University of Delaware researchers are developing data-based tools for assessing extreme weather impacts at coastal military facilities.

Led by the University of Delaware’s Carolyn Voter, assistant professor of civil and environmental engineering and Earth sciences, the research aims to produce a modeling toolbox that incorporates data such as changing rainfall patterns and rising sea levels to help the military identify and evaluate infrastructure needs. The toolbox will be used to screen six military installations, including Dover Air Force Base, in Dover, Delaware, with a focus on infrastructure systems for drinking water, wastewater and stormwater management.  

A core faculty member in UD’s Center for Applied Coastal Research, Voter has a background in hydrology, the science of how water moves, including expertise in how to manage water resources, from natural systems to urban infrastructure to agriculture. She’s particularly interested in how researchers represent and model those processes to better predict and plan for future changes. UDaily recently caught up with Voter to discuss the project.

Q: What is the problem you are trying to help solve with this work?

Voter: We often consider sea level rise and intensifying storms as challenges facing coastal communities. However, rising seas also correspond with rising groundwater levels. This can be hard to see because it’s below ground, making it a hidden threat that can lead to things like saltwater intrusion, where salt water from the ocean pushes into the groundwater system, leading to shallower, saltier water below ground. We're interested in improved ways to represent how this shallower, saltier groundwater affects communities — particularly at military installations.

Q: What are the potential impacts of saltier groundwater to our water infrastructure?

Voter: Most of our stormwater infrastructure was designed to manage stormwater by infiltrating it into the ground. When groundwater levels are closer to the surface, those systems don't always work the way that we design them. An extreme example would be if groundwater levels rise so high that they're above the surface, which can lead to flooding from groundwater. One issue we're interested in is how this shallower groundwater, and wetter subsurface conditions in general, interact with leaky wastewater pipes found in nearly all communities. If groundwater levels rise in ways that leave these pipes sitting in groundwater more often, this excess water may leak into our wastewater conveyance systems, leading to higher amounts of flow at wastewater treatment plants. In coastal systems, we're also interested in whether that inflow is growing saltier, and, if so, whether the saltiness poses challenges for wastewater treatment. 

Q: What specific part of the problem is this project designed to work on?

Voter: Good question. We want to develop the ability to design models that can represent these interactions well, which is quite difficult. In hydrology, we have models that are good for modeling urban systems including paved surfaces and the pipe systems that convey wastewater and stormwater. There also are good models for groundwater that can handle the complexities of trying to represent saline, or salty, groundwater. But our urban models generally do groundwater very poorly, and our groundwater models generally can't handle paved surfaces and certainly not pipe flows. With this project, a main goal is to develop a way to couple a widely used stormwater management model with a widely used groundwater model, so that we can look at how groundwater might interact with these urban infrastructure systems. Put simply, we want the models to talk to each other. For instance, we want to have the groundwater model pass information about groundwater levels to the stormwater management model so we can calculate how much leakage might be coming into wastewater conveyance pipes. Similarly, we want the stormwater model to tell the groundwater model how much water is infiltrating the ground and inform our understanding of how much water will ultimately reach the groundwater table. 

Q: How is knowing these details useful?

Voter: This information can help us pinpoint things like whether our water infrastructure systems are at risk of not performing well under future sea level or precipitation conditions and describe what that vulnerability might be in terms of water infrastructure. For example, would there be problematic interactions between groundwater and wastewater? If so, what might be some warning signs and when might we need to act? We plan to simulate three levels of sea level rise and various storm intensities at Dover Air Force Base, our demonstration site, to address some of these questions.

Q: Why are military installations particularly important to protect and how will your work help?

Voter: Military installations exist to protect the country and its citizens. But they operate like communities, so we must think about multiple things, from ensuring the safety of troops and the built infrastructure to potable water, wastewater management and flood management. We're hoping to deliver a modeling toolbox that could be deployed like a standard operating procedure of sorts for what to look at in any community, where to find information and how to do the studies, complete with data collected at other sites.

Q: Are the tools your team is developing specific to the military?

Voter: While the team’s focus right now is developing this around military installations, the hope is the tools will be more broadly useful and available to resource managers in civilian communities. We are starting with Dover Air Force Base in the Northeast, but also looking at military installations situated from Virginia to Florida, the Gulf States and beyond. It's not only the Mid-Atlantic that's vulnerable to this kind of hazard. One place we are interested in screening is the Marshall Islands in the central Pacific Ocean, where bases can be especially vulnerable to saltwater intrusion problems in groundwater.

Q: Why is Delaware a good home base for this type of research?

Voter: This project focuses on a real gap in the field, and it requires people with expertise on both the surface and the subsurface, as well as in contaminant transport. In Delaware, which is a very coastal state, this problem is a bit of a hidden threat. Delaware is well positioned to be thinking about these coastal challenges, and UD has the interdisciplinary expertise to look at it more holistically. 

Our project team is interdisciplinary, with management oversight by the Delaware Environmental Institute (DENIN). My background is in hydrology, while Holly Michael, who directs DENIN, brings strong expertise in groundwater modeling to represent saltwater intrusion. Paul Imhoff has background in stormwater management and design best practices and in groundwater contamination, including legacy landfills and brownfields. Finally, Larry Trout and his team of engineers at Straughan Environmental, Inc., have extensive field reconnaissance experience to ensure we have good data to put into our models. They will also lead any economic impact analysis and cost assessments associated with potential solutions. The project also will include four graduate and undergraduate researchers, and a few field assistants.

This work is supported by $1.5 million in funding from the U.S. Department of Defense.