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

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

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

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

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

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.

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

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.

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.

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

Performance of DCD Based DSM2

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 +/- 1000 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.

Beta Release Packages Linkage to the DCD V1.0 model package   https://data.cnra.ca.gov/dataset/dcd-v1-0 Linkage to the DSM2 V8.2.0 Beta 1 model package   https://data.cnra.ca.gov/dataset/dsm2-8-2-0-beta1 Contact Min Yu, minyu@water.ca.gov

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

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

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.

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

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.

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

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

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.

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.

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 ?