Water at the Top of the World

Rapid Arctic warming is melting ice, thawing permafrost, and changing the Arctic hydrologic cycle, impacting river systems that are critical for terrestrial and marine ecosystems and communities. In these talks, Del Vecchio and Piliouras will describe where rivers begin and end in the Arctic - Del Vecchio will focus on the onset of channelization (and why that might look different from temperate landscapes), and Piliouras will focus on river deltas that filter riverine fluxes to the ocean.

In the first talk, Joanmarie will tell the tale of water tracks. Water tracks are widespread Arctic hillslope features that transport snowmelt and rainfall downslope without carving channels, dispersing water across frozen, porous soils and preventing the development of headwater streams. Because early-season flow cannot incise frozen ground and tundra peat and vegetation readily transmit water, water tracks fundamentally reorganize surface hydrology, a pattern now linked to pan-Arctic stream density and colder climates. In this talk, she will synthesize recent work defining what water tracks are, why they form (highlighting the role of thermal channelization), and where they occur across diverse Arctic landscapes. She will then present ongoing research, much of it led by William & Mary undergraduate students, investigating how water tracks are distributed and how they are changing under a warming climate.

Next, Anastasia will describe the dynamics of Arctic river deltas - complex networks of channels and wetlands that are also under the influence of ice and permafrost at high latitudes. These landscapes connect some of the world’s largest rivers to the world’s smallest ocean basin, altering the spatial distribution, timing, and magnitude of riverine fluxes of water, sediments, nutrients, and heat. In this presentation, she will highlight some of the unique ways that ice and permafrost imprint on deltaic landscapes, and describe how those characteristics were used to inform a novel model of suspended sediment transport in river deltas. She will present results showing how Arctic deltas can trap 10-70% of incoming riverine suspended sediments, greatly modifying river-ocean fluxes that impact marine ecosystems.

Bios
Dr. Joanmarie Del Vecchio is an Assistant Professor of Geology at William & Mary in Virginia, U.S.A., studying permafrost landscape response to climate change. Her work integrates field and computational approaches to understand surface processes in past and present frozen landscapes. She earned her Ph.D. and M.S. in Geoscience from Penn State and was a Neukom Postdoctoral Fellow at Dartmouth College.

Anastasia Piliouras is an Assistant Professor in the Department of Geosciences at Penn State University. She received her bachelors in Earth Science from the University of Pennsylvania and her PhD in Geological Sciences from the University of Texas at Austin in 2016. Previously, she worked as a Staff Scientist at Los Alamos National Lab, where she also did her postdoctoral research and first became interested in high latitude processes. As a geomorphologist, her research focuses on understanding the dynamics of modern river, coastal, and deltaic landscapes, especially at high latitudes and in response to the changing climate.

All seminars will be presented online live at 11:00 a.m. ET on the third Thursday of each month. Seminar recordings will be posted later. Please register in advance for all talks.

Co-hosts: Devon Kerins, University College Dublin; Bryn Stewart, Caltech; Marguerite Xenopoulos, Trent University, Canada; Margaret Zimmer, University of Wisconsin, Madison; Li Li, Penn State