EAR-PF: Investigating the effects of bedrock dip angle on knickpoint morphology and evolution via flume experimentation and numerical modeling

Chilton, Kristin, Blacksburg VA

Investigators

Abstract

Dr. Kristin Chilton has been awarded an NSF EAR Postdoctoral Fellowship to investigate how the orientation of rock fractures (cracks) in river beds influences the ease with which that rock is eroded (worn away) by flowing over waterfalls (also called knickpoints). Knickpoints are often zones of concentrated erosion within rivers and this project will involve creatively designed experiments that examine the role of cracks in controlling river erosion into rock. The results of this study will allow scientists to better predict how Earth’s surface will change over time, interpret climatic and geologic histories from the landscapes we see today, and improve engineering designs for the safety and longevity of important infrastructure. The work will be carried out at Virginia Tech and West Virginia University in collaboration with mentors, Dr. Kyle Strom and Dr. Charles Shobe, respectively. Dr. Chilton’s project will also provide opportunities for undergraduate involvement in academic research, support diversity in STEM fields through summer outreach programs, and introduce a broader audience to Earth science topics via educational videos and blog posts focused on river erosion processes. The primary goal of this project is to test how the orientation of discontinuities (which can be fractures, joints, or bedding planes) influences hydraulic plucking of bedrock blocks within knickpoints, and therefore knickpoint morphology and evolution. This will be accomplished via a series of flume experiments, which will use stacked porcelain tiles to simulate layered sedimentary bedrock at various dip orientations, coupled with continuous monitoring of knickpoint morphology, retreat rate, and plucking events. The results of the flume experiments will then be integrated into numerical landscape evolution models to expand implications to broader spatial and temporal scales. This investigation will fill a critical gap in our understanding of the fundamental controls on bedrock channel morphology and fluvial incision processes, improve robustness of landscape evolution models by incorporating specific bedrock characteristics, and help ensure appropriate interpretation of knickpoints as indicators of climatic and uplift history by characterizing a potential control on knickpoint form and celerity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.