[Note: this is an internal working document of a USGS-SFSU collaboration. Data, analysis and results herin should not be considered as final or accurate. Final results will be presented in print.]
Parameters from Model Fits
Rating Curves
( references |Delta Discharge |Rating Curves |Gaussian rating curve )

The UVM velocity can be used to determine discharge if it is calibrated by ADCP measurements of the full vector velocity distribution. This leads to a rating curve, showing the mean channel velocity as a function of UVM velocity. Here we discuss the rating curves from three different calibrations. We have fit a model for the rating curve to these three data sets. We discuss the variation of the daily discharge calculated from the different rating curves. We use this to estimate the error on the discharge due to the uncertainty in the calibration.

calibration fit conditions theta
a (offset)
b (kink) c (amplitude of Gaussian)
d (width of Gaussian)
change in smoothed daily discharge
(% of maximum tidal flow)a
TMS1-2 Full Gaussian bulge 44.409 -0.00857 0.00030 0.00913 0.384 0b
TMS3 Full Gaussian Bulge 42.593 0.00171 -.01857 0.00697 0.322 0.30
TMS4 Full Gaussian Bulge, c not varied in fit 42.256 0.00121 -0.01873 0.008c 0.220 -0.49
  1. Maximum tidal flow at 3-Mile Slough: 30,000 cfs, or 900 m3/sec.
  2. The reference discharge is that computed with the TMS1-2 calibration, full fit.
  3. Not varied in fit.
Table I. Results from fitting three rating curves to the Gaussian-loop model.