From the Proceedings of the 1984 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona-Nevada Academy of Science - April 7, 1984, Flagstaff, Arizona / Post-disaster studies of the October 1983 flood lead to serious questions concerning the applicability to southern Arizona of nationally standardized procedures for flood hazard evaluation. When the U.S. Water Resources Council method of determining flood flow frequency is applied to the Santa Cruz River annual peak flow record at Tucson for the period 1915-1982, the 1983 flood discharge is predicted to have an exceedence probability of less than 0.001. Hydro-climatological considerations suggest that such large floods occur much more frequently. The standard procedure for flood hazard zonation utilizes step-backwater calculations for the extant channel and valley floor geometry to route the discharges obtained from the standard flood flow frequency analysis. This procedure, as used in the Federal Emergency Management Agency flood insurance study, greatly overestimated the areas of overbank flooding along the Santa Cruz River as experienced in the 1983 flood. A detailed post-flood study was performed to assess channel change for reaches of Pantano Wash, Tanque Verde Creek, the Rillito, and the Santa Cruz River in the Tucson Basin. Bank erosion occurred as cutbank recession of actively migrating meander bends except where local areas of bank were preserved by revetments. Where revetments remained intact during the flooding they served to concentrate and enhance bank erosion in the unprotected reaches immediately downstream. From an overall river management perspective, piecemeal bank protection generates greater channel instability than does no protection at all.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/296129 |
| Date | 07 April 1984 |
| Creators | Baker, Victor R. |
| Contributors | Department of Geosciences, University of Arizona, Tucson, Arizona 85721 |
| Publisher | Arizona-Nevada Academy of Science |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Proceedings |
| Rights | Copyright ©, where appropriate, is held by the author. |
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