HR: 1340h
AN: H13B-1337    [Abstracts]
TI: The Influence of Hyporheic Flow on the Temperature of a Riffle-Step-Pool Stream
AU: Rothwell, E
EM: jmcnamar@boisestate.edu
AF: Department of Geosciences Boise State University, 1910 University Dr., Boise, ID 83725
AU: * McNamara, J
EM: jmcnamar@boisestate.edu
AF: Department of Geosciences Boise State University, 1910 University Dr., Boise, ID 83725
AU: Luce, C
EM: cluce@fs.fed.us
AF: Boise Aquatic Sciences Lab Rocky Mountain Research Station, 316 East Myrtle Street, Boise, ID 83702
AB: The ability to predict stream temperature is important due to the many direct and indirect water use and watershed management effects on streams. One approach to evaluate stream temperature change is to construct a heat-energy budget. Failures of the energy budget approach to modeling stream temperature are often due to inadequate representation of all the processes that control stream temperature. Hyporheic flow influences stream temperature by temporarily removing water from the heating impact of solar radiation and other positive heat fluxes at the surface of the stream, heat conduction to the substrate, and mixing with groundwater, all resulting in flow returning from the substrate out of phase with stream temperature. The influence of hyporheic flow is not often included in energy budget models to predict temperature change. In this study stream temperature change is successfully modeled for a 400-meter long reach in a small headwater stream by using an energy budget temperature model that includes the often-neglected effects of advected water through the hyporheic zone as a major component of the energy budget. Hyporheic flow was evaluated using instream tracer techniques and darcian flux calculations. The dominant energy fluxes into the stream during summer months are net radiation and sensible heat exchange with the atmosphere (61 and 36 percent respectively). The dominant heat energy flux out of the stream was from hyporheic flow, providing 36 to 75 percent of the energy sink.
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: Fall Meeting 2005