# Solution to Exercise 16

16) In the accompanying figure flow lines (black lines) form two flow tubes, A and B. If conditions are isotropic and homogeneous and flow is at steady state, create equipotential lines under the following conditions.

16a) For A, assume the aquifer thickness and hydraulic conductivities are constant.

The volumetric flow rate in flow tube A must be constant, so the increasing distance between the flow lines (indicated by the black arrows) in a system where the aquifer thickness and hydraulic conductivity is constant indicates the gradient needs to decrease (equipotential lines space further apart).

b) For B, assume the thickness of the aquifer increases from left to right while all other conditions remain constant.

The volumetric flow rate in flow tube B must be constant, if the thickness of the aquifer is increasing from left to right, the flow area is increasing to the right. As a result, the gradients must decrease to the right, requiring larger distance between equipotential lines.