries
 Working with SFEI and USGS

Corte Madera Creek Study
 Wetland wave attenuation study
 Resilience of tidal marsh to sea level rise and
coastal flooding
 Improve analytical tools for assessing flood risk
 Improve guidance for local decision makers
 Use data to build and calibrate 2D and 3D models
 Collect and analyze sediment cores for
sedimentation rates and peat accumulation
Working with USGS and Marin County Flood Control &
Water Conservation District
Modeling Can Help
 Tidal Hydrology
 Watersheds
 Sediment Transport
Need
Flood Districts and Watersheds