Mountain-front recharge to the Tucson Basin from Tanque Verde Canyon, Arizona

Abstract

The Tucson basin, Pima County, Arizona, is an alluvial aquifer partially recharged by underflow from bordering mountain ranges. Llountain-front recharge from Tanque Verde Canyon to the Tucson basin was analyzed to estimate the magnitude of underflow. Chemical, physical, and stable isotope analyses of well and spring water were used to locate and qualitatively describe underflow along the Tanque Verde mountain front. Stratigraphie and structural data helped identify zones of recharge and describe the hydrologic system. Petrologic and stratigraphic data were used in geochemical correlations. Two distinct types of underflow were identified discharging from Tanque Verde Canyon. Mountain-front recharge of ground water in the alluvial aquifer of the Tucson basin occurs as subsurface flow through the unconsolidated sediments of ephemeral mountain-draining stream channels. The alluvial aquifer is also recharged by ground-water flow through the fractured bedrock of the mountain mass. Total recharge was found to be minimal.