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Laboratory alluvial fans in one dimension
L Guerit1, F Métivier1, O Devauchelle1
1Institut de Physique du Globe de Paris -Sorbonne Paris Cité, Université Paris Diderot, CNRS, UMR7154, 1 rue Jussieu, 75238 Paris Cedex 05, France.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 13, 2014
Summary
Rivers form cone-shaped alluvial fans when sediment settles on flat plains. This study uses a simplified 1D experiment to show how water discharge controls the fan
Area of Science:
- Earth Science
- Geomorphology
- Fluid Dynamics
Background:
- Rivers transport sediment and deposit it on plains, forming alluvial fans.
- Alluvial fans are cone-shaped geological structures crucial for understanding sediment transport and landscape evolution.
- Previous studies have explored alluvial fan formation, but simplified experimental models offer unique insights into fundamental processes.
Purpose of the Study:
- To reproduce key features of alluvial fan formation in a simplified, one-dimensional experimental setup.
- To investigate the relationship between sediment discharge, water discharge, and the resulting fan morphology and growth dynamics.
- To analyze the factors influencing the slope and profile curvature of a developing alluvial fan.
Main Methods:
- A controlled laboratory experiment using a mixture of water and glycerol to transport glass beads (simulating sediment).
- Sediment deposition occurred within a narrow gap between two transparent panels, creating a quasi-one-dimensional fan.
- Systematic variation of sediment and water discharge to observe effects on fan growth and structure.
Main Results:
- The experiment successfully replicated basic features of one-dimensional alluvial fan formation.
- Fan slope was primarily determined by water discharge, maintaining a state just above the sediment transport threshold.
- Sediment discharge influenced the fan's growth velocity, with a slight profile curvature correlating with sediment transport rates.
Conclusions:
- Water discharge is a critical factor controlling the slope of alluvial fans.
- Sediment discharge dictates the speed of fan growth rather than its fundamental slope.
- The study provides a simplified yet effective model for understanding the physics of alluvial fan development.
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