ie =Δ h /l, represent gradient formula where Δ h=potential drop and l is the average of last field in the flow net at the exit end.

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.

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

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

Based on Dupuit-Forchheimer assumptions, the slope of the drawdown curve was assumed to be equal to hydraulic agent.

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

A flow net can be utilized for determination of seepage, seepage pressure, hydrostatic pressure, and exit gradient.

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

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