Summer Undergraduate Research Fellowship (SURF) to assist with “Permafrost Riverbank Erosion in Flume Experiments” at Caltech, Pasadena, CA, USA
Project: Permafrost Riverbank Erosion in Flume Experiments
Disciplines: Environmental Science and Engineering, Geomorphology
Mentor: Dr. Michael Lamb, Professor of Geology (mpl@caltech.edu)
AO Contact: Maria Schmeer, Graduate Student (mschmeer@caltech.edu)
Background:
Rivers in the Arctic can contain significant permafrost in their banks. In the single-threaded, meandering reaches of these rivers, lateral erosion into the floodplain and deposition of sediment in point bars alters the distribution of materials along the channel. Under different thermal regimes, permafrost in the banks can thaw or re-form on deposited sediments. However, it is unclear whether thaw and erosion in these systems are thaw-limited or sediment transport-limited; what may be the role of cohesion of frozen bank sediments; and how variations in bank erodibility due to permafrost could also change the rates and spatial patterns of river migration. We aim to better understand these controls on bank erosion in permafrost-dominated environments and determine how sediment transport and increased Arctic warming impact permafrost thaw and erosion rates and the evolution of river geometries.
As the climate warms, communities in the Arctic are experiencing permafrost thaw and bank erosion hazards, such as flooding and sinking or shifting ground. These hazards disproportionately affect Indigenous communities, which can be forced to relocate or and suffer significant economic costs from harm to infrastructure. Thus, the processes that lead to changing thaw and erosion rates are important to understand for hazard mitigation and prediction. Further, this research also has implications for understanding the sources and sinks of sediment-borne organic carbon through Arctic river systems in a warming world.
Description: The student will participate in conducting physical experiments to address these knowledge gaps. There will be two possible experiments in the Earth Surface Dynamics Laboratory: one using a 10-m long indoor river in frozen sand, and another using a 7-m long river in frozen clay/mud. Experiment goals are to determine the conditions under which Arctic riverbank thaw and erosion are limited by thaw and/or sediment transport; quantify rates of sediment and heat transport; and describe river sensitivity to warming. The clay/mud experiments will also explore the role of cohesion in frozen riverbank materials. The student will help to set up and run the experiments to form a channel with erodible bank(s), measure sediment fluxes, collect bank temperatures, identify regions of erosion and deposition, and measure resultant channel features. Daily activities will include hands-on work in preparing and running experiments in the flume, collecting data, and coding to visualize and analyze experimental data.
References:
- Douglas, M. M., Miller, K. L., Schmeer, M. N., & Lamb, M. P. (2023). Ablation‐limited erosion rates of permafrost riverbanks. Journal of Geophysical Research: Earth Surface, 128(8), e2023JF007098. DOI: 10.1029/2023JF007098.
- Rowland et al., (2010). Arctic landscapes in transition: Responses to thawing permafrost. DOI: 10.1029/2010EO260001.
- Dupeyrat, et al., (2011). Effects of ice content on the thermal erosion of permafrost: Implications for coastal and fluvial erosion. DOI: 10.1002/ppp.722.
- Douglas, M. M., Dunne, K. B. J., & Lamb, M. P. (2023). Sediment entrainment and slump blocks limit permafrost riverbank erosion. Geophysical Research Letters, 50, e2023GL102974. DOI: 10.1029/2023GL102974.
Student Requirements:
- Introductory classes in geology, geomorphology, mechanical/civil or environmental engineering.
- Coursework and experience in hands-on work in physical experiments and in mechanics or hydraulics also preferred.
- Experience with Matlab or Python required.
Programs:
This AO can be done under the following programs:
- Amgen Scholars (non-Caltech students only)
- SURF (both Caltech and non-Caltech students)
