Although the amount of flow in the basin is small most of the time, the area is subject to floods. The streamflow is extremely variable from year to year, and annual flows have a coefficient of variation close to or exceeding unity at most stations. The median number of days per year in which there is no flow ranges from 4 at Sonoita Creek near Patagonia to 335 at Rillito Creek near Tomson. Elsewhere, flow occurs only in direct response to precipitation. Ground water sustains low flows only at Santa Cruz River near Nogales, Sonoita Creek near Patagonia, and Pantano Wash near Vail. Most streams in the 3,503-square-mile basin are ephemeral. Flood-peak information collected from the gaging stations has been projected on a regional basis from which estimates of flood magnitude and frequency may be made for any site in the basin. The analysis provides information on flow duration, low-flow frequency magnitude, flood-volume frequency and magnitude, and storage requirements to maintain selected draft rates. Cruz River at Tucson to 6 years for Pantano Wash near Vail. Records are available for 15 sites, and the length of record ranges from 60 years for the gaging station on the Santa. Streamflow records obtained in the upper Santa Cruz River basin of southern Arizona, United States, and northern Sonora, Mexico, have been analyzed to aid in the appraisal of the surface-water resources of the area. Streamflow in the upper Santa Cruz River basin, Santa Cruz and Pima Counties, Arizona
0 kommentar(er)
