San Francisco Bay

lameubiquityΜηχανική

21 Φεβ 2014 (πριν από 3 χρόνια και 3 μήνες)

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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

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 Erosion

The New World: Sediment Deficit

Changed
Situation

0
200
400
600
800
1000
1200
1400
1600
SSC, mg/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

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


Oakland Museum Creek
Guide

Sediment Supply
Shift: from the
Delta to local
tributaries

Changed Situation

A Large Water and
Sediment
-
shed

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




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

Percent of all Disposal

FINAL EIS/EIR

LTMS MANAGEMENT STRATEGY
FOR

THE
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

Shoreline

Protection

Climate


Change


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.

Need

Shorelines, 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

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

Flood Districts and Watersheds

Need