NSF CAREER Award to Improve Flood Hazard Assessments
MES/CEE Assistant Professor Samuel Muñoz was awarded a $718,000 NSF CAREER award for “Sedimentary signatures of large riverine floods to constrain risk and build resiliency.”
Samuel Muñoz, assistant professor, marine and environmental sciences and civil and environmental engineering, has been awarded a $718,000 National Science Foundation CAREER grant to study floodplain sedimentation through observation and simulation to improve flood hazard assessments.
Flood hazard assessments are crucial tools for developers, municipalities, and insurers in deciding where to site new buildings or infrastructure near rivers. Used to determine the likelihood of flooding in a particular area, these assessments rely chiefly on historical data—measures of a river’s high and low points over the years, or the volume of water that has flowed through it. Muñoz points out a problem with this common approach, however.
“We tend to underestimate how much water can flow through a river,” he says, because relevant historical records in the United States only go back so far, in many cases only a few decades. Describing a mere fraction of the geologic time scales in which rivers exist, these records provide a very limited view of their behavior.
“It leads to some pretty poor decisions about where we build things in floodplains,” Muñoz explains. “The economic losses associated with flooding over the last 30 or 40 years keep increasing.”
To better understand the dynamics of rivers, including their potential for flooding, Muñoz has focused for much of his career on the field of paleoflood hydrology. By examining the shape and size of channels that rivers carve in a landscape, as well as nearby sedimentary deposits, scientists can piece together a record of how that river rose, fell, flooded, and changed its course in the distant past. While combining such observations with recorded historical measurements can yield a fuller picture of a river’s history, it can still create inaccuracies when applied to flood frequency analysis, according to Muñoz, due to uncertainties inherent in prehistoric geological study.
Muñoz’s project, “Sedimentary Signatures of Large Riverine Floods to Constrain Risk and Build Resiliency,” aims to mitigate such uncertainty by combining systematic, long-term observations with hydraulic model simulations to create more accurate flood hazard assessments. Key to his research project is the creation of a floodplain observatory, a collection of data-gathering instrumentation including sediment traps, water level and temperature sensors, and accelerometers, situated on a stretch of the Merrimack River in Concord, New Hampshire. Muñoz chose the location in part due to its “oxbow” lakes, features characteristic of low-lying rivers that represent paths taken by the river in the past. Muñoz will collect sediment from these lakes, and from nearby surface areas and subsurface core samples, to establish when and how the floodplain was inundated in the past.
Data from the observatory will be used to calibrate and validate a computer model of flooding in the study area—a model that can then be used to generate simulations of flooding events under different circumstances. The insights developed through observations and simulations will help generate high-quality paleoflood estimates—the first for the Merrimack River, according to Muñoz.
The workflow and toolsets that will result from his project could transform our ability to reconstruct prehistoric floods on lowland river systems. “Going forward,” he says, “anyone could do this on an area of interest and vastly decrease the uncertainty in our flood hazard assessments.”
Combined with his research strategy is an education and outreach plan intended to broaden participation in scientific research by students from underrepresented groups. Another reason he chose the Merrimack River for his floodplain observatory, Muñoz explains, is that a community college, New Hampshire Technological Institute (NHTI), sits beside it, among the oxbow lakes he intends to study. Muñoz plans to enlist the help of NHTI students in the operation of the observatory, providing opportunities for capstone projects and practical experience with instrumentation and computational techniques. He also foresees additional student opportunities related to the study via internships at Northeastern and a K-12 outreach program that introduces youth to local habitats and the tools and methods that scientists use to study the environment.
Muñoz hopes that this engagement with students serves to diversify the next generation of geoscientists and helps the public recognize the critical role of rivers in maintaining valuable services for society.