Susannah Does Science!
Landslides + sediment at
geologic timescales
collaborators: Greg Tucker, Irina Overeem, Benjamin Campforts, Charlie Shobe,
Alison Duvall
Over geologic timescales, landslides produce diagnostic topographic signatures that can be detected in real-world topographic data. We're interested in exploring magnitude/frequency relationships between landslides and landscape morphology for a range of tectonic and climatic scenarios.

What is a megaflood?
Megafloods are catastrophic floods with a fast-moving peak discharge of at least a million cubic meters per second. That's about the volume of 400 Olympic-sized swimming pools per second! Typically these floods are sourced from the sudden drainage of lakes formed behind unstable landslide or glacier dams.

Paleohydraulics of an eastern Himalayan megaflood
collaborators: Kate Huntington, Mike Turzewski, Dave Montgomery, Mahathi Mangipudi
Here, we present the first 2D simulation of a megaflood over the rugged 3D topography of the Yarlung-Siang River in the eastern Himalaya. The simulated flood resutls from instantaneous failure of a 81 cubic kilometer lake impounded immediately upstream of the Yarlung Tsanpo Gorge.
The legacy of megaflood deposited boulders
collaborators: Kate Huntington, Charlie Shobe, Karl Lang, Alison Duvall, Graham Johnson
We find that megaflood deposited boulders can protect the river from being eroded, causing other processes, like uplift, to outcompete erosion. Megaflood boulder bar deposits cause small steps (knickpoints) to form within the river. Our modeling shows that these effects can be felt for > 20 kyr after a single flood. These results suggest that megaflood deposition (in addition to erosion can cause significant, unique change in mountain river processes.


Backflooding along the megaflood pathway
collaborators: Kate Huntington, Karl Lang, Charlie Shobe, Srinanda Nath, Chloe Loreen
Numerical simulations (Morey et al., 2022) predict extensive tributary backflooding in the Siyom River valley of the eastern Himalaya. We investigate evidence for megaflood deposition in fluvial terraced exposed along this tributary to test these model results.
Latest Publications...
Megaflood deposited boulders & their legacy
Megafloods can transport a LOT of material, including car- to house-sized boulders. Because these boulders are so big, they remain in the landscape until the next megaflood or until they weather into smaller pieces. We use a landscape evolution model to understand the impact of these megaflood deposited boulders on mountain river processes. Find out more about the legacy of these megaflood deposited boulders by reading our paper!
Paleohydraulics of an eastern Himalayan megaflood
While previous scientists have studied the flow of megafloods in other, lower relief parts of the world, little is known about how these immense floods behave in steep mountain landscapes. We simulated a megaflood in the eastern Himalaya and found that the simulated flood had a peak discharge of 3.1 million cubic meters per second--three times higher than predicted from simple estimates using lake volume and dam height. Find out more about the implications for the erosion and depositional potential of eastern Himalayan megafloods by reading our paper!