Aqueduct and Reservoir Capacities for Distribution Systems

The determination of the design capacity and operation policy of water delivery systems for farming areas is complicated by the temporal variability of demands and the corresponding use of delivery capacity, the probabilistic occurrence of supplies, the spatial distribution of users, and losses in the distribution systems. This paper develops a general method to integrate the choices of delivery system capacity and of conjunctively operated local reservoir capacities (the decisions of delivery system operators and farmers) to make more efficient use of water resources. The method consists of using the results from local economic optimization models of farm water requirements and benefits in a discrete dynamic programming model of the delivery system to determine the most efficient method of distributing limited water supplies. In previous papers, the writers have worked with intrayearly probabilistic supplies and transportation losses. The main improvments here are that the method: (1) Allows variable peak-delivery proportions; (2) includes local (on-farm) intrayear storage; (3) is compatible with many other existing optimization models for farms; (4) addresses irrigation scheduling problems; and (5) addresses efficiency-equity conflicts.