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University of Arizona (1980)

Monitoring of responses to a local base-level change in an ephemeral stream

Kaehler, Charles Alfred

Titre : Monitoring of responses to a local base-level change in an ephemeral stream

Auteur : Kaehler, Charles Alfred

Université de soutenance : University of Arizona

Grade : Master of Science (MS) 1980

Résumé
A long-term program has been established in the Tucson Moun tains to monitor changes caused by removal of a sm all dam whose reservoir was fille d with sediment, and to describe the ch aracteristics of the associated flu v ia l system. For th is ephemeral stream, data are collected using cross-channel p r o file s, scour chains, longitudinal p r o file s, plane-table mapping, painted rocks, crest-stage gages, and measurement of sedim ent-size d istrib u tion . The drainage basin, de o scribed using topographic maps, has an area of 3.78 km , and length of 3910 m, a to ta l r e lie f of 547 m, an elongation ratio of 0.56, and a drainage density of 10.4 km/km . Three sm all post b a se-lev el drop flow events resulted in net deposition (with widely interspersed short reaches of net erosion) and increases in width-depth ra tio downstream from the b a se-lev el f a ll, , and formation of a gully and headcuts, lo ca l steepening of the stream gradient by 145%, and a decrease in the width-depth ratio by roughly upstream from the b a se-lev el f a ll. The morphologic changes^at in tervals along the length of the streambed in response to the 2.5 m high b a se-lev el f a ll. The data appear to ind icate a greater change in gradient than in width-depth ratio during in it ia l response to the b a se-lev el f a ll.

Mots clés : Ephemeral streams. ; Stream channelization. ; Stream measurements.

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