Advantage of Irrigation (merits / benefits):
1. Increase in food production:- Food production is increased to a great extent by reliable irrigation. Due to the controlled and timely supply of water to the crop, the yield is increased.
2. Optimum utilization of water for optimum benefits:- Optimum benefits ( Max. Crop yield ) are possible by optimum utilization of irrigation water. Optimum utilization, we mean, obtaining optimum crop yield with an optimum quantity of water.
3. Protection from famine and drought control:- The construction of irrigation works helps during the famine and drought period in two ways. During the construction of the irrigation works, employment is carried to the people and thus they get relief against famine. After the construction of such works, continuous water supply is maintained during drought.
5. Generation of Hydro-electric power:- Irrigation helps in generation hydro-electric power, thus developing the country industrially. Major river valley project are usually planned to provide hydro-electric power together with irrigation. Also, falls on the irrigation channels can be utilized to generate electricity which may help in industrializing the rural area, and also in solving the problem of electricity shortage.
6. Cultivation of Cash Crops:- Irrigation makes it possible to grow cash crops such as sugar-cane, indigo, tobacco, cotton, jute, tea, etc.
8. Domestic and Industrial water supply:- The canals can also be utilized for domestic and industrial water supply.
9. Water for other purposes:- Irrigation water can be provided for swimming, bathing, cattle watering, boating, washing, fisheries, etc.
10. Inland navigation:- Larger irrigation canals can be used and generally developed for navigation.
11. Improving underground water storage:- Due to the constant percolation and seepage of water, the ground water table is raised in the area which is beneficial for ground water storage.
12. Removing deficiency of water:- The deficiency of water which occurs due to insufficient rainfall is removed by irrigation work.
13. Less dependency on Rainfall:- Due to irrigation system the dependency on the rainfall is decrease which helps the farmer grown any crops without the worrying about the rainfall occurs or not.
14. Facilities for Transport:- Irrigation canals are generally provided with embankments and inspection road. These paths or roads provide a good roadway to the villagers for walking, cycling or sometimes driving of the vehicles.
15. Flood Control:- The distribution of River water into different canals helps in reducing the extra river water which prevents from flooding.
16. Aid in Civilisation:- Due to the introduction of river valley projects, the violent tribes adopt irrigation as their profession and settle peacefully. Also, due to the increased yield and value of the cops, the standard of living of a common cultivator is improved, and he becomes more civilized.
17. Increases the value of land:- Due to irrigation facility, the value of land is increased. Also due to increase in the yield of the crop, and due to the growing of cash crops, the farmers become prosperous(Rich and Successful), and thereby their living standard is improved.
18. Increases the Revenue of Country:- Almost all the irrigation projects are so designed that they bring some revenue to the state and which helps to increase the revenue of the country.
19. Improvements of Communication:- Almost all the irrigation channels are provided with inspection roads. These roads can be metalled, and be used as means of communication.
20. General Development of Country:- The most important benefit due to irrigation is the general development of an agricultural country such as India. Due to the increased yield and value of the crop, means of communication, such as road-ways, railway and post and telegraph, facilities are introduced. Due to the increase in agriculture revenue of the state, and due to rise in the living standards of the people, schools, hospitals and other facilities are provided. All these helps in general development of the country.
21. Employment:- During the constructions of irrigation works, employment is provided.
Disadvantage of Irrigation (demerits / ill-Effects) :
1. Water-logging:- Over-irrigation may lead to water-logging of the area. If the water table is near the ground surface, over-irrigation may raise the water table. This saturates the crop root-zone completely, causes efflorescence and the whole area becomes water-logged.
2. Pollution of under-ground water:- Irrigation creates many ways to the pollution of underground water. The first is the seepage of nitrates applied as fertilizer to the soil into the ground water trough irrigation of crops. Sometimes even more than 50% of the nitrates sinks into the underground water reservoir which pollute the ground water and causes many disease such as anemia. This polluted water sometimes reach to the sea through underground and affect the life of fishes which is a matter of research.
3. Breeding places for Mosquitoes:- Due to excess application of water, and due to leakage of water, ponds and depressions get filled up with water and create breeding places for mosquitoes.
4. Damp Climate:- The areas which are already damp and cold, become damper and colder due to irrigation.
5. Increase the Expenditure of Government:- Irrigation increase the expenditure of government as the construction costs of such projects is very high. Sometimes cheaper water is provided at the cost of government and revenue returning are low.