1.2 Definition of irrigation. Necessity of irrigation advantages/disadvantages of irrigation

Necessity of irrigation

Even today more than 50 percent people in India depend upon agriculture for their living. Remaining 50 percent depend upon it for the food production. India being tropical country natural rainfall cannot suffice entire water requirement of the crops throughout the year. Most of the water during rain is wasted through percolation, runoff etc. Without dependable supply of water, whole year it is difficult to grow cash and other crops. In that case we’ll have to depend upon foreign countries for food supply leading to expensive foreign currency. In order to become self sufficient in food production it is necessary to have dependable supply of water to crops throughout the year.

Definition of Irrigation Engineering

Irrigation is technique of supplying water to crops by artificial methods throughout the crop period for its complete growth. Engineering is application of science to everyday problems. Irrigation is addition to the natural rainfall. Monsoon rain is stored and channelized by various means to reach to the soil as per crop requirement.

Necessity of Irrigation

• India being tropical country, rainfall is available only for 3-4 months of the year.
• The rainfall is not uniform over the country.
• The rainfall is inadequate.
• For cash crops like cotton, sugarcane or tobacco, which takes about 12 months for maturity.
• When controlled w/s is needed like in floriculture.
• Advantages of irrigation

· Increase in food production – timely and optimum supply of water to the fields helps in increasing crop yield. This solves food problem of the country.

· Elimination of mixed cropping - means sowing together of two or more crops in the same field. If the weather conditions are not favorable for one crop the famer will at least gets yield from the other. If irrigation is assured mixed cropping can be eliminated or reduced.

· General prosperity of the region- Due to assured supply of water cash crops like sugarcane, cotton, tobacco can be grown by which prosperous and their standard of living improves.

· Revenue to state- Increased food production saves foreign exchange spent on import. Also water charges levied increase revenue of the state.

· Generation of hydroelectric power – same projects designed for irrigation can be used for hydro electric power generation at cheaper cost.

· Domestic water supply – irrigation structures constructed can be used for town water supply schemes.

· Famine protection – Irrigation works helps during famine and drought in two ways. During construction, employment is carried to the people and after construction continuous water supply is maintained.

· Transportation – Larger irrigation channels can be used for inland navigation purposes also embankments and inspection roads make pathway for commuters.

· Recreation – Irrigation structures like reservoirs, canals etc are used for boating, bathing, swimming, water games and other recreations.

· Afforestation – Due to percolation of water along the banks of canal trees are grown along the banks of canals which increases timber wealth and reduces soil erosion.

Disadvantages of excessive irrigation

• · Due to over irrigation water table rises up to ground level causing water logging and self efflorescence making the field unsuitable for cultivation.
• · Due to excessive irrigation all pools and depressions around the canals are filled up with water causing creation of breeding places for mosquitoes
• · Number of cross drainage works is required to be for natural drainages.
• · Large amount of country income is spent on irrigation projects
• · Irrigation water becomes cause of quarrels in villages.
• · Seepage of water makes the environment unhealthy for living.