ASBOG Hydrogeology 4

Question 1

In a gaining stream, the relationship between groundwater and surface water is best described as:

Accepted Answer

Groundwater discharges into the stream, raising baseflow

Answer

A gaining stream receives groundwater discharge because the water table elevation near the stream is higher than the stream stage.

Question 2

The retardation factor (R) for a contaminant in groundwater is defined as:

Accepted Answer

R = v_water / v_contaminant

Answer

R = v_water / v_contaminant; a retardation factor greater than 1 means the contaminant travels slower than the groundwater due to sorption.

Question 3

Which of the following best describes the concept of 'hydraulic head'?

Accepted Answer

The total mechanical energy per unit weight of water, expressed as an elevation

Answer

Hydraulic head is the sum of pressure head and elevation head, representing total mechanical energy per unit weight expressed as a length (elevation).

Question 4

What is the primary cause of land subsidence associated with groundwater withdrawal in unconsolidated sedimentary basins?

Accepted Answer

Compaction of fine-grained interbeds as pore pressure declines

Answer

When pore pressure decreases in pumped systems, the effective stress on clay and silt interbeds increases, causing irreversible compaction and land subsidence.

Question 5

The Dupuit assumption in analytical groundwater models for unconfined aquifers states that:

Accepted Answer

Flow is horizontal and hydraulic gradient equals the slope of the water table

Answer

The Dupuit-Forchheimer assumption neglects vertical flow components and assumes flow is horizontal with the gradient equal to the water table slope.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Hydrogeology 4