State of irrigation in Tamil Nadu: trends and turning points

Irrigation is a vital input for food security in the State of Tamil Nadu. Rice is the major staple food, accounting for three-fourths of the consumption of food grains. Irrigation covers most parts of the rice area. In 2000, 96% of the rice production was carried out under irrigation conditions. Groundwater contributes to a major part of the irrigated area. However, recent trends of groundwater water use in the state show that its abstractions in many regions exceed the total net annual recharge (CGWB 2006). Overall, groundwater exploitation exceeds 85% of the annual recharge. Moreover, irrigated areas under tank commands, once a dominant source of irrigation in Tamil Nadu, and under canal commands are decreasing. Besides, the cropping and irrigation patterns are changing to meet the increasing demand of non-grain food products. In view of the recent trends in irrigation, meeting food security in Tamil Nadu will indeed be a major challenge. What factors have influenced these changes in the state of irrigation in Tamil Nadu, and how significant are they in the long run? Given the past trends, what types of investments in agriculture, especially in irrigation, will yield higher returns and can meet food security in the state? Answers to these questions are important for assessing future water demand, since irrigation shares more than 90% of total water withdrawals at present. The major purpose of this report is to assess the trends of irrigation development in Tamil Nadu over the last 35 years (1970-2005). After a brief introduction to the districts and regions, in section 2 we assess the trends of major exogenous drivers that influence the water sector development. Section 3 presents the spatial and temporal trends of land use and cropping patterns, and crop production. Finally, we discuss major drivers that will influence the patterns of irrigation water use in the future.