Snow Card Inputs - Optional

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The following tables list all project file cards pertaining to snow accumulation, melt, and melt-water transport.


Cards calling which snow melt algorithm to use

Melt Method Card Description
Hybrid Energy Balance
default (no card required)
The Hybrid Energy Balance Method for melting snow is the default, so it is utilized if NWSRFS_SNOW and EB_SNOW are not present in the Project File.
Temperature Index
NWSRFS_SNOW
The Temperature Index Method for melting snow is utilized if this card is present in the Project File.
Energy Balance
EB_SNOW
The Energy Balance Method for melting snow is utilized if this card is present in the Project File.



Cards Associated with All Three Melt Methods

Card Argument Units Description
NWSRFS_SCF     ##.##
real fraction Snow Cover Factor (adjusts for mis-readings in the gage data (see Continuous:Snowfall_Accumulation_and_Melting).
SNOW_TEMP_BASE ##.##
real °C Base Temperature (MBASE) at which melt begins in snow.
SNOW_NO_INFILTRATE
    This option prevents infiltration in any cell containing snow.
INIT_SWE_DEPTH #.# or File
real or File m Initializes the snow water equivalent (SWE) for the entire model. If a value is specified the entire model initializes with that value of SWE. A map file may also be specified. The projection and spatial coordinates must be the same as the model. An example input file is shown below.
SNOW_SWE_FILE  ***.swe
File m Outputs time-series snow water equivalent maps (similar to DEP file).

Example file when using INIT_SWE_DEPTH
Init Snow.jpg



Cards Associated with BOTH Hybrid Energy Balance and Temperature Index Methods

Card Argument Units Description
NWSRFS_FR_USE  ##.##
real fraction Specifies the fraction of precipitation in the form of rain when the temperature in the cell drops below MBASE.
NWSRFS_TIPM       ##.##
real   Snow Cover Thermal Gradient
NWSRFS_NMF        ##.##
real mm/°C/dt Negative Melt Factor.
NWSRFS_FUA        ##.##
real   Empirical Wind Function Factor.
NWSRFS_PLWHC      ##.##
real  % Percent Liquid Water Holding Capacity.
NWSRFS_ELEV_SNOW  File
File depends on parameter This card allows some of the parameters related to snow to be varied depending on elevation using elevation bands. The format of the input file is shown below.

Example file when using NWSRFS_ELEV_SNOW
Band NWSRFS.jpg
Elevations are in meters, all other values are in their standard formats.


Cards Associated with JUST Temperature Index Method

Card Argument Units Description
NWSRFS_MF_MAX  ##.##
real mm/°C/dt Maximum Melt Factor, only works with NWSRFS_SNOW.
NWSRFS_MF_MIN  ##.##
real mm/°C/dt Minimum Melt Factor, only works with NWSRFS_SNOW.



Cards Associated with Vertical Melt Water Transport (Vertical MWT)

Card Argument Units Description
SNAP_RETENTION
    Uses the SNAP model (Albert & Krajeski, 1998) to simulate the vertical transport of melt-water through the snow pack (Vertical MWT).
VERT_SNOW_RETENTION
    Uses the SNAP model (Albert & Krajeski, 1998) to simulate the vertical transport of melt-water through the snow pack (Vertical MWT), but also distributes the melt incrementally over an hour instead of abruptly at every timestep that SNAP is run (which is hourly).



Cards Associated with Lateral Melt Water Transport (Lateral MWT)

Card Argument Units Description
SNOW_DARCY     ##.##
real m s-1 Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) (Lateral MWT). The user specifies the initial hydraulic conductivity of the snow pack (m s-1), but the hydraulic conductivity changes with time according to the SNAP model (Albert & Krajeski, 1998).
SNOW_REYNOLDS  ##.##
real   Reynolds Number at which flow simulation switches from Darcian to regular Overland. Only effects cells covered by snow and only works when SNOW_DARCY card present in Project File.



Cards Associated with Orographic Effects

Card Argument Units Description
HMET_OROG_GAGES  ***.txt
File see Orographic Effects Adjusts the temperature in each cell based on elevation differences between the cell and multiple gage sites. The file must have a specific format as shown in Orographic Effects.
OROGVAR_HMET
    Adjusts the temperature in each cell based on elevation differences between the cell and the gage site (Orographic Effects). Only works when HMET_ELEV_GAGE and HMET_LAPSE_RATE cards present in Project File. This is an additional option if you do not want to use HMET_OROG_GAGES. Only one temperature gage used for this option.
HMET_ELEV_GAGE   ##.##
real m Elevation (m) of the gage site where temperature is measured. Only works when OROGVAR_HMET and HMET_LAPSE_RATE cards present in Project File.
HMET_LAPSE_RATE  ##.##
real °C km-1 Dry adiabatic lapse rate of the area modeled. Only works when OROGVAR_HMET and HMET_ELEV_GAGE cards present in Project File.


GSSHA User's Manual

3 Project File
3.1     Required Inputs
3.2     Mapping Table – Optional
3.3     Overland Flow – Required
3.4     Interception – Optional
3.5     Rainfall Input and Options – Required
3.6     Infiltration – Optional
3.7     Channel Routing – Optional
3.8     Continuous Simulations – Optional
3.9     Saturated Groundwater Flow – Optional
3.10     Soil Erosion – Optional
3.11     Constituent Transport – Optional
3.12     Subsurface Drainage Network – Optional
3.13     Output Files – Required