Increasing Frequency of Flood Events across the Central United States: A Hierarchy of Whys
About the Talk
The frequency of flood events has been increasing across large areas of the central United States since the second half of the 20th century. Little is known about what is driving these changes, and the fundamental question we ask ourselves is: why? Using an observation-driven approach, we develop a statistical framework to attribute the changes in the frequency of flood peak events to changes in the climate system and to land use / land cover. We focus on 287 U.S. Geological Survey sites with at least 50 years of daily discharge measurements between the second half of the 20th century and the present. Our analyses are performed at the seasonal level and consider five predictors (i.e., precipitation, temperature, antecedent wetness conditions, agriculture, and population density). Results indicate that precipitation and antecedent wetness conditions are the strongest predictors, with the role of the latter that increases as we lower the threshold for the event identification. Furthermore, we highlight the role of weather types in explaining the observed changes in precipitation and, consequently, in the frequency of flood events.
The aim of this presentation is to provide insights into the possible reasons responsible for the changes in the frequency of flood events across the central United States, providing basic information that may enhance our capability of predicting and projecting these changes.
About the Speaker
Gabriele Villarini is an associate professor in the Department of Civil and Environmental Engineering at the University of Iowa, and the Director of IIHR-Hydroscience & Engineering. He received his M.S. in Civil Engineering in 2003 from the University of Rome “La Sapienza,” and his Ph.D. in Civil and Environmental Engineering in 2008 from the University of Iowa; he also received his Executive MBA from the Tippie School of Business at the University of Iowa in 2018. He was a researcher in the Department of Civil and Environmental Engineering at Princeton University from 2008 to 2012. His research interests focus on flood hydrology, extreme events, hydroclimatology, and climate predictions and projections. He has received a number of national and international awards, including the “Hydrological Sciences Outstanding Young Scientist Award” by the European Geosciences Union (2013), the National Science Foundation’s CAREER Award and the Editor’s Award – Journal of Climate” by the American Meteorological Society (2014), and the James B. Macelwane Medal by the American Geophysical Union (2016). He is a Fellow of the American Geophysical Union (2016). He has published over 170 peer-reviewed papers, including articles in Nature, Science, Nature Climate Change and the Proceedings of the National Academy of Sciences. He served as a member of the American Geophysical Union Precipitation Committee and of the U.S.-CLIVAR Working Group on Hurricanes and Climate.