Document Type
Thesis
Abstract
In this study we model the influence of various bedrock weathering scenarios on the channel geometry and slope of a channel cross section as they respond to changes in base level lowering rate (U) and maximum possible erodibility (Kw) using MATLAB. We ran trials that varied Kw, which represents the extent of weathering, from values that represent relatively high weathering rates to values that represent no weathering. For the first set of trials we held U constant for the duration of each trial and for the next set of trials we allowed channels to reach steady state and then perturbed them by increasing U. Results indicate that incorporating cross-channel variability in erodibility as caused by weathering into the cross section channel model changes the evolution of the channel geometry and slope as well as the response to perturbations. The extent of weathering is positively correlated with the width/depth ratio and negatively correlated for slope. Channels that experience weathering take a longer time to equilibrate in terms of channel geometry than channels that do not experience weathering but they equilibrate faster in terms of slope. Incorporating cross-channel variability in erodibility as caused by weathering seems to change the style and rate by which the channel adjusts to a change in base level. Weathering channels react more quickly and with a greater change in terms of channel geometry as represented by width/depth ratio. Channels that undergo weathering seem to react faster than non-weathering channels in terms of slope as well but they do not undergo as significant of a change in slope. Additionally, we observed that channels that undergo weathering take longer to reach the new equilibrium channel geometry compared to non-weathering channels. We also believe that these distinctions at the cross-sectional level in both channel development and response to perturbations between weathered and constant erodibility channels correspondingly impact the development of the entire longitudinal profile of the channel, even going so far as to affect the propagation of knickpoints through a channel and we recommend that the model be expanded to encompass an entire longitudinal profile.
Date Awarded
2016
Department
Geology
Advisor 1
Gregory S. Hancock
Recommended Citation
Flaherty, Sarah E., "Impact of Weathering on Bedrock Channel Geometry and Channel Response to Base Level Change" (2016). Geology Senior Theses. William & Mary. Paper 360.
https://scholarworks.wm.edu/geologyseniors/360
