Abstract
The development of bedforms under unidirectional, oscillatory and combined-flows results from temporal changes in sediment transport, flow and morphological response. In such flows, the bedform characteristics (for example, height, wavelength and shape) change over time, from their initiation to equilibrium with the imposed conditions, even if the flow conditions remain unchanged. These variations in bedform morphology during development are reflected in the sedimentary structures preserved in the rock record. Hence, understanding the time and morphological development in which bedforms evolve to an equilibrium stage is critical for informed reconstruction of the ancient sedimentary record. This article presents results from a laboratory flume study on bedform development and equilibrium development time conducted under purely unidirectional, purely oscillatory and combined-flow conditions, which aimed to test and extend an empirical model developed in past work solely for unidirectional ripples. The present results yield a unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows. The experimental results show that the processes of bedform genesis and growth are common to all types of flows, and can be characterized into four stages: (i) incipient bedforms; (ii) growing bedforms; (iii) stabilizing bedforms; and (iv) fully developed bedforms. Furthermore, the development path of bedform; growth exhibits the same general trend for different flow types (for example, unidirectional, oscillatory and combined-flows), bedform size (for example, small versus large ripples), bedform shape (for example, symmetrical or rounded), bedform planform geometry (for example, two-dimensional versus three-dimensional), flow velocities and sediment grain sizes. The equilibrium time for a wide range of bed configurations was determined and found to be inversely proportional to the sediment transport flux occurring for that flow condition.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2063-2085 |
| Number of pages | 23 |
| Journal | Sedimentology |
| Volume | 61 |
| Issue number | 7 |
| DOIs | |
| State | Published - Dec 1 2014 |
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Keywords
- Bedform
- Combined-flows
- Development
- Equilibrium
- Oscillatory
- Unidirectional
ASJC Scopus subject areas
- Geology
- Stratigraphy
Cite this
A unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows. / Perillo, Mauricio M.; Best, James Leonard; Yokokawa, Miwa; Sekiguchi, Tomohiro; Takagawa, Tomohiro; Garcia, Marcelo Horacio.
In: Sedimentology, Vol. 61, No. 7, 01.12.2014, p. 2063-2085.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows
AU - Perillo, Mauricio M.
AU - Best, James Leonard
AU - Yokokawa, Miwa
AU - Sekiguchi, Tomohiro
AU - Takagawa, Tomohiro
AU - Garcia, Marcelo Horacio
PY - 2014/12/1
Y1 - 2014/12/1
N2 - The development of bedforms under unidirectional, oscillatory and combined-flows results from temporal changes in sediment transport, flow and morphological response. In such flows, the bedform characteristics (for example, height, wavelength and shape) change over time, from their initiation to equilibrium with the imposed conditions, even if the flow conditions remain unchanged. These variations in bedform morphology during development are reflected in the sedimentary structures preserved in the rock record. Hence, understanding the time and morphological development in which bedforms evolve to an equilibrium stage is critical for informed reconstruction of the ancient sedimentary record. This article presents results from a laboratory flume study on bedform development and equilibrium development time conducted under purely unidirectional, purely oscillatory and combined-flow conditions, which aimed to test and extend an empirical model developed in past work solely for unidirectional ripples. The present results yield a unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows. The experimental results show that the processes of bedform genesis and growth are common to all types of flows, and can be characterized into four stages: (i) incipient bedforms; (ii) growing bedforms; (iii) stabilizing bedforms; and (iv) fully developed bedforms. Furthermore, the development path of bedform; growth exhibits the same general trend for different flow types (for example, unidirectional, oscillatory and combined-flows), bedform size (for example, small versus large ripples), bedform shape (for example, symmetrical or rounded), bedform planform geometry (for example, two-dimensional versus three-dimensional), flow velocities and sediment grain sizes. The equilibrium time for a wide range of bed configurations was determined and found to be inversely proportional to the sediment transport flux occurring for that flow condition.
AB - The development of bedforms under unidirectional, oscillatory and combined-flows results from temporal changes in sediment transport, flow and morphological response. In such flows, the bedform characteristics (for example, height, wavelength and shape) change over time, from their initiation to equilibrium with the imposed conditions, even if the flow conditions remain unchanged. These variations in bedform morphology during development are reflected in the sedimentary structures preserved in the rock record. Hence, understanding the time and morphological development in which bedforms evolve to an equilibrium stage is critical for informed reconstruction of the ancient sedimentary record. This article presents results from a laboratory flume study on bedform development and equilibrium development time conducted under purely unidirectional, purely oscillatory and combined-flow conditions, which aimed to test and extend an empirical model developed in past work solely for unidirectional ripples. The present results yield a unified model for bedform development and equilibrium under unidirectional, oscillatory and combined-flows. The experimental results show that the processes of bedform genesis and growth are common to all types of flows, and can be characterized into four stages: (i) incipient bedforms; (ii) growing bedforms; (iii) stabilizing bedforms; and (iv) fully developed bedforms. Furthermore, the development path of bedform; growth exhibits the same general trend for different flow types (for example, unidirectional, oscillatory and combined-flows), bedform size (for example, small versus large ripples), bedform shape (for example, symmetrical or rounded), bedform planform geometry (for example, two-dimensional versus three-dimensional), flow velocities and sediment grain sizes. The equilibrium time for a wide range of bed configurations was determined and found to be inversely proportional to the sediment transport flux occurring for that flow condition.
KW - Bedform
KW - Combined-flows
KW - Development
KW - Equilibrium
KW - Oscillatory
KW - Unidirectional
UR - http://www.scopus.com/inward/record.url?scp=84919458067&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84919458067&partnerID=8YFLogxK
U2 - 10.1111/sed.12129
DO - 10.1111/sed.12129
M3 - Article
AN - SCOPUS:84919458067
VL - 61
SP - 2063
EP - 2085
JO - Sedimentology
JF - Sedimentology
SN - 0037-0746
IS - 7
ER -