Late at night on September 26, 2024, Hurricane Helene made a powerful landfall on Florida’s Big Bend, leaving a trail of physical devastation. While the visible destruction was immediately apparent, an unseen consequence was brewing beneath the surface. Within weeks, hydrologists Dr. Dini Adyasari from Texas A&M University and Xiaolang Zhang from Florida Atlantic University arrived at Apalachee Bay, the site of Helene’s first landfall, to investigate the storm’s impact on shallow coastal aquifers. Their findings, presented at the GSA Connects 2025 conference in San Antonio, Texas, revealed significant changes in groundwater chemistry.
As climate change accelerates, leading to rising sea levels and more frequent extreme storms, coastal aquifers are increasingly vulnerable. Florida’s unique low-lying and permeable bedrock geology makes it particularly susceptible to these changing hydrologic conditions. Dr. Adyasari emphasized the need for thorough investigation into these systems, as they play a critical role in the region’s water resources.
Investigating the Aftermath of Hurricane Helene
Dr. Adyasari and her team conducted four research trips to Apalachee Bay over the eight months following Hurricane Helene. Their goal was to assess both the immediate and long-term impacts of the storm on the region’s shallow coastal aquifers. Groundwater samples were collected from about two meters below the surface in October and November 2024, as well as January and May 2025, and analyzed for various chemical properties, including nutrient levels.
Initial observations indicated a significant shift in groundwater conditions. During the early trips, the water samples had little odor, but by the final trip in May, the samples emitted a strong sulfide smell. “The samples were so smelly, like sulfide,” noted Dr. Adyasari, “which means that it’s already in anoxic conditions.”
Uncovering Chemical Changes
Laboratory analyses confirmed that the storm had introduced oxygen into the typically anoxic shallow groundwater. This influx of storm and sea water temporarily oxygenated the aquifers, but as the months passed, the oxygen was consumed by microbial activity, returning the groundwater to its usual state. This storm-induced pulse of oxygenation led to the production of nutrients such as nitrate.
The increase in nutrients could potentially trigger phytoplankton blooms, which may disrupt connected surface waters like rivers and lakes that support vital aquatic ecosystems. Moreover, changes in shallow aquifers could pose risks to deeper groundwater reservoirs used for drinking and irrigation.
Understanding the Broader Implications
Interestingly, despite the significant storm surge, salinity levels in the shallow coastal aquifers remained relatively stable. This stability is likely due to the already brackish conditions of the sampled aquifers. However, the broader implications of these findings are significant. Understanding how interconnected groundwater systems respond to extreme weather events is crucial for managing water resources in a changing climate.
Dr. Adyasari is now focusing on the microbial communities present in the groundwater samples to further understand their role in altering water chemistry. “We want to see if the microbial analysis will support the geochemical findings that we have now,” she explained. The processes believed to be driving the geochemical nutrient changes are “supported by microbial activities, so I’m really waiting for those results.”
Looking Ahead: Future Research and Challenges
The research conducted by Dr. Adyasari and her team underscores the importance of continued study into the effects of extreme storms on groundwater systems. As climate change continues to influence weather patterns and sea levels, understanding these dynamics is essential for developing effective water management strategies.
Future research will likely focus on the long-term impacts of such chemical changes on both groundwater quality and the ecosystems that depend on these water resources. As scientists like Dr. Adyasari delve deeper into the microbial and geochemical interactions within aquifers, their findings will be critical in shaping policies and practices aimed at safeguarding water supplies in vulnerable coastal regions.
The hidden impacts of Hurricane Helene serve as a reminder of the complex and often unseen consequences of extreme weather events, highlighting the need for comprehensive research and adaptive management strategies in the face of a changing climate.
