The Unsat ET conc in UZT: Unsaturated-Zone Transport Package (MT3D-USGS) pane is on the MODFLOW Features tab of the Object Properties dialog box.
This tab is used for specifying the concentration of evapotranspiration from the unsaturated zone in the Unsaturated Zone Flow (UZF) package.
The data that can be specified in this pane are the Starting time, Ending time, and Unsaturated ET concentration (CUZET).
Starting time and Ending time are explained in the help for the MODFLOW Features tab.
CUZET is the concentration of ET fluxes originating from the unsaturated zone. As a default, this array is set equal to 0 and only overridden if the user specifies it. If empirical evidence suggest volatilization of simulated constituents from the unsaturated zone, this may be one mechanism for simulating this process, though it would depend on the amount of simulated ET originating from the unsaturated zone.
