CONFINED HETEROGENEOUS AQUIFER
Solve the following problem analytically and using MAGNET and compare the results.
i. Calculate the groundwater flow per unit width of a confined
aquifer in the section between the two parallel rivers shown in the figure above. The aquifer can be divided into three homogeneous areas with different hydraulic
conductivities:
- K1 = 6.2xl0-5 m/s,
- K2 = 7.9xl0-4 m/s,
- K3
= 4.1x10-4 m/s.
Draw a
calculation scheme showing all parameters necessary for the solution.
ii. Determine the position of the
piezometric surface on the cross-section.
iii. Determine the "equivalent
hydraulic conductivity" and compare it with the average (arithmetic) hydraulic
conductivity. Also compare the results
of groundwater flow calculation using these two conductivities with the result
obtained using the original calculation scheme.
MAGNET/Modeling Hints:
- Use 'Synthetic Mode' to set up your flow model ( 'Other Tools' > 'Utilities' > 'Go to Synthetic Case Area'). The default model domain for synthetic mode is identical to the domain depicted in the figure above.
- Make a 1-layer confined aquifer model. Use zone features to assign K1, K2, and K3.
- Add prescribed head line or zone features along the left and right edges to represent River 2 and River 1, respectively. Note that the rivers are fully connected to the aquifer.
- Analyze the results in cross-section view ( 'Analysis Tools' > 'Analysis' > 'Display Charts') to visualize the shape of the water table.