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December 1, 2023

A StreamStats migration on December 1, 2023 updated regression equations for estimating the magnitude and frequency of floods in Illinois. The regression equations, which were developed using streamgages within Illinois and bordering areas of Wisconsin and Indiana, can be used to estimate annual exceedance probability statistics at ungaged basins in seven hydrologic regions of Illinois.

Except for northeastern Illinois (hydrologic region 2), these equations did not use data that include substantial effects of regulation or urbanization. However, the peak-flow quantile estimates and associated confidence intervals calculated by StreamStats for ungaged locations outside of northeastern Illinois (hydrologic region 2) will be urbanization-adjusted values. The regional regression estimates in northeastern Illinois already incorporate the effects of more substantial urbanization. The following report documents the available peak-flow quantile regression equations for Illinois, the methods used to develop the equations and to measure the basin characteristics used as explanatory variables in the equations, and the uncertainty associated with the estimates obtained from the equations:

  • 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 (Report No. FHWA-ICT-23-014). Illinois Center for Transportation. https://doi.org/10.36501/0197-9191/23-019.

Additional details on these regional regression equations as well as other streamflow statistics for ungaged sites in Illinois can be found on the Illinois StreamStats page.

 

Illinois StreamStats

Illinois StreamStats

Northeastern Illinois peak-flow update

Northeastern Illinois peak-flow update

StreamStats regression equation updates for Puerto Rico and Region 2 in Illinois

StreamStats regression equation updates for Puerto Rico and Region 2 in Illinois

Illinois StreamStats peak-flow update

Illinois StreamStats peak-flow update

Warning on use of Illinois StreamStats - Resolved

Warning on use of Illinois StreamStats - Resolved

Warning on use of Illinois StreamStats Basin Delineations - Resolved

Warning on use of Illinois StreamStats Basin Delineations - Resolved

Illinois StreamStats peak-flow regression equations report now available

Illinois StreamStats peak-flow regression equations report now available

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