Abstract Freeze and Witherspoon 1,2) have simulated regional groundwater flow in two- and three-dimensional heterogeneous and anisotropic groundwater basins, using mathematical models. The principal directions of the permeability tensor were always parallel to the network axes (i.e. horizontal and vertical). The study of the relations between fracture geometry and permeability tensor in fractured media 3) led us to simulate any desired permeability tensor by a certain fracture geometry. Changing the fracture geometry from place to place, we may simulate any heterogeneous, anisotropic permeability field in a groundwater basin. In a two-dimensional basin, the potential field is easily determined by an electric analog made of conducting paper.