2023 CSDMS meeting-111: Difference between revisions
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|CSDMS meeting abstract title=Testing the Influence of Sediment Cover on Channel Steepness and Erosion Rates in Layered Rocks with the SPACE Model | |||
|Working_group_member_WG_FRG=Terrestrial Working Group | |Working_group_member_WG_FRG=Terrestrial Working Group | ||
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|CSDMS meeting coauthor first name abstract=Joel | |||
|CSDMS meeting coauthor last name abstract=Johnson | |||
|CSDMS meeting coauthor institute / Organization=University of Texas at Austin | |||
|CSDMS meeting coauthor town-city=Austin | |||
|CSDMS meeting coauthor country=United States | |||
|State=Texas | |||
|CSDMS meeting coauthor email address=joelj@jsg.utexas.edu | |||
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|CSDMS meeting coauthor first name abstract=Nicole | |||
|CSDMS meeting coauthor last name abstract=Gasparini | |||
|CSDMS meeting coauthor institute / Organization=Tulane University | |||
|CSDMS meeting coauthor town-city=New Orleans | |||
|CSDMS meeting coauthor country=United States | |||
|State=Louisiana | |||
|CSDMS meeting coauthor email address=ngaspari@tulane.edu | |||
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{{CSDMS meeting abstract template 2023 | |||
|CSDMS meeting abstract=Rivers are key drivers of landscape evolution. Transient signals of base level fall propagate up rivers and cause increased erosion rates, which in turn increases channel steepness. In landscapes with horizontally layered rocks, erosion rates vary in both space and time as different layers are eroded and exposed at the surface, complicating how these landscapes respond to base level fall and influencing the topographic expression of different lithologies. Lithologic variations further influence river response by producing sediment, which can armor the channel bed and reduce bedrock erosion. Motivated by the lithologic variability found in the Guadalupe Mountains of Texas and New Mexico, we use the Stream Power with Alluvium Conservation and Entrainment (SPACE) model to test how sediment cover affects channel steepness and erosion rates in horizontally layered rocks. We simulate 1.2 million years of landscape evolution with an imposed uplift rate of 1.0 mm/yr in alternating layers of hard and soft rock, systematically varying the relative amount of alluvial cover. We compare the normalized channel steepness of the model output against the steepness values predicted by the stream power incision model, which is the most commonly used model for interpreting steepness variations in real landscapes. We find that in model runs with sediment cover, channel steepness is systematically higher than predicted by the stream power model in soft rock layers, and lower than predicted in hard rocks. Sediment cover also exerts a strong control on erosion rates. Sediment cover preferentially accumulates over soft rock layers, decreasing erosion rates in these layers while increasing erosion in the unarmored hard rock layers. As the degree of sediment cover is increased, the maximum erosion rate at any given point along the channel decreases. Increasing the sediment cover effectively decreases the erodibility contrast between hard and soft rocks, illustrating the importance of considering the role of sediment when interpreting channel profiles. | |||
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Latest revision as of 07:02, 1 April 2023
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Testing the Influence of Sediment Cover on Channel Steepness and Erosion Rates in Layered Rocks with the SPACE Model
Grace Guryan,
(she/her),University of Texas at Austin Austin Texas, United States. gguryan@utexas.edu
Joel Johnson, University of Texas at Austin Austin Texas, United States. joelj@jsg.utexas.edu
Nicole Gasparini, Tulane University New Orleans Louisiana, United States. ngaspari@tulane.edu
Rivers are key drivers of landscape evolution. Transient signals of base level fall propagate up rivers and cause increased erosion rates, which in turn increases channel steepness. In landscapes with horizontally layered rocks, erosion rates vary in both space and time as different layers are eroded and exposed at the surface, complicating how these landscapes respond to base level fall and influencing the topographic expression of different lithologies. Lithologic variations further influence river response by producing sediment, which can armor the channel bed and reduce bedrock erosion. Motivated by the lithologic variability found in the Guadalupe Mountains of Texas and New Mexico, we use the Stream Power with Alluvium Conservation and Entrainment (SPACE) model to test how sediment cover affects channel steepness and erosion rates in horizontally layered rocks. We simulate 1.2 million years of landscape evolution with an imposed uplift rate of 1.0 mm/yr in alternating layers of hard and soft rock, systematically varying the relative amount of alluvial cover. We compare the normalized channel steepness of the model output against the steepness values predicted by the stream power incision model, which is the most commonly used model for interpreting steepness variations in real landscapes. We find that in model runs with sediment cover, channel steepness is systematically higher than predicted by the stream power model in soft rock layers, and lower than predicted in hard rocks. Sediment cover also exerts a strong control on erosion rates. Sediment cover preferentially accumulates over soft rock layers, decreasing erosion rates in these layers while increasing erosion in the unarmored hard rock layers. As the degree of sediment cover is increased, the maximum erosion rate at any given point along the channel decreases. Increasing the sediment cover effectively decreases the erodibility contrast between hard and soft rocks, illustrating the importance of considering the role of sediment when interpreting channel profiles.
