Hydrogeology Flashcards
7 cards from real ASBOG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hydrogeology flashcards as text
Which equation is the governing partial differential equation for transient groundwater flow in a confined, homogeneous, isotropic aquifer?
Answer: Diffusion equation: ∇²h = (S/T)(∂h/∂t)
The diffusion (or heat) equation relates the Laplacian of head to storativity divided by transmissivity times the time derivative of head.
What is the primary mechanism for dispersion in a heterogeneous porous medium at the field scale?
Answer: Mechanical mixing caused by velocity variations due to heterogeneity
Field-scale (macrodispersion) is dominated by spatial variations in hydraulic conductivity that create a range of groundwater velocities.
During a slug test analyzed with the Bouwer and Rice method, what parameter is primarily being estimated?
Answer: Hydraulic conductivity of the formation near the well
The Bouwer and Rice method estimates horizontal hydraulic conductivity from the rate of water-level recovery after a slug displacement.
Which of the following is NOT typically an assumption of the Theis solution for pumping test analysis?
Answer: The aquifer has a free (unconfined) water table that drains under gravity
The Theis solution assumes a confined aquifer; drainage from the water table (specific yield) violates the elastic storage assumption.
The concept of 'effective porosity' is most important for calculating:
Answer: Average linear groundwater velocity
Average linear velocity equals hydraulic conductivity times gradient divided by effective (kinematic) porosity, so only interconnected pores that transmit flow matter.
A potentiometric surface map shows closely spaced contours in one area and widely spaced contours in another. What does this pattern indicate?
Answer: Higher transmissivity where contours are widely spaced
Wide contour spacing means a low gradient; to maintain the same flux, transmissivity must be higher in that area (by Darcy's law).
Which of the following best describes 'specific retention'?
Answer: Water held in an aquifer against gravity after drainage
Specific retention is the volume of water retained by capillary and adhesive forces after gravity drainage, equal to total porosity minus specific yield.