civil and environmental engineering
Dan Moser, July 24, 2025
Husker researcher studying impacts of rain-on-snow flood risk
Roy to leverage local information to address global challenge
Nearly six years ago, about 230 scientists from around the world identified 23 of the most pressing unsolved problems in hydrology. University of Nebraska–Lincoln researcher Tirthankar Roy is now tackling one of them — understanding the flood risk posed by rain falling on snow, a threat especially severe in the Midwest.
Roy, associate professor of civil and environmental engineering, has received a five-year, $673,168 grant from the National Science Foundation’s Faculty Early Career Development Program to support this work.
The phenomenon is well known to Midwesterners: When the ground is covered by a significant snowpack, rainfall and rising temperature can create rapid snowmelt.
“This often leads to exceptional runoff, causing flooding and destruction in the communities impacted,” Roy said.
The most recent widespread rain-on-snow event in Nebraska, in spring 2019, contributed to historic flooding.
Roy will lead a team to conduct a comprehensive assessment of rain-on-snow flood risk in the Midwest, using machine learning and other methods to investigate the factors that contribute to these events, their characteristics, and how they vary in space and time.
“To my knowledge, the study will be the most comprehensive assessment of rain-on-snow flooding carried out to date,” Roy said.
He expects the findings to set a benchmark for assessments elsewhere in the world, noting the inclusion of the rain-on-snow phenomenon on th elist of unsolved problems published by Hydrological Sciences Journal in July 2019.
“ROS floods are not thoroughly considered in mainstream water resources-related decision-making, and we want to bridge that gap through this comprehensive assessment and the associated outreach activities,” he said.
Roy said the research could lead to better flood mitigation efforts.
As part of the education and outreach component of his CAREER project, Roy will create curricula for students as well as resources and information for community leaders. He will also train and mentor undergraduate and graduate students in research under this project.
The National Science Foundation’s CAREER award supports pre-tenure faculty who exemplify the role of teacher-scholars through outstanding research, excellent education, and the integration of education and research.
