The hydro-institutional challenge of managing Tanks: A study of tanks in rural Andhra Pradesh

Abstract

Tanks are an important form of wetland in South India. The chapter contests the prevailing theories about ‘decline of tanks’ in South India, and postulates an alternate theory. In order to test this theory, a study was carried out in Andhra Pradesh. The study examined the determinants of change in historical performance of irrigation tanks. It showed that intensity of land use and density of wells in the catchment are major determinants of tank performance. While low density of wells and low land use intensity in the catchment provide favourable conditions for sustaining the hydrological integrity of tanks and therefore their good performance, high density of wells in either catchments or commands and high degree of crop cultivation in the catchment were clearly indicative of their deterioration. Increasing intensity of wells and expansion in area under cultivation in the catchment adversely affects tank inflows. While the first relationship is attributed to hydraulic inter-connectedness, the second one is attributed to hydrological impact. Managing tanks is increasingly becoming a hydro-institutional challenge. Therefore, the ‘moribund idea of taking up every tank for rehabilitation, on the justification that an institution would be created to manage it, needs a critical review, as there are external factors adversely influencing the tank systems that are beyond the control of these institutions. Instead, the protocol for tank rehabilitation should include estimation of the yield potential of the tank catchment using rainfall-runoff models, based on existing catchment land use. This should be followed by estimation of the water demand in the command, which takes into the variations in crop water demands in lieu of the rainfall variability from dry year to wet year.