11. Effects of Urbanisation on Tank Irrigation: A Study of Tamil Nadu State

Tanks are an important traditional and low-cost source of irrigation water in India, as they pose few environmental problems. But, tank irrigation has been on the decline, with its use deteriorating over the years. At the all-India level, it accounted for about 18 per cent of net irrigated area in 1950–51, dropping to a meagre 3 per cent in 2010–11. Despite the continuous reduction in area under tank irrigation, its role in increasing the growth of agriculture, recharging of groundwater and livestock development cannot be ignored, especially in south Indian states of Andhra Pradesh, Karnataka and Tamil Nadu where tanks play an important role in agricultural development even today. Why is the area under tank irrigation declining continuously? Numerous studies have attempted to answer this question using micro- and macro-level data. Most of them cite variations in rainfall, boom in groundwater irrigation, breakdown of village-level local institutions, encroachment in catchment areas and supply channels or poor maintenance as the main reasons for the sharp decline in the performance of tank irrigation in India. In recent years, urban agglomeration, which encroaches upon the catchment area of tanks, its water-spread area and supply channels for construction of private and public buildings, has been found to pose a serious threat to the existence of tank irrigation in many parts of the country. Although this problem has been identified in a few studies, the impact of urban agglomeration on tank irrigation has not been studied taking into account the district-level time series data. Tamil Nadu is among the important states in which tank irrigation is still widely employed in agriculture in spite of its urban population growing at a fast clip. This study makes an attempt to assess the impact of urbanisation on the number of tanks as well as on the area under tank irrigation in Tamil Nadu taking district-wise data from 1970–71 to 2009–10 as the basis. It is observed that there is a considerable reduction in area under tank irrigation in most districts where urban population is higher or where the growth of urban population is above the state’s average. But, more studies that make use of disaggregated data (taluk/block level) are needed to validate the results of our study