ASBOG Hydrogeology 3

Question 1

Which equation is the governing partial differential equation for transient groundwater flow in a confined, homogeneous, isotropic aquifer?

Accepted Answer

Diffusion equation: ∇²h = (S/T)(∂h/∂t)

Answer

The diffusion (or heat) equation relates the Laplacian of head to storativity divided by transmissivity times the time derivative of head.

Question 2

What is the primary mechanism for dispersion in a heterogeneous porous medium at the field scale?

Accepted Answer

Mechanical mixing caused by velocity variations due to heterogeneity

Answer

Field-scale (macrodispersion) is dominated by spatial variations in hydraulic conductivity that create a range of groundwater velocities.

Question 3

During a slug test analyzed with the Bouwer and Rice method, what parameter is primarily being estimated?

Accepted Answer

Hydraulic conductivity of the formation near the well

Answer

The Bouwer and Rice method estimates horizontal hydraulic conductivity from the rate of water-level recovery after a slug displacement.

Question 4

Which of the following is NOT typically an assumption of the Theis solution for pumping test analysis?

Accepted Answer

The aquifer has a free (unconfined) water table that drains under gravity

Answer

The Theis solution assumes a confined aquifer; drainage from the water table (specific yield) violates the elastic storage assumption.

Question 5

The concept of 'effective porosity' is most important for calculating:

Accepted Answer

Average linear groundwater velocity

Answer

Average linear velocity equals hydraulic conductivity times gradient divided by effective (kinematic) porosity, so only interconnected pores that transmit flow matter.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Hydrogeology 3