Sustainability of rice-dominated cropping system in the Hirakud canal command, Orissa, India

The present rice-based cropping system in the canal command of the Hirakud irrigation project, Orissa (India), is under severe threat due to waterlogging in the monsoon season and acute irrigation water deficit in the non-monsoon season. Estimation of irrigation water supply and demand reveals that at the present level of cropping, canal water availability during the monsoon is just sufficient to meet the irrigation requirements of crops at only 10% probability of exceedance. During the non-monsoon season, irrigation water requirement at 10% probability of exceedance exceeds canal water availability by more than 1050 million m(3). Groundwater table fluctuation study reveals that during the monsoon more than 90% of the command area remains and during the non-monsoon, in more than 40% of the area the groundwater table remains within 2-4 m of the surface. Hence there is ample scope for groundwater development. However, even at the permissible limit of groundwater development, the annual water deficit is more than 1000 million m(3) at 50% probability of exceedance of irrigation water demand, which can only be mitigated by replacing the existing non-monsoon rice by other crops with low water requirements as cultivated in the command. Copyright 2008 John Wiley & Sons, Ltd.