4. Model Input File

As with any model, half the battle in getting a correct model run is in providing the appropriate model input. Without having all the correct model input, the tRIBS Model will exit with an appropriate error message.

4.1. Input File Contents

The tRIBS Model Input File (*.in) is currently the primary user interface to the model. Although not a graphical medium, it is an easy and efficient means of manipulating all modeling options, parameters and inputs. Those parameters that are not required for a particular run are ignored by the model. The *.in file is organized by keywords. The format for each parameter consists of a line of descriptive text followed by the value of the parameter itself on a second line. Table 4.1 presents a list of the keywords. Note that all keywords are capitalized. The values associated with each parameter may be a number or a string. If the units are specified as ints or doubles, this implies that the parameters are dimensionless, otherwise a unit is expressed. The difference between a pathname and a base pathname is simply that the pathname includes the entire path plus the entire name of the file, including the extension, while a base pathname is only the path and the base name of the file (no extension). See Templates for an example input file. NOTE: Even if they are note being used, all keywords in the input file must be present for proper model execution.

Table 4.1 List of Model Parameters in tRIBS Model Input File

Keyword	Units	Description
STARTDATE	date format	Date of start of simulation
RUNTIME	hours	Total number of hours in run
TIMESTEP	mins	Unsaturated zone time step
GWSTEP	mins	Saturated zone time step
METSTEP	mins	Meteorological data input time step
ETISTEP	hours	ET, interception and snow time step
RAININTRVL	hours	Rainfall data input time step
INTSTORMMAX	hours	Interstorm interval
RAINSEARCH	hours	Rainfall search interval
BASEFLOW	m3/s	Minimum baseflow discharge
VELOCITYCOEF	double	Discharge-velocity coefficient
KINEMVELCOEF	double	Kinematic routing velocity coefficient
VELOCITYRATIO	double	Stream-hillslope velocity coefficient
FLOWEXP	double	Nonlinear discharge coefficient
CHANNELROUGHNESS	double	Uniform channel roughness value
CHANNELWIDTH	double	Uniform channel width
CHANNELWIDTHCOEFF	double	Coefficient in width-area relation
CHANNELWIDTHEXPNT	double	Exponent in width-area relation
CHANNELWIDTHFILE	pathname	Input file name for channel widths
CHANNELCONDUCTIVITY	double	Hydraulic conductivity in channel
TRANSIENTCONDUCTIVITY	double	Hydraulic conductivity during transient period
TRANSIENTTIME	double	Time until transient period ends
CHANNELPOROSITY	double	Porosity in channel
CHANPOREINDEX	double	Pore index parameter in channel
CHANPSIB	double	Matric potential in channel
OPTMESHINPUT	int	Option for Mesh generation
RAINSOURCE	int	Source of rainfall data
OPTEVAPOTRANS	int	Option for Evapotranspiration scheme
OPTSNOW	int	Option for snow
HILLALBOPT	int	Option for hillslope albedo
OPTRADSHELT	int	Option for radiation sheltering of snow
OPTINTERCEPT	int	Option for Interception scheme
OPTLANDUSE	int	Option for static or dynamic land cover
OPTLUINTERP	int	Option for land cover interpolation
OPTSOILTYPE	int	Option for soil parameter format
GFLUXOPTION	int	Option for Ground heat flux scheme
METDATAOPTION	int	Point or Grid weather data
CONVERTDATA	int	Processing weather or raingauge data
OPTBEDROCK	int	Option for uniform or variable depth
OPTGROUNDWATER	int	Option to turn on groundwater module
OPTGWFILE	int	Option for groundwater input file
WIDTHINTERPOLATION	int	Option for interpolating width variables
OPTRUNON	int	Option for hillslope runon
OPTRESERVOIR	int	Option for reservoir routing
OPTPERCOLATION	int	Option for channel percolation losses
INPUTDATAFILE	base pathname	Input file base name for Mesh files
INPUTTIME	int	Time slice for Mesh file input
ARCINFOFILENAME	base pathname	Input file base name for Arc files
POINTFILENAME	pathname	Input file name for Points files
SOILTABLENAME	pathname	Soil parameter reference table
SOILMAPNAME	pathname	Soil texture ASCII grid
LANDTABLENAME	pathname	Land use parameter reference table
LANDMAPNAME	pathname	Land use ASCII grid
GWATERFILE	pathname	Ground water ASCII grid
DEMFILE	pathname	DEM for sheltering
RAINFILE	base pathname	Radar Rainfall ASCII grids
RAINEXTENSION	extension	Extension for Radar Rainfall grids
DEPTHTOBEDROCK	meters	Uniform depth to bedrock
BEDROCKFILE	pathname	Bedrock depth ASCII grid
LUGRID	pathname	Dynamic land cover ASCII grid list
SCGRID	pathname	Spatially-variable soil parameter ASCII grid list
HYDROMETSTATIONS	pathname	Hydrometeorological station file
HYDROMETGRID	pathname	Hydrometeorological ASCII grid list
HYDROMETCONVERT	pathname	Hydrometeorological data input file
HYDROMETBASENAME	base pathname	Hydrometeorological data file
GAUGESTATIONS	pathname	Rain gauge station file
GAUGECONVERT	pathname	Rain gauge data input file
GAUGEBASENAME	base pathname	Rain gauge data file
RESPOLYGONID	pathname	Reservoir polygon ID file
RESDATA	pathname	Reservoir data table
OUTFILENAME	base pathname	tMesh and variable output
OUTHYDROFILENAME	base pathname	Hydrograph output
OPINTRVL	hours	Output interval
SPOPINTRVL	hours	Spatial output interval
OUTHYDROEXTENSION	extension	Extension for hydrographs
RIBSHYDOUTPUT	int	Compatibility with RIBS Output
NODEOUTPUTLIST	pathname	Node output list file
HYDRONODELIST	pathname	Node runtime output list file
OUTLETNODELIST	pathname	Interior node output list
OPTSPATIAL	int	Option for generating spatial output
OPTINTERHYDRO	int	Option for generating intermediate hydrographs
OPTHEADER	int	Option for generating headers in output files
FORECASTMODE	int	Forecast mode options
FORECASTTIME	int	Time in hours from start
FORECASTLEADTIME	int	Total lead time (hrs)
FORECASTLENGTH	int	Total forecast length (hrs)
FORECASTFILE	pathname	Forecast file directory
CLIMATOLOGY	double	Climatology rainfall (mm/hr)
RAINDISTRIBUTION	int	Spatial or lumped rainfall
STOCHASTICMODE	int	Stochastic model option
PMEAN	double	Mean rainfall intensity (mm/hr)
STDUR	double	Mean storm duration (hrs)
ISTDUR	double	Mean time interval between storms (hrs)
SEED	int	Random seed
PERIOD	double	Period of variation (hrs)
MAXPMEAN	double	Maximum value of mean rainfall intensity (mm/hr)
MAXSTDURMN	double	Maximum value of mean storm duration (hrs)
MAXISTDURMN	double	Maximum value of mean interstorm duration (hrs)
WEATHERTABLENAME	filename	Stochastic weather file name
TLINKE	double	Atmospheric turbidity parameter
MINSNTEMP	double	Minimum snow temperature allowed (Celsius)
SNLIQFRAC	double	Liquid water holding capacity
TEMPLAPSE	double	Temperature lapse rate
PRECLAPSE	double	Precipitation lapse rate
PARALLELMODE	int	Option to run as serial (0) or parallel (1) mode
GRAPHOPTION	int	Option for graph file type (0, 1 or 2)
GRAPHFILE	filename	Reach connectivity (graph) filename
RESTARTMODE	int	Option for restart mode (0, 1, 2 or 3)
RESTARTINTRVL	hours	Time set for restart output
RESTARTDIR	pathname	Path of directory for restart output
RESTARTFILE	filename	Filename of restart file
OPTVIZ	int	Option to write viz binary files
OUTVIZFILENAME	filename	Filename for viz binary files

4.2. Input File Options

4.2.1. Model Run Parameters: Time Variables

The STARTDATE keyword is used to indicate the starting time of the model simulation in the following format: MM/DD/YYYY/HH/MM (Month/Day/Year/Hour/Minutes). Values of the rainfall and meteorological inputs must exist for this starting date for the model to execute properly. The RUNTIME keyword is used to specify the number of hours in the total length of the simulation. Similarly, there must be hydrometeorologic data that span the period between the start date and the end date. The TIMESTEP parameter is used to specify the Unsaturated Zone computational time step in minutes. For proper execution, the unsaturated time step should be on the order of minutes. The GWSTEP represents the groundwater or Saturated Zone computational time step, also in minutes. Typically, the groundwater time step can be on the order of tens of minutes for most applications. METSTEP specifies the time step of hydrometeorological data input from weather stations, in minutes. This time step is usually set to 60 minutes since the weather parameters are available at this temporal resolution. ETISTEP specifies the interval for the evapotranspiration, interception and snow model calculations in hours. The RAININTRVL keyword is used for the input time interval of rainfall data, either from radar rainfall grids or from raingauges, in hours. This interval will depend on the resolution of the radar data which is available from 15 minute up to daily intervals. INTSTORMMAX is the amount of hours without rainfall that the model considers to be sufficient for an interstorm period to begin, while RAINSEARCH is the amount of hours that the model will search for the next rainfall file without producing an error message and exiting the program.

4.2.2. Model Input Files and Pathnames: Mesh Generation

The OPTMESHINPUT keyword is used to indicate the option for inputting the topographic data into the model. It controls the sort of mesh data that is read by the model and necessary input data files related to the model mesh. Seven options currently are implemented within the tRIBS Model: 1 = tMesh files from a prior run are used to recreate the mesh (*.nodes, *.edges, *.tri, *.z); 2 = Point file used to create a new mesh (*.points); 3 = Arc/Info Grid file is read and sampled randomly to create the mesh; 4 = Arc/Info Grid file is read and sampled hexagonally to create the mesh; 5 = Arc/Info Ungenerated TIN file used to create a Points File (*.net); 6 = Arc/Info Ungenerated TIN files used to create a Points File (*.pnt and *.lin); 7 = Mesh constructed from scratch; 8 = Point File used with Tipper Triangulation procedure (*.points); 9 = Meshbuilder routines to deal with very large TIN domains (>200,000 to 10s of millions of nodes). The Meshbuilder is a separate executable that operates with an input file (*.in) and a points file (*.points).

When specifying the OPTMESHINPUT option, the model will require that the pathname of the input files be included within the Mesh Generation section of the Model Input File. The INPUTDATAFILE option is used to input the basename for the Mesh input files produced during a previous run (OPTMESHINPUT = 1), while the INPUTTIME keyword specifies the time slice for mesh input (for tRIBS, INPUTTIME should always be set to zero). If using OPTMESHINPUT = 2, then the POINTFILENAME keyword must be used to specify the pathname and filename of the Points File (*.points). If using OPTMESHINPUT = 2 through 6, then the keyword ARCINFOFILENAME specifies the pathname and basename for the Arc/Info grids or output files (*.asc, *.net, *.lin, *.pnt).

4.2.3. Model Run Parameters: Routing Variables

The tRIBS has a simplified hydrologic scheme for hillslope routing and a finite-element channel routing scheme. The model allows for non-linear routing based on the discharge at a single watershed outlet and two parameter values, the stream velocity and the hillslope velocity, shared by all TIN nodes of that particular type. The hydrologic routing scheme utilizes the discharge at the closest stream node to determine the hillslope velocity. Six routing parameters are specified to the model: BASEFLOW, VELOCITYCOEF, FLOWEXP, VELOCITYRATIO, CHANNELROUGHNESS, and CHANNELWIDTH. (Note: The WIDTHINTERPOLATION keyword is used to specify whether or not channel widths will be interpolated between the measured and observed widths (= 0) or only between the measured channel widths (= 1), inputted to the model through the file name specified using the keyword CHANNELWIDTHFILE.)

BASEFLOW is used to specify the minimum flow in the stream network in cubic meters per second, a required parameter since the flow network velocities depend on the outlet discharge in some linear or nonlinear fashion. If the BASEFLOW parameter is not specified, a value of 0.001 cubic meters per second is assigned as default. VELOCITYCOEF is used to specify the coefficient in the relationship between the stream velocity and the outlet discharge, while the FLOWEXP is the exponent on the discharge in this relationship. Specifying FLOWEXP = 0 implies a linear relationship between the stream velocity and the outlet discharge. The VELOCITYRATIO keyword is the ratio between the calculated stream velocity and the hillslope velocity assigned to non-stream nodes. The last two parameters: CHANNELROUGHNESS and CHANNELWIDTH are both uniform parameters for the entire stream network in this model version. The roughness parameters refers to a non-dimensional Manning’s coefficient while the width is a channel width in meters.

4.2.4. Model Run Parameters: Hydrologic Processes

This section is dedicated to the model run options used to specify which hydrological processes are chosen for a particular model run.

The OPTEVAPOTRANS parameter indicates the evapotranspiration option selected during the model run. The choice of the particular option will set the required parameter values used from the land use reclassification table and the meteorological data file. Five options are available for evapotranspiration: 0 = Inactive; 1 = Penman-Monteith method; 2 = Deardorff method; 3 = Priestley-Taylor method; 4 = Pan Evaporation measurements. The OPTINTERCEPT option allows the user to choose between three particular interception routines: 0 = Inactive, 1 = Canopy storage method; 2 = Canopy water balance method. The choice of the particular option will set the required parameter values used from the land use reclassification table. The GFLUXOPTION keyword allows two types of ground heat flux calculations to be performed: 0 = Inactive; 1 = Temperature gradient method, 2 = Force-restore method. The choice of the particular option will set the required parameter values used from the soil reclassification table.

The OPTSNOW parameter indicates the snow pack option used. Currently, either the single-layer energy balance module is on (OPTSNOW = 1) or off (OPTSNOW = 0). With the single-layer EB model, it has been found necessary to also input a minimum allowable temperature in Celsius (MINSNTEMP) in order to allow numerical stability. Additionally, the maximum fraction of liquid water, SNLIQFRAC, in the snowpack must also be specified.

The OPTLANDUSE parameter is used to indicate if static or dynamic land cover maps will be used in the simulation. Two options exist: OPTLANDUSE = 0 (static representation read in at the initial time period) and OPTLANDUSE = 1 (dynamic updating of the land cover at times specified by the available grids). If the dynamic updating is specified, then the user must indicate the pathname of the file containing the filenames of the ASCII grids to be read. This is specified using the keyword LUGRID (pathname to a Grid Data File, *.gdf). This file should contain the pathnames to the dynamic land cover grids. File naming convention only uses up to the hourly time stamp (no minutes, for example). The files need to be within the time boundaries of the simulation period. The keyword OPTLUINTERP allows for two types of interpolations between available land cover maps (at different time periods). OPTLUINTERP = 0 assigns the current gridded time step value to all model time steps up until the next available file. OPTLUINTERP = 1 linearly interpolates the land cover parameter values between two different grid time steps.

The OPTSOILTYPE keyword is used to activate the use of gridded soil parameter data input into the model. This option replaces the use of a soil grid index map and a soil parameter table. Two options exist: OPTSOILTYPE = 0, uses the traditional tabular soil data associated with a soil map of soil type numbers; OPTSOILTYPE =1, activates the use of gridded soil data, a new functionality. If OPTSOILTYPE = 1 then an additional folder named SoilTexture must be created in the main tRIBS directory where folders like Input and Output are located. This new folder should contain a database (*.gdf) file indicating the paths to all the grid files for each soil parameter. The format is similar to that used for the dynamic land cover maps. The directory path to the new folder is indicated under SCGRID keyword in the Input File.

The OPTBEDROCK keyword is used to specify the format of the bedrock depth data: 0 = Uniform bedrock depth over the basin; 1 = Grid bedrock file. If OPTBEDROCK = 0, then the DEPTHTOBEDROCK keyword is required (input is a double), otherwise the BEDROCKFILE keyword is required (input is a path and filename with extension *.brd).

The OPTGROUNDWATER runs the groundwater module; 1 = the groundwater module is on, 0= the groundwater module is off.

The OPTGWFILE keyword is used to specify the format of the initial groundwater input file. 0 = Resample ASCII grid file indicated in GWATERFILE; 1 = Read in Voronoi polygon file with groundwater levels output from previous run. GWATERFILE keyword only used for OPTGWFILE option 0, otherwise, the Voronoi GW file is read in through user interaction with model run (e.g. through screen).

The OPTRESERVOIR keyword is used to activate the use of the linear reservoir module (tReservoir) in the model. 0 = Disable the use of Reservoirs. 1 = Activate the use of Reservoirs. If OPTRESERVOIR = 1 then additional information is required by specifying the path to the file containing the TIN nodes (or Voronoi polygons) to be used as reservoirs in RESPOLYGONID (*.res) and the path to the file containing the elevation-discharge-storage information for each type of reservoir in RESDATA (*.eds).

The OPTPERCOLATION keyword allows the user to select from several options for channel percolation losses. 0 = No channel percolation. 1 = Constant loss method where the infiltration rate is equal to the channel saturated hydraulic conductivity specified under CHANNELCONDUCTIVITY. 2 = Constant loss method with a transient period applied with the transient hydraulic conductivity specified as TRANSIENTCONDUCTIVITY and the transient time period specified as TRANSIENTTIME. 3 = Green-Ampt infiltration equation with the parameters specified as CHANNELPOROSITY, CHANPOREINDEX and CHANPSIB.

4.2.5. Mesh Input Files and Pathnames: Spatial Data

The path and filenames of the grid input and the reclassification tables for the soil and land use data are grouped together within this section of the Input File. The soil grid (*.soi), land use grid (*.lan) and initial groundwater table position (*.iwt) are specified using the SOILMAPNAME, LANDMAPNAME and GWATERFILE keywords. The DEM used to derive the remote sheltering grids is specified by the DEMFILE keyword. The DEM used should encompass the study area and all significant surrounding topographic features, possibly outside the study area.

Additionally if OPTBEDROCK =1, then the path and filename with extension to the ascii grid must be specified using BEDROCKFILE. Likewise if either OPTSOILTYPE = 1 and or OPTLANDUSE = 1 then a grid data file (.gdf) will need to be specified with the keywords *SCGRID and LUGRID, respectively.

4.2.6. Mesh Input Files and Pathnames: Meteorological Data

The path and filenames of the meteorological data are grouped together in this section of the Model Input File.

The RAINSOURCE keyword is used to indicate the rainfall data source given to the model. Two types of radar rainfall data, as well as raingauge measurements are considered in the tRIBS Model: 1 = NEXRAD Stage III Radar (cm/hr); 2 = WSI Precipitation Radar (mm/hr); 3 = Rain Gauge station data (mm/hr).The radar rainfall grid (for RAINSOURCE = 1 or 2) base name is specified using the RAINFILE keyword and the extension is inputted by using the RAINEXTENSION keyword.

The METDATAOPTION is used to indicated the input format for the meteorological data: 0 = Inactive; 1 = Weather station point data; 2 = Grid meteorological data. The particular choice determines which type of text files, grid or point data files are required during model execution. The CONVERTDATA option is used to indicate whether or not meteorological pre-processing is activated: 0 = Inactive pre-processing; 1 = Activated pre-processing of meteorological data from RFC Point Data; 2 = Activated pre-processing of meteorological data from gridded observations provided by University of Washington (DMIP).

If METDATAOPTION = 1, then the Station Data File (*.sdf) must be specified in HYDROMETSTATIONS and the Meteorological Data File (*.mdf) basename in HYDROMETBASENAME. Otherwise, if METDATAOPTION = 2, then the HYDROMETGRID keyword must contain the Grid Data File (*.gdf). If CONVERTDATA = 1, then the HYDROMETCONVERT parameter must specify the path and filename of the Meteorological Data Input (*.mdi) File. If CONVERTDATA = 2, then the GAUGECONVERT parameter must be specify the path and filename of the rain gauge conversion file (*.mdi). The GAUGEBASENAME keyword is used to specify the base pathname of the MDF raingauge files. Finally, if RAINSOURCE = 3, then the GAUGESTATIONS keyword is used to specify the rain gauge SDF file. If CONVERTDATA = 3, then preprocessing of DMIP formatted observed energy forcings is performed. This results in an MDF file particular to the basin of interest (1992-2000 period) with somewhat altered list of meteorological parameters that can be ingested into the model. A separate SDF file must be prepared to correspond with this data.

Lapse rates have been implemented in the model for precipitation and temperature. The temperature lapse rate is assigned from TEMPLAPSERATE. The precipitation lapse rate is specified by PRECLAPSE in mm/m. Scattered light from opposing hillslopes can be a significant component of incoming radiations in snowy environments. HILLALBOPT = 0 uses the snow albedo for the hillslope albedo, HILLALBOPT = 1 uses the land-use albedo for the hillslope albedo, and HILLALBOPT = 2 uses a dynamic representation of albedo, where the snow albedo is used if there is snow in the canopy and a vegetative fraction weighted average of snow and land-use albedo is used otherwise. OPTRADSHELT tells what radiation sheltering scheme is used: 0 = local; 1 = remote controls on diffuse shortwave radiation; 2 = remote controls on entire shortwave radiation; 3 = no sheltering.

4.2.7. Mesh Input Files and Pathnames: Output Data

The path and basenames of the output data are grouped in this section of the Model Input File. The keyword OUTFILENAME is used to specify the location and basename of the output mesh and the voronoi file (*.nodes, *.tri, *.edges, *.z and *.voi) as well as the dynamic variable output (*.pixel and *.dat). The keyword OUTHYDROFILENAME specifies the path and basename of the outputted hydrograph and hyetograph time series. The format of the hydrograph and hyetograph file (*.mdf) depends on the value of RIBSHYDOUTPUT: = 0, not compatible with RIBS output; or = 1, compatible with RIBS output. This distinction is necessary if the *.mrf files are to be used with the RIBS graphical user interface. The NODEOUTPUTLIST specifies the path and filename of the Node Output List (*.nol) file used to input the node IDs for dynamic variable output. The OUTLETNODELIST keyword specifies the interior stream nodes to be used for output of the interior hydrographs (*.nol) file. OPTINTVL notifies the model at what interval the model output will be produced. Likewise, SPOPTINTVL specifies at what interval the dyanmic spatial files (*_00d) are written out.

4.2.8. Model Modes: Rainfall Forecasting Mode

The tRIBS model can be used for real-time flood forecasting given predicted rainfall data from any number of sources (radar extrapolation, numerical weather prediction). Currently, the Rainfall Forecasting Mode allows the user to specify the forecast time, lead time and forecasting interval using the FORECASTTIME, FORECASTLEADTIME and FORECASTLENGTH keywords. The Forecasting mode is turned on using FORECASTMODE. Three options are available: Single or Updating forecast, Persistence Forecast or Climatological Forecasting. They differ in the product used after the forecast time. For single or updating, the FORECASTFILE directory is read for the forecast product. Otherwise, a persistence of the last available rainfall or the climatological value are used. The RAINDISTRIBUTION enables the inputted rainfall to be spatially-averaged within tRIBS.

4.2.9. Model Modes: Stochastic Rainfall Mode

The tRIBS model can be forced with real rainfall data or stochastic rainfall input using the Eagleson or Rodriguez-Iturbe type Poisson storm process at a point. The STOCHASTICMODE keyword is used to specify whether or not stochastic rainfall forcing is used as an alternative to providing observed data from radar (grid field) or rain gauge (point). The stochastic mode is off (= 0) or on in various ways: Mean forcing (= 1), random forcing (= 2), sinusoidal forcing (= 3), mean and sinusoidal forcing (= 4) and random and sinusoidal forcing (= 5). The parameters of the stochastic mode include a random seed, a periodicity, a mean/max storm duration, a mean/max interstorm duration, a mean/max rainfall intensity.The keywords PMEAN, STDUR, ISTDUR are used alone (option 1: mean forcing), in conjunction with the random seed SEED (option 2: random forcing), in conjunction with periodic forcing using the PERIOD, MAXPMEAN, MAXSTDURMN and MAXISTDURMN (option 3: sinusoidal forcing), in combination of both mean and sinusoidal (option 4: mean and sinusoidal forcing) or in combination of both mean and random forcing (option 5: mean and random forcing). A complete stochastic weather generator for all climatic variables can also be utilized by specifying STOCHASTICMODE = 6 and a filename for WEATHERTABLENAME.

4.2.10. Model Modes: Restart Mode

The tRIBS model can output binary files corresponding to the entire set of model states at a particular time interval. This may be necessary for recovering from a system crash and can be very useful in data assimilation and forecasting schemes. The restart mechanism is invoked by using the RESTARTMODE keyword which has four options: No restart mechanism (option 0), Write files only (option 1), Read files only (option 2), Read and write files (option 3). In this context, writing implies making model output states at a specified interval defined by the keyword RESTARTINTRVL (in hours); while reading implies using a previously generated restart file as your initial state. The restart output is written to a directory specified by the keyword RESTARTDIR (pathname of directory); while the restart reading is from a file specified by the keyword RESTARTFILE (filename). The restart mechanism should be utilized with caution with respect to file space as the restart files can be large.

4.2.11. Model Modes: Parallel Mode

The tRIBS model can be run in either serial or parallel mode. The keyword PARALLELMODE is used to specify either serial (option 0) or parallel (option 1) computation. If the parallel mode is used, then attention needs to be paid to the graph file partitioning option. Three methods for graph partitioning can be selected utilizing the keyword GRAPHOPTION: (a) A default partitioning of the graph (option 0); (b) A reach-based partitioning (option 1); and (c) An inlet/outlet-based partitioning (option 2). If either option 1 or 2 are selected, the keyword GRAPHFILE needs to be specified with the name of the graph file to be used (either reach or inlet/outlet based). Otherwise, no filename is required.