**The
Kozeny-Carman equation is one of the most widely accepted and used
derivations of permeability as a function of the characteristics
of the medium. This equation was originally proposed by Kozeny
(1927) and was then modified by Carman (1937, 1956) to become the
Kozeny-Carman equation. In essence, this equation will estimate
the permeability of media based on a grain size distribution. This
equation is given by:**

Where

ρ = density

g = acceleration due to gravity

μ = dynamic viscosity

n = porosity

d_{10} = 10% cumulative passing (geotechnical grain size
distribution)

**Input**

*Groundwater temperature
estimate**: *
** **^{o}C

*n (porosity)***: **

**Click
here for information on porosity values**

*d*_{10 }(from a geotechnical plot;
% passing)**: **
**m**

**Click here
for information on d**_{10} and particle sizes

**Hydraulic
Conductivity: **
**m/s**

**Example:**

**A soil matrix has a
porosity of 0.30 and a d**_{10} value of 0.1 mm. The
groundwater is 10^{o}C. Determine the hydraulic
conductivity.

**The resulting hydraulic
conductivity should be 0.000023 m/s.**

**What would be a common
error in this example?**

**- forgetting to convert
the d**_{10} value from mm to m. The input should be
0.0001 m.

*
***
See our Newsletter on **
*Hydraulic Conductivity
Estimates**
and Reelogger**
**
*