# Problem 4 Solution

**Question:** The figures below show a potentiometric contour map of a confined aquifer and a cross section along transect A-A′. What is the depth of the water level in the well shown (relative to ground surface)? Explain.

a) 3 m

b) 5 m

c) 7.5 m

d) 10 m

**Solution:** The correct answer is 5 m deep, because the hydraulic head at the position of the well is 35 m (as indicated by the potentiometric contour map). Since water level in a well is equal to hydraulic head, the water level elevation in the well must be 35 m. Since the groundwater surface elevation is 40 m, the depth to water must be 5 m (40-35).