8276

• UCREFRP Catalog Number: 8276
• Author: Williss, C. C.
• Title: Documentation of Temperature Model Prepared by the Instream Flow and Aquatic Systems Group, in Cooperation with the U.S. Soil Conservation Service and the U.S. Fish and Wildlife Service.
• USFW Year: 1984.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

Important assumptions of the temperature model include:
- Water in the system is instantaneously and thoroughly
mixed at all times and places. This does not allow
lateral temperature distribution across the stream
channel.
- Stream geometry is characterized by average
conditions. For example, each reach has average slope,
shade, and azimuth.
- Distribution of water in the network is based on mass
balance, so discharges vary linearly between points of
known flow.
- Thermodynamics are assumed to be constant for the
duration of a time step. Steady state hydrometeorologi-
cal inputs are presumed to be present long enough for
steady state temperatures to reach the lowest point in
the stream network. If travel time from the rim station
to the downstream end of the network is signi-
ficantly larger than the time step period, the results
are less reliable.
- Average shade conditions in the basin are held
constant in our analysis.
• - Groundwater inflow is assumed to be at ambient air
temperature.
- Solar radiation, meteorological, and hydrological
parameters are 24-hour averages.
Prewitt et. al. (1981), Theurer and Voos (1982), and Theurer et.
al. (1982) have completed temperature modeling studies in the
Upper Colorado River Basin. These acomplishments were the
catalyst for the development of the basin-wide temperature model
used for this study. Input data to the basin-wide model was
first developed by Guy and Theurer (1984); the hydrologic,
meteorologic, and water temperature data used in Guy and
Theurer's work covered the period from water year 1960 to 1982.
A brief description of their work follows.
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