Project File:Continuous Simulations – Optional
From Gsshawiki
Continuous simulations require general information about the watershed location, selection of a method to calculate evapo-transpiration (ET), hydrometeorological (HMET) data in one of three available formats, and the appropriate distributed data either from the Mapping Table file or from GRASS ASCII maps.
Contents
- 1 3.8.1 Required Inputs
- 2 3.8.2 Seasonal Canopy Resistance - Optional
- 3 3.8.3 Format of Hydrometeorological (HMET) Data – Required, Select One Format
- 4 3.8.4 ET Parameter Assignment – Required, Select Mapping Table or GRASS ASCII maps
- 5 3.8.5 Optional Inputs
- 6 3.8.6 Snow Card Inputs - Optional
- 7 3.8.7 Distributed Hydrometeorology Data - Optional
- 8 3.8.8 Continuous Frozen Ground Index (CFGI) Index Model - Optional
- 9 GSSHA User's Manual
3.8.1 Required Inputs
| Card | Argument | Units | Description |
|---|---|---|---|
LONG_TERM |
none | Specifies continuous simulation. REQUIRES one of ET_CALC_PENMAN or ET_CALC_DEARDORFF. REQUIRES one of three HMET formats. Also REQUIRES INF_REDIST or INF_RICHARDS. | |
LATITUDE ##.## |
real | decimal degrees |
Latitude of catchment centroid. |
LONGITUDE ##.## |
real | decimal degrees |
Longitude of catchment centroid. |
GMT ##.## |
real | hr | Number of hours difference between the time zone of the catchment and Greenwich Mean Time (e.g. –5 for EST). |
SOIL_MOIST_DEPTH ##.## |
real | m | Depth of the active soil moisture layer from which ET occurs (m). |
EVENT_MIN_Q ##.## |
real | m3/s | Threshold discharge for continuing runoff events. |
ET_CALC_PENMAN |
none | none | Calculate evapo-transpiration using the Penman-Monteith (1971) method. Select EITHER Penman or Deardorff. |
ET_CALC_DEARDORFF |
none | none | Calculate evapo-transpiration using the Deardorff method. Select EITHER Penman or Deardorff |
3.8.2 Seasonal Canopy Resistance - Optional
| Card | Argument | Units | Description |
|---|---|---|---|
SEASONAL_RS |
none | none | Specifies that the values of canopy resistance vary seasonally |
SEASONAL_RS_SPRING |
integer | month | Optional card to specify the month that spring begins; canopy resistance will decrease linearly from a canopy resistance multiplication factor of 4.0 to 1.0 until the SEASONAL_RS_SUMMER_START month is reached. Default is 3 for latitudes below 37 degrees and 4 for latitudes above 37 degrees. |
SEASONAL_RS_SUMMER_START |
integer | month | Optional card to specify the month that begins the peak summer growing season, with a canopy resistance mulitplication factor of 1.0. Default is 5 for latitudes less than 37 and 7 for latitudes above 37. MUST be specified if SEASONAL_RS_SPRING card is included. |
SEASONAL_RS_SUMMER_END |
integer | month | Optional card to specify the month that ends the peak summer growing season, with a canopy resistance multiplication factor of 1.0. Default is 9. MUST be specified if SEASONAL_RS_SPRING card is included. |
SEASONAL_RS_FALL |
integer | month | Optional card to specify the month that begins the winter dormant period with a canopy resistance multiplication factor of 4.0. Default is 11. MUST be specified if SEASONAL_RS_SPRING card is included. |
3.8.3 Format of Hydrometeorological (HMET) Data – Required, Select One Format
| Card | Argument | Description |
|---|---|---|
HMET_SURFAWAYS "filename.hmt" |
file name | ASCII file with hourly HMET data formatted in the form of the NOAA/NCDC Surface Airways Data. Mutually exclusive with HMET_SAMSON and HMET_WES; one required for LONG_TERM. |
HMET_SAMSON "filename.hmt" |
file name | ASCII file with hourly HMET data formatted as per the NOAA/NCDC SAMSON CD-ROM data set. Mutually exclusive with HMET_WES and HMET_SURFAWAYS; one required for LONG_TERM. |
HMET_WES "filename.hmt" |
file name | ASCII file with hourly HMET data written using a simple format discussed in the Continuous Simulation Section of this document. Mutually exclusive with HMET_SURFAWAYS and HMET_SAMSON; one required for LONG_TERM. |
3.8.4 ET Parameter Assignment – Required, Select Mapping Table or GRASS ASCII maps
Long-term simulation parameters must be assigned using either the Mapping Table or providing the GRASS ASCII maps as described below. Albedo, wilting point, transmission coefficient, vegetation height and canopy resistance are also required for ET_CALC_PENMAN.
| Card | Argument | Description |
|---|---|---|
ALBEDO "filename.alb" |
map name | Name of GRASS ASCII map containing short-wave albedo values (0.0 – 1.0). |
WILTING_POINT "filename.wtp" |
map name | Name of GRASS ASCII map containing values of the wilting point volumetric water content (0.0 - 1.0). |
TCOEFF "filename.tcf" |
map name | Name of GRASS ASCII map containing values of the canopy optical transmission coefficient. (0.0 - 1.0). |
VHEIGHT "filename.vht" |
map name | Name of GRASS ASCII map containing values of the vegetation height in m. This value is used in calculating the aerodynamic resistance of the reference crop (m) and used in assigning root depth when using INF_RICHARDS. |
CANOPY "filename.cpy" |
map name | Name of GRASS ASCII map containing values of the canopy average stomatal resistance (s/m). |
3.8.5 Optional Inputs
| Card | Argument | Units | Description | |
|---|---|---|---|---|
TOP_LAYER_DEPTH ##.## |
real | m | If using GAR, can specify a top layer that is less than or equal to SOIL_MOIST_DEPTH, default is SOIL_MOIST_DEPTH (m). | |
END_TIME [yr mo day hr min] |
date and time | date and time | Absolute date and time to end the long term simulation. Takes the form year month day hour min, such as 2002 6 30 24 00. Used for stopping the simulation before the end of data. | |
START_DATE [yr mo day ] |
date | year month day | Absolute date to start the long term simulation. Takes the form year month day, such as 2002 6 30. Used for starting the the simulation after the beginning of the hmet data start. Must be used with START_TIME. Start time and date must coincide with a date and time in the hmet series that is not within a precipitation event. | |
START_TIME [hr min] |
time | hour minute | Absolute date and time to end the long term simulation. Takes the form of hour min, 24 00. Used for starting the the simulation after the beginning of the hmet data start. Must be used with START_DATE. Start time and date must coincide with a date and time in the hmet series that is not within a precipitation event. |
3.8.6 Snow Card Inputs - Optional
Prior to version 6.1 there are no snow options. Additional snow capability has been added in v6.1 and beyond. Please note the GSSHA version numbers when using these cards.
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
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. Model elevation (*.ele file) must be in meters. The format of the input file is shown below. |
Example file when using NWSRFS_ELEV_SNOW
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. Available in versions 6.2 and beyond. (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). Available in versions 6.2 and beyond. |
Cards Associated with Lateral Melt Water Transport (Lateral MWT)
| Card | Argument | Units | Description |
|---|---|---|---|
ROUTE_LAT_SNOW ##.## |
none | Simulates the lateral transport of melt-water through the snow pack based on work by Colbeck (1974) (Lateral MWT). The hydraulic conductivity is calculated over time according to the SNAP model (Albert & Krajeski, 1998) unless the user specifies a value with the SNOW_DARCY card. In versions 6.1 and beyond. | |
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 hydraulic conductivity of the snow pack (m s-1) used for the duration of the simulation. In versions 6.1 and beyond. |
Cards Associated with Orographic Effects Orographic effects are available in v6.1 and beyond. Note that the cards change between versions 6.1 and v6.2
| 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. Requires HMET_ELEV_GAGE. The file must have a specific format as shown in Orographic Effects. Model elevations (*.ele file) must be in meters. Available in version 6.1 and beyond. Do not use when using OROGRVAR_HMET in v6.1 or with YES_DALR_FLAG in v6.2 and beyond. |
HMET_ELEV_GAGE ##.## |
real | m | Elevation (m) of the gage site where temperature is measured. For GSSHA v6.1 include the OROGVAR_HMET and HMET_LAPSE_RATE cards in the Project File. For versions 6.2 and beyond include the YES_DALR_FLAG in the project file if you want to specify the lapse rate, otherwise GSSHA calculates the lapse rate. |
OROGVAR_HMET |
Adjusts the temperature in each cell based on elevation differences between the cell and the gage site (Orographic Effects). Works only when the HMET_ELEV_GAGE and HMET_LAPSE_RATE cards are included in the Project File. Only one temperature gage used for this option. Does not work with and is exclusive with HMET_OROG_GAGES. Model elevation (*.ele file) must be in meters. Use for version 6.1. For version 6.2 and beyond use YES_DALR_FLAG, described below. | ||
HMET_LAPSE_RATE ##.## |
real | °C km-1 | Dry adiabatic lapse rate of the area modeled. Works only when the OROGVAR_HMET and HMET_ELEV_GAGE cards are included in the project Project File. Used in version 6.1. Exclusive to HMET_OROG_GAGES. In v6.2 and beyond use YES_DALR_FLAG, as described below. |
YES_DALR_FLAG ##.## |
real | °C m-1 | Dry adiabatic lapse rate of the area modeled. Works only when the HMET_ELEV_GAGE card is included in the Project File. Use for versions 6.2 and beyond. Exclusive to HMET_OROG_GAGES. For versions 6.1 use the OROGVAR_HMET and HMET_LAPSE_RATE cards, as described above. |
3.8.7 Distributed Hydrometeorology Data - Optional
This function allows GSSHA to read in raster-based hydrometeorology data. The input files must be in the same projection as the GSSHA model and must be larger than the model domain. Please see Distributed HMET Data for more details.
| Card | Argument | Units | Description |
|---|---|---|---|
HMET_ASCII ***.txt |
File | see Distributed HMET Data | Inputs hyrometeorology data (temperature, cloud cover, direct radiation, global radiation, pressure, relative humidity, and wind speed) in each cell based on hourly Arc/Info ASCII grid files, giving the model more spatial variability. The files must have a specific format as described in Distributed HMET Data. |
3.8.8 Continuous Frozen Ground Index (CFGI) Index Model - Optional
These options are only valid with verions 6.2 and later. In previous versions the CFGI model is applied for any LONG_TERM simulations.
| Card | Argument | Units | Description |
|---|---|---|---|
CFGI |
none | Use the CFGI model to simulate frozen soil effects. | |
CFGI_INDEX |
real | degree C hours | Threshold value (negative degree C hours) to differentiate between frozen and unfrozen soils. Default: 83.0. |
CFGI_K |
real | dimensionless | Snow thermal effect constant (K) in CFGI equation. Default: 0.5. |
GTFSM |
none | dimensionless | Use frozen soil hydraulic conductivity equation. If not used then assumed to be 0. |
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
