Determining%20the%20Spatial%20Distribution%20of%20Benthos%20in%20the%20Western%20Arctic%20Ocean

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Determining the Spatial Distribution of Benthos
in the Western Arctic Ocean
CE 394K.3 GIS in Water Resources Term Project
Presentation

• Jon Goodall
• Environmental and Water Resources Engineering
• December 6, 2001

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Overview

• Background
• Identify Study Region
• Introduce Benthic Biomass Data Sets
• Explain Ordinary Kriging
• Benthic Biomass in the Western Arctic Ocean
• Account for Global Trends
• Present Biomass Interpolated Surface
• Discuss Results
• Conclusions

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What is Benthic Biomass?
Measurement of amount of living material on the
ocean floor (g/m2)
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Study Region
Western Arctic Ocean
Siberia
Canada
Alaska
Bering Strait
Pacific Ocean
Projection Lamberts Azimuthal Equal-Area
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Data Sets
Complete Data Set (1970 1995)
Stoker (1970 1974)
Wacasey (1971 1975)
Carey (1971-1976)
Broad (1975 1981)
Feder (1979 1986)
Grebmier (1984 1995)
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Benthic Biomass at Each Location
Siberia
Alaska
Canada
Image created in ArcScene with 3D Analyst
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Why Use Geostatistics?
The Geostatistical Analyst uses sample points
taken at different locations in a landscape and
creates (interpolates) a continuous
surface. -ArcGIS Help Menu
Point data
Continuous Surface
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Source http//www.aqd.nps.gov/ard/figure3.html
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How Ordinary Kriging Works
h Separation Distance Z(i) Attribute value
at i N samples separated by distance h
You can find value at any location based on
known values at neighboring locations
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• One of the main issues concerning Ordinary
  Kriging is whether the assumption of a constant
  mean is reasonable.
• - ArcGIS Help Menu

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Location of Data Split
68.5 º N
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(-43 for overall data set)
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(-43 for overall data set)
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Benthic Biomass Spatial Distribution(Northern
Data Set)
Legend
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Benthic Biomass Spatial Distribution(Southern
Data Set)
Legend
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Semivariograms
North
South
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Small-Scale Variation a Problem in Southern Data
Set
Biomass (g/m2) 1216 720 405
254 Which is it?
Biomass (g/m2)
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Small-Scale Variation in Northern Data Set
Biomass (g/m2) 840 270
269
Biomass (g/m2)
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Conclusions

• It was possible to interpolate the biomass on a
  continuous scale with relatively high certainty
  for the northern region
• This method was not capable of accurately
  predicting biomass in the southern region due to
  small-scale variability of biomass measurements

Future work Is small-scale variability a result
of measuring errors or is it an inherent
property of the benthic biomass?
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Acknowledgements
Dr. Dunton Marine Science Institute UT-Austin
Dr. Maidment Center for Research in Water
Resources
Susan Schonberg Marine Science Institute UT-Austin

Jóna Finndís Jonsdottír Previous M.S.
Student Center for Research in Water Resources
Dr. Barrett Center for Research in Water
Resources
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• Questions?