If S_y is the specific yield of the aquifer, then

(11.31) (11.32)

Now change in storage in time dt can be written as,

(11.33)

For maintaining continuity

Net flow in time dt = change in storage in time dt

(11.34) (11.35)

Now

(11.36) (11.37) (11.38)

Putting in

(11.39) (11.40)

Putting, σ = B/K₁

(11.41)

In case of non-homogeneous isotropic aquifer

(11.42)