Free General Groundwater and Wells Exam Practice Questions

Sample Practice Questions

Try these 10 sample questions from the General Groundwater and Wells Exam practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1Which sequence lists common unconsolidated particles from smallest to largest grain size?

   1. A. Gravel, sand, silt, clay
   2. B. Sand, clay, gravel, silt
   3. C. Clay, silt, sand, gravel
   4. D. Silt, gravel, clay, sand

   Answer: C

   Explanation: USGS lists, "in order of increasing grain size, clay, silt, sand, and gravel." That is the required smallest-to-largest sequence.

   Reference: Usgs Basic Ground Water Hydrology — Rocks and Water, Unconsolidated Deposits

2. 2For water-well work, which definition best describes an aquifer?

   1. A. Any dry layer above the water table
   2. B. A geologic formation that can yield usable quantities of water
   3. C. Only a human-made water-storage cavity
   4. D. A layer that prevents all groundwater recharge

   Answer: B

   Explanation: USGS says an aquifer can "yield water in a usable quantity" to a well or spring. That directly matches the usable-water formation in B.

   Reference: Usgs Basic Ground Water Hydrology — Aquifers and Confining Beds

3. 3What occupies the interconnected openings in the unsaturated zone?

   1. A. Water only
   2. B. Air only
   3. C. Cemented grout only
   4. D. Both air and water

   Answer: D

   Explanation: USGS says the zone "contains both water and air" and calls it the unsaturated zone. Both therefore occupy its interconnected openings.

   Reference: Usgs Basic Ground Water Hydrology — Subsurface Water

4. 4In a water well affected by pumping, what is drawdown?

   1. A. The depth from land surface to the well bottom
   2. B. The difference between static and pumping water levels
   3. C. The rise in water level after pumping stops
   4. D. The thickness of the well screen

   Answer: B

   Explanation: USGS defines drawdown as "The difference between the water level in a well before pumping and the water level in the well during pumping". Option B matches.

   Reference: Water Resources Glossaries — drawdown

5. 5A driller logs a loose, soil-like deposit whose grains are not cemented into a solid mass. How should it be classified?

   1. A. Metamorphic rock
   2. B. Consolidated sedimentary rock
   3. C. Igneous rock
   4. D. Unconsolidated deposit

   Answer: D

   Explanation: USGS describes surface materials as "soil and by unconsolidated deposits" and contrasts them with consolidated rocks. The described loose, uncemented material is therefore an unconsolidated deposit.

   Reference: Usgs Basic Ground Water Hydrology — Rocks and Water

6. 6What is the principal hydraulic effect of a confining bed?

   1. A. It always raises groundwater temperature
   2. B. It creates primary pores in bedrock
   3. C. Its low hydraulic conductivity restricts groundwater movement
   4. D. It guarantees a flowing well

   Answer: C

   Explanation: USGS describes a confining bed as having "very low hydraulic conductivity" and explains that this restricts groundwater movement into or out of adjacent aquifers. Restriction is therefore its principal hydraulic effect.

   Reference: Usgs Basic Ground Water Hydrology — Aquifers and Confining Beds

7. 7Which pore-water condition defines the subsurface saturated zone?

   1. A. All interconnected openings are filled with water
   2. B. Only capillary openings contain water
   3. C. Every pore is filled with air
   4. D. The formation lies above land surface

   Answer: A

   Explanation: USGS says "all interconnected openings are full of water" in the saturated zone. Option A states that defining condition.

   Reference: Usgs Basic Ground Water Hydrology — Zone of Saturation

8. 8When documenting a well before pumping begins, which measurement is the static water level?

   1. A. Water level at maximum pumping rate
   2. B. Depth of the completed borehole
   3. C. Water level when the well is not being affected by pumping
   4. D. Height of casing above grade

   Answer: C

   Explanation: USGS describes available drawdown using "the static (nonpumping) water level" and a practical pumping level. The static value is the pre-pumping baseline in option C.

   Reference: Usgs Basic Ground Water Hydrology — Supply-Well Problems—Decline in Yield

9. 9In sand and gravel, the pore spaces formed when the deposit accumulated are what type of openings?

   1. A. Primary openings
   2. B. Secondary openings
   3. C. Solution openings
   4. D. Fracture openings

   Answer: A

   Explanation: USGS begins the controlling sentence, "The pores in sand and gravel", and classifies those depositional pores as primary openings. Secondary, solution, and fracture openings form after the material or rock formed.

   Reference: Usgs Basic Ground Water Hydrology — Water-Bearing Properties of Rocks

10. 10Porosity is calculated as the volume of openings divided by which quantity?

    1. A. Volume of interconnected openings only
    2. B. Volume of water released by gravity
    3. C. Volume occupied by solid grains only
    4. D. Total volume of the rock or sediment

    Answer: D

    Explanation: USGS states, "The ratio of openings (voids) to the total volume", and names that ratio porosity. The denominator is therefore the total rock-or-sediment volume.

    Reference: Usgs Basic Ground Water Hydrology — Porosity