The report below documents the regression equations available in StreamStats for Indiana, the methods used to develop the equations and to measure the basin characteristics used in the equations, references to GIS data layers used in the analysis, and the errors associated with the estimates obtained from the equations. Users should familiarize themselves with this report before using StreamStats to obtain estimates of streamflow statistics for ungaged sites.
- Rao, A.R., 2005, Flood-Frequency Relationships for Indiana: Joint Transportation Research Program, Purdue University, FHWA/IN/JTRP-2005/18, 14 p.
The Indiana application of StreamStats features some unique functionality associated with "coordinated discharges." The flood frequency values for many stream reaches in Indiana have been coordinated by the Indiana Department of Natural Resources, the Natural Resources Conservation Service, the U.S. Army Corps of Engineers, and the USGS. That is, these agencies have agreed on flood frequency values for selected stream reaches for use in water resources investigations and planning activities. StreamStats users who select points along these coordinated stream reaches will be provided with the coordinated discharges instead of flow estimates obtained from regression equations. More information about coordinated discharges can be found here.
Stream slope is used as an explanatory variable in the peak-flow regression equations for all hydrologic regions of Indiana except for region 8. The method used by StreamStats to compute stream slope is somewhat different than the method used to develop the dataset used by Rao (2005) for his regression analyses. The average difference between the StreamStats values of stream slope and the values used by Rao is about 4 percent, but differences for some individual stations exceeded 100 percent. As a result, users should consider that the errors associated with the flow estimates provided by StreamStats are probably somewhat greater than the published standard errors of prediction.
StreamStats for Indiana was developed in cooperation with the Indiana Department of Natural Resources.
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