Equilibrium and transient morphologies of river networks : discriminating among fluvial erosion

We examine the equilibrium and transient morphology of alluvial and bedrock river networks. We apply analytical methods and an iterative model to solve for equilibrium slope-area and texture- area (in alluvial networks) relationships under different tectonic and climatic forcings. Transient morphology resulting from a change in uplift or precipitation rate is simulated using the CHILD landscape evolution model. In alluvial networks, it is well recognized that both channel slope and mean grain size usually decrease downstream. These variables play an important role in determining sediment transport rates, and their mutual adjustment to a change in the forces that drive erosion can yield surprising results. Adjustments in grain size can lead to spatially variable channel concavity and larger trans port rates on shallower slopes. As a consequence, equilibrium channel slopes may decrease under higher uplift conditions (or, similarly, faster base-level lowering). Selective erosion and deposition can cause transient channel slopes to both increase and decrease and surface texture to both coarsen and fine, all in response to a single change in forcing. In bedrock rivers, increasing attention has been given to the role of sediment flux on incision processes. We find that all applied erosion rules (stream-power and three sediment-flux models) produce similar equilibrium morphologies, although some details lead to differences in sensitivity.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• Gasparini, Nicole Marie, 1972-

Advisor dc:contributor.advisor

• Rafael L. Bras.

• Civil and Environmental Engineering.

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/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29755

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29755