NEED OF IRRIGATION IN INDIA

The rainfall in India is extremely erratic in its spatial as well as temporal variations. The average annual rainfall for India has been estimated at 1,143 mm which varies from 11,489 mm around Cherrapunji in Assam (with the utmost one-day rainfall equal to 1040 mm) to 217 mm around Jaisalmer in Rajasthan. Besides, 75% to 90% of the annual rainfall occurs during 25 to 60 rainy days of the four monsoon months from June to September (2). additionally , there is also a large variation from year to year, the coefficient of variation being quite 20% for many parts of the country (2).

Erratic behaviour of the south-west monsoon is that the main cause of India’s frequent droughts (Table 1.) and floods. The recent proposal (Appendix–1) of the govt of India on interlinking of some major rivers of the country is aimed toward (i) increasing the utilizable component of the country’s water resources, and (ii) solving the issues of shortages and excesses of water in some parts of the country. Table 2.  shows the values of the approximate probability of deficient rainfall (deficiency adequate to or greater than 25 per cent of the normal) for different regions (8). Dependability of rainfall is thus rather low from the agriculture point of view and storage is important to sustain crops during non-monsoon periods and also to providewater for irrigation during years of low rainfall. For an outsized part of any crop season, the evapotranspiration (i.e., the water need of a crop) exceeds the available precipitation and irrigation is important to increase food and fibre production. About 45 per cent of agricultural production in India remains dependent on natural precipitation. the necessity and importance of irrigation in India are often appreciated from the mere fact that the country would need to produce 277 million tonnes (against the assembly of about 185 million tonnes for 1994-95) of food to meet the per capita requirement of 225 kg (i.e., about one-fourth of a tonne) per annum for an estimated population of 1,231 million within the year 2030 (8).

Table 1. Frequency of droughts in India (7)

Table 2. Periodicity of droughts in different regions (8)

In addition, the export of agricultural products earns a serious part of foreign exchange. Because of vastly different climate in different parts of the country, a spread of crops are produced in India. The country exports basmati rice, cotton, fruits (mango, apple, grapes, banana etc.), vegetables (potato, tomato etc.), flowers (rose etc.), and processed food products in order to earn precious foreign exchange. Still further, about seventy per cent of the country’s population is used in agricultural sector and their well-being, therefore, primarily depends on irrigation facilities within the country.