I study rivers and the ways they transport sediment to understand flood hazard in the Pacific Northwest. I use data analysis, remote sensing and models to investigate how rivers are changing in shape and hydrologic regime.

PROJECTS

River Bed Morphodynamics During & Between Floods

"Can spatial changes in river planform geometry predict regions prone to erosion and deposition during floods?"

2021-Present

Ahrendt_Figure1_B007.tif

Modeling HydroGemorphic Hazards (MoHGeoH)

"How do the ways rivers transport sediment affect flooding?"

2018-Present

Flood hazards in most basins are typically assumed to be driven by the frequency and intensity of high discharge events, but changes in a river’s conveyance capacity can also contribute substantially to flood hazards. Take the channel shown in the figure on the left where Q-bankfull is the bankfull flow capacity of the channel. This river section can flood by two mechanisms. 1: it can experience a discharge event ‘Q’ that exceeds Q-bankfull, or 2: sediment can deposit in the channel changing the channel’s conveyance capacity and causing water to flow overbank for what was previously a Q-bankfull event. It’s these changes in channel conveyance capacity that we are trying to understand in order to improve flood risk predictions.

Flood Mechanisms

Investigate the results here!

Ahrendt, S., Horner-Devine, A. R., Collins, B., Morgan, J., Istanbulluoglu, E., (2022) Channel Conveyance variability can influence flood risk as much as streamflow variaibility in western Washington State, Water Resources Research. https://doi.org/10.1029/2021WR031890

This collaborative project is funded as part of the NSF PREEVENTS program.

PUBLICATIONS

  • Ahrendt, S., Blom A., Van Denderen, R. P., Schielen, R. M. J., Horner-Devine, A. R., (in review) Geometric floodplain controls on riverbed elevation change within and between flood events, River Flow 2022, The Eleventh International Conference on Fluvial Hydraulics
     

  • Ahrendt, S., Horner-Devine, A. R., Collins, B., Morgan, J., Istanbulluoglu, E., (2022) Channel Conveyance variability can influence flood risk as much as streamflow variaibility in western Washington State, Water Resources Research. https://doi.org/10.1029/2021WR031890
     

  • Morgan, J. A., Kumar, N., Horner-Devine, A. R., Ahrendt, S., Istanbullouglu,
    E., Bandargoda, C., (2020), Simulating large-scale and long-term fluvial morphodynamics: The efficacy of using a morphological acceleration factor. Geomorphology, 356, p. 107088, https://doi.org/10.1016/j.geomorph.2020.107088

SELECTED PRESENTATIONS

AGU 2020 Virtual Presentation

CSDMS Summer Series 2020, Virtual Presentation

POSTERS

FIELD NOTES

Observing Sediment Transport Processes in Northern Minnesota:

Field Exercise for Hillslope Geomorphology with Dr. Alison Duvall

Map of Study Sites: Magnetic Rock Trail, MN

Digital Field Notes:

© Shelby Ahrendt 2022