Growth of channel belts
Evolution of an experimental channel belt.
Channel belts are wide corridors created by the movement of a river over time, as shown by geologic indicators such as abandoned channels and eroded valley margins. Channel belts paint a picture of past landscape dynamics, and over geologic timescales are transformed into important aquifers and foundational elements of the sedimentary record. Yet our ability to interpret channel belts is relatively limited when those features are created by braided rivers. To address this gap, we ran a set of large-scale experiments and developed a dimensionless framework to reconcile how differences in discharge, bed slope, sediment grain size, and time affect channel belt growth. This analysis showed that the experimental channel belts follow a consistent evolutionary trajectory. In comparison, analysis of the database of natural channel belts showed that discharge is the dominant predictor of channel belt width for natural cases. These results suggest several practical considerations for interpreting ancient fluvial deposits and subsurface aquifers, including quantitative estimates for the variability in the width of channel sand bodies.
Related papers:
- Limaye, A. B., How do braided rivers grow channel belts?, 2020, Journal of Geophysical Research: Earth Surface, doi:10.1029/2020JF005570.
- Wang, Y., Limaye, A. B., and Chadwick, A. J., in revision, Kinematics of channel threads in a laboratory braided river from particle image velocimetry.
This work was supported by the American Chemical Society Petroleum Research Fund.
Submarine channels and deposits
An experimental submarine landscape at St. Anthony Falls Laboratory, University of Minnesota.
Channels abound not only on planetary surfaces, but also on Earth’s seafloor. These submarine channels host sediment-laden density currents, which transport clastic sediment from continental margins to the deep ocean. Viewed in geophysical images, submarine channels often look like river channels—but the strength of the analogy remains incompletely understood. To compare and contrast the morphodynamics and sedimentary deposits of rivers and submarine channels, we worked with colleagues at the University of Minnesota to design and run experiments in a new flume to mimic both environments. The experiments suggest that compared to rivers, submarine channels develop both larger flow depths and slopes to transport a given sediment load. Read more about the setup at the Sediment Experimentalists Network Knowledge Base.
Related papers:
- Limaye, A. B., Grimaud, J.-L., Lai, S. Y. J., Foreman, Y., Komatsu, Y., and Paola, C., 2018, Geometry and dynamics of braided channels, bars, and associated deposits under experimental density currents, Sedimentology.
- Lai, S. Y. J. , Hung, S. S. C., Foreman, B. Z., Limaye, A. B., Grimaud, J. L., and Paola, C., 2017, Stream power controls the braiding intensity of submarine channels similarly to rivers, Geophysical Research Letters 44, doi:10.1002/2017GL072964. [PDF]