EVT: Evapotranspiration Package Pane

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The EVT: Evapotranspiration package pane is on the MODFLOW Features tab of the Object Properties dialog box.

The data that can be specified for the Evapotranspiration package are the Starting time, Ending time, Evapotranspiration rate, Evapotranspiration surface, Evapotranspiration depth, and sometimes Evapotranspiration layer. Whether or not Evapotranspiration layer is present depends on the choice of return location in the EVT: Evapotranspiration package pane of the MODFLOW Packages and Programs dialog box. If Specified layer was selected on the EVT: Evapotranspiration package pane but Time varying EVT layers was not selected, the layer at any location will be determined by the layer of the lowest cell selected by the object at that location.

Starting time and Ending time are explained in the help for the MODFLOW Features tab.

Evapotranspiration rate is is the maximum evapotranspiration (ET) flux (volumetric flow rate per unit area with units of L/t).

Evapotranspiration surface is the elevation of the ET surface. If the head in the cell with a EVT boundary is higher than the ET surface, the ET flux will be set to the maximum ET flux.

Evapotranspiration depth is the ET extinction depth. If the head in the cell with a EVT boundary is below than the ET surface minus the ET extinction depth, the ET flux will be set to zero. If the head in the cell with a EVT boundary is below than the ET surface but is above ET surface minus the ET extinction depth, the ET flux will be linearly interpolated between zero and the maximum ET flux.

Evapotranspiration layer is the layer indicator variable. For each horizontal location, it indicates the layer from which ET is removed. If some layers are nonsimulated, it is important to remember that Evapotranspiration layer represents the MODFLOW layer not the layer in the ModelMuse model. ModelMuse layers include both simulated and nonsimulated layers.

If parameters are used with an object, a multiplier for Evapotranspiration rate must be defined for each parameter. MODFLOW will multiply the multiplier by the parameter value (specified in the MODFLOW Packages and Programs dialog box) to determine the evapotranspiration rate to apply.

hmtoggle_plus1For MODFLOW experts

When parameters are used to assign the EVT, RCH, and ETS boundary conditions, the objects used to define the values of the parameters also define the spatial extent where the parameters apply by assigning the values to a hidden zone array that is used by MODFLOW to determines where each parameter applies.