HR: 0800h
AN: C21C-1114    [Abstracts]
TI: Effect of Morphology and Permafrost on Hyporheic Dynamics in Two Tundra Streams on the North Slope of Alaska
AU: * Zarnetske, J P
EM: zarnetske@cc.usu.edu
AF: Utah State University, Dept. of Aquatic, Watershed, and Earth Resources, 5210 Old Main Hill, Logan, UT 84322
AU: Gooseff, M N
EM: mgooseff@mines.edu
AF: Colorado School of Mines, Dept. of Geology and Geological Engineering, 1516 Illinois Street, Golden, CO 80401
AU: Bowden, W B
EM: breck.bowden@uvm.edu
AF: University of Vermont, Rubenstein School of Environment and Natural Resources, 81 Carrigan Drive, Burlington, VT 05405
AU: Johnston, M E
EM: mjohnsto@uvm.edu
AF: University of Vermont, Rubenstein School of Environment and Natural Resources, 81 Carrigan Drive, Burlington, VT 05405
AU: McNamara, J P
EM: jmcnamar@boisestate.edu
AF: Boise State University, Dept. of Geosciences, 1910 University Drive, Boise, ID 83725
AU: Bradford, J H
EM: jbradfor@boisestate.edu
AF: Boise State University, Dept. of Geosciences, 1910 University Drive, Boise, ID 83725
AU: Brosten, T R
EM: troybrosten@mail.boisestate.edu
AF: Boise State University, Dept. of Geosciences, 1910 University Drive, Boise, ID 83725
AB: Multiple stream-tracer injections were used to examine the influence of channel morphology on hyporheic exchange flows in two Arctic tundra streams during the summer thaw season (May-August) of 2005. A longitudinally arrayed well and piezometer network allowed for direct observations of tracer movement through the hyporheic zone of the reach. Tracer data in the surface and hyporheic water was corroborated with detailed topographic and water surface characterizations to develop a coupled dynamic groundwater-surface water flow model. While each study stream has drastically different morphologies both are proximal to each other, have comparable discharge regimes, and are underlain by permafrost at depths of less than 2.5 m. The alluvial stream, 8I, is composed of pool-riffle sequences, cobbly-substrate, and conforms to a shallow trapezoidal cross-sectional shape with width:depth values of <<1.0. The other reach, PI, is composed of large, deep pools connected by narrow, deep runs, has organic (i.e. peat) substrate, and width:depth values close to 1.0. Both morphologies are indicative of the streams located throughout the Arctic. The results from the flow observations and model simulations indicate much greater hyporheic exchange rates and depth of stream water penetration in 8I. This is due to greater morphologic variability found in 8I. This study demonstrates that the immediate control on hyporheic zone dynamics is channel morphology while the underlying permafrost is a secondary control limiting its overall development.
DE: 0408 Benthic processes (4804)
DE: 0702 Permafrost (0475)
DE: 0744 Rivers (0483, 1856)
DE: 1830 Groundwater/surface water interaction
DE: 1847 Modeling
SC: Cryosphere [C]
MN: Fall Meeting 2005