Department of Water Resources Home

Michal Koller
Environmental Planning and Information Branch
Dayflow Program
3500 Industrial Blvd.
West Sacramento, CA 95691
(916) 376-9728

Mailing Address:
P.O. Box 942836
Sacramento, CA 94236-0001
Dayflow Documentation

The Dayflow Documentation has been modified over the years as the computational scheme has changed to reflect conditions and data. The original Dayflow Documentation contains the computational scheme that was used to back-calculate the 1930-1956 Dayflow output. The 1986 Dayflow documentation guided Dayflow estimates until 1996. The full Dayflow Documentation describes the computational scheme used for the current releases of all Dayflow output. Dayflow output between 1997 and present is calculated based on the current documentation. Some Dayflow Parameters are observed data, which are not calculated by Dayflow. Dayflow input station maps lists these parameters.

Summaries of annual Dayflow output highlights and modifications are presented annually in the IEP Newsletter. The same summaries are archived on the Dayflow Data Through Water Year 2016.

The following link provides quick access to all Dayflow parameters:

Observed Data Parameters

Computational Scheme Part 1

  • Net Delta Outflow Index (NDOI) At Chipps Island (QOUT) (compare NDO vs NDOI)
  • Total Delta Inflow (QTOT)
  • Eastern Delta Inflow(QEAST)
  • Miscellaneous Stream Flow (QMISC)
  • Yolo Bypass Addition to the Delta Water Balance (QYOLO)
  • Delta Precipitation Runoff Estimate (QPREC)
  • Deltawide Gross Channel Depletion Estimate (QGCD)
  • Net Channel Depletion (QCD)
  • Total Delta Exports and Diversions/Transfers (QEXPORTS)
  • Export⁄Inflow Ratio (EXPIN)

Computational Scheme Part 2

Interior Delta Flow Estimates

  • Delta Cross Channel and Georgiana Slough Flow Estimate (QXGEO description and equation)
  • San Joaquin River Flow Estimate Past Jersey Point (QWEST)
  • Sacramento River Flow Estimate Past Rio Vista (QRIO)

Summary of Fish-Related Parameters and Indices

Input Data Documentation

Estimated Input Parameters Requiring Further Explanation

  • Delta Gross Channel Depletion Estimates (QGCD)
  • Delta Precipitation Runoff Estimates (QPREC)
  • Delta Cross-Channel and Georgiana Slough Flow Estimate (QXGEO)
  • State Water Project Exports (QSWP)
  • Miscellaneous Water Diversions⁄Transfers (QMISDV)
  • Estimated distance from Golden Gate to 2 ppt Sailinity, km (X2)

Methodology for Dayflow Output Generation

Summary of Equations

Tables Figures
Table 1 – Definition of Quantities Used to Determine QEFFECT Figure 1 – Map
Table 2 – Input Data Documentation Figure 2 – Delta Hydraulic Scheme
Table 3 – Delta-Wide Gross Channel Depletion Estimates Figure 3 – Streamflow and Precipitation Stations
Table 4 – Miscellaneous Diversions Figure 4 – Relationships Between Flows in Georgiana Slough, Delta Cross-Channel, and Sacramento River
Table 5 – Delta Islands Flooded From 1955-1984 Figure 5 – Hydrologic Data for the Sacramento – San Joaquin Estuary
Table 6 – Dayflow Input DSS Pathnames