[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.]
Discussion of the
Greatest Attainable Accuracy
in Measuring the
Fresh-Water Discharge into the San Francisco Bay Estuary
( references |ORE UVM errors |ADCP errors |Rating Curves |Software )

One of the important variables in California water use is the flow of fresh water into the San Francisco Bay through the Carquinez Straits (the Delta Discharge). It is impossible to measure this flow directly at the Carquinez Straits; the small net flow is swamped by the huge semi-diurnal tidal flow, and sound refraction by layers of different salinity further complicate the measurement. These problems can be reduced by moving upstream to four measurement sites in the Delta.

Here we discuss these measurement problems, with particular reference to the Three-Mile Slough measurement site. We examine the major sources of error, and compare them with the precision required to accurately measure the Delta Discharge during the dry season.

Analysis
(click on image for blowup)
Indexing and Calibration Discharge Errors due to Uncertainty in the Rating Curve Timing by Cross-Correlation Chiu's Constant-Entropy Velocity Distributions. Research Log
Numerical model using si3d