"Surrogate" Constituent Models are developed at USGS streamflow gages, called Super Gages, throughout Ohio, Kentucky, and Indiana. Each Super Gage deploys a variety of in-situ continuous water-quality monitors and is intermittently sampled for water-quality constituents over the range of hydrologic and seasonal conditions. By statistically combining continuous water-quality data with intermittent samples, models are developed to continuously estimate constituents that are not easily measured in real-time. For example, after a Surrogate Constituent Model is developed, turbidity (clarity of water) may be used to estimate suspended sediment concentration. Click here for a list of Ohio-Kentucky-Indiana Water Science Center Surrogate Constituent Models.
Many states provide hourly computed concentrations and loads for sediment, nutrients, bacteria, and many additional constituents; uncertainty values and probabilities for exceeding drinking water or recreational criteria; frequency distribution curves; and all historical hourly in-stream sensor measurements.
USGS National Real-Time Water-Quality Web Site
Ohio-Kentucky-Indiana Water Science Center regression models are listed in the table below. The list of these models also is available as a Microsoft Excel spreadsheet.
| Data | Sampled Concentration Rangea |
Regression Model | Explanatory variable range (FNU)b |
RMSE | R2 | n | Bias correction or smear factor |
NRTQW web sitec |
Date Model Approvedd |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Start | End | Start | End | ||||||||
| Yellow River near Oak Grove, IN (USGS Site ID: 05516665) | |||||||||||
| 2012 | 2013 | 1-169 | log10(SSC)=0.7856*log10(TURB)+0.5645 | 0.8-130 | 0.157 | 0.83 | 22 | 1.0632 | 2014 | present | 8/19/2014 |
| Yellow River at Knox, IN (>USGS Site ID: 05517000) | |||||||||||
| 2012 | 2013 | 14-1050 | log10(SSC)=1.2269*log10(TURB)+0.0854 | 9.7-160 | 0.21 | 0.84 | 17 | 1.1146 | 2014 | present | 8/13/2014 |
| Yellow River near Brems, IN (USGS Site ID: 05517010) | |||||||||||
| 2012 | 2013 | 4-1150 | log10(SSC)=0.745+(0.191*sqrt(TURB)) | 0.3-150 | 0.18 | 0.91 | 27 | 1.083 | 2015 | present | 8/27/2014 |
| White River at Hazleton, IN (USGS Site ID: 03374100) | |||||||||||
| 2010 | 2011 | 16-434 | log10(SSC)=0.968*log10(TURB)+0.330 | 9-170 | 0.08 | 0.96 | 13 | 1.015 | 2014 | present | 2/21/2012 |
| Eagle Creek at Zionsville, IN (USGS Site ID: 03353200) | |||||||||||
| 2010 | 2014 | 4-903 | log10(SSC)=0.7837*log10(TURB)+0.6015 | 2-460 | 0.26 | 0.77 | 37 | 1.1722 | 2014 | present | 5/20/2015 |
| Kankakee River at Davis, IN (USGS Site ID: 05515500) | |||||||||||
| 2013 | 2015 | 1.2-130 | SSC=14.362*sqrt(TURB)-8.662 | 7-161 | 8.74 | 0.94 | 20 | NA | 2016 | present | 03/7/2016 |
aConstituent and unit of measurement: suspended-sediment concentration (SSC) in milligrams per liter (mg/L).
bExplanatory Variables: Turbidity (TURB, YSI 6136).
cYears regression has been available on USGS National Real-Time Water-Quality (NRTQW) web site.
dModels listed followed protocols from Rasmussen, P.P., Gray, J.R., Glysson, G.D., and Ziegler, A.Z., 2009, Guidelines and Procedures for Computing Time-Series Suspended-Sediment Concentrations and Loads from In-Stream Turbidity-Sensor and Streamflow Data: U.S. Geological Survey Techniques and Methods book 3, chap. C4, 53 p.