Kansas Real-Time Water Quality

Kansas Real-Time Water Quality

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USGS station:	Go to NWISWeb
Constituent:
Time period:
Model Form:

Model Form #3

NO3+NO2 = 1.77 - 0.00065 SC - 0.0995 Chls + 0.163 sin(2π D / 365) - 0.0823 cos(2π D / 365)

where:

NO3+NO2 is computed nitrate plus nitrite, in milligrams per liter as nitrogen
SC is specific conductance at 25 degrees Celsius, in microsiemens per centimeter
Chls is chlorophylls, in relative fluorescence units
D is day of year, in the range of integers 1 through 365

Model Calibration

Basic Data

Number of measurements:	73
Mean squared error:	0.106276
Multiple R²:	0.615
Bias correction (smearing) factor:	1

Explanatory Variables

Variable	Value	Standard error
Intercept	1.77	0.128
SC	-0.00065	0.000188
Chls	-0.0995	0.0179
sin(2π D / 365)	0.163	0.0555
cos(2π D / 365)	-0.0823	0.0625

Correlation Matrix

	Intercept	SC	Chls	sin(2π D / 365)	cos(2π D / 365)
Intercept	1	-0.886	0.217	0.136	0.456
SC	-0.886	1	-0.567	-0.162	-0.442
Chls	0.217	-0.567	1	0.204	0.266
sin(2π D / 365)	0.136	-0.162	0.204	1	0.116
cos(2π D / 365)	0.456	-0.442	0.266	0.116	1

Reference

Williams, T.J., 2021, Linear Regression Model Documentation and Updates for Computing Water-Quality Constituent Concentrations or Densities using Continuous Real-Time Water-Quality Data for the Kansas River, Kansas, July 2012 through September 2019: U.S. Geological Survey Open-File Report 2021-1018, 18 p.