UTCHEM is a small scale, local model with simple boundary conditions. Boundary conditions can be set at the left, right or both ends of the model. The other two boundaries and the bottom are no-flow boundaries.
The Top Boundary is open check box specifies whether the model domain is confined.
When the Vadose Only or Both option is chosen in the Zone to Be Modeled selection group, you must use the Water Table Elevation view windows to specify the boundary between the vadose and the saturated zones.
The Pressure at Top Layer view windows allows you to specify a hydraulic gradient.
The Concentration of Water, Concentration of Chloride, and Concentration of Calcium view window all specify background concentration values for each boundary.
Related Links:
Building a UTCHEM model
Saving a UTCHEM Simulation