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

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

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

Using the formula, hW = h -Z

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.

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.

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

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

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