Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois
Research Report
FHWA-ICT-23-014
Links
- More information: Publisher Index Page (via DOI)
- Data Releases:
- USGS data release - Geographic Data for the Estimation of Peak Flow Statistics for Illinois
- USGS data release - Data for Estimating Peak-Flow Quantiles for Selected Annual Exceedance Probabilities in Illinois
- USGS data release - Peak-Flow Frequency Analysis for 464 U.S. Geological Survey Streamgages in Illinois, Indiana, and Wisconsin, Based on Data Through Water Year 2017
- Open Access Version: Publisher Index Page
- Download citation as: RIS | Dublin Core
Abstract
This report presents the methods, results, and applications of an updated flood-frequency study for the State of Illinois. This study, which uses data through September 2017, updates two previous studies that used data through 1999 and 2009, respectively. Flood-frequency estimates are used for a variety of land-use planning and infrastructure design purposes, including for the hydraulic design of bridges. The flood frequencies presented are the stream discharges (or quantiles) that are exceeded each year with a given probability, called the annual exceedance probability (AEP). Estimates are provided for eight AEPs: 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002. The basic data used are the annual maximum discharges (peak flows) at streamgages in and near Illinois and the measurable physical properties (basin characteristics) of the basins upstream from those streamgages. The logarithms of the peak flow records at qualifying streamgages were fit to the Pearson Type 3 distribution using federally recommended methods, providing one of the two primary products of the study, which is the set of peak-flow quantiles at the streamgages and their uncertainties. The other primary product is sets of equations, determined by least-squares regression, that relate the peak-flow quantiles and the basin characteristics. There is one set of equations for each of Illinois’ seven hydrologic regions, and, for each region, one equation for each AEP. These regional equations allow the estimation of peak-flow quantiles at ungaged locations throughout the state and their uncertainties. A set of illustrative example applications is provided, and tables of all results at all study streamgages and regions are provided in associated data releases. The study results are also being made available in a web application, StreamStats.
Suggested Citation
Over, T.M., Marti, M.K., O’Shea, P.S., Sharpe, J.B., 2023, Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois: Research Report FHWA-ICT-23-014, viii, 72 p., https://doi.org/10.36501/0197-9191/23-019.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | State or Local Government Series |
| Title | Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois |
| Series title | Research Report |
| Series number | FHWA-ICT-23-014 |
| DOI | 10.36501/0197-9191/23-019 |
| Year Published | 2023 |
| Language | English |
| Publisher | Illinois Center for Transportation |
| Contributing office(s) | Illinois Water Science Center, Iowa Water Science Center, Central Midwest Water Science Center |
| Description | viii, 72 p. |
| Country | United States |
| State | Illinios |