Precipitation, streamflow, and major floods at selected sites in the Gila River drainage basin above Coolidge Dam, Arizona

Abstract

The Gila River Phreatophyte Project is a water-budget study to measure evapotranspiration from a 15-mile reach of the Gila River flood plain above Coolidge Dam in southeastern Arizona. Its principal purpose is to determine how much the water yield of the project area can be increased by replacing deep-rooted nonbeneficial woody plants with shallow-rooted beneficial grasses. Necessary to the study, and also for the application of the findings to other areas, is an understanding of the hydrologic variables and relations that affect the quantity of water draining toward the project area and of the environmental changes that would result from vegetation alteration. This report, which is based on available precipitation and runoff data at selected sites, is an analysis of those variables and relations.