Uses of Canal Irrigation, Causes & Effects

Cheap labour and availability of cement reduces the cost of canal construction
Huge quantities of water from Monsoon rainfall & melting of snow can be stored in reservoirs during summer season.
Irregular supply of water in the rivers is then regulated by construction of dams & barrages. Canal system irrigates a vast area. Even the deserts have been made productive.

Causes:

Abundance of silt eroded from the Karakoram, Hindu Kush and Himalayan mountains.
Deforestation - ruthless cutting of trees for fuel and timber. Rivers form narrow and deep valleys in the mountainous areas. Most of the eroded material is washed down into the plains and piles up in reservoirs of the dams.

Effects:

  • Blockage of canals because silt accumulates.
  • Weakens the foundation of dams.
  • Reduced capacity of reservoir and less flow of water affects the generation of hydro-electric power. It also results in availability of less water for irrigation purposes.
  • Flow of floodwater is hampered which may cause heavy damage to the dam because of mounds of silt which block the flow of water.
  • Large-scale afforestation especially on the foothills of Himalayas.
  • Cemented embankment of canals. .
  • Installation of silt trap before the water flows to the dams.
  • Structural measures such as operating the reservoir at lower level during flood and allowing free flow during low flow season for sluicing sediments from the reservoir.

Uses of Irrigation:

  1. Soft soil and level land of the Indus Plain makes digging of canals easier than in the rugged lands of Balochistan.
  2. By canal irrigation millions of gallons of water are utilized that would flow into the Arabian Sea.
  3. Cheap labour and availability of cement reduces the cost of canal construction
  4. Canal system irrigates a vast area. Even the deserts have been made productive.
  5. Irregular supply of water in the rivers is then regulated by construction of dams & barrages.
  6. Huge quantities of water from Monsoon rainfall & melting of snow can be stored in reservoirs during summer season.
  7. Southward slope of the rivers makes construction of canals easier, because water flows southwards naturally.

Comments

Post a Comment

Popular posts from this blog

Lane’s Weighted Creep Theory

Image
Bligh, in his theory, had calculated the length of the creep, by simply adding the horizontal creep length and the vertical creep length, thereby making no distinction between the two creeps. However, Lane, on the basis of his analysis carried out on about 200 dams all over the world, stipulated that the horizontal creep is less effective in reducing uplift (or in causing loss of head) than the vertical creep. He, therefore, suggested a weightage factor of 1/3 for the horizontal creep, as against 1.0 for the vertical creep. Thus in Fig–1,  the total Lane’s creep length (L l ) is given by L l = (d 1 + d 1 ) + (1/3) L 1 + (d 2 + d 2 ) + (1/3) L 2 + (d 3 + d 3 ) = (1/3) (L 1 + L 2 ) + 2(d 1 + d 2 + d 3 ) = (1/3) b + 2(d 1 + d 2 + d 3 ) To ensure safety against piping, according to this theory, the creep length Ll must no be less than C1H L , where H L is the head causing flow, and C 1 is Lane’s creep coefficient given in table –2 Table – 2: V
Read more

What is Soil in Geotechnical Engineering.

Image
Definition of Soil The word ‘soil’ is derived from the Latin word solium which, according to Webster’s dictionary, means the upper layer of the earth that may be dug or plowed; specifically, the loose surface material of earth in which the plants grow. The above definition of soil is used in the field of agronomy (The application of soil and plant sciences to land management and crop production) where the main concern is in the use of soil for raising crops. In geology, earth’s crust is assumed to consist of unconsolidated sediments, called mantle or regolith, overlying rocks. The top soil contains a large quantity of organic matter and is not suitable as a construction material or as a foundation for structure. The top soil is removed from the earth’s surface before the construction of structure. The term ‘ soil ’ in the soil engineering is defined as an unconsolidated material , composed of solid particles , produced by the disintegration of rocks . The void space
Read more

What is Mill bent in Industrial Buildings?

Image
The assembly of roof truss attached to and supported on column at both the ends is known as bent, mill bent or transverse bent . An industrial buildings consists of a series of such transverse bent supporting the roof. The distance between the two adjacent transverse bents is known as bay . The space between the column lines is usually called an aisle.
Read more