Critical Hydrology Research in the Critical Zone

Bryan with the undergraduate research team about to depart for Pennsylvania
(Photo courtesy of Bryan Shuman)

With support from EPSCoR, Paleohydrology Professor Bryan Shuman took four UW undergrads to Pennsylvania this past summer to study the long history of drought in the area. With a study area of hundreds of square miles and timeframe of thousands of years, the team sought to answer questions about the hydrological past and illuminate the future.

Ground-penetrating radar allowed the team to see the ancient shorelines of these lakes, establishing a water record dating back millennia. The team pushed plastic tubing into the lake bed to collect sediment core samples. This technique allows researchers to grab a cross-section of silt layers. 

Undergraduate researchers hard at work collecting samples on the lake
(Photo courtesy of Bryan Shuman)

  As Bryan explains, “Because this is a history of drought in natural reservoirs – when water levels were high, when they were low – we can learn about hydrology and climate change over several timescales.” Lake sediment can also be used to plot forest fires, since researchers can measure fossil charcoal deposits from burned trees. “Everything washes into these lakes over time. They’re like time capsules, big memory cells that record environmental change.”

Why Pennsylvania? Ocean temperatures in the Atlantic influence conditions throughout North America. The Atlantic coastline also boasts several Critical Zone Observatories, which study the interactions between life on the earth’s surface, microbes underground, and water flowing through the ground. These complex processes generate soil, contribute to erosion, and determine what plants grow and which animals survive. The “critical zone” is the zone where this vital interaction between geology, hydrology, and biology takes place.

The EPSCoR grant offers Bryan’s team access to these Critical Zone Observatories, and two of these sites are in Pennsylvania. The team is interested in the role water plays in these interactions, especially as it changes over time. “It’s great to take students out in the field and have them see these things for the first time. Being out in the field is such a different experience from sitting in the classroom. Learning is so much more tangible when you can pull samples out of the ground.” 

Undergraduate research team with core samples
(Photo courtesy of Bryan Shuman)

The team found evidence of drastic rises in Pennsylvania water levels. “The magnitude of that change is kind of equivalent to going from the amount of rain we have on the Great Plans to the amount of water we have on the North Coast right now. Not making it a desert, but in terms of ecosystems and plants, that would be a pretty big shift. If you were to make Pennsylvania like Illinois, that would have a big impact on the water resources that people depend on and the plants they grow.”

So far, the results seem to indicate a large increase of water in the North Atlantic region, a pattern Bryan says is similar to most of the places in the US that he has studied. The pattern extends to Wyoming, which you might be surprised to learn is much soggier than it was a few thousand years ago. “There’s definitely precedent for Wyoming being drier than it is now.” The team confirmed an overall pattern of water increase, but also found evidence of droughts lasting not just a year or two but centuries.

Bryan believes that hydrological history in the state is crucial to awareness of water conditions now and in the future. “Water’s important. We need water, and we don’t know how constant our water supply is. Looking at the past gives us a chance to see how much it can change, and what that means for the land around us.”

Posted to Wyoming EPSCoR by Jess White