As the United States repurposes former military zones for civilian use, a silent threat lingers beneath the waters: unexploded ordnance (UXO). These remnants from past conflicts, especially from World War II, pose significant risks in shallow waters now frequented by the public. Advancements in sonar detection, spearheaded by researchers like Connor Hodges at the University of Texas at Austin, are crucial in addressing this hidden danger.
Over 400 underwater sites across the U.S. are potentially contaminated with UXOs—bombs and munitions that failed to detonate upon deployment. These devices can remain dormant for decades, but when disturbed by human activity or natural movements, they can still detonate, leading to catastrophic consequences. Traditional sonar systems, which rely on detecting shapes and materials, struggle to identify UXOs as they corrode and blend into their surroundings. The weakened acoustic signals returned by these aged munitions increase the risk of false negatives during detection surveys, missing potentially dangerous UXOs.
Connor Hodges and his team at the University of Texas are at the forefront of research aimed at improving sonar detection of UXOs. By studying the acoustic signatures of degraded munitions, the team seeks to understand how factors like corrosion and encrustation affect sonar readings. Their work with AN-Mk 23 practice bombs, submerged for over 80 years, has revealed that degradation significantly alters an object’s acoustic resonance, complicating detection efforts.
“Many of these sites are in shallow water, potentially posing a threat to human safety, and date back several decades,” said Hodges. “This long exposure to the environment leads to corrosion as well as encrustation in the form of barnacles or algal growth.”
Acoustic scattering techniques play a crucial role in identifying underwater UXOs. These techniques provide insights into the internal structure of objects beneath the seafloor, offering a way to “see” beyond the surface. However, as Hodges emphasizes, the interaction of old munitions with sonar technology is increasingly important as military sites are repurposed for civilian use.
“Acoustic scattering techniques give an insight into the internal structure of the object imaged, as well as a method to ‘see’ into the seafloor,” said Hodges, noting that using sonar to map the seafloor and detect munitions is also faster and cheaper than other techniques.
With over 400 contaminated sites across the U.S., the need for effective UXO detection is urgent. The work conducted by Hodges’ team is an essential step in ensuring that these areas can be safely transitioned for public access. By improving understanding of how these munitions degrade and interact with sonar, researchers can develop more reliable detection models, crucial for both public safety and environmental remediation.
“There is a risk of detonation if they are stepped on or otherwise disturbed,” Hodges said. “This poses a larger risk to human safety in shallow waters, and UXO identification and recovery becomes vital as old sites are transitioned away from military use.”
Looking ahead, Connor Hodges plans to broaden his research to encompass a wider variety of munitions and different environmental conditions. By exploring diverse corrosion and encrustation scenarios, Hodges aims to create comprehensive models that enhance the reliability of sonar-based UXO detection. These models are not only vital for military operations but also for environmental and humanitarian missions.
As Hodges notes, “Underwater UXO can be tricky to find and recover, so it is important that this can be done safely and effectively. We hope this work will ultimately help save lives.”
The transition of military sites to civilian use is a growing trend across the United States. However, the presence of UXOs poses a substantial risk to both public safety and environmental health. As these areas open to the public, the potential for accidental detonation increases, making effective detection and remediation strategies imperative.
The work of researchers like Connor Hodges is pivotal in addressing these challenges. By enhancing our ability to detect and recover UXOs, we can prevent accidents, protect lives, and preserve the environment. As we continue to navigate the legacy of past conflicts, harnessing technology to ensure that our waters remain safe and accessible for all is not just a scientific endeavor—it is a societal imperative.
