[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.]
Research Log of Work
Effect of Changing the Rating Curve Slope Angle
on the
Smoothed Daily Discharge
( references |Software )

The question arose as to whether the difference in smoothed daily discharge for the Oct 10-Nov. 21 1996 test period was due to the different slope angle in the TMS1 calibration. Presumably the TMS1 calibration is the right one to use in 1996, and the two others reflect in their parameters the different position of the east piling, after it broke off in the storm of Jan. 1997. So in this test I changed the TMS1 angle to be the same as TMS3, and repeated the calculation of discharge.
It is still true that TMS3 and TMS4 give the same discharge, to remarkable precision. And it is still true that they disagree with TMS1. Now the average difference is about 6 m3/sec, TMS1 higher. This compares with a difference of about 4.5 m3/s with the best-fit angle for TMS1. Thus, the difference is not due to the difference in slope angle.