STREAM-AQUIFER INTERACTION MODELING IN LOWER CIENEGA CREEK BASIN, ARIZONA USING FINITE ELEMENTS

Abstract

Only a few areas in the deserts of the southwestern United States possess perennial streamflows. Cienega Creek near Tucson, Arizona is one of them (Figurel). Because of ground -water punping, some of these streams are in jeopardy of becoming ephemeral. The variability of surface water supply in the southwestern United States is very important because of its effects on riparian systems. Declines in water table and ground -water storage (over - exploitation of pumping wells) pose major concern as land subsidence and earth fissures, and produce stream and vegetation losses through ground and surface -water interactions. This report examines the Lower Cienega Creek Basin (LCCB) and the potential impact of nearby commercial development on the perennial stream. This area was chosen because it contains a natural preserve and a perennial stream. Perennial water flow and shallow water levels along the creek support various riparian species which shelter many types of insects and wildlife. The stream contained several species of fish including the endangered Gila Topminnow before they were extinct from this creek. This natural preserve, near the basin's exit, is one of the few desert places in the U.S. supporting a suitable habitat for animals, birds, and fishes because of its lush vegetation. An important riparian indicator for water table levels are cottonwood trees. These trees require shallow water to survive. As water levels decline, the cottonwoods produce less leaves. These cottonwoods could limit their existence by ceasing reproduction. Ultimately, a detrimental impact will be noticed in the surrounding ecosystem.