Question

What is/are the disadvantage/s of tube well irrigation systems?
A. Groundwater is used as the source
B. Can be dug at any convenient place.
C. Simplest and cheapest source.
D. Both A and B.

Answer 1

Hint: A tube well irrigation system consists of a type of water well, which is a long, 100–200 millimetre in width, made up of stainless steel tube like structure and pipe is bored into an underground water source. In this system the lower end is fixed with a strainer, and a pump pulls-out the water for irrigation. The water thus obtained is used for irrigation in fields.

Complete answer:
Disadvantages of tube well irrigation system.
-With one tube well system, only a limited or a part of the area can be irrigated. Generally it irrigated upto 1 to 8 hectares of land.
-It becomes purposeless, if it gets dried up, after continuous usage for a long time.
-Tube wells installation is not possible in the area or land having brackish groundwater.
-Only limited areas can be irrigated.
-When there is a drought in the summer, the ground water level gradually falls and therefore tube well water is not enough to meet the daily requirement of water at that place.

Advantages of tube well irrigation system.
-It is the simplest and cheapest source of water to irrigate the land or field in irrigation.
-Well can be dug at any suitable land or place.
-Use of many chemicals like nitrate, chloride, phosphates, sulphates, etc. generally gets mixed in well water. -In this way it also increases the fertility of soil as nutrients in the form of salts reach the agricultural field along with well water.

The main disadvantage of using tube well systems for irrigation purposes is that it leads to depletion of the groundwater because of which the groundwater stock or pool may get exhausted and ground water is only used as a source. However, installation of tube wells is only possible in that area of land where the groundwater level is not too low as more power is needed to drain water.

Option A and B are incorrect because both options come under the advantages of tube wells.
Option D is also incorrect because it includes option B as well, that is the advantage of tube-wells.

Hence, the correct answer is option (A).

Note: There is a low recharge of groundwater because only a small quantity of rain-water goes down to earth's surface and gets stored in the form of groundwater. So, the use of tubes well for irrigation purposes is limited as only some percentage of water gets down to the water table and forms groundwater.