Channel change in the Rillito Creek system, southeastern Arizona : implications for floodplain management

Persistent Link:
http://hdl.handle.net/10150/191316
Title:
Channel change in the Rillito Creek system, southeastern Arizona : implications for floodplain management
Author:
Pearthree, Marie Slezak.
Issue Date:
1982
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Changes in channel morphology of the ephemeral streams of the Rillito Creek system through time have constituted greater hazards for the Tucson metropolitan area than has overbank flooding. The behavior of this stream system has been investigated to document past channel instability, determine potential sites of bank erosion, and suggest floodplain management alternatives to the federal regulations currently applied to semiarid regions. Rillito Creek and its main tributaries, Pantano Wash and Tanque Verde Creek, were mapped from Houghton Road to the mouth of Rillito Creek using aerial photographs taken between 1941 and 1979. These maps, in conjunction with streamflow and channel composition data, detail channel change within this stream system. Prior to and including 1941, the Rillito Creek system exhibited braided plan-view patterns. By the early 1960's, single channel patterns had developed, accompanied by extensive decreases in channel widths. Pantano Wash continued to narrow to 1979 as its depth increased. Tanque Verde Creek and Rillito Creek widened extensively in 1965 and 1978 during prolonged winter flows, and narrowed during intervening periods dominated by low magnitude summer flows. Channel banks were eroded locally throughout this system during the periods of channel narrowing, however. The greatest amounts of bank erosion have occurred on the outer banks of channel bends and at locations where the silt-clay content of the banks and the density of riparian vegetation have been the least. In compliance with federal regulations, management of the floodplains of the Rillito Creek system has been focused mainly on those areas subject to flooding by 100-year floods. Frequent changes in channel morphology have created problems for floodplain management by altering the areas subject to flooding. In addition, bank erosion during lower magnitude flows historically has posed a greater hazard than has overbank flow. For more effective floodplain management, zones of potential bank erosion based on past erosional sites, historical channel positions, and current stream channel patterns should be considered for land-use regulation as well as potential areas of flooding. The principles established herein are applicable to other ephemeral stream systems in semiarid regions.
Type:
Thesis-Reproduction (electronic); text
LCSH Subjects:
Hydrology.; Floodplain management -- Arizona -- Rillito River.; Erosion -- Arizona -- Rillito River.; River channels -- Arizona.; Geomorphology -- Arizona -- Rillito River.
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleChannel change in the Rillito Creek system, southeastern Arizona : implications for floodplain managementen_US
dc.creatorPearthree, Marie Slezak.en_US
dc.contributor.authorPearthree, Marie Slezak.en_US
dc.date.issued1982en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractChanges in channel morphology of the ephemeral streams of the Rillito Creek system through time have constituted greater hazards for the Tucson metropolitan area than has overbank flooding. The behavior of this stream system has been investigated to document past channel instability, determine potential sites of bank erosion, and suggest floodplain management alternatives to the federal regulations currently applied to semiarid regions. Rillito Creek and its main tributaries, Pantano Wash and Tanque Verde Creek, were mapped from Houghton Road to the mouth of Rillito Creek using aerial photographs taken between 1941 and 1979. These maps, in conjunction with streamflow and channel composition data, detail channel change within this stream system. Prior to and including 1941, the Rillito Creek system exhibited braided plan-view patterns. By the early 1960's, single channel patterns had developed, accompanied by extensive decreases in channel widths. Pantano Wash continued to narrow to 1979 as its depth increased. Tanque Verde Creek and Rillito Creek widened extensively in 1965 and 1978 during prolonged winter flows, and narrowed during intervening periods dominated by low magnitude summer flows. Channel banks were eroded locally throughout this system during the periods of channel narrowing, however. The greatest amounts of bank erosion have occurred on the outer banks of channel bends and at locations where the silt-clay content of the banks and the density of riparian vegetation have been the least. In compliance with federal regulations, management of the floodplains of the Rillito Creek system has been focused mainly on those areas subject to flooding by 100-year floods. Frequent changes in channel morphology have created problems for floodplain management by altering the areas subject to flooding. In addition, bank erosion during lower magnitude flows historically has posed a greater hazard than has overbank flow. For more effective floodplain management, zones of potential bank erosion based on past erosional sites, historical channel positions, and current stream channel patterns should be considered for land-use regulation as well as potential areas of flooding. The principles established herein are applicable to other ephemeral stream systems in semiarid regions.en_US
dc.description.notehydrology collectionen_US
dc.typeThesis-Reproduction (electronic)en_US
dc.typetexten_US
dc.subject.lcshHydrology.en_US
dc.subject.lcshFloodplain management -- Arizona -- Rillito River.en_US
dc.subject.lcshErosion -- Arizona -- Rillito River.en_US
dc.subject.lcshRiver channels -- Arizona.en_US
dc.subject.lcshGeomorphology -- Arizona -- Rillito River.en_US
thesis.degree.nameM.S.en_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.oclc219700147en_US
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