1992
Siedl, M. A.; Dietrich, W. E.
The problem of channel erosion into bedrock Journal Article
In: Catena Suppl., vol. 23, pp. 101-124, 1992.
Abstract | Links | BibTeX | Tags: bedrock, channel erosion, erosion law
@article{Siedl1992,
title = {The problem of channel erosion into bedrock},
author = {M. A. Siedl and W. E. Dietrich},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Seidl_1992_CatenaSuppl.pdf},
year = {1992},
date = {1992-00-00},
journal = {Catena Suppl.},
volume = {23},
pages = {101-124},
abstract = {Although river incision into the bedrock of uplifted regions creates the dissected topography of landscapes, little is known about the process of channel erosion into
bedrock. Here we present a testable framework for the study of fluvial incision into
bedrock that combines theory with field observation. We quantify a simple erosion
law by measuring drainage areas and slopes on both principal channels and tributaries. The data suggest that both a bedrock tributary and main stem will lower at the same rate at their confluence if the ratio of main stem to tributary drainage
area equals the ratio of tributary to main stem channel slope at the junction. Erosion
across several tributary junctions is therefore linearly related to stream power.
Tributary slopes greater than about 0.2 deviate from this linear prediction,
apparentiy because debris flows scour these steep tributaries. Further field study
suggests that the common elevation of tributary and main stem may result from the
upslope propagation of locally steep reaches generated at tributary mouths. This
propagation continues only to the point on the channel where the channel slope is
too steep to preserve the oversteepened reach, or knickpoint, and debris flow scour
dominates channel erosion.
Our results suggest three general mechanisms by which bedrock channels erode:
(1) vertical wearing of the channel bed due to stream flow, by such processes as
abrasion by transported particles and dissolution; (2) scour by periodic debris flows;
and (3) knickpoint propagation. Consequently, application of a single erosion law to the entire bedrock channel network may be inappropriate.},
keywords = {bedrock, channel erosion, erosion law},
pubstate = {published},
tppubtype = {article}
}
Although river incision into the bedrock of uplifted regions creates the dissected topography of landscapes, little is known about the process of channel erosion into
bedrock. Here we present a testable framework for the study of fluvial incision into
bedrock that combines theory with field observation. We quantify a simple erosion
law by measuring drainage areas and slopes on both principal channels and tributaries. The data suggest that both a bedrock tributary and main stem will lower at the same rate at their confluence if the ratio of main stem to tributary drainage
area equals the ratio of tributary to main stem channel slope at the junction. Erosion
across several tributary junctions is therefore linearly related to stream power.
Tributary slopes greater than about 0.2 deviate from this linear prediction,
apparentiy because debris flows scour these steep tributaries. Further field study
suggests that the common elevation of tributary and main stem may result from the
upslope propagation of locally steep reaches generated at tributary mouths. This
propagation continues only to the point on the channel where the channel slope is
too steep to preserve the oversteepened reach, or knickpoint, and debris flow scour
dominates channel erosion.
Our results suggest three general mechanisms by which bedrock channels erode:
(1) vertical wearing of the channel bed due to stream flow, by such processes as
abrasion by transported particles and dissolution; (2) scour by periodic debris flows;
and (3) knickpoint propagation. Consequently, application of a single erosion law to the entire bedrock channel network may be inappropriate.
bedrock. Here we present a testable framework for the study of fluvial incision into
bedrock that combines theory with field observation. We quantify a simple erosion
law by measuring drainage areas and slopes on both principal channels and tributaries. The data suggest that both a bedrock tributary and main stem will lower at the same rate at their confluence if the ratio of main stem to tributary drainage
area equals the ratio of tributary to main stem channel slope at the junction. Erosion
across several tributary junctions is therefore linearly related to stream power.
Tributary slopes greater than about 0.2 deviate from this linear prediction,
apparentiy because debris flows scour these steep tributaries. Further field study
suggests that the common elevation of tributary and main stem may result from the
upslope propagation of locally steep reaches generated at tributary mouths. This
propagation continues only to the point on the channel where the channel slope is
too steep to preserve the oversteepened reach, or knickpoint, and debris flow scour
dominates channel erosion.
Our results suggest three general mechanisms by which bedrock channels erode:
(1) vertical wearing of the channel bed due to stream flow, by such processes as
abrasion by transported particles and dissolution; (2) scour by periodic debris flows;
and (3) knickpoint propagation. Consequently, application of a single erosion law to the entire bedrock channel network may be inappropriate.