The general head boundary package simulates flow to or from a model cell from an external source by two IDFs: the elevation (L) and the conductance (L\({}^{2}\)/T) of the general head boundary. The GHB package assumes an unlimited source of water and is often used to model large water bodies which border the area of interest.
Figure 12.13: Principle of the General Head Boundary package (Harbaugh, 2005)