Water availability for the Central Arizona Project : a projection for 1985-2040

Abstract

The Central Arizona Project Water Availability Model (CAPWAM) is a simplified model of the hydrology and operations of the Colorado River designed to estimate water availability for the Central Arizona Project (CAP) for the period 1985 to 2040. CAPWAM differs from other models of the basin in that it uses synthetic streamflow data. When historic streamflow data are used in CAPWAM, results are very similar to those of the Bureau of Reclamation Colorado River Simulation System (CRSS). However when data from a first-order autoregressive streamflow generator are used in CAPWAM, there is greater average availability of water for the CAP and also greater variability in diversion. Both surplus deliveries and severe shortage deliveries to southern Arizona are more frequent in CAPWAM than CRSS. Using only historic data in a river operations model produces results in which extreme events--both floods and droughts--are underestimated.