Pre-development hydrologic conditions of the Salt River Indian Reservation, East Salt River Valley, central Arizona, with an emphasis on the groundwater flow regime

Abstract

A study of the Salt River Indian Reservation in central Arizona evaluated pre-development hydrologic conditions with an emphasis on simulating ground-water flow conditions within the reservation, where data was scarce before extensive aquifer pumping began in 1940 in adjoining portions of the East Salt River Valley. Water-resource development began in the valley with the completion of the Tempe Canal in 1871. Additional canals and irrigated agriculture spread quickly in areas along the Salt River, which has a mean annual flow of about 1.25 million acre-feet. Pre-development ground-water flow was horizontal and steady-state. The simulation indicated that the available water-level data, though corrupted in areas adjacent to the river, more properly described the virgin system than flow estimates. Sensitivity analyses indicated that simulated heads on the reservation were sensitive to all processes except evapotranspiration. Recharge through the riverbed, evapotranspiration, and subsurface outflow were all co-dependent.