San Francisco Bay “Its All About the Sediment” Brenda Goeden San Francisco Bay Conservation and Development Commission.

San Francisco Bay

“Its All About the Sediment”

Brenda GoedenSan 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

Area subject to high tide with 16 inches of sea level rise

Current 100-year flood plain

Changed Situation

The New World: Sea Level Rise

Floods

Storm Surge

Shoreline and Beach ErosionShoreline and Beach Erosion

The New World: Sediment Deficit

Changed Situation

0

200

400

600

800

1000

1200

1400

1600

SS

C, m

g/L

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 LeveesHabitatSea 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

Oakland Museum Creek Guide

Sediment Supply Shift: from the Delta to local tributaries

Changed Situation

A Large Water A Large Water and Sediment-and Sediment-shedshed

Clemson University

Local Tributaries are Becoming Increasingly Important

Embayments: Erosional & Depositional

Fregoso, Jaffe, Foxgrover, USGS

South Bay - Depositional

San Pablo Bay - Erosional

Central Bay - Erosional

Ebb-Tide Delta Erosion

Dallas & Barnard, USGS

• Sediment Removal from system

• Changed wave refraction

• Erosion along outer coast

Sand mining removing sand

Patrick Barnard & Rikk Kvitek

Sand appears slow to replenish

Dredging Projects

✳ Federal Channels

✳ Ports

✳ Refineries

✳ Marinas

In-Bay Disposal Sites

In-Bay Disposal Sites✳ Alcatraz✳ San Pablo Bay✳ Carquinez Strait✳ Suisun Channel

Ocean Disposal Site

Dispersive In Bay sites

LTMS EIS/EIR

Carquinez San Pablo

Alcatraz

Ocean Disposal Removes Sediment from the System

Per

cen

t of

all

Dis

posa

l

FINAL EIS/EIRLTMS MANAGEMENT STRATEGY FOR THE

PLACEMENT OF DREDGED SEDIMENT IN THE BAY AREA

MONTEZUMAWETLANDS

MONTEZUMAWETLANDS

HAMILTON WETLANDS WITH BEL MARIN KEYS

PARCEL V ADDITION

SONOMA BAYLANDS

In An Ever Changing World “New” Issues to Contend With…

Habitat Restoration

and Maintenance

Dredging and Aggregate

Mining

Sediment Supply and

Demand

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.

NeedShorelines, Marshes and Beaches need sediment to keep up with sea level rise

PWA & PRBO in review

Walnut Creek

Ballona Creek

Flood Protection is a Key

Component in Regional Sediment

Management

Need to Find New Ways to Protect From Flooding and Support

Sediment Supply to Wetlands

and the Bay

To Respond to a Changing Bay, A New Approach and Much Coordination is Needed

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

Flood Districts and Watersheds

Need