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Model Report

STREAM NETWORK TEMPERATURE

Last Revision Date: 10/06/2009 View as PDF
General Information Back to Top
Model Abbreviated Name:

SNTEMP
Model Extended Name:

STREAM NETWORK TEMPERATURE
Model Overview/Abstract:
The Stream Network Temperature (SNTEMP) model is a mechanistic, one-dimensional heat transport formulation that predicts daily mean and maximum water temperature as a function of stream distance and environmental heat flux. Net heat flux is calculated as the sum of heat to or from long-wave atmospheric radiation, direct short-wave solar radiation, convection, conduction, evaporation, streamside vegetation (shading), streambed fluid friction, and the water's back radiation. The heat transport model is based on the dynamic temperature - steady flow equation and assumes that all input data, including meteorological and hydrological variables, can be represented by 24-hour averages. The heat flux model includes the incorporation of groundwater influx.

SNTEMP is applicable to a stream network of any size or order. It includes (1) a solar model to predict the solar radiation penetrating the water as a function of latitude and time of year, (2) a shade model that predicts the riparian and topographic shading, (3) algorithms that make meteorological corrections that predict changes in air temperature, relative humidity, and atmospheric pressure as functions of elevations within the watershed, and (4) regression algorithms that smooth and/or fill missing observed water temperature measurements. Turbulence is assumed to thoroughly mix the stream both vertically and transversely. Time steps ranging from one month to one day have been used in SNTEMP.

SNTEMP requires that the spatial layout of the hydrologic network be defined by subdividing it into stream segments of homogeneous characteristics, such as flow, width, and shading. Each homogeneous stream segment is described by its length, width, slope, roughness (Manning's n) or travel time, and shading characteristics. The meteorological influences are described by air temperature, relative humidity, wind speed, percent possible sun (inverse of cloud cover), and ground-level solar radiation. Water flows into the segment and groundwater accretions along the segment, along with their temperatures, are also required inputs.

The Stream Segment Temperature Model (SSTEMP) is a subset of SNTEMP that can be useful in a scoping mode. Applicable only to a single stream segment and single time period, SSTEMP is exceptionally easy to use as it is modeled after a simple computer spreadsheet application.

Keywords:
Model Technical Contact Information:
John Bartholow
U.S. Geological Survey
Fort Collins, CO
(970) 226-9319
John_Bartholow@USGS.Gov

The model was developed by the U.S. Fish and Wildlife Service and is maintained by John Bartholow.

Model Homepage: http://smig.usgs.gov/SMIC/model_pages/sntemp.html Exiting the EPA Site

User Information Back to Top
Technical Requirements
Computer Hardware
486 PC with 612 KB RM and 10 MB ROM (minimum)
Other Software Required to Run the Model
Visual Basic and Fortran
Download Information
The model is publicly available from the U.S. Geological Survey, Fort Collins CO.
Using the Model
Basic Model Inputs
More complex model with greater input requirements, but no substantial modular or sub-model components.

The model requires calibration with measured water temperature.

User Support
User's Guide Available?
Documentation is publicly available from the U.S. Geological Survey, Fort Collins CO.

Paper copies are available by e-mailing: John_Bartholow@USGS.Gov

Provides: (1) an abstract or abstract equivalent in the introduction, (2) schematic/diagram showing model structure and interaction of model components, (3) equations, equation solution methodologies, and related simplifying assumptions, (4) example input/output files, (5) input and output variable documentation including definitions, units, temporal/spatial dimensions, temporal/spatial resolution options, and (if applicable such as with FORTRAN) format, (6) guidance on selecting and/or estimating values and/or distributions for input variables (including guidance on calibration and selecting default values and/or distributions), (7) guidance on the analysis and interpretation of output, and (8) description of sensitivity analysis, uncertainty analysis, and testing (validation) methodologies and results.


Model Science Back to Top
Summary of Model Structure and Methods
The model uses fixed units (S.I.).

The model provides mathematical guidance to assist the user when selecting modeling parameters.

Governing equations are solved numerically.

Model Evaluation
Code verification and substantial model testing (evaluation) has been performed by using the model at numerous geographic locations.

Sensitivity analysis has been performed. These analyses are application specific; but, examples are available


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