Hyporheic and Parafluvial Zones in…

The Arctic

Tundra!

The hydraulic characteristics and geochemistry of hyporheic and

parafluvial zones in Arctic tundra streams, north slope, Alaska

Edwarson et al. (2003): Advances in Water Resources

Purpose: Investigate the hydrologic and chemical dynamics of hyporheic and parafluvial zones in Arctic tundra streams

Importance: Essentially no information on Arctic streams

– First comprehensive description of hyporheic and parafluvial zones in Arctic tundra streams

– Continuous permafrost• Limit the importance of hyporheic processes?

Scope of Work• 17 conservative tracer additions on 7

streams from 1994-1996– Stream reaches varied greatly

• Characterize in-stream hydrologic parameters using hyporheic samplers and OTIS-P simulations

• Biogeochemical and nutrient processing in hyporheic and parafluvial zones

Background: Definitions and Key Concepts

• Transient storage zones• Parafluvial• Beaded stream• Importance of hyporheic and parafluvial

zones• 3 key factors that control water movement

in these zones• DO in the hyporheic zone• Modeling limitations

Study Area

Study Area: Kuparuk R. and Oksrukuyik Cr.

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MouthOfKupa

Oks

Whole Lotta Methods:• Hyporheic Samplers• Tracer Additions• Conservative Tracer

Analysis• Solute Modeling• Vertical Hydraulic

Gradient (VHG)• Nutrient Chemistry

http://pubs.usgs.gov/sir/2005/5255/section4.html

http://water.usgs.gov/ogw/gwrp/images/photos/rhodamineWT_injection.jpg

Results: OTIS Modeling

• No significant relationship between As/A and discharge – General relationship held true

• Average storage zone cross-sectional area of the Arctic streams– 43% (Range: 8 – 254%)– 32% (Range: 8 – 112%) without Imnavait Cr.

Results:Channel, Upwelling, and Downwelling Sites

Transient Storage Zones

Results: Channel, Upwelling, and Downwelling Sites

Tracer Penetration

Hyporheic

Parafluvial

Hyporheic

Parafluvial

Bottom of RiffleTop of Riffle

Results: Channel, Upwelling, and Downwelling Sites

Water Quality

Results: VHG and Temperature

VHG

Riffle Parafluvial zones in left and right point bars

Results: Benthic Uptake

Key Discussion Points and Conclusions

• Transient storage in Arctic Streams– Similarity to temperate regions

• As/A relationship not signifcant

– Δmorphology and Δstage height are boss.– Importance of eddies

• BUT hyporheic storage still muy importante!– Biogeochemical importance of hyporheic

flowpath.

• Permafrost– Hyporheic flow not limited by permafrost in ice-free

season– Spring ice-out (thaw) may results in much lower As/A

values due to high snow-melt Q and reduced interstitial area

• Water Quality– Interstitial waters served as sources of NO3, NH4,

PO4, and CO2

– Interstitial temperature inversely related to VHG and residence time in hyporheic and parafluvial zones.

Key Discussion Points and Conclusions

Questions?

NOQUESTIONS