HR: 13:40h
AN: H13K-01 INVITED     [Abstracts]
TI: Stream Temperature: Distinguishing between Influences Using Diurnal Patterns
AU: * Johnson, S L
EM: sherrijohnson@fs.fed.us
AF: Pacific Northwest Research Station USDA Forest Service, 3200 SW Jefferson Way, Corvallis, OR 97331 United States
AB: Stream temperature controls many instream processes and is influenced by multiple factors. Temperature integrates landscape influences and can be a useful parameter to examine sources, residence times and interchanges of stream water within landscapes. Changes in maximum and minimum temperatures between points within stream networks can suggest geomorphic and or biotic influences. Geomorphic factors, such as substrate type, hyporheic flowpaths and groundwater inputs, have specific and identifiable impacts on stream temperatures. For example, bedrock reaches tend to have wide diurnal temperature fluctuations, with high maxima and low minima. Reaches with a large proportion of flow through the hyporheos have damped diurnal fluctuations, but the daily mean temperature remains similar to that observed upstream. Groundwater inputs often lower the thermograph, with decreases in both maximum and minimum temperatures. And changes in biotic factors, such as gaps in riparian vegetation longitudinally, can result in increased maximum as well as minimum temperatures. Heat energy budgets, if calculated using onsite microclimatic measurements, can be used to provide a check of our current understanding of dominant mechanisms; however, challenges remain in determining the upstream extent of zone of influence for temperatures at a given point, due to the complex distribution of hydraulic retention times within a channel.
DE: 1825 Geomorphology: fluvial (1625)
DE: 1871 Surface water quality
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: Fall Meeting 2005