km Landsat TM and ETM from the Minthorn Springs node on the Umatilla River, Oregon. Assessing scales of thermal influence in alluvial floodplains using Relative Hyporheic Potential (RHP) Scott O’Daniel, University of California – Santa Barbara, Geography Department, 200B

Acknowledgements NASA Grant #NAG Department of Energy Grant # BI Confederated Tribes of the Umatilla Indian Reservation Grant # Collaborators: Alicia Arrigoni, Geoff Poole, Leal Mertes, William Woessner, Steve Thomas, Dan Haug, Jeff Howarth, James Webster and Jeff Mason

Outline of the Talk Statement of Problem Hypothesis Objectives Background Methods Interim Results Implications

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.

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.

Statement of the Problem Waterbodies listed for temperature on Oregon’s 303d list in January of 2002 Waters listed for temperature limitations on the Oregon State 303d list - January, 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 Return to the River: Restoration of Salmonid Fishes in the Columbia River Ecosystem. Document #96-6. Northwest Power Planning Council, Portland, OR.

Extent of 1998 Forward Looking Infrared Radiometer (FLIR) data capture Umatilla River Watershed

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

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

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

Interim Results

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 (<1m) metric to predict hyporheic upwelling at separate, finer scales ( m). 3)Experiment with robust statistical tools to predict hyporheic flowpath length at multiple scales.