Shanti Penprase
Tell us about yourself:
My name is Shanti Penprase and I’m a Ph.D. candidate in the Earth & Environmental Sciences Department and Saint Anthony Falls Laboratory at the University of Minnesota, Twin Cities, working with Andy Wickert. My research interests include fluvial response to base level change, geochronology, and paraglacial landscape evolution. I have a B.A. in Geology from Carleton College. After Carleton and before my time at the University of Minnesota, I worked for a few years in environmental non-profits and local government doing community education, outreach, and field monitoring of stormwater runoff and urban water quality in Minneapolis. I’m originally from Southern California and before moving to Minnesota for Carleton, I’d never seen snowfall. Now, almost a decade later, I can’t imagine a year without seasons (although I do miss the beach)!
What is your research about?
Most broadly, my research studies how rivers respond to base level change. To study this, I’m focusing on the Whitewater River in southeastern Minnesota, a mixed alluvial-bedrock river and tributary to the Mississippi River with a well-constrained history of base level change. I’m first working to reconstruct the river’s channel long profile over time. To do this, I’m using a variety of techniques including DEM analysis, seismic refraction, optically stimulated luminescence (OSL) dating, and 10Be cosmogenic nuclide dating. Once I have reconstructed the river channel long profile evolution, I plan to pair my field-based data with theoretical models for mixed-alluvial bedrock river systems to better understand connections between real-world and modeled systems. As a river with well-constrained base level in a tectonically inactive setting, the Whitewater is a compelling study site for these types of questions. My field area was also heavily impacted by Euro-American farming practices of the late 1800s, which led to catastrophic sediment aggradation along the valley bottom. I plan to use paired OSL/10Be dates to constrain pre-settlement erosion rates and aggradation rates. I’ll then compare these to post-settlement and modern erosion rates to understand how erosion in the river valley changed from natural to human timescales.
What excites you about your research?
A big component of my work is thinking of changes in river systems across timescales. I find it really exciting to think about how the rivers that flow across our landscapes today are records of changes in their environment that can stretch thousands of years back in time. Despite the fact that the Laurentide Ice Sheet retreated from Minnesota thousands of years ago, the modern landscape is still responding to the impacts of this glaciated past. To envision the landscape as a record of this past, with multiple, complex stories overlying and intertwined within it is really exciting. I see my work as an effort to help place ourselves in this larger geologic story and to help understand where that story might take us in the future as our landscapes continue to evolve.
What broader importance does your research have for society?
In Minnesota, much of the modern landscape is still destabilized by the impacts of glaciation. In many parts of the state, the landslides and floods communities face today can be connected to changes in the landscape driven by glacial processes that have been exacerbated by modern climate change and land use. In my field area, for example, much of the modern valley bottom is inhabitable because of massive sediment deposition brought on by agriculture the edges of the valley. While the farming practices of early Euro-American farmers greatly exacerbated the problem, the sediment transport and deposition within in the valley is largely governed by the knickzone and broad downstream alluvial valley present in the modern river system. Both of these geomorphic characteristics were generated by changes in glaciation, which in turn modulated base level at the mouth of the Whitewater River. Thus, my work aims to understand the glacial undercurrent that acts as the foundation for the landscape dynamics we experience along more human timescales. Further, my work connecting field-based and theoretical models will allow us to better our understanding of how rivers respond to changes in base level. This is particularly important with rising sea level and dramatically shifting climate patterns due to climate change, which may result in more variable base level and result in dramatic shifts in our modern and future river systems.
What inspired you to pursue a career in Earth Science?
Growing up, I loved European History. By the age of ten, I could tell you anything you might want to know about Tudor England. Studying history felt like solving a mystery. You had to work with the few “clues” you could find in the present to piece together the “mystery” of what took place in the past. I saw myself as this great detective, piecing together the hidden story, clue by clue. When I got to college I was convinced I would continue this love of European History and pursue a career in an archive or museum. However, my undergraduate institution had a well-known geology department so I decided to take my first geology course as a sophomore to see what all the fuss was about. In that class, I realized that Earth Science was basically the same “detective work”, just working with different clues and along much longer timescales. Plus, you got to spend time outside while you were doing it! Now in my work I get to ask questions about the world around us and how the landscapes we see today came to be. And the clues I use involve an exciting combination of lasers, hydraulic samplers, seismic waves, and glowing sand. How cool is that?
What are you looking to do after you complete your PhD or postdoc?
I really love sharing my excitement for science with others and find helping other people discover their interests in science incredibly rewarding. As such, I want to pursue a career in teaching where I can help future generations learn how to connect with and relate to the world around them. As citizens of Earth, I think we all deserve to know a bit about the amazing processes that take place our small, blue planet and I hope to use my skills to help future students do just that.
Given unlimited funding and access to resources, what is your dream project that you would pursue?
Wow, what a concept! If given the chance, I would love to build a “fieldwork–field-trip” program with schools/museums that lets students and community members learn about and try out the actual science techniques we use in the field to understand natural systems. A lot of this program would mimic some of the activities covered in an introductory course, but geared towards hands-on learning and demonstration. Groups of participants would come out to the field with us and, after posing a hypothetical research question, would get to learn/try out the methods we’d use to answer that question. This could be anything from a hand auger demonstration, to the basics of field surveying or soil descriptions. The activities would mostly be fairly simple, but the key would be to open up the door to everyone so that they can learn about ways we study the landscape. I did something like this when I was working in outreach before graduate school where I ran a simple demonstration with high school students where we measured the turbidity, dissolved oxygen, salinity, etc. of a bucket of water that we called a "lake". After teaching them how to use a water quality probe, we incrementally added leaves, salt, and soil to our “lake”, taking measurements after each addition. It was a great activity because the students I worked with got to learn how to use the actual probe we used for water quality monitoring and see in real time (with real data) how different inputs impacted our “lake”. I find science outreach like this particularly compelling because it shows how “lofty” science actually uses a lot of really easy, exciting methods, increases science accessibility, and helps people see themselves as scientists.
What else do you do? Any hobbies or interests outside of work?
Like many Earth Science folks, I love any excuse to spend time outdoors so much of my free time is spent walking my dog, biking, and hiking. I also enjoy yoga and dance (I did Kathak, a form of classical Indian dance, for 6 years). I’m also still a major history nerd and avid reader of all things historical fiction.
Personal website
https://spenprase.github.io/