Channel changes of the San Xavier Reach of the Santa Cruz River, Tucson, Arizona 1971-1988

Abstract

Aerial photographs of the San Xavier reach of the Santa Cruz River near Tucson, Arizona, were used to interpret four planimetric surface classes and to generate hydraulic variables for analysis of channel change. Variables were regressed to determine the extent to which channel form is controlled by "catastrophic" flows. Channel width analysis, in combination with channel overlay maps provided the means of assessing spatial variations in channel form through time. Results indicate that the study reach is dominantly controlled by equilibrium conditions rather than catastrophic events as determined in previous studies in arid and semi-arid climates. The definition and implementation of the braid index variable as a measure of channel pattern in this study account for measurement errors inherent in defining hydraulic variables in a channel which changes pattern through time. Such errors may be critical sources of inconsistency in previous studies of channel change in fluvial systems.