The influence of drying on the aeolian transport of river-sourced sand

Journal of Geophysical Research Earth Surface
By: , and 



Transgression and regression of water levels (stages) have impacted the evolution of aeolian landforms and sedimentary deposits throughout geologic history. We studied this phenomenon over a five-day period of reduced flow on the Colorado River in Grand Canyon National Park, AZ, USA, in March 2021. These transient low flows exposed river-channel sand deposits to the air, causing progressive desiccation (drying) and thereby making these deposits susceptible to aeolian transport. We measured aeolian threshold friction velocities (u*t) for sand saltation and PM10 dust emissions, as well as other characteristics, on a subaerially exposed sandbar and downwind aeolian dunefield during each day of the low river flow. The sandbar transitioned from supply-limited to transport-limited aeolian sediment transport conditions during the regression in river water stage. A possible tipping point between the two transport conditions occurred approximately 48 hours after the drop in river flow. The empirically measured u*t decreased as the sandbar sediment dried with increased subaerial exposure time. Theoretical estimates and empirical measurements of u*t corresponded closely on the aeolian dunefield and on the sandbar when it was drier during the third and fourth day of the experiment. Eighty-seven percent of the variability in u*t was explained by empirical models that provide practical estimates of aeolian transport potential of subaerial river sediment deposits using monitoring data that are commonly available in this and other river systems. The work provides theoretical insight into the response of aeolian processes to sediment supply changes driven by periods of anthropogenic activity, drought, and climate change.

Study Area

Publication type Article
Publication Subtype Journal Article
Title The influence of drying on the aeolian transport of river-sourced sand
Series title Journal of Geophysical Research Earth Surface
DOI 10.1029/2022JF006816
Volume 127
Issue 12
Year Published 2022
Language English
Publisher American Geophysical Union
Contributing office(s) Southwest Biological Science Center
Description e2022JF006816, 24 p.
Country United States
State Arizona
Other Geospatial Grand Canyon National Park
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