Exploring subsurface dams: Idaho’s supplement for energy-water systems

As Idaho's population expands and droughts increase in frequency, the state faces unprecedented challenges in balancing energy-water supply with rising demand. Such challenges press the following questions: what might the energy systems of tomorrow look like, and how can we improve their efficiency and resilience?

To address this question, Boise State University's Geotechnical Engineering Program faculty and students are researching how alpine subsurface dams can supplement water retention and hydroelectric capacity of Idaho's energy-water systems.

Boise State civil engineering department chair Bhaskar Chittoori, civil engineering professor Nick Hudyma and graduate student Shreya Mul are co-investigators on a multidisciplinary project, "Idaho Community-engaged Resilience for Energy-Water Systems (I-CREWS)." Their work, in collaboration with Idaho State University researchers in fields of geology, engineering, hydrology and sociology, focuses on using subsurface dams in order to increase groundwater storage, and provides a comprehensive view of challenges and potential solutions for energy-water systems.

"Projects such as these are critical for the State and the science," Kathy Araújo, a lead for Boise State with I-CREWs said. "We're quite pleased that Bhaskar, Nick and Shreya are advancing the I-CREWs priorities in such a vital way with their ISU partners."

This project is funded largely by the National Science Foundation's Established Program to Stimulate Competitive Research, also known as EPSCoR.

"We are trying to address different problems like limited and seasonal water storage shortages and evaporation losses that occur," said Mul, a first-year student in the civil engineering graduate program. "By studying past design methods, our major goal is to explore a more sustainable and reliable way to manage water and energy resources."

A geotechnical standpoint

Boise State's team is examining the issue from a geotechnical standpoint, focusing on Idaho's unique glacial soil composition, comprising a range of materials from fine silts, clays and gravel to larger stones and boulders. Their knowledge of the engineering behaviors of these substances helps them evaluate a site's potential for construction.

In this case, alpine lakes are great candidates for subsurface dams due to their interconnected nature and high elevation. The snowpack in the mountains naturally flows downward, recharging not only the lakes but also the groundwater. Thus, alpine lake systems offer a great deal of potential hydroelectric energy.

Design benefits

According to the Idaho Strategic Energy Alliance, 114 hydropower facilities operate across the state, and hydropower generates 60% of annual energy use. However, traditional surface dams have some disadvantages, one of the largest being evaporation loss. According to the Stockholm Environmental Institute, evaporation loss from four traditional surface dams located in Washington state's southeast corner is equivalent to about $110 million worth of water each year.

Subsurface dams, due to their enclosed underground systems, have a number of design benefits. They offer physical barriers against evaporation loss. Additionally, subsurface containment reduces the risk of contamination by minimizing exposure to external pollutants. Combined with a remote alpine placement, subsurface dams can improve capacity, purity and power potential.

Working with nature

Along with EPSCoR partners, Chittoori, Hudyma and Mul are currently reviewing literature to help design structural parameters and create a working physical model. Their combined studies, along with numerical and physical models, are expected to show how alpine subsurface dams will provide greater efficiency to current systems while protecting the integrity of natural resources.

"When you drive along our beautiful rivers, you see [hydroelectric dams] all the time, but the geology that we have means that subsurface dams are something we can actually attempt," Hudyma said. "So we can use our natural environment, but not destroy our natural environment. This is crucial because, as Idahoans, we love nature."

Future potential

Mul, whose program emphasis is in geotechnical engineering, expressed her appreciation for the research opportunity.

"This project has had a strong impact on both my academics and career goals," she said. "It's made me understand how what I learn in class connects to real-world environmental and water-related challenges, and that's something I'd really like to continue working on in the future."

This publication was made possible by the NSF Idaho EPSCoR Program and by the National Science Foundation under award number No. OIA-2242769.

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