UToledo-Led Research Explores Flooding Impact on Freshwater Coastlines

UToledo-Led Research Explores Flooding Impact on Freshwater Coastlines

University of Toledo environmental researchers trooped through the woods and wetlands of the Ottawa National Wildlife Refuge for a week in early June.

Their mission?

To outfit an approximately 16-acre site with nearly 300 sensors that will constantly monitor a slew of metrics related to the soil, water and plants, including the flow of sap through trees.

"Think of it like a patient in the ICU," said Dr. Michael Weintraub, a soil ecologist and professor in the Department of Environmental Sciences. "We're trying to get as much information as possible."

The latest infrastructure installation advances the work of a large-scale collaborative project known as Coastal Observations, Mechanisms and Predictions Across Systems and Scales: Field Measurements and Experiments (COMPASS-FME), which seeks to understand how coastal environments respond to flooding. The objective is to inform and improve models that forecast how coastal ecosystems will function under changing water levels.

Adding these sensors heralds a shift in focus from the observational to the experimental: After more than three years of monitoring three sites in northwest Ohio, researchers are now preparing to flood one of these sites in collaboration with the Ottawa National Wildlife Refuge in a large-scale field experiment.

"To understand the effects of flooding, it helps to have some floods," said Weintraub, a co-principal investigator on COMPASS-FME. "It can be challenging to wait for them to occur. So rather than just relying on natural events, we're creating the ability to introduce controlled floods in one of our monitoring sites. That's going to give us the ability to control the timing, duration and magnitude of the flooding event, things that we don't have control over with natural events."

The Department of Energy's Pacific Northwest National Laboratory launched COMPASS with a $20 million investment in 2021, with COMPASS-FME focusing on two regions: The Smithsonian Environmental Research Center leads operations on the salty Chesapeake Bay, while UToledo leads operations on the freshwater coast of Lake Erie.

The U.S. Department of Energy has since awarded more than $7 million to UToledo, which has allowed it to support five faculty, four post-doctoral researchers and dozens of graduate and undergraduate students who participate in the data collection and analysis at reference sites along Crane Creek and the Portage River in the Ottawa National Wildlife Refuge in addition to Old Woman Creek in Huron, Ohio - less than 30 and more than 75 miles from UToledo's Main Campus, respectively.

Large research grants like COMPASS-FME support UToledo's prestigious Carnegie R1 Classification announced in February. UToledo is one of only 187 higher education institutions in the country recognized for very high research activity by the Carnegie Classification of Institutions of Higher Education.

UToledo researchers and their collaborators across the country have shared their observations related to vegetation, soil and hydrology - some of it challenging conventional wisdom when it comes to coastline ecosystems- in numerous peer-reviewed research articles since the launch of COMPASS-FME.

Dr. Inke Forbrich, another co-investigator and assistant professor in the UToledo Department of Environmental Sciences, is exploring the impact of flooding on emissions of the potent greenhouse gas methane. She and Dr. Angela Che Ing Tang, a research assistant professor in Forbrich's group, recently led research that yielded an unexpected outcome: As reported in the peer-reviewed journal Global Change Biology, they found that high water levels and consequent shifts in vegetation actually decreased methane emissions along low-lying coastal wetlands at Old Woman Creek.

"We identified two mechanisms that are involved," Forbrich said. "First, plants differ in their capability of transporting methane, which is important to consider when species' composition change. In addition, we found that a large amount of methane can effectively be consumed in standing water. The deeper the water column, the more methane is being removed."

Dr. Kennedy Doro, another co-investigator and associate professor in the UToledo Department of Environmental Sciences, brings an expertise in geophysics and soil hydrology to the project. It's important to study how water moves beneath the soil surface because this, in part, controls how soils respond to flooding and whether they will lack sufficient oxygen to support plants, potentially resulting in "ghost forests" of dead and dying trees.

However, soil responses to flooding may be more complex than originally thought.

"We thought we would be looking at clay over bedrock, which doesn't allow for much groundwater movement," Doro said. "But one of the cool things we've found is that the soils in this ecosystem are heterogeneous and that the movement of water within them sometimes goes against what we had assumed."

The researchers' observation and analysis will continue as they move toward the large-scale field experiment they anticipate will start in summer 2027. Setup for the experimental flood is an intensive and yearslong process, requiring researchers to first install a pump that can rapidly flood the forested wetland, which is diked to contain water. They also need to build out the power and communications infrastructure to support equipment they began to install this summer with the assistance of collaborating researchers from across the country.

Weintraub said they're looking forward to advancing their work.

"This is one of the biggest coastal research projects in the history of the United States," he said. "We've learned a lot already and we know we'll learn even more in this next stage."