Hydraulic conductivity can vary by orders of magnitude in the subsurface, depending on the size, shape and interconnectedness of the pores or open spaces between solid materials.  For example, the size of interconnected pores in sands and gravels is much greater than in finer grained soils such as silts.  As a result, sands and gravels generally have a greater hydraulic conductivity than the finer-grained soils.

A. Calculate the effective vertical hydraulic conductivity of the stratified formation between the lake and the aquifer shown below. Also compute the vertical seepage flux from the lake to the aquifer using the Darcy's law based on the effective conductivity.

Hints:  consider how to compute harmonic mean; and how to generate a stratified random field with a known geometric mean and lnK variance.

B. Verify the results using MAGNET.

MAGNET/Modeling Hints:

• Use ‘Synthetic mode’ in MAGNET to create a model domain.
• Create a 2-layer model to represent the aquitard and aquifer layers.
• Add a prescribed head  zone feature to the aquitard (1st) layer to represent the lake
• Use a zone feature of the entire aquifer area to assign the hydraulic conductivity as a random field realization for the aquitard layer  
• Analyze the plots and charts using the DisplayCharts tool ( 'Analysis Tools' > 'Analysis' > 'Display Charts' )