# Engineering Hydrology Questions and Answers – Groundwater Depletion Curve or Base Flow Curve

This set of Engineering Hydrology Multiple Choice Questions & Answers (MCQs) focuses on “Groundwater Depletion Curve or Base Flow Curve”.

1. The river water is derived from groundwater only when no water is obtained from ___________
a) Rains
b) Melting of snow
c) Melting of snow and waterfalls
d) Rains and melting of snow

Explanation: When surface runoff is not obtained from either rains or melting of snow then river water is derived from groundwater only. Therefore, in this case baseflow or ground water inflow is the only source of river water supply.

2. When water is supplied to the river from the groundwater inflow then water table _________
a) Moves upwards
b) Moves downwards
c) Remains at the same position
d) Never moves below the bed level of the river

Explanation: When water is supplied from the ground water inflow, the ground water table moves downloads. Water is supplied to the river in this way and maximum discharge from the ground water inflow occurs when surface runoff is not obtained from rains and melting of snow. As the ground water table moves below the river bed level, the flow of groundwater into the river stops.

3. What is base flow curve?
a) Hydrograph of Runoff
b) Hyetograph of runoff
c) Hydrograph of ground water inflow
d) Hyetograph of ground water inflow

Explanation: The hydrograph of ground water inflow is known as base flow curve. The hydrograph depicts a depleting curve. Base flow curve is known as the ground water depletion curve.

4. The hydrograph of river when it obtains water only from ground water is similar to ________
a) Hydrograph of runoff
b) Hydrograph of surface runoff
c) Hydrograph of ground water inflow
d) Hydrograph of flow stream

Explanation: When water is not obtained from rains and melting of snow then water is supplied to the river only from ground water table. This results in lowering of water table. The hydrograph of river in this condition is similar to the hydrograph of ground water inflow for the time period from the change in position of water table from its maximum height to the position below the river bed level where there will be no flow.

5. Ground water depletion curve is plotted at zero surface runoff.
a) True
b) False

Explanation: When the surface runoff is zero then river gets supply of water from ground water inflow. So, at that period of time the hydrograph of river is depicted by the hydrograph of ground water inflow that is the ground water depletion curve.

6. The recession curve of the annual hydrograph of river in an area having slight rainfall is represented by __________
a) Summation curve
b) Rain water depletion curve
c) Runoff curve
d) Ground water depletion curve

Explanation: The hydrograph of a river is equal to the hydrograph of ground water inflow when there is no surface runoff. In an area of slight rainfall, the surface runoff is not obtained when there is no rainfall. So, at that point of time the hydrograph of ground water inflow is similar to the hydrograph of river which is the ground water depletion curve. Therefore, the recession curve of the annual hydrograph is represented by ground water depletion curve in an area of slight rainfall.

7. The ground water depletion curves completely develops in all kinds of areas.
a) True
b) False

Explanation: In areas of slight rainfall or no rainfall, the ground water depletion curve develops completely. In areas of heavy to moderate rainfall when there are no rainless long periods then the ground water depletion curve does not develop properly or completely.

8. During post monsoon period, most of the rivers in Indian peninsula get supply of water from ___________
a) Surface runoff
b) Drainage
c) Ground water
d) Melting of snow

Explanation: After the monsoon period, there is less amount of rainfall in Indian peninsula. So, the amount of surface runoff is very less. Therefore, in the post monsoon period, most of the rivers in Indian peninsula get supply of water from ground water inflow.

9. What is the time period of post monsoon flow?
a) October to December
b) October to May
c) September to December
d) September to May

Explanation: After the monsoons, the rivers of Indian peninsula mostly run by getting supply of water from ground water inflow. This off-season flow is known as post monsoon flow. The time period of post monsoon flow is from October to May.

Sanfoundry Global Education & Learning Series – Engineering Hydrology.

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