Where the River Meets the Sea: Turbidity Maxima in the Columbia River Estuary

Matthew EspieKhalilha Haynes

2

Introduction: An Estuary is…

• Partially enclosed, brackish waters• Formed when freshwater bodies meet and mingle with saltwater

from the ocean • Among the most productive environments on earth • An assortment of habitats, in and around the water: salt marshes,

swamps, oyster reefs, mangrove forest, and tidal pools…• Home to thousands of species of mammals, birds, and fish• Coastal regions today are the home for 110 million people and is

expected to increase to 127 million by the year 2010 (http://estuaries.org/)

Washington

Oregon

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Estuarine Turbidity Maxima (ETM)

What Makes an ETM:• ETM are areas of elevated levels of suspended

sediments.• ETM vary in strength and move with the tides.• ETM are thought to be an important factor in the

productivity of estuaries• ETM are the points in the estuary that are most

turbid (opaque)• High biological activity• Provides nutrients for bacteria and smaller animals

at lower trophic levels• Columbia River ETM seems to follow the leading

edge of the salt wedge as it makes its way upstream as the tide is flooding, and then as it retreats during an ebb tide.

(http://depts.washington.edu/cretmweb/CRETM.html)

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Introduction: CMOP

• CMOP’s Vision: To understand and predict the response of coastal margins to human and climate influences

• Focus on the Columbia River and the adjacent Pacific Northwest estuaries

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Objectives

• Find and predict the location of the elusive estuarine turbidity maximum (ETM) for the Columbia River estuary

• Analyze sensor data from the Saturn 01 and 03 systems. Analyze relationships between variables:– Turbidity– Salinity– Chlorophyll– Tide

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Process

Read background information

Explore CMOP database (http://www.stccmop.org/datamart

)

Examine data from multiple stations in the estuary (

http://www.stccmop.org/datamart/station/timeseries

)Import data into Excel

Make plots

Perform correlation analyses

Analyze the different types of tides.

Research ETM.

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Process

Analyze data time series.

Analyze data time series to provide context for previous

research cruises. (http://www.stccmop.org/node/1566

)

Download data from station SATURN01 and graph them in

Excel. Analyze the spikes in turbidity.

Create a diagram of the ETM

Download data from Aug. 2007 cruise where samples were taken

during an ETM.

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Process

Create a program that imports the ETM data into

Matlab.

Import the data into Matlab. Make graphs that show

relationship between turbidity and another variable. Make

graphs of the max turbidity at each station sampled and the corresponding salinity values.

Find peaks in graphs of turbidity, salinity, tides, and change in salinity (include time of

peak).

Find time differences between peaks in each parameter and

peaks in tidal peaks.

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Process

Sort time differences according to tidal type

.

Perform statistical analyses on sets of data.

Redesign sediment distribution maps.

Analyze sediment

distribution trends in regard

to the ETM

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Conclusion and Future Work

• Using the results of the statistical analyses of SATURN01 sensor data, we were able to better predict the timing of the ETM at the sensor location.

• Future statistical analyses should be done over multiple seasons, with a more diverse data and representative data supply, including data from SATURN03.

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THANK YOU!!

We would like to thank our mentors Nirzwan Bandolin, António Baptista, Grant Law, and Karen Wegner and all of our parents for their help and support!...and everyone else at CMOP who also assisted us!

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The Goods: How the ETM works…

http://depts.washington.edu/cretmweb/CRETM.html

At the foot of the salt wedge there is lots of turbulence and mixing of the salt water and the

sediment found on the river bed; the ETM should be close.

Material in the water column is re-suspended and advected

up the salt wedge and dispersed on it’s way to the

ocean.

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August 2007 RV Barnes Research Cruise

Turbidity (NTU) and Salinity (PSU) at Station 22

Turbidity (NTU) and Oxygen (mg/L) at Station 22

Casts Casts

Dep

th (

m)

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August 2007 RV Barnes Research Cruise

Tu

rbid

ity

(NT

U)

Sali

nit

y (P

SU

)

stations

stations

Corresponding Salinity Values

Max Turbidity at each Station

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Time series

0

5

1 0

1 5

2 0

2 5

3 0

1 4 3 8 5 1 2 7 1 6 9 2 1 1 2 5 3 2 9 5 3 3 7 3 7 9 4 2 1 4 6 3 5 0 5 5 4 7 5 8 9 6 3 1 6 7 3 7 1 5 7 5 7 7 9 9 8 4 1 8 8 3 9 2 5 9 6 7 1 0 0 9 1 0 5 1 1 0 9 3 1 1 3 1 1 7 1 2 1 1 2 6 1 3 0 3 1 3 4 1 3 8 1 4 2

-0 .5

0

0 .5

1

1 .5

2

2 .5

3

3 .5

1 9 1 7 2 5 3 3 4 1 4 9 5 7 6 5 7 3 8 1 8 9 9 7 1 0 5 1 1 3 1 2 1 1 2 9 1 3 7 1 4 5 1 5 3 1 6 1 1 6 9 1 7 7 1 8 5 1 9 3 2 0 1 2 0 9 2 1 7 2 2 5 2 3 3 2 4 1 2 4 9 2 5 7 2 6 5 2 7 3 2 8 1

Salinity[psu]

Δ Salinity

Turbidity[NTU]

Tide

Time

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Predicting Turbidity

  Type 1 Type 2 Type 3 Type 4

Mean 19.89 16.28 13.27 17.21

Standard Error 1.35 0.97 1.37 1.62

Median 20.69 16.06 13.26 18.11

Standard Deviation 4.06 3.07 3.87 4.85

Range 13.14 9.35 12.87 12.84

Minimum 12.05 12.426 8.17 9.97

Maximum 25.19 21.76 21.04 22.81

Sample Size 9 10 8 9

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Predicting Change in Salinity

Type 1 Type 2 Type 3 Type 4

Mean 5.14 0.86 4.26 0.77

Standard Error 0.11 0.42 0.41 0.09

Median 5.28 0.65 4.17 0.74

Standard Deviation 0.32 1.25 1.1 0.26

Range 0.92 4.53 3.17 0.78

Minimum 4.68 -0.5 3.23 0.3

Maximum 5.6 4.03 6.4 1.08

Sample Size 8 9 7 8

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Predicting Salinity

small large

Mean 0.06 0.07

Standard Error 0.15 0.21

Median 0.23 -0.01

Standard Deviation 0.46 0.67

Range 1.15 2.37

Minimum -0.62 -0.6

Maximum 0.53 1.77

Sample Size 10 10

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What the Numbers Mean…

1 2 3 4

Tide

Time

Heig

ht

(m)

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Sediment Distribution Maps

*

*blue: positively skewed magenta: negatively skewed

South Channel

North Channel

Sedimentary Processes & Environments in the Columbia River Estuary

C. Sherwood J. Creager E. Roy G. Gelfenbaum T. Dempsey

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Sediment Distribution Maps

Sedimentary Processes & Environments in the Columbia River Estuary

C. Sherwood J. Creager E. Roy G. Gelfenbaum T. Dempsey

*blue: positively skewed magenta: negatively skewed

*

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Time series

Time

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Tides

Time

Slack tide Ebb tideFlood tide

Heig

ht

(m)

24Graphs and Analyses

TIME

TIME

Salinity is high when tubidity is low.

Turbidity has a pattern: low spike, high spike… high spike, low spike,… etc

Turbidity pattern coincides with flood and ebb tides.

June 1-11, 2008

June 1

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The Estuary