### GWF-EVTA #### Structure of Blocks _FOR EACH SIMULATION_ ``` BEGIN OPTIONS READASARRAYS [FIXED_CELL] [AUXILIARY ] [AUXMULTNAME ] [PRINT_INPUT] [PRINT_FLOWS] [SAVE_FLOWS] [TAS6 FILEIN ] [OBS6 FILEIN ] [EXPORT_ARRAY_NETCDF] END OPTIONS ``` _FOR ANY STRESS PERIOD_ ``` BEGIN PERIOD [IEVT -- READARRAY] SURFACE -- READARRAY RATE -- READARRAY DEPTH -- READARRAY AUX -- READARRAY END PERIOD ``` #### Explanation of Variables ##### Block: OPTIONS * `READASARRAYS` indicates that array-based input will be used for the Evapotranspiration Package. This keyword must be specified to use array-based input. When READASARRAYS is specified, values must be provided for every cell within a model layer, even those cells that have an IDOMAIN value less than one. Values assigned to cells with IDOMAIN values less than one are not used and have no effect on simulation results. * `FIXED_CELL` indicates that evapotranspiration will not be reassigned to a cell underlying the cell specified in the list if the specified cell is inactive. * `auxiliary` defines an array of one or more auxiliary variable names. There is no limit on the number of auxiliary variables that can be provided on this line; however, lists of information provided in subsequent blocks must have a column of data for each auxiliary variable name defined here. The number of auxiliary variables detected on this line determines the value for naux. Comments cannot be provided anywhere on this line as they will be interpreted as auxiliary variable names. Auxiliary variables may not be used by the package, but they will be available for use by other parts of the program. The program will terminate with an error if auxiliary variables are specified on more than one line in the options block. * `auxmultname` name of auxiliary variable to be used as multiplier of evapotranspiration rate. * `PRINT_INPUT` keyword to indicate that the list of evapotranspiration information will be written to the listing file immediately after it is read. * `PRINT_FLOWS` keyword to indicate that the list of evapotranspiration flow rates will be printed to the listing file for every stress period time step in which "BUDGET PRINT" is specified in Output Control. If there is no Output Control option and "PRINT_FLOWS" is specified, then flow rates are printed for the last time step of each stress period. * `SAVE_FLOWS` keyword to indicate that evapotranspiration flow terms will be written to the file specified with "BUDGET FILEOUT" in Output Control. * `TAS6` keyword to specify that record corresponds to a time-array-series file. * `FILEIN` keyword to specify that an input filename is expected next. * `tas6_filename` defines a time-array-series file defining a time-array series that can be used to assign time-varying values. See the Time-Variable Input section for instructions on using the time-array series capability. * `OBS6` keyword to specify that record corresponds to an observations file. * `obs6_filename` name of input file to define observations for the Evapotranspiration package. See the "Observation utility" section for instructions for preparing observation input files. Tables ref{table:gwf-obstypetable} and ref{table:gwt-obstypetable} lists observation type(s) supported by the Evapotranspiration package. * `EXPORT_ARRAY_NETCDF` keyword that specifies input griddata arrays should be written to the model output netcdf file. ##### Block: PERIOD * `iper` integer value specifying the starting stress period number for which the data specified in the PERIOD block apply. IPER must be less than or equal to NPER in the TDIS Package and greater than zero. The IPER value assigned to a stress period block must be greater than the IPER value assigned for the previous PERIOD block. The information specified in the PERIOD block will continue to apply for all subsequent stress periods, unless the program encounters another PERIOD block. * `ievt` IEVT is the layer number that defines the layer in each vertical column where evapotranspiration is applied. If IEVT is omitted, evapotranspiration by default is applied to cells in layer 1. If IEVT is specified, it must be specified as the first variable in the PERIOD block or MODFLOW will terminate with an error. * `surface` is the elevation of the ET surface (L). * `rate` is the maximum ET flux rate (LT-1). * `depth` is the ET extinction depth (L). * `aux` is an array of values for auxiliary variable AUX(IAUX), where iaux is a value from 1 to NAUX, and AUX(IAUX) must be listed as part of the auxiliary variables. A separate array can be specified for each auxiliary variable. If an array is not specified for an auxiliary variable, then a value of zero is assigned. If the value specified here for the auxiliary variable is the same as auxmultname, then the evapotranspiration rate will be multiplied by this array. #### Example Input File ``` BEGIN OPTIONS READASARRAYS AUXILIARY var1 var2 PRINT_INPUT PRINT_FLOWS SAVE_FLOWS END OPTIONS BEGIN PERIOD 1 #For a structured grid, IEVT defaults to model # layer 1, so no need to enter IEVT here. #ET surface elevation SURFACE constant 150.0 #Maximum ET rate RATE constant 0.007 #ET extinction depth DEPTH constant 15.0 #auxiliary variable (var1) array var1 constant 100.0 #auxiliary variable (var2) array var2 constant 0.0 END PERIOD ```