1. Beta Release of Delta Channel Depletion Model (DCD v1
Beta Release of Delta Channel Depletion Model (DCD v1.0) and its compatible DSM2 Historical Simulation
Lan Liang
Bay-Delta Office
Department of Water Resources
Delta Modeling User Group
June 20th, 2018

2. Acknowledgements DWR Bay-Delta Office Tariq Kadir Bob Suits
Nicky Sandhu
Tara Smith
Jon Shu
Wenli Yin
Yu Zhou

3. Goals for developing channel depletion models
The actual Delta hydrology
The historical Delta outflow
Salinity intrusion
Local channel depletions impact on local water quality

4. Model Development History
Delta channel depletion models in Bay-Delta Office CU
DICU
DCD v1.0 (DETAW v2.0 is included)

5. Channel Depletion
The amount of water transferred between Delta island ground surface and adjacent channels
Components Diversions(+)
Seepage(+)
Drainage(-)
NDO = inflows – exports – Delta channel depletion

6. behind DCD V1.0 Development
Guiding Ideas
behind DCD V1.0 Development
Channel depletions are not necessarily equal to consumptive use.
The current methodology to apply consumptive use to estimate channel depletions should be systematic and simple.
DSM2 can be used to develop and test a first attempt at this concept.
Hopefully there will be future collaboration and inclusion of all Delta models in the effort.

7. Principle behind DCD V1.0 Island root zone water balance:
Crop evapotranspiration (ET) =
effective irrigation + effective seepage + effective rainfall + soil moisture change
Channel water loss:
- Irrigation
- Leach applied water
- Seepage
Supplied ET
Stored in root zone
Stored in groundwater
Channel depletion
Channel depletion
Channel water gain:
- Runoff
- Drainage of the residual irrigation
- Leach drainage
- Drainage to maintain the groundwater table in the Lowlands

8. The Characteristics of DCD v1.0 Beta Release
Estimates daily channel depletions including diversions, seepages and drainages of 168 islands and DSM2 nodes.
Simulation periods: WY1922 – 2016.
Synthesizes the concepts of DICU and DETAW v2.0.
Considers surface water and groundwater contributions to meet ET.
Integrates DCD v1.0 and DSM2 to estimate relatively reasonable magnitudes of subsurface water/groundwater contributions, Delta channel depletion and Delta outflow.

9. The Characteristics of DSM2 v8.2.0 Beta 1
It adopts DCD v1.0 daily channel depletions to replace DICU monthly values.
The dispersion coefficients in the confluence area of Sacramento River and San Joaquin River were calibrated due to introducing DCD v1.0 channel depletions.
DSM2 code and the pathnames to retrieve the DCD v1.0 data have been modified accordingly.

10. Performance of DCD v1.0
Minimums, maximums and averages of DCD-estimated monthly
Delta ET and channel depletion from 1975 through 2015

11. Performance of DCD Based DSM2

12. Performance of DCD Based DSM2
Compared to DICU-based Delta simulations
Monthly Delta channel depletion estimated by DCD can differ from DICU’s by more than +/ cfs.
Channel depletion under DCD tends to be:
lower during irrigation season
higher during the winter months.
With recalibration, simulated historical EC under DCD
generally closer to observed than DICU-based simulation and much closer to observed when DICU-based simulation shows greater error.

13. Beta Release Packages Linkage to the DCD V1.0 model package
Linkage to the DSM2 V8.2.0 Beta 1 model package
Contact
Min Yu,

14. DCD V1.0 Beta Release Package
Technical reports User’s manual
DCD program

15. File Structure of DCD v1.0 Inputs Outputs Input 1: DETAW outputs
\DCD_inputs
Input 2: DICU parameters
\NODCU
Input 3: Leach application
\NODCU\LEACHAPL.DAT
Run DCD model: DCD.py
DCD_MMMYYYY.dss
Input 4: Leach drainage \NODCU\LEACHDRN.DAT
Input 5: Groundwater contribution rate \NODCU\GW_RATES.txt

16. Input 1: DETAW Outputs Under the folder \DCD_inputs
The DETAW v2.0 outputs
Daily crop ET
Runoff
Effective seepage
Applied water
Water surface evaporation
They are processed to be DCD v1.0 inputs automatically.

17. Input 2: DICU Parameters
\NODCU
Only this file requires updating.

18. Input 3 & 4: Leach Application and Drainage
Five times of the annual leach water as DICU assumed to meet better EC estimation.
The monthly distribution of the annual leach water have been adjusted based on DICU assumption.
Need more investigation.

19. Input 5: Groundwater Contribution Rate
Annual rate
For Delta uplands only
Based on the amount of irrigation wells
Keep 0.4 for the following years

20. Run DCD v1.0 Install Python and Vtools
Install Command Prompt (optional)
DETAW v2.0 runs automatically when DCD is called.

21. Outputs DCD_MMMYYYY.dss in \DCDv1.0
Daily diversions, drainages and seepages on DSM2 nodes from 1922 through 2016.
It can be directly taken as the Delta consumptive use input for DSM2 v8.2.0 beta 1.

22. Final Comments
DCD is beta release. Any suggestions or questions are welcome.
The documents are intended to provide answers for technical questions.
The calibration of the integrated DCD-DSM2 model determines the Delta-wide channel depletion and Delta outflow in reasonable magnitudes.
Further investigation: the internal physics to cause much higher winter diversions; the spatial distribution of ET; the locations and amounts of local diversions and drainages.

23. The Achieved Goals for DCD v1.0?
The actual Delta hydrology
The historical Delta outflow
Salinity intrusion
Local channel depletions impact on local water quality ?