Document Type

Article

Publication Date

6-2007

Keywords

Tectonic geomorphology, Channel width, Wind gap, Stream power, Thrust fault, New Zealand

Abstract

The role of channel width and slope adjustments to differential uplift in rivers within actively deforming terrains remains contentious. Here high‐resolution topographic surveying of formerly antecedent outwash channels demonstrates marked changes in channel width as a primary response to differential uplift. For five Late Quaternary alluvial paleochannels crossing small folds along the active Ostler fault zone of southern New Zealand, nearly continuous measurements of paleochannel width and concomitant incision reveal abrupt narrowing of widths toward minimum values at channel positions coincident with the initial uplift. When the magnitude of differential uplift is sufficiently small, narrowing alone permits these channels to remain antecedent. In the context of a unit stream power model for fluvial erosion, observed limits on the magnitude of channel narrowing suggest that above some threshold amount of differential uplift, continued incision requires concomitant changes in channel gradient. Thus when crossing small growing folds, alluvial rivers simply narrow their channels, whereas larger folds that demand greater incision prompt an initial narrowing followed by channel steepening.

Publication Title

Journal of Geophysical Research: Earth Surface

Volume

112

Issue

F2

DOI

10.1029/2006JF000672

Required Publisher's Statement

Link to publisher version: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2006JF000672

https://doi.org/10.1029/2006JF000672

Subjects - Topical (LCSH)

Faults (Geology)--New Zealand; Topographical surveying--New Zealand; Morphotectonics--New Zealand; Differential forms

Geographic Coverage

New Zealand

Genre/Form

articles

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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