2%20km

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Assessing scales of thermal influence in alluvial
floodplains using Relative Hyporheic Potential
(RHP)
2 km

• 1991

1999
Landsat TM and ETM from the Minthorn Springs node
on the Umatilla River, Oregon.
Scott ODaniel, University of California Santa
Barbara, Geography Department, 200B
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Acknowledgements
NASA Grant NAG13-02030 Department of Energy
Grant BI2001-011-00 Confederated Tribes of the
Umatilla Indian Reservation Grant 032-51
Collaborators Alicia Arrigoni, Geoff Poole, Leal
Mertes, William Woessner, Steve Thomas, Dan Haug,
Jeff Howarth, James Webster and Jeff Mason
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Outline of the Talk
Statement of Problem Hypothesis Objectives Backgro
und Methods Interim Results Implications
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Hypotheses

• Geomorphic diversity equals thermal diversity in
  alluvial rivers.
• Abrupt thermal change associated with the
  geomorphic boundaries/features are predictable
  through a set of DEM derived metrics.

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Research Objectives

• Assess the thermal importance of hyporheic
  exchange at several spatial scales in a semi-arid
  floodplain.
• Develop a DEM derived metric that aids in the
  identification of categorical lengths of
  hyporheic flow paths.
• Calibrate the relationship among thermal
  variation in the Umatilla River, grain size of
  particles deposited across alluvial floodplains,
  and multiple scales of DEM data.
• Test predictions of hyporheic flowpath length
  and duration against field and remotely sensed
  data.

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Statement of the Problem

• Presently, stream temperature models are 2
  dimensional representations.
• Address floodplain functions as multi-scale
  hierarchical patch dynamics problem.
• High stream temperature is the most pervasive
  limiting factor for inland Columbia River
  salmonids (ISC,1996).

Independent Scientific Group. 1996. Return to the
River Restoration of Salmonid Fishes in the
Columbia River Ecosystem. Document 96-6.
Northwest Power Planning Council, Portland, OR.
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Umatilla River Watershed
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Why the Umatilla River?

• Excellent opportunity for experimentation
  on a partially constrained, partially wild
  alluvial floodplain
• Presence of 4 species of Pacific Salmon
• Opportunity to change existing land use
  patterns
• Two decades of salmonid life stage monitoring

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Drivers of Hyporheic Flow

• Valley morphology (Trend in Valley Width)
• Channel morphology
• Alluvial properties (Slope)
• Side- and Flood-channels (Floodplain width)
• Stream-bed undulation (Variance in slope)
• Sinuosity

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Methods
Primary drivers of hyporheic exchange 1- Scale of
Hyporheic Exchange 2- Channel Morphology 3-
Volume of actively exchanging substrate 4-
Substrate Properties 5- First order Montgomery
and Buffington channel type 6- Flow Regime 7-
Stream Size
Data Sources Valley morphology Basin
area Precipitation regime Stream slope
class Lithology Vegetation
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Interim Results
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Implications

• 1) Lateral floodplain connectivity provides
  thermal diversity for stream habitat.
• 2) Sediment inputs and changes in channel or
  floodplain morphology are potential pathways for
  degradation of thermal regimes. (Fine Sediments
  Channel Engineering Beaver Large Wood).
• 3) Stream temperature management should include
  restoration of processes that promote historic
  channel morphology (basin hydrology and LWD),
  fine sediment control, and, where feasible,
  removal of engineered structures.
• 4) 30m DEM floodplain data sets show promise in
  helping to explain 3 dimensional variability.

Next Steps

1. Complete regressions and sensitivity analysis of
   mainstem Umatilla River RHP parameters.
2. Develop a unit scale fine grain DEM (lt1m) metric
   to predict hyporheic upwelling at separate, finer
   scales (10-1-102m).
3. Experiment with robust statistical tools to
   predict hyporheic flowpath length at multiple
   scales.