Modeling the dynamics and depositional patterns of sandy rivers

This thesis seeks to advance our understanding of the dynamic nature, spatial organization and depositional record of topography in sand-bedded rivers. I examine patterns and processes over a wide range of scales, on Earth and Mars. At the smallest scale, ripples and dunes (bedforms) arise spontaneously under most natural flow conditions, acting as the primary agents of sediment transport and flow resistance in sandy rivers. I use physical modeling in a laboratory flume to explore the feedbacks among bedform geometry, fluid flow and sediment transport. Field observations of dunes in the North Loup River, Nebraska, show that bed roughness displays a statistical steady state and robust scaling. Motivated by these data, I develop a nonlinear stochastic surface evolution model for the topography of sandy rivers which captures the essence of bedform evolution in space and time. I then use a simplified kinematic model for bedform evolution to simulate the production of stratigraphy from migrating dunes, allowing a more accurate reconstruction of river flow conditions from preserved bedform remnants in rocks. At the channel scale I examine the conditions that lead to avulsion, the rapid abandonment of a river channel in favor of a new course at lower elevation.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Jerolmack, Douglas J

Advisor dc:contributor.advisor

• David Mohrig.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/37277
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/37277

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/37277