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, onedimensional 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 longwave atmospheric radiation, direct shortwave 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 24hour 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 groundlevel 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) 2269319
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


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 submodel 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 emailing: 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

