The general solution of the Laplace equation yields two sets of curves orthogonal to each other. One set of curves is known as the flow lines and the other is set as equipotential lines.

The net formed by intersecting the possible flow lines and equipotential lines is known as flow net. Flow net is a graphical representation of seepage flow through a soil mass.

A flow line represents the path traced by an individual water particle. An equipotential line is a contour or line joining points of equal potential or head. The flow lines and equipotential lines cut each other at right angles i.e.they are mutually orthogonal. The space between any two adjacent flow lines is called flow channel