Check 15 - Uniform flow in a two-layer confined/unconfined aquifer with uniform recharge
Checks confined/unconfined domain, spatially-variable area sinks for vertical leakage, constant head line boundary, normal flux line boundary, uniform recharge, 3D pathlines, minimum saturated thickness where head drops to base of unconfined domain.
This is the same as check 14, but with two layers, both of which are combined confined/unconfined domains. The upper domain (level 1) spans elevation 5-10 and the lower domain (level 2) spans elevation 0-5.
The vertical conductivity is high enough that there are very small head differences between the two levels, so the solution should be nearly identical to check 14, which it is.
Heads in level 1 fall below the base (5) at the right side of the model, where the minimum saturated thickness (0.0001 * 5) is invoked; discharges in this zone are very small.
The graph below shows aquifer discharge (Qx) as a function of x in each layer and the sum of the two. The sum is nearly identical to a similar plot for check 14, as expected.