Confined - Unconfined Aquifer System
Calculate the radial flow to a well in a confined - unconfined aquifer system.
Solve the governing equation
`1 / r del / (delr) (rbK (delh) / (delr)) = 0 `
where `b =` constant saturated thickness of the aquifer when confined, and `b = h - z_b` when unconfined.
Subject to: `h = h_w` at well radius, `h = h_0` at radius of influence.