The seepage analysis is done on the assumptions that the flow is laminar and Darcy’s law is valid and further assumed that the soil to be dewatered is homogeneous and isotropic.

The flow lines and equipotential lines always meet at right angles to one another.

The equation hW=h – Z, can be used to plot pressure net representing lines of equal water pressure without the saturated soil mass since all the three quantities in the equation can be expressed a the percentage of total hydraulic head H.

The graphical method of flow net construction first given by Forchheimer in 1930, based on trial sketching.

Complete design of dewatering system consists of the diameter and spacing of well points or wells, penetration of wells and the pumping capacities.

The portion between any two successive flow lines is called a flow channel and the portion enclosed between two successive equipotential lines and successive flow lines are known as field.

Using the formula, hW = h -Z

The seepage medium is replaced by an electric conductor consisting of water with some salt or dilutes hydrochloric acid.

Where the dewatering system consists of a number of closely spaced well points or wells a simplified solution can be obtained by considering the lines of wells equivalent to a linear drainage slot.

The electric models suggested by ohm, have the same geometric shape as the soil through which the water flows. And both Darcy and ohm’s law have corresponding analogous quantities.