In addition to system-dependent boundary conditions available in version 2.x of HYDRUS-2D, several new options are available in HYDRUS. These new options are specified in the Boundary Condition Options dialog window that is called using the menu command Edit->Boundary Conditions->Boundary Conditions Options or from the Edit Bar for Water Flow Boundary Conditions version using the BDRC Options command. This dialog window has four tabs: a) Time-Variable Head/Flux BCs, b) Special Boundary Conditions, and c) Triggered Irrigation, and d) Reservoir Boundary Condition.