CWD Geology & Groundwater Hydrology 5

Question 1

What does a negative water-level trend in a long-term monitoring well most likely indicate?

Accepted Answer

Aquifer depletion where withdrawals exceed recharge

Answer

A persistent downward trend in water levels indicates the aquifer is being mined—long-term withdrawals exceed natural recharge rates.

Question 2

Which of the following BEST describes a gaining reach of a stream in relation to the local aquifer?

Accepted Answer

The stream receives groundwater discharge because the water table is higher than the stream

Answer

In a gaining reach, the water table in adjacent banks is higher than the stream stage, driving groundwater into the stream channel.

Question 3

Effective porosity differs from total porosity because it:

Accepted Answer

Excludes isolated pores and pores occupied by immobile water

Answer

Effective porosity (kinematic porosity) counts only interconnected pores through which water can actually flow, excluding dead-end and isolated pore spaces.

Question 4

A well drilled in a valley-fill alluvial aquifer adjacent to a perennial stream is likely to exhibit what behavior?

Accepted Answer

Induced recharge from the stream when pumped heavily

Answer

Heavy pumping can reverse the hydraulic gradient between the stream and aquifer, inducing the stream to recharge the aquifer—a process called induced infiltration.

Question 5

What is the primary reason shale acts as a confining unit for aquifers?

Accepted Answer

Very low hydraulic conductivity due to fine grain size and high clay content

Answer

Shale's extremely fine clay particles pack tightly together, resulting in very low permeability that restricts vertical groundwater movement between aquifer units.

(CWD) Certified Well Driller Practice Test

(CWD) Certified Well Driller Practice Test

CWD Geology & Groundwater Hydrology 5