Climate variability over California
reflected in changes in sediment
fluxes to tidal marshes in the San
Francisco Bay over the past 3
millennia
…or…
Frances Malamud-Roam, Dept of Geography, UC Berkeley
Lynn Ingram, Depts. of Geography and Earth & Planetary
Sciences, UC Berkeley
Karl Malamud-Roam, Contra Costa Mosquito and Vector
Control District, Concord, CA
Mud talks
Watershed
region of the
San
Francisco
Estuary
Mineral (detrital) sediments
are collected from the
catchment areas and
transported by the two major
river systems
Sacramento River
Drainage
San Joaquin
River Drainage
Watershed region
of the San
Francisco Estuary
… and deposited on the Estuary marsh surfaces
Precipitation patterns over the
Watershed
North to South differences:
timing is the same, but
amount of precipitation and
type differ.
Timing of river flows also
differs
Proportion of Sacramento
flows relative to San
Joaquin flows: Fs/Fsj
1965–1977: 2.1
1977–1987: 1.7
Knowles, 2002
Runoff patterns over the Watershed
North to South
differences:
amount and timing
differ
Oltmann, 1996
Questions
1. CALFED: For tidal marsh restoration
and future maintenance, can we
discern the relative percentage of the
sediments feeding tidal marshes
derived from the larger watershed vs.
from local?
2. Climate: can we detect changes in
North to South patterns reflected in the
sediments delivered by these two major
river systems?
California
Geology
River basins
drain different
lithologies
California
Geology
Bay Area:
Franciscan
River basins
drain different
lithologies
Northern
range:
volcanic
Southern
range:
granitic
Simple mixing model for sediment
sources
Using elemental concentrations as
geochemical fingerprints
Inductively coupled plasma
mass spectrometry (ICPMS) & optical emissions
spectrometry (ICP-OES)
U.C. Davis ICP-MS
Mn Ni Cu Zn Rb Sr Nb Mo
Ba La Nd Sm Dy Yb Pb U
Suspended
sediment sample
collection
Results
Suspended loads
Elemental compositions of river sediments
Results
Suspended loads
Elemental compositions of river sediments
Discriminant Analysis
4
3
Local
Watershed
2
San
Joaquin
Watershed
1
0
-1
Sacramento
Sacramento
Watershed
Watershed
-2
-3
-4
-2
-1
0
1
2
3
4
5
6
Canonical1
Discriminant analysis
7
8
9
10
4
3
Local
Watershed
2
San
Joaquin
Watershed
1
Bay
Samples
0
-1
Sacramento
Sacramento
Watershed
Watershed
-2
Total n: 54
Misclassified: 3
% Misclassified: 5.66
-3
-4
-2
-1
0
1
2
3
4
5
6
7
8
9
Canonical1
Discriminant analysis - Bay samples included
10
Marsh core sites
Petaluma Marsh
China Camp Marsh
Results
China Camp marsh core
Stratigraphy
Core
stratigraphy
Core
stratigraphy
Sum measured
elements
Core
stratigraphy
Sum measured
elements
Low
Organics
– high
mineral
content
Results
China Camp marsh core
Stratigraphy
End-member source
contributions
Results from core analyses: China Camp
Down-core
results
showing the
fraction of
detrital
sediments
from each
source to
the marsh
surface
Results from core analyses: China Camp
Expressed as
deviations from
mean/std
deviation
Results from core analyses: China Camp
Comparing
changes in
source
contributions
from
Sacramento
valley and San
Joaquin valley
Vegetation history from China Camp core
Marsh plant types
C3 vs C4
plants
Results from core analyses: China Camp
At times in the
past the two
systems shift in
the similar
direction, and
other times
dissimilar
Results from core analyses: China Camp
Relatively fresh
on the marsh
and on other
sites in the Bay
(e.g., Goman
and Wells,
2000)
Elsewhere in
California:
Mono lake high
stand (Stine,
1990)
Pyramid lake
and Owens
lakes show
evidence of
cool, wet
(Benson et al.
2002)
Results from core analyses: China Camp
Period of
degraded
marsh
Other sites in
Estuary show
shift to more
saline
conditions (e.g.,
Byrne et al.
2001; Goman
and Wells
2000).
Mono lake low
stand, later the
first MCA
drought (Stine,
1990, 1994),
Results from core analyses: China Camp
After ca 750 cal yr
B.P. conditions
freshen (Byrne et
al 2001; Starratt
2004)
Evidence of 2
floods between
850 - 450 cal yr
B.P. Flood
evidence
elsewhere
(Goman and
Wells 2000,
Ingram et al.
1996).
Flood also in
Sacramento
Oxbow lake
(Sullivan, 1982);
Santa Barbara
Basin
(Schimmelmann
1998, 2003)
River Reconstructions from
tree rings
Yrs A.D.
Red line is San Joaquin
Green line is Sacramento
Earlier drought: good
agreement with Meko
reconstruction
Later drought: not seen
in marsh records.
Results
Petaluma marsh core
End-member source
contributions
Petaluma core
Moist period
corresponding
with Little Ice
Age seen in
other records
Floods not as
pronounced as
China Camp
record.
Comparing records from the two marshes
Local
creeks show best agreement
Local
creeks
CC (solid line)
Petaluma (dashed)
General agreement for
Sacramento input
San Joaquin has
some inconsistency
at ca 500-400 yr BP,
and at ca 250 BP
Sediment circulation in Bay
NASA,
RST,
2001
Differences between sites could be due to complex
circulation patterns under different flow regimes
Summary
• Geochemical fingerprinting provides a method for
distinguishing between the contributions of three
potential end-member sources providing sediments to
the San Francisco Bay tidal marshes
• Using sediment fluxes to the Bay tidal marshes can be
an important way to detect changes in the sediment
loads and flows between the two major catchments of
the San Francisco Bay estuary
• China Camp marsh shows good agreement with other
S.F. Bay and California records particularly for ca.
3,000 - 3,800 cal BP cool wet and early Medieval
drought
• Circulation patterns in the estuary will have an impact
on the strength of the sediment flux signal at different
marsh locations
Acknowledgements
Research Mentors:
J. Collins, San Francisco Estuary
Institute
David Schoellhamer, U.S.G.S.
Many thanks to:
D.R. Powell, R. Byrne, B. Watson, G.
Fitzsimmons, E. Prado, M. Goman, W.
Yang, L. Reidy, M. Malamud,
Interdisciplinary Center for Plasma Mass
Spectrometry, UCD, and members of the
B.A.S.K. (Bay Area Sea Kayakers)
Funding support:
CALFED Science/CA Sea Grant