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

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.

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.

Dewatering of fine grained cohesive soil can be done only electro-osmosis method.

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 application of electro-osmosis to dewatering of soil was largely developed by L. Casagrande.

For fine-grained soils, the well point system can be extended by the vacuum method.

According to practical suggestion given by A.Casagrande, every transition in the shape of curve is smooth, being either elliptical or parabolic in shape.

Fully penetrating slot is used for both confined and unconfined case of flow.

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.