Therefore, let's assume that all the wells have such infinitesimally small-screen lengths so as to preclude them from intersecting any more than one equipotential surface. This figure depicts flat, but slightly, downwardly oriented equipotential surfaces - like the pages in a book which is leaning to the side in your bookcase. The 70 foot equipotential surface can be described locating two other wells somewhere else on this surface, provided that at least one of these wells intersect this surface at a different depth. The answer to this is that the 70 foot equipotential surface does not have to be intersected by even one well with an infinitesimally small well screen. Just as interpolation was used to define the equipotential lines for the water table, interpolating between two wells with static water levels just above and below the 70 equipotential surface can be used to approximately define the 70 equipotential surface.
Equipotential surfaces can be bent into varied shapes.
Bent equipotential surfaces are more commonly the rule even under naturally occurring hydrogeologic conditions that are unaffected by pumping of the ground water. We will see this in future examples. Arrows to define ground-water flow can't be located at a right angle to the equipotential surface. Arrows to denote ground-water flow direction are located normal to the constructed equipotential surface. Remember, that ground-water flow is typically in 3 dimensions and that equipotential lines are just the surface expression of a equipotential surface.