Real time operation of reservoir based canal irrigation systems

It is proposed that real-time adaptive operation of reservoir based canal irrigation systems be carried out in two phases, a plan phase and operation phase. In the plan phase, biweekly reservoir releases are optimized for a set of target releases and mean inflows. This is done by minimizing a water supply deficit function using dynamic programming. In the operation phase, real-time releases are made according to plan for the current interval. The releases are transferred to the field level after accounting for conveyance losses. At this level, the allocations of available field supplies to competing crops are also optimized. The plan for the remaining intervals of the season is then modified by replacing the inflow for the previous interval with the observed inflow during the interval. The current interval inflow is replaced by the corresponding forecast inflow. The forecasts are obtained from a time series model of weekly inflows. These four steps, namely, (i) releasing supplies from reservoir according to seasonal plan in the current interval, (ii) determining the fraction of the releases available to crops at field level, (iii) allocating the field level supply to competing crops, and (iv) modifying the reservoir release plan for the remaining intervals of the year based on inflows and forecasts, operate sequentially in real-time for each interval. As the season advances, this cycle repeats successively from the first to last intervals of the year. The application of the procedure is demonstrated using data from a case study irrigation project in India. (C) 1998 Elsevier Science B.V. All rights reserved.