NGWA ADVANCED GROUNDWATER
PROFESSIONAL EXAM 2026/2027
1. Which parameter in Darcy’s Law represents the ease with which a fluid can move through
pore spaces or fractures?
A. Hydraulic Gradient
B. Hydraulic Conductivity
C. Specific Storage
D. Transmissivity
Answer: B
Conceptual Explanation: Hydraulic conductivity (K) is a measure of the ability of a porous
medium to transmit water. Transmissivity is K multiplied by the thickness of the aquifer.
2. In a confined aquifer, the level to which water will rise in a tightly cased well is called the:
A. Water table
B. Vadose zone surface
,C. Potentiometric surface
D. Cone of depression
Answer: C
Conceptual Explanation: The potentiometric surface is an imaginary surface representing
the static head of groundwater in a confined aquifer.
3. Which of the following describes the ‘Specific Capacity’ of a well?
A. The porosity of the formation surrounding the screen
B. The total volume of water stored in the well
C. The maximum flow rate before cavitation
D. The ratio of yield to drawdown
Answer: D
Conceptual Explanation: Specific capacity is calculated by dividing the pumping rate
(yield) by the drawdown (the drop in water level).
4. What is the primary function of bentonite in a drilling fluid (mud) program?
A. To act as a lubricant for the drill bit only
B. To lower the pH of the drilling environment
C. To prevent all water from entering the well
D. To increase density and create a filter cake on the borehole wall
, Answer: D
Conceptual Explanation: Bentonite increases viscosity and creates a low-permeability
filter cake to stabilize the hole and prevent fluid loss.
5. The Theis equation is primarily used to determine which of the following?
A. Well depth required for specific yield
B. Aquifer transmissivity and storativity from pumping test data
C. The pH of an unconfined aquifer
D. The concentration of dissolved solids in groundwater
Answer: B
Conceptual Explanation: The Theis equation describes the flow of groundwater to a
pumping well and is used to calculate aquifer properties like T and S.
6. What causes ‘Water Hammer’ in a pumping system?
A. Low voltage to the motor
B. Excessive air in the pressure tank
C. Sudden change in fluid velocity, often from a valve closing rapidly
D. Pumping sand into the plumbing
Answer: C
PROFESSIONAL EXAM 2026/2027
1. Which parameter in Darcy’s Law represents the ease with which a fluid can move through
pore spaces or fractures?
A. Hydraulic Gradient
B. Hydraulic Conductivity
C. Specific Storage
D. Transmissivity
Answer: B
Conceptual Explanation: Hydraulic conductivity (K) is a measure of the ability of a porous
medium to transmit water. Transmissivity is K multiplied by the thickness of the aquifer.
2. In a confined aquifer, the level to which water will rise in a tightly cased well is called the:
A. Water table
B. Vadose zone surface
,C. Potentiometric surface
D. Cone of depression
Answer: C
Conceptual Explanation: The potentiometric surface is an imaginary surface representing
the static head of groundwater in a confined aquifer.
3. Which of the following describes the ‘Specific Capacity’ of a well?
A. The porosity of the formation surrounding the screen
B. The total volume of water stored in the well
C. The maximum flow rate before cavitation
D. The ratio of yield to drawdown
Answer: D
Conceptual Explanation: Specific capacity is calculated by dividing the pumping rate
(yield) by the drawdown (the drop in water level).
4. What is the primary function of bentonite in a drilling fluid (mud) program?
A. To act as a lubricant for the drill bit only
B. To lower the pH of the drilling environment
C. To prevent all water from entering the well
D. To increase density and create a filter cake on the borehole wall
, Answer: D
Conceptual Explanation: Bentonite increases viscosity and creates a low-permeability
filter cake to stabilize the hole and prevent fluid loss.
5. The Theis equation is primarily used to determine which of the following?
A. Well depth required for specific yield
B. Aquifer transmissivity and storativity from pumping test data
C. The pH of an unconfined aquifer
D. The concentration of dissolved solids in groundwater
Answer: B
Conceptual Explanation: The Theis equation describes the flow of groundwater to a
pumping well and is used to calculate aquifer properties like T and S.
6. What causes ‘Water Hammer’ in a pumping system?
A. Low voltage to the motor
B. Excessive air in the pressure tank
C. Sudden change in fluid velocity, often from a valve closing rapidly
D. Pumping sand into the plumbing
Answer: C
