The DRT: Drain Return package pane is on the MODFLOW Features tab of the Object Properties dialog box.
The data that can be specified for the Drain Return package are the Starting time, Ending time, Elevation, Conductance, and Return fraction and the Return location. Of these, all but the Return fraction and Return location are also part of the Drain package and are explained in the help for the DRN: Drain package pane. The Return Fraction is the fraction of the groundwater that exits through the drain that returns to the groundwater at the return location. The Return location is the location in the model where water extracted at drains returns to the groundwater.
Starting time and Ending time are explained in the help for the MODFLOW Features tab.
If parameters are used with an object, Elevation and Return Fraction must be defined for each parameter as well as a multiplier for the Conductance. MODFLOW will multiply the multiplier by the parameter value (specified in the MODFLOW Packages and Programs dialog box) to determine the conductance to apply.
The Return location method allows the user to choose between three methods of specifying the return location: Object, Location, and Cell.
If Object is selected, a combo box is displayed in which the user can choose among the point objects in the model. The Return location will be the cell containing the point object.
If Location is selected, three edit boxes will appear in which the user can specify the X, Y, and Z, coordinates of the return location. The Return location will be the cell containing those coordinates.
If Cell is selected, three edit boxes will appear in which the user can specify the Column, Row, and Layer, of the return location. The Return location will be the cell defined by those values. With MODFLOW-OWHM models, setting Layer to -1 allows the user to specify the Farm number as the return location and setting Layer to -2 allows the user to specify the SWR reach number as the return location.
The user may also select none in which case no return location is defined.
