Ebrahim Ahmadisharaf, Ph.D., F.EWRI, poses at Central Pond in Innovation Park in Tallahassee, Florida on May 14, 2025. (Scott Holstein/FAMU-FSU College of Engineering)
Transformative Research Methodology Reveals Escalating Infrastructure Vulnerabilities
The escalating number of U.S. dams at risk of overtopping represents a critical threat to structural integrity and downstream communities, according to pioneering research from the FAMU-FSU College of Engineering. This comprehensive study, published in Nature Communications, analyzed five decades of water level data across 33 strategically selected dam sites to quantify how overtopping probability has evolved since 1973.
The research findings reveal a concerning trend: an increasing number of dams now exhibit critical overtopping probabilities spanning low, moderate and high-risk categories, while those with non-critical (very low) overtopping probabilities have declined significantly. This shift represents a fundamental change in the risk profile of America’s aging dam infrastructure.
“Decades ago, dam builders used the best available technology knowledge, but things have been changing, so aging infrastructure is something that is a concern,” explained paper co-author Ebrahim Ahmadisharaf, an assistant professor in the FAMU-FSU College of Engineering and the Resilient Infrastructure and Disaster Response (RIDER) Center. “In this study, we showed where hazards from overtopping are greatest, both because of risk of occurrence and possible consequences. It is a guide to where infrastructure spending could have the greatest impact.”
Comprehensive Data Analysis Framework and Site Selection Criteria
The research team employed a rigorous methodology to ensure statistical reliability and comprehensive coverage. From the United States’ more than 90,000 dams of varying sizes, researchers focused on approximately 130 sites with at least 50 years of publicly available water level data. Through systematic exclusion of dams influenced by upstream regulation or those lacking statistical independence in water level data, the study concentrated on 33 sites that met stringent analytical criteria.
The selected dams represent critical infrastructure elements: 30 were classified as large structures with crest heights exceeding 15 meters according to International Commission on Large Dams standards. Additionally, 31 dams received “high hazard” classifications from the Federal Emergency Management Agency (FEMA), indicating that failure could result in loss of life.
The analytical framework involved examining water level data against dam crest height measurements. Researchers analyzed every 30-year period within the broader 50-year dataset to estimate temporal changes in overtopping probability. This methodology provided robust statistical foundations for understanding long-term risk evolution patterns.
Geographic Risk Distribution and High-Priority Infrastructure Sites
The study identified six dams exhibiting the highest overtopping probability, strategically located across Texas, Kansas and California. These critical infrastructure sites and their respective downstream communities include:
- Canyon Dam: New Braunfels, Texas
- Kanopolis Dam: Marquette, Kansas
- Milford Dam: Junction, Kansas
- Somerville Dam: Somerville, Texas
- Whiskeytown Dam: Anderson, California
- Whitney Dam: Waco, Texas
This geographic distribution highlights regional vulnerability patterns that correlate with changing precipitation patterns and extreme weather frequency increases associated with climate variability.
“We have to plan upfront for this potential risk,” Ahmadisharaf emphasized. “This information can help dam managers to consider whether they need to revisit their emergency action plans and strategy for operating dams.”
Infrastructure Vulnerability Mechanics and Failure Mode Analysis
Overtopping occurs when stored water exceeds reservoir capacity and spills over the top of dam structures. While this phenomenon does not necessarily result in immediate catastrophic failure, it progressively weakens dam structural integrity and significantly increases the risk of complete failure if conditions persist.
According to the Association of State Dam Safety Officials, overtopping attributable to inadequate spillway design, debris blockage of spillways, or settlement of dam crest accounts for approximately 34% of all U.S. dam failures. This statistic underscores the critical importance of understanding and mitigating overtopping risk factors.
The age profile of American dam infrastructure compounds the vulnerability. Many U.S. dams were constructed nearly a century ago, when engineering standards, materials science and climate understanding differed substantially from current knowledge. Aging construction materials and evolving environmental hazards compound this crucial infrastructure’s risk factors.
Contemporary Infrastructure Assessment and Future Research Directions
The 2025 infrastructure report card from the American Society of Civil Engineers assigned U.S. dams a D+ rating, reflecting significant improvement from previous assessments but underscoring the continued urgency of comprehensive reassessment and modernization initiatives. This rating emphasizes the critical need for systematic infrastructure evaluation and strategic investment prioritization.
The current study focused specifically on water levels and dam height relationships, acknowledging important limitations in available data. Additional factors influencing overtopping likelihood include spillway capacity, sedimentation buildup and inflow rate dynamics, but comprehensive data for these components were not available for the selected sites.
Future research directions will integrate these additional variables to create more comprehensive risk assessment models. The study also concentrated on overtopping probability estimation without quantifying potential consequences and downstream risks, representing important areas for continued investigation.
“This study represents the first step toward a comprehensive assessment of dam overtopping probabilities in the U.S. Understanding this potential risk is crucial for protecting communities and prioritizing dam rehabilitation before catastrophic failures occur,” stated co-author Eunsaem Cho, a former FSU postdoctoral researcher currently serving as a research associate at NASA Goddard Space Flight Center.
Strategic Implications for Infrastructure Investment and Policy Development
The research findings provide essential guidance for infrastructure investment prioritization and risk management strategy development. The study enables targeted resource allocation for maximum protective impact by identifying high-risk sites and quantifying probability trends.
The comprehensive nature of this analysis supports evidence-based policy development for dam safety programs, emergency preparedness planning and long-term infrastructure resilience initiatives. The methodology developed can be scaled and applied to broader dam populations, creating systematic approaches for national infrastructure risk assessment.
This pioneering research from FAMU-FSU College of Engineering establishes new benchmarks for dam safety analysis while providing actionable intelligence for protecting American communities from infrastructure-related flood risks. Integrating historical data analysis with contemporary risk assessment methodologies demonstrates the institution’s commitment to addressing critical societal challenges through rigorous scientific investigation.
Editor’s Note: This article was edited with a custom prompt for Claude Sonnet 4, an AI assistant created by Anthropic. The AI optimized the article for SEO discoverability, improved clarity, structure and readability while preserving the original reporting and factual content. All information and viewpoints remain those of the author and publication. This disclosure is part of our commitment to transparency in our editorial process. Last edited: July 21, 2025.
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