Engineering Geology Multiple Choice Questions on “Engineering Considerations of Groundwater”.
1. Which of the following doesn’t control aquifer behaviour?
a) Wind conditions
b) Nature of the rock
c) Structural disposition
d) Climate conditions like precipitation
Clarification: As a storage reservoir, the aquifer behaviour is controlled by- the nature of the rock and its porosity, structural disposition, with regard to the recharge points or places, climate conditions like annual precipitation.
2. An aquifer can hold water _________ and the state of water is _________
a) Permanently – State of flow
b) Temporarily – State of flow
c) Permanent – State of stagnancy
d) Temporary – State of stagnancy
Clarification: It must be remembered that an aquifer can hold water only temporarily, as the water is always in a state of flow in it. However, the rate of flow of water through an aquifer is very slow compared to surface waters.
3. Groundwater is a subordinate to surface water.
Clarification: The importance of groundwater in water supply system can hardly be over emphasized. It is in no way subordinate to that of surface waters.
4. The quantity of water that can be withdrawn annually and also the rate at which this withdrawal could be made without adversely affecting the inventory of the aquifer is called __________
a) Annual yield
b) Percent yield
c) Operational yield
d) Monthly yield
Clarification: The quantity of water that can be withdrawn annually and also the rate at which the withdrawal could be made without adversely affecting the inventory of the aquifer, therefore, determine what may be called operational yield.
5. When an aquifer is used to artificially recharge by making it pass through an intervening layer, the aquifer acts as __________
a) A cooling agent
b) An aerating agent
c) An odour agent
d) A filter plant
Clarification: An aquifer may be made to serve as a filter plant when artificial recharge is made to pass through an intervening layer of rock, which acts as a natural filter.
6. When would the dam become irrelevant?
a) When the rocks are strong
b) When the rocks are impermeable
c) When the rocks are porous
d) When the rocks are weathered to a certain extent
Clarification: A dam is built across a river primarily to store water in the form of a reservoir. The whole idea of a dam would become irrelevant if the foundations on which it is built are made of porous rocks or if a stretch of a reservoir rock is permeable.
7. Which quality of rock should be known properly for the foundations of dams, reservoirs, etc.?
a) Colour knowledge
d) History of the formation of rocks
Clarification: The position of the water table and hydrogeological qualities of rocks forming foundations and abutments of dams and reservoirs must be known.
8. Groundwater is a source of trouble at which place?
Clarification: Groundwater is a major source of trouble for the stability of slopes. Many slope failures, especially in hilly regions are due to direct or indirect involvement of groundwater.
9. An associated protection of rising water-table is the development of __________
a) Loss of nutrients
b) Loss of good quality of water
c) Salinity of water
d) Increase in turbidity
Clarification: An associated trouble with rising water-table is the development of salinity of the soils. The rising groundwater may be rich in some undesirable salts that are left at or near the surface during its loss to atmosphere due to evaporation.
10. The root system of crops in water-logged areas get __________
b) Enriched with nutrients
d) Growth inhibited
Clarification: The root system of crops in water-logged areas gets decomposed. Large areas of land in Indian subcontinent are affected by water-logging.
11. The lubricating action of water is a positive action for slope rocks.
Clarification: Soil creep and solifluction are caused mainly due to groundwater. The lubricating action of water besides its negative effect on the strength parameters of rocks is the major cause in initiating massive landslides.