2024 CSDMS meeting-095
(if you haven't already)
Log in (or create account for non-CSDMS members)
Forgot username? Search or email:CSDMSweb@colorado.edu
Browse abstracts
Strange Knickpoints: A Case Study in Using Landscape Evolution Models to Understand Site-Specific Landscape Complexities
One such event is likely present in Hocking Hills State Park in central Ohio, known for its hundreds of 30-50 m-tall waterfalls. These knickpoints were likely created when the upper reaches of the Salt Creek watershed were blocked by one of the ice sheets, forming a glacial lake that spilled over a drainage divide and rerouted the channel network from a west-flowing to a south-flowing configuration. The stream capture event would have also produced a local base level drop that created the knickpoints. This hypothesis implies that the knickpoints were all created at the same time; if true, we can constrain the timing of the capture event using catchment averaged erosion rates and knickpoint celerity models.
However, the hypothesis also implies that the waterfalls should be located at the same approximate χ value. This is not the case; rather, there is prominent, N-S trend in χ values. Without an explanation for this trend, any age constraints on the capture timing will be suspect.
We used Landlab-based landscape evolution models (LEMs) to explore several possible explanations for the trend in χ values. We found that following a single capture event, the trend can be explained by the specific combination of (a) the pre-capture channel topology; (b) the precise capture location; and (c) the spatial extent of different rock layers. We believe that this in an “Occam’s razer” scenario, because it allows the χ trend to be explained by a single, stream capture forcing. However, without the insights provided by our LEMs, we would have considered multiple forcings or stream capture events to be more likely. These simulations are a novel and interesting case study in how LEMs can be applied to understand unique complexities of specific field sites and also have important implications for using knickpoint celerity models to assess landscape evolution.