Interactions between onshore bedrock-channel incision and nearshore wave-base erosion forced by eustasy and tectonics

Basin Research
By: , and 

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Abstract

We explore the response of bedrock streams to eustatic and tectonically induced fluctuations in base level. A numerical model coupling onshore fluvial erosion with offshore wave‐base erosion is developed. The results of a series of simulations for simple transgressions with constant rate of sea‐level change (SLR) show that response depends on the relative rates of rock uplift (U) and wave‐base erosion (ɛw). Simple regression runs highlight the importance of nearshore bathymetry. Shoreline position during sea‐level fall is set by the relative rate of base‐level fall (U‐SLR) and ɛw, and is constant horizontally when these two quantities are equal. The results of models forced by a realistic Late Quaternary sea‐level curve are presented. These runs show that a stable shoreline position cannot be obtained if offshore uplift rates exceed ɛw. Only in the presence of a relatively stable shoreline position, fluvial profiles can begin to approximate a steady‐state condition, with U balanced by fluvial erosion rate (ɛf). In the presence of a rapid offshore decrease in rock‐uplift rate (U), short (∼5 km) fluvial channels respond to significant changes in rock‐uplift rate in just a few eustatic cycles. The results of the model are compared to real stream‐profile data from the Mendocino triple junction region of northern California. The late Holocene sea‐level stillstand response exhibited by the simulated channels is similar to the low‐gradient mouths seen in the California streams.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Interactions between onshore bedrock-channel incision and nearshore wave-base erosion forced by eustasy and tectonics
Series title Basin Research
DOI 10.1046/j.1365-2117.2002.00169.x
Volume 14
Issue 2
Year Published 2002
Language English
Publisher International AIDS Society, European Association of Geoscientists and Engineers
Contributing office(s) California Water Science Center
Description 23 p.
First page 105
Last page 127
Country United States
State California
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