The transient response of bedrock river networks to sudden base level fall

Following a change in the factors that determine landscape form, a transient signal of adjustment propagates through the river network, progressively adjusting channels and hillslopes to the new conditions. When conditions favor incision, the rate and mechanism by which this signal propagates throughout the network determines basin response time. This ultimately influences the growth and stability of mountain ranges and the tempo of sediment delivery to depositional basins. As this incision signal propagates through the river network, its upstream extent is often recognized as a discrete, steep convexity in the channel profile, defined here as a knickpoint. In this thesis, theoretical, numerical, and field-based research techniques are utilized to study the initiation and distribution of knickpoints within fluvial networks. Field observations are derived from the Waipaoa River on the North Island of New Zealand. In the Waipaoa, 236 knickpoints distributed throughout the network define the upstream extent of a large magnitude incision signal initiated -18,000 years ago. These features, frequently located at the confluence between small drainage area tributaries and trunk-streams, are characterized as near-vertical single or multi-step waterfalls.

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

• Crosby, Benjamin T. (Benjamin Thomas)

Advisor dc:contributor.advisor

• Kelin X. Whipple.

• 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/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/38253

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38253