Document Type

Article

Journal/Book Title/Conference

Earth Surface Processes and Landforms

Publisher

John Wiley & Sons Ltd.

Publication Date

3-25-2019

Keywords

confinement, rivers, drainage network, River Styles, fluvial geomorphology, river restoration

First Page

1

Last Page

55

Abstract

In this article, we demonstrate the application of a continuous confinement metric across entire river networks. Confinement is a useful metric for characterizing and discriminating valley setting. At the reach scale, valley bottom confinement is measured and quantified as the ratio of the length of channel confined on either bank by a confining margin divided by the reach length. The valley bottom is occupied by the contemporary floodplain and/or its channel(s); confining margins can be any landform or feature that makes up the valley bottom margin, such as bedrock hillslopes, terraces, fans, or anthropogenic features such as stopbanks or constructed levees. To test the reliability of calculating confinement across entire networks, we applied our geoprocessing scripts across four physiographically distinct watersheds of the Pacific Northwest, USA using freely available national datasets. Comparison of manually digitized and mapped with modeled calculations of confinement revealed that roughly one‐third of reaches were equivalent and about two‐thirds of the sites differ by less than ±15%. A sensitivity analysis found that a 500 m reach segmentation length produced reasonable agreement with manual, categorical, expert‐derived analysis of confinement. Confinement accuracy can be improved (c. 4% to 17% gains) using a more accurately mapped valley bottom and channel position (i.e. with higher‐resolution model inputs). This is particularly important when differentiating rivers in the partly confined valley setting. However, at the watershed scale, patterns derived from mapping confinement are not fundamentally different, making this a reasonably accurate and rapid technique for analysis and measurement of confinement across broad spatial extents.

Comments

This is the peer reviewed version of the following article: O'Brien, G. R., Wheaton, J. M., Fryirs, K., Macfarlane, W. W., Brierley, G., Whitehead, K., Gilbert, J., and Volk, C. ( 2019) Mapping valley bottom confinement at the network scale. Earth Surf. Process. Landforms, https://doi.org/10.1002/esp.4615., which has been published in final form at https://doi.org/10.1002/esp.4615 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

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