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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.

Conditions and Assumptions

The aquifer becomes unconfined towards the pumping well
The aquifer is confined at a greater distance from the pumping well
The aquifer has a seemingly infinite areal extent
The aquifer is homogeneous and of uniform thickness over the area influenced by the test
Prior to pumping, the piezometric surface is horizontal (or nearly so) over the area that will be influenced by the test
The aquifer is pumped at a constant discharge rate
The well penetrates the entire aquifer and thus receives water from the entire saturated thickness of the aquifer

Inputs

Hydraulic Conductivity of Aquifer (

$K$ )

m/s

Top of Aquifer (

$z_t$ )

mOD

Base of Aquifer (

$z_b$ )

mOD

Head in Well (

$h_w$ )

mOD

Head at Zero (

$h_0$ )

mOD

Radius of Influence (

$R_0$ )

Radius of Well (

$r_w$ )

Output

Value of pumping rate for input values:

Q_w =

m³/s

Q_w =

Litre/sec

Table of Values: Head at radius, r

Graph

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