Short-Term Real-Time Reservoir Operation for Irrigation

Abstract

The development and management of irrigation facilities has been recognized as the key to national development in India. Despite their high priority and massive investments, the performance of major irrigation projects has been disappointing. Substantial benefits can be achieved from relatively small increases in operating efficiencies. The main objective of this study is to develop a short-term, real-time reservoir operating policy in a multicrop, multiseason environment integrating reservoir release decisions with field irrigation requirements. A real-time reservoir operation model defines the set of releases to be made into each offtake on the main canals of a reservoir for a known set of release targets, reservoir storage state, and forecasted inflow in the current period, minimizing the deficit function. An intercrop allocation model allocates reservoir releases of the current period among competing crops. On implementing the irrigation decisions of the intercrop allocation model for the current period, soil moisture is updated with the rainfall that actually occurred and irrigation that was applied in the current period. A new set of irrigation targets for the remaining periods is determined by running the single-crop intraseasonal allocation model for each crop constraining the allocations of the previous periods to the actual irrigation performed. With the revised targets and updated reservoir storage, reservoir operation and intercrop allocation models are run sequentially for all time periods in real time. The models developed are demonstrated through a case study of the Nagarjuna Sagar Reservoir Project. The real-time reservoir operation model is run for data from the years 2004–2005 with and without updating irrigation targets, and the results are discussed. The crop production measure is found to be high in the case of updated targets, underscoring the importance of updating irrigation targets.