Optimal Timing, Sequencing, and Sizing of Multiple Reservoir Surface Water Supply Facilities

This paper outlines a method whereby the timing, sequencing, and sizing of a water supply development is validly performed. The method takes care of the vital fact that although it is firm water that is demanded or sold, it is reservoir capacity at a particular site that is costed, and the two are not simply related, nor is the relationship independent of previously constructed reservoirs and the stream‐reservoir configuration. A feature of this method is a simple firm water determination concept that is applicable to any steam‐reservoir configuration and that uses rational and reasonable operating rules at each basic time period for the calculations of reservoir storage changes resulting from excess or deficit streamflows relative to demand in those periods. Details of interchanges of water between reservoirs are not relevant to this concept. Streamflows are taken to be the subnormal flow hydrographs that would correspond to a critical period analysis method, but no advantage is taken of any supposed knowledge about future flows.