Holly Michael
Director, Delaware Environmental Institute University of Delaware
- Newark DE
Holly Michael's academic work has had a significant impact on the discipline of hydrogeology
Media
Social
Biography
Areas of Expertise
Media Appearances
Drinking Water Map Shows States With Most Contaminants
Newsweek online
2025-10-13
The reasons California, Texas and New York all have higher numbers of contaminants in their water is largely due to their higher populations and "substantial industry, including a lot of petroleum activity," Holly Michael, director of the Delaware Environmental Institute and professor of Earth Sciences and Civil, Construction and Environmental Engineering at the University of Delaware, told Newsweek.
Scientists went hunting for freshwater deep beneath the Atlantic Ocean. What they found could have global implications
CNN online
2025-09-17
“We think that the freshwater got there thousands of years ago, when sea level was much lower and the continental shelf was exposed on land,” said Holly Michael, a professor of Earth sciences and civil and environmental engineering at the University of Delaware, who was part of the expedition.
Saltwater intrusion leading to “ghost forests” along Delmarva’s coast
Coast TV online
2024-04-23
"The slow process is sea level rise which is happening over decades and then fast processes superimposed on that is storm surges, high high tides that tend to move farther and farther inland as sea level rises, and then there are also climatic factors like drought which can allow saltwater to intrude where it wasn't before," explained Dr. Holly Michael, the Delaware Environmental Institute Director.
What is seawater intrusion? A hydrogeologist explains the shifting balance between fresh and salt water at the coast
The Conversation online
2023-10-11
I am a coastal hydrogeologist and have studied water across the land-sea interface for 25 years. I think of seawater intrusion as being like a seesaw: The place where fresh water and salt water meet is the balance point between forces from land and forces from the sea.
Climate change could threaten Philly’s drinking water
WHYY online
2023-04-05
It’s these extreme climate-driven events — piled on top of sea level rise — that are concerning, said Holly Michael, a professor at the University of Delaware who studies groundwater dynamics and water supply sustainability.
Articles
Invisible groundwater threats to coastal urban infrastructure
Nature2025-08-06
Groundwater-associated hazards in coastal cities can be as acute as surface flood hazards, but are often overlooked, more persistent, and harder to identify. Here we discuss how climate change is causing flooding and corrosion of coastal infrastructure by driving groundwater rise and salinization.
Terrestrial groundwater drives coastal ecosystem shifts
Geophysical Research Letters2025-07-17
Rising sea levels and stronger storms are driving saltwater intrusion along global coastlines, forcing marshes inland and replacing forests and farmland across the Delmarva Peninsula. While sea level rise and storms have long been blamed, our research shows that changes in terrestrial groundwater levels play a larger role in pushing saltwater into freshwater systems. We also found that heavy rainfall during storms can help flush saltwater out, allowing groundwater to recover—revealing that land-based hydrology is a key driver of coastal ecosystem change in this region.
The impacts of climate change on coastal groundwater
Nature Reviews Earth & Environment2025-01-11
Coastal groundwater (CGW) is a critical water resource for many communities and can be a key part of coastal ecosystems. Owing to its location, CGW faces both terrestrial and marine effects of climate change while simultaneously being impacted by anthropogenic activities.
Feedbacks Regulating the Salinization of Coastal Landscapes
Annual Review of Marine Science2024-09-11
The impact of saltwater intrusion on coastal forests and farmland is typically understood as sea-level-driven inundation of a static terrestrial landscape, where ecosystems neither adapt to nor influence saltwater intrusion. Yet recent observations of tree mortality and reduced crop yields have inspired new process-based research into the hydrologic, geomorphic, biotic, and anthropogenic mechanisms involved.
A comparison of sea-level rise and storm-surge overwash effects on groundwater salinity of a barrier island
Journal of Hydrology2024-11-01
Coastal fresh groundwater is threatened by salinization due to both sea-level rise and storm-surge overwash. Most studies of subsurface saltwater intrusion focus on sea-level rise, but storms that are becoming more frequent and intense with climate change could have more imminent and permanent effects on aquifer salinity.
The hidden influence of terrestrial groundwater on salt marsh function and resilience
Nature Water2025-02-03
Salt marshes are hotspots of nutrient processing and carbon sequestration. So far, studies addressing spatiotemporal variability in and drivers of salt marsh biogeochemical function, carbon storage and resilience have focused on ocean-driven surface hydrologic influences, neglecting effects of terrestrial hydrology through subsurface connections.
Accomplishments
Geological Society of America James B. Thompson, Jr. International's Distinguished Lectureship
2018
NSF Faculty Early Career Development Award
2012
Oak Ridge Associated Universities Ralph E. Powe Junior Faculty Award
2010
Education
Massachusetts Institute of Technology
Ph.D.
Hydrology
2005
University of Notre Dame
B.S.
Civil Engineering
1998
Affiliations
- American Geophysical Union
- Geological Society of America
- International Association of Hydrogeologists
- International Association of Mathematical Geosciences
