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Navigation: Main Menu and Buttons > Model > MODFLOW Dialog Boxes > MODFLOW Packages and Programs Dialog Box > FMP: Farm Process (for MODFLOW OWHM Version 2) LAND_USE: Farm Process V4 Land Use Options |
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The LAND_USE: Farm Process V4 Land Use Options pane is used to activate the LAND_USE block in the Farm Process in MODFLOW-OWHM version 2 and specify options for it. It is in the Farm Process group on the MODFLOW Packages and Programs dialog box.
The pane has three collapsible tabs on it. The tabs can be opened or closed by clicking on their headers.
The three tabs are
For a detailed description of the data printed see the the files in doc\Output_Header_Defintion of the MODFLOW-OWHM release. PRINT BYWBS: Summarize output by each water balance subregion (WBS)/farm PRINT BYWBS_BYCROP: Summarize output by each WBS for each crop in WBS/Farm PRINT BYCROP: Summarize output by each crop across entire model PRINT BARE: Summarize output by any bare soil/fallow crops in model PRINT ALL: Summarize output of of every crop by model cell -includes additional info, such as head and root elevation PRINT ALL_VERBOSE: Summarize output by of every crop by model cell -includes enormous amount of crop information from head to root pressures to crop fractions PRINT ET_BYWBS_BYCROP: ETref, ETpot, and ETact by each WBS for each crop in WBS/Farm. Note that ETpot <-> CU_INI and ETact <-> CU PRINT ROW_COLUMN: Same as PRINT ALL, except (INT, INT) is the model grid (ROW, COL) to print all crop information. This reduces the file size significantly. Specify crops to print: Due to the large file size produced by PRINT ALL and PRINT ALL_VERBOSE, the SPECIFY_PRINT_ALL_CROPS allows for only declaring which crops are printed in them. The choice for printing or not printing a specific crop is specified in the Farm Land Use Properties dialog box. |
Some land use properties are specified for individual cells and others are specified for each land use. Static data specified as arrays are specified using data sets. Transient data specified as arrays are specified as a MODFLOW Feature in an object. Properties specified for each land use (list) are specified in the Farm Land Use Properties dialog box. Land use names are also defined in the Farm Land Use Properties dialog box. Land use location: LOCATION specifies the location of specific land uses and can be static or transient. It is only used if SINGLE_LAND_USE_PER_CELL is selected. If LOCATION is static, it is specified with the Land_Use_ID data set. If transient, it is specified as a MODFLOW Feature in an object. Land use fraction: LAND_USE_AREA_FRACTION is required if MULTIPLE_LAND_USE_PER_CELL is selected. It represents the fraction of a cell area occupied by a particular land use. It can only be specified by cell if MULTIPLE_LAND_USE_PER_CELL is selected but it can be specified either for each cell or for each land use if SINGLE_LAND_USE_PER_CELL is selected. If the sum of all the crop fractions for a cell exceeds 1, then the crop fraction for that cell are scaled to equal 1. If the sum of all the crop fractions are less than 1, then the undefined area is set to bare soil. If SINGLE_LAND_USE_PER_CELL is specified, then LAND_USE_AREA_FRACTION is optional and specifies the area that the land use covers and the rest is considered bare/fallow land. If not specified, then where ever LOCATION has a crop identified (>0) uses 1.0 as the fraction (crop occupies entire cell). Crop coeff. and Consumptive use: CROP_COEFFICIENT and CONSUMPTIVE_USE are two different ways of specifying the potential consumptive use. If both are used at the same location, their effects are combined. If CROP_COEFFICIENT is used, its contribution to the potential consumptive use is the crop coefficient times the reference evapotranspiration. CONSUMPTIVE_USE contributes to the potential consumptive use directly. CROP_COEFFICIENT (Kc) is multiplied by the ETref to get CU -- input requires REFERENCE_ET (ETref) to be specified CONSUMPTIVE_USE (CF) specifies directly the CU Potential Consumptive Use CU = CF + Kc*ETref If not specified then consumptive use is set to zero. If CU = 0.0, then no consumption is possible and the crop is treated as if it is scraped clean earth. All precipitation either becomes runoff or deep percolation. If the ZERO_CONSUMPTIVE_USE_BECOMES_BARE_SOIL option is specified, groundwater evaporation will occur with a potential rate set to (in order of priority): 1) If POTENTIAL_EVAPORATION_BARE is provided, it is used as the potential evaporation of groundwater underneath the bare soil 2) If REFERENCE_ET is provided, it is used as the potential evaporation of groundwater underneath the bare soil 3) There is no groundwater evaporation Irrigation: Irrigation is used to indicate what type of irrigation, if any, is applied to a particular land use. The irrigation types themselves are defined in the Farm Irrigation Types dialog box. Irrigation is an integer variable. Zero represents no irrigation. Irrigation can be specified as a data set if it is a static array. If it is specified as transient array data, it is specified as a MODFLOW Feature in an object. If specified as a list, it is specified in the Farm Land Use Properties dialog box. Root depth: is the crop root depth below land surface. It can be static or transient and can be specified as an array or list. If used, it must be greater than zero. Root pressure: ROOT_PRESSURE determines if CONCEPT ONE orCONCEPT TWO is used. CONCEPT ONE an empirical root pressure formulation is used (when specified). CONCEPT TWO is a linear groundwater uptake/linear anoxia model. If ROOT_PRESSURE is not specified, or all pressures are set to 0.0, the linear model is used. If ROOT_PRESSURE is specified then SOIL block COEFFICIENT must be specified. If all pressures are specified as 0.0, then the root pressure calculation is not made and the linear uptake model is used for that crop. For an explanation of CONCEPT ONE and CONCEPT TWO, see Crop Consumptive-Use Flag. ROOT_PRESSURE is always specified as a list in the Root Pressure Pane of the Farm Land Use Properties dialog box. Groundwater Root Interaction: GROUNDWATER_ROOT_INTERACTION is an integer variable that can take on values from 0 through 5. It can be specified as an array or list. If specified as a list, it is specified in the Farm Land Use Properties dialog box. ModelMuse only support specifying GROUNDWATER_ROOT_INTERACTION as a static variable. 0 = No Transpiration ==> Zeros out any Transpiration requirement 1 = No Groundwater Interaction ==> No Root-Groundwater Uptake, No Anoxia or Stress Reduction, Full Consumptive Use (CU) must be met through surface sources (Precip or Irrigation) 2 = Has Anoxia/Soil Stress Loss, NO Root-Groundwater Uptake ==> CU Reduced from any anoxia and soil stress, but CU may only be satisfied with surface sources 3 = Has Root-Groundwater Uptake, NO Anoxia/Soil Stress Loss ==> Anoxia and Soil Stress losses are either added to Root-Groundwater Uptake or surface consumption requirement (i.e. if there is root-groundwater uptake, then the amount lost through anoxia is consumed as root-groundwater uptake. However if there is no root-groundwater uptake then the anoxia is added to the surface sources consumption (Precip or Irrigation) 4 = Has Root-Groundwater Uptake and Soil Stress Loss, NO Anoxia Loss ==> Anoxia losses are either added to Root-Groundwater Uptake or surface consumption requirement (i.e. if there is root-groundwater uptake, then the amount lost through anoxia is consumed as root-groundwater uptake. However if there is no root-groundwater uptake then the anoxia is added to the surface sources consumption (Precip or Irrigation) 5 = Full Interaction ==> HAS Anoxia/Soil Stress Reduction, HAS Root-Groundwater Uptake (DEFAULT) Transpiration fraction: TRANSPIRATION_FRACTION (FTR) is the fraction of consumptive use that is the potential transpiration of the crop. It is formally defined as FTR = Kcb/Kc = Basal Crop Coefficient / Crop Coefficient. It can be viewed as the fraction of a unit cropped area covered by leaf matter, i.e. crop cover. If set to zero, then crop is assumed to be fallowed or its area is bare soil. It can be static or transient and can be specified as an array or list. Evap irrig. fraction: EVAPORATION_IRRIGATION_FRACTION (FEI) is the fraction of a cropped area that is irrigated but is not covered by a crop. It should be less than or equal to 1 - FTR (That is FEI + FTR <= 1), but this is not required. If FEI + FTR > 1, then the final consumptive use can be larger than the input specified due to evaporation. It can viewed as the water that evaporates before it reaches the crop or evaporates while sitting atop of the leaves. Including the keyword EVAPORATION_IRRIGATION_FRACTION_SUM_ONE_CORRECTION forces FMP to correct FEI + FTR > 1 by setting FEI = 1 - FTR (Not Recommended). EVAPORATION_IRRIGATION_FRACTION can be specified by crop or by irrigation type if it is specified as a list. Depending on which is selected, it is specified in the Farm Land Use Properties dialog box or the Farm Irrigation Types dialog box. If FEI = -1, then it is recalculated as FEI = 1 - FTR Fraction of precip. to surface water: Any precipitation not consumed by the crop becomes an inefficient loss. The inefficient loss becomes either runoff or deep percolation. SURFACEWATER_LOSS_FRACTION_PRECIPITATION indicates the fraction of inefficient losses from precipitation that goes to surface water compared to deep percolation. (e.g. 0.75 indicates 75% of unconsumed precip becomes surface runoff) Fraction of irrig. to surface water: SURFACEWATER_LOSS_FRACTION_IRRIGATION: indicates the fraction of inefficient losses from irrigation that go to surface water compared to deep percolation. (e.g. 0.75 indicates 75% of extra irrigation becomes surface runoff). SURFACEWATER_LOSS_FRACTION_IRRIGATION can be specified by crop or by irrigation type if it is specified as a list. Depending on which is selected, it is specified in the Farm Land Use Properties dialog box or the Farm Irrigation Types dialog box. Pond depth: If CONCEPT TWO, linear uptake, linear anoxia model is used, the ponding depth is a height of water above the land surface that the crop can tolerate. CONCEPT TWO occurs when either ROOT_PRESSURE is not specified or for crops that have all four ROOT_PRESSUREs set to 0. If not set, then it is automatically set to zero. Added demand: Specify any additional demands to include with the crop demand. This only applies to irrigated crops and the additional demanded water only becomes surface runoff or deep percolation based on the fraction specified in the WBS Block "ADDED_DEMAND_RUNOFF_SPLIT." It may only be specified as a Length per Time (LENGTH or FLUX) or Volume per Time (RATE). The added demand is summed with other added demands (e.g. WBS Block ADDED_CROP_DEMAND) Zero consumptive use means bare soil: Given that: •CF = CONSUMPTIVE_USE •Kc = CROP_COEFFICIENT •ETref = REFERENCE_ET If the Potential Consumptive Use is CU = CF + Kc*ETref = 0, then the crop is assumed to be scraped clean earth with no evapotranspiration (CU = 0). This occurs when CF and Kc are set to zero indicating there is no potential consumption. If it is desired to convert CU = 0 to Fallow/Bare soil, then it is necessary to specify the keyword ZERO_CONSUMPTIVE_USE_BECOMES_BARE_SOIL. With this keyword, if CF and Kc are set to zero, then CU = REFERENCE_ET_TO_BARE * ETref or CU = POTENTIAL_EVAPORATION_BARE and only groundwater evaporation is allowed. ZERO_CONSUMPTIVE_USE_BECOMES_BARE_SOIL is optional. If ZERO_CONSUMPTIVE_USE_BECOMES_BARE_SOIL is not specified, then all Crops become bare soil when CU = 0 ET irrig. frac. correction: EVAPORATION_IRRIGATION_FRACTION_SUM_ONE_CORRECTION causes FMP to check if EVAPORATION_IRRIGATION_FRACTION (FEI) needs to be corrected so FEI + FTR = 1 when FEI + FTR > 1. If not specified, the default is not to check nor correct FEI + FTR > 1 which is ok since it is possible to have highly evaporative irrigation (like sprinklers). |
