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Bedrock rivers are steep but not narrow; hydrological and lithological controls on river geometry across the USA

James Buckley, Rebecca A. Hodge and Louise J. Slater
Bedrock rivers are steep but not narrow; hydrological and lithological controls on river geometry across the USA
Geology (Boulder) (March 2024) Pre-Issue Publication

Abstract

Bedrock rivers are commonly expected to have steeper and narrower channels than alluvial rivers. However, understanding of bedrock river characteristics has largely been based on small samples of sites in specific climates and upland locations. We provide the first systematic assessment of bedrock and alluvial river channel characteristics for 1274 sites across a broad climatic gradient. We assess whether the width, width-to-depth ratio, and slope of bedrock channels differ from those of alluvial channels and the extent to which these differences are correlated with drainage area, mean annual flow (QMAF), grain size, and lithology. We find that bedrock channels occur at all drainage areas. For the same drainage area, bedrock channels are wider and steeper than alluvial channels. They also have a higher mean annual precipitation and hence QMAF, which likely causes the increased width. After accounting for differences in QMAF, both bedrock and alluvial channels have similar hydraulic scaling. Lithology affects both types of channels in a similar way, with channels on sedimentary lithologies being wider and less steep compared to those on igneous-metamorphic lithologies. Overall, our findings raise new questions about the evolution of bedrock river channels and pave the way for more accurate landscape evolution modeling.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: Pre-Issue Publication
Title: Bedrock rivers are steep but not narrow; hydrological and lithological controls on river geometry across the USA
Affiliation: Durham University, Department of Geography, Durham, United Kingdom
Published: 20240327
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2024-032163
Categories: Geomorphology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
Secondary Affiliation: University of Oxford, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2024
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