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

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.

EA= extra length factor, which is a function of the ratio of slot penetration p to the thickness of pervious stratum b.

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

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.

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.

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

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

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

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.