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2019 | OriginalPaper | Chapter

3. Slope Gradients

Author : Dan Bowman

Published in: Principles of Alluvial Fan Morphology

Publisher: Springer Netherlands

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Abstract

Discharge is the first-order factor controlling fan slope. The greater the stream discharge, the gentler and flatter will be the slope of the fan. The slope is inversely proportional to the size of the catchment area and to the fan area. Longitudinal fan profiles typically show a concave-upward outline. Concavity is the result of the down-fan water loss, the spread of the water, and the decrease in the caliber of the bed material.

Most fans reported in the literature are in the 1–6° slope range. These typical high slopes of the fans make the flow almost invariably supercritical (Fr > 1). Megafans represent an ultralow slope category, ranging up to 0.001 - 0.00023. Humid-region fans have lower slopes than fans of arid regions. Debris flows form steeper fan gradients compared to fluvially dominated fans and to intermediate flows.

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Title: Slope Gradients
Author: Dan Bowman
Publisher: Springer Netherlands
Book: Principles of Alluvial Fan Morphology
Print ISBN: 978-94-024-1556-8

Electronic ISBN: 978-94-024-1558-2

Copyright Year: 2019
DOI: https://doi.org/10.1007/978-94-024-1558-2_3