Thomas Over, hydrologist at the U.S. Geological Survey’s (USGS) Illinois Water Science Center, is currently serving as co-principal investigator on Illinois Center for Transportation/Illinois Department of Transportation (ICT/IDOT) project R27-144 “Development and Implementation of Updated Urban Regional Flood Frequency Equations for Illinois.”
The objective of this research is to update the 1979 Illinois urban regional flood-frequency equations to current urbanized conditions and implement the resulting equations in StreamStats, a Web-based geographic information systems (GIS) application used in water resources planning and management and in engineering design.
A set of regional urban flood frequency equations for Illinois was last determined in 1979 using streamflow data through 1976; while these equations remain part of the Illinois Department of Transportation Drainage Manual, additional streamflow data have been obtained since the time of the study, and the nature of urbanization has changed.
“When completed, the updated urban regional flood frequency equations will be implemented in StreamStats so that the up-to-date peak-flow estimates can be conveniently and accurately obtained for the urban areas of Illinois,” says Over. “It is anticipated that IDOT will make use of this study to check the design peak-flow discharges provided by consultants in a quick-and-easy, but also scientifically justified, manner.”
The project, led by an IDOT Technical Review Panel chaired by Matthew O’Connor, Bridge Hydraulic Engineer at IDOT, is expected to be completed by the end of January, 2016.
Over has also assisted with several other ICT/IDOT projects, including “Pier Scour Prediction in Cohesive Soils: Use of EFA-SRICOS Method in Illinois” (R27-019), completed in 2010, and “Improvement of IDOT Bridge Scour Estimation Method at Sites with Cohesive Soils Using SRICOS Zmax” (R27-105), completed in 2013. Both projects focused on developing methods for estimating bridge scour in cohesive soils in Illinois and were undertaken for the purpose of replacing other commonly used methods, which resulted in overestimates of scour potential and potentially unnecessary construction expense. Through a combination of field, laboratory, and modeling work, Over and Timothy D. Straub, principal investigator on both projects, also of the USGS Illinois Water Science Center, developed a scientifically justifiable approach to reduce the overdesign of bridge foundations while maintaining a suitable safety factor.
Over holds bachelor’s and master’s degrees in civil engineering from Massachusetts Institute of Technology and Stanford University, respectively, and a Ph.D. in geophysics from the University of Colorado. He is a member of a USGS-wide team working on the National Water Census to develop and test daily streamflow estimation methods for application throughout the United States.