36.5.3. Unconfined Aquifer

Try these first

1. 1.

   What is an unconfined aquifer?

   Hint

   Think about the definition based on layers of rock.

2. 2.

   What does drawdown refer to?

   Hint

   It's about how much lower the water level is after pumping.

3. 3.

   What is a key characteristic of unconfined aquifers?

   • A. They are capped by impermeable layers.
   • B. They allow gravitational drainage.
   • C. They are always freshwater sources.

   Hint

   Think about atmospheric pressure.

4. 4.

   True or False: The storage coefficient typically ranges from 0.1 to 0.3 in unconfined aquifers.

   • True
   • False

   Hint

   Recall the definitions of storage coefficients.

5. 5.

   A farmer extracts water from an unconfined aquifer at a rate of 150 liters per minute. The aquifer has a storage coefficient of 0.25 and average rainfall contributes 100 liters per minute back to the aquifer. Assess the sustainability of this extraction rate.

   Hint

   Think about recharge versus discharge.

6. 6.

   If the water table in an unconfined aquifer drops by 5 meters due to extended drought, and it previously was 15 meters deep, calculate the new water table level. Discuss the potential risks associated with prolonged drought on water resources.

   Hint

   Simple subtraction reveals the new depth.