2020 CSDMS meeting-043
Isolating tributary response to glacial–interglacial cycling in the upper Mississippi River watershed
Shanti Penprase, University of Minnesota Minneapolis Minnesota, United States. firstname.lastname@example.org
Andrew Wickert, University of Minnesota Minneapolis Minnesota, United States. email@example.com
Phil Larson, Minnesota State University, Mankato Mankato Minnesota, United States.
Daniel Gardner, Minnesota State University, Mankato Mankato Minnesota, United States.
Fiona Clubb, Durham University Durham , United Kingdom.
The Whitewater River in southeastern Minnesota is one of numerous tributaries of the upper Mississippi River. However, unlike many of the tributaries to the Mississippi north of the Whitewater River, which received glacially derived sediment and water directly from the Laurentide Ice Sheet margin, the Whitewater watershed remained ice free. Instead, glacial–interglacial cycling predominately shaped the watershed via changes in base-level and sediment inputs on the mainstem Mississippi. Thus, the aggradation and incision of the mainstem upper Mississippi acted as the primary source of glacial signal in the watershed. In this study, we seek to understand how the complex glacial history of the upper Mississippi River impacted the long-profile evolution of the Whitewater River. To do this, we combine one-meter LiDAR topography with the topographic analysis package, LSDTopoTools to study the modern channel network and adjacent terraces. By extracting modern and historic river terraces, we are able to reconstruct channel long-profile changes over time. We pair this study with bedrock geology composition and depth to bedrock for the watershed to understand transitions within the watershed from transport to detachment limited and linkages between bedrock type and channel morphology. This work allows us to better constrain how glacial–interglacial signals propagate through fluvial systems via tributaries. This information can better inform our understanding of how tributaries respond to mainstem changes and how these changes propagate over time.