SOUTH AMERICAN SUBBASIN GSPGSP Working Group Workshop # 8

CoSANA Model Session 3

1

October 16, 2020

SASb GSPWG:

• County of Sacramento

• Northern Delta

• Omochumne-Hartnell Water

District

• Sacramento Central

Groundwater Authority

• Sloughhouse RCD

CoSANA Model – Development and Application Agenda

▪ Session 1- June 2020 GSPWG Meeting No. 3

▪ Introduction to the Model

▪ Model Development History

▪ Model Features

▪ Session 2- September 2020 GSPWG Meeting No. 7

▪ CoSANA Model Background

▪ Model Development

▪ Model Grid

▪ Hydrology

▪ Land Use and Water Demand

▪ Session 3- October 2020 GSAPWG Meeting No. 8

▪ Hydrogeology

▪ Water Supplies

▪ Model Calibration

▪ Historical Water Budgets

▪ Baseline Assumptions

2

3

Model Grid Network

HydrogeologySubregion and

Subarea Delineation

Stream Network & Geometry Soil Types

Element Configuration

Model Stratigraphy

Surface Water Delivery

ET and Crop Water Use

GW Pumping & Wells

Land Use and Cropping Pattern

Rainfall Rate and Distribution Streamflow

Urban Water Use

Boundary Conditions

Initial Conditions

Small Watershed

Runoff

Calibration Calibration Wells

Stakeholder Collaboration

CoSANA Model Data Needs

3

Water Supplies

4

Water Supply Data – South American Subbasin

5

DRAFT

Hydrogeology

6

7

South American SubbasinGeologic Map

Source: Wagner, D.L. et al. Geologic Map of the Sacramento quadrangle, California. 1981.

Formation Thickness Physical Characteristics

Alluvium 0-100 Unconsolidated sand, gravel, silt and clay

Laguna Formation 125-200 Bedded silts, clays, and sands

Mehrten Formation 200-1200Beds of black volcanic sand, brown clay and sand,

andesitic origin

Valley Springs

Formation75-125

Beds of light colored sand and ash, greenish brown

silty sand, rhyolitic origin

Ione Formation 100-400 medium grained quartz sandstone, thick beds of clay

Basement -Slate, sandstone, greenstone, schist, metavolcanics,

granodiorite

Model Hydrogeologic Layers – 5 Layer

G’

South

G

North

D’

EastD

West

8

Geologic Profiles Along Rivers

9

SASb Aquifer System

10

Formation Approx.

Thickness (Ft)

Geologic Age Approximate

Age

Alluvium 0-100 Victor/Fair

Oaks/Riverbank

/Alluvium

Present to

3 MYA

(Million Years

Ago)

Laguna 125-225+ Late Pliocene to

early

Pleistocene

1-3 MYA

Mehrten 200-1,200 Middle Miocene

to Middle

Pliocene

4-10 MYA

Valley Springs 75-125 Middle Miocene 15 MYA

Ione 100-400 Middle Eocene 40 MYA

DWR Bulletin-118 (2003)

11

Source: CA Department of Water Resources

▪ Develop a relationship between:

▪ Land surface processes

▪ Hydrology cycle:

▪ Climate

▪ Surface

▪ Subsurface

▪ Geology

▪ Movement of water through the entire system

CoSANA Model Concept

Collaborative Calibration

▪ Following Entities Have Been Engaged in the Calibration Process:

▪ Regional Water Authority

▪ GSA Representatives (NASb, SASb, COSb)

▪ Consultants: Woodard & Curran, EKI, LWA, GEI

▪ W&C: Overall model development and calibration

▪ EKI: Calibration of the Cosumnes Subbasin portion of the model

▪ LWA: Cosumnes River corridor data development

▪ Numerous model collaboration workshops

▪ Model Calibration Review and Completion Workshop: September 29, 2020

12

Calibration Goals and Process

▪ Ensure reasonable water budget for various components of the Model

▪ Modify aquifer parameters within reasonable range to achieve reasonable match between model calculated values and reported/observed data for:

▪ Land surface processes: ET, Ag Demand, Runoff, Percolation

▪ GW Processes:

▪ GW Levels at select wells

▪ GW Flow Directions

▪ Subsurface Flows

▪ Stream System:

▪ Streamflows at select stream gaging stations

▪ Stream-aquifer interaction

13

• Select GW Level Hydrographs and Calibration Statistics

• Select Streamflow Hydrographs

• Stream-Aquifer Interaction

• Water Budgets• Land & Water Use

• Groundwater

Calibration Results

14

Map of ALL Target Calibration Wells

15

▪ South American Subbasin has 152 wells used for calibration*

▪ Calibration uses data from 1990-2018

*Note: multicompletion wells are counted as 1 well for

each interval

Groundwater Hydrographs (SASb)

DRAFT

Groundwater Hydrographs (SASb)

DRAFT

Calibration Statistics

▪ Map of Residuals

▪ Scatter Plots

▪ Residual Histogram

18

Model Calibration Summary – Residuals

DRAFT – Subject to RevisionDRAFT

Simulated vs. Observed (SASb)

DRAFT

Residuals (SASb)

DRAFT

Calibrated Parameter Ranges (SASb)

1 2 3 4 5

Min 3.4 2.8 1.0 1.2 0.6

Avg 40.3 26.1 15.6 12.6 9.3

Max 108.1 73.1 45.3 30.4 40.9

Min 0.06 0.07 0.07 0.07 0.07

Avg 0.12 0.12 0.12 0.12 0.10

Max 0.24 0.22 0.20 0.21 0.20

Min 3.11E-06 1.87E-06 1.54E-06 5.05E-06 9.80E-06

Avg 3.85E-05 4.00E-05 3.92E-05 3.85E-05 5.02E-05

Max 7.62E-05 6.96E-05 7.30E-05 6.09E-05 7.83E-05

Layer

Kh

[ft/day]

Sy

[unitless]

Ss [1/ft]

South American

Subbasin

DRAFT

Streamflow Calibration

23

Streamflows for Sacramento River at Freeport

24

1

10

100

1,000

10,000

100,000

1,000,000

0%

10

%

20

%

30

%

40

%

50

%

60

%

70

%

80

%

90

%

100

%

Stre

amfl

ow

(cf

s)

Exceedance Probability

Sacramento River at Freeport

DRAFT

American River Stage at H Street Bridge

25

DRAFT

Cosumnes River Stage near McConnell

26

DRAFT

???

Cosumnes River Profile Animation

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DRAFT

Cosumnes River Profile Animation

28

DRAFT

Cosumnes River Wet/Dry Channel*

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0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1/1/2004 9/27/2006 6/23/2009 3/19/2012 12/14/2014 9/9/2017

Flo

w (

AF/

mo

)

Date

Site 1 - Stream Node 1767

CoSANA Dry Observations

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1/1/2004 9/27/2006 6/23/2009 3/19/2012 12/14/2014 9/9/2017

Flo

w (

AF/

mo

)

Date

Site 2 - Stream Node 1751

CoSANA Dry Observations

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1/1/2004 9/27/2006 6/23/2009 3/19/2012 12/14/2014 9/9/2017

Flo

w (

AF/

mo

)

Date

Site 3 - Stream Node 1682

CoSANA Dry Observations

DRAFT* Dry Riverbeds identified based on satellite imagery; LWA (2020)

Cosumnes River Wet/Dry Channel

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DRAFT* Dry Riverbeds identified based on satellite imagery; LWA (2020)

Water Budgets

31

SASb Land & Water Use Budget

321

97

0

19

72

19

74

19

76

19

78

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

20

00

20

02

20

04

20

06

20

08

20

10

20

12

20

14

20

16

20

18

-200

-150

-100

-50

0

50

100

150

200

Tho

usa

nd

Acr

e-F

eet

Water Year

Ag GW Ag SW Ag Demand

19

70

19

72

19

74

19

76

19

78

19

80

19

82

19

84

19

86

19

88

19

90

19

92

19

94

19

96

19

98

20

00

20

02

20

04

20

06

20

08

20

10

20

12

20

14

20

16

20

18

-250

-200

-150

-100

-50

0

50

100

150

200

250

300

Tho

usa

nd

Acr

e-F

eet

Water Year

Urban GW Pumping Remediation Pumping Urban SW Deliveries

Urban Demand Urban RW Deliveries

From: CoSANA v0.2.6

DRAFT

SASb Land & Water Use Budget

33

158,500

175,500

Average 2000 - 2018(Acre-Feet/Year)

Ag Demand Urban Demand

Total Demand

Adjusted for Shortage/Surplus

Total Demand = Total Supply (Excluding Remediation Pumping) = 334,000 AFY

From: CoSANA v0.2.6

DRAFT

South American Subbasin GW Budget

34From: CoSANA v0.2.6DRAFT

SASb Groundwater Budgets

35From: CoSANA v0.2.6DRAFT

Inflows to GW System Outflows from GW System

Rural Residential Water Balance

36

Estimating the Rural Residential Water Budget

▪ To characterize the water budget in the Subbasin, we need to properly estimate water use and return flows in rural residential areas not served by a municipal water supplier or municipal wastewater agency

▪ These areas are shown on the map to the right along with population/acre from US Census Bureau population data

DRAFT

Estimating the Rural Residential Water Budget

▪ Balance of Use & Return = Pumping – Deep Percolation

▪ Pumping per acre estimated using population and estimates of gallons per capita per day

▪ Deep Percolation of indoor water use:▪ 100% of indoor use assumed to return to aquifer (via

septic systems)

▪ Deep Percolation of outdoor water use:▪ Percentage of pumping that returns to aquifer estimated

as a function of land use and soil permeability

DRAFT

Estimated Net Groundwater Use Rural Residential Areas

Groundwater

Pumping

Deep Percolation

Indoor Use

Outdoor Use

▪ Average Annual Estimates (AF per Acre):

▪ Pumping: 0.37

▪ Deep Percolation: 0.21 to 0.24

▪ Balance of Use vs Return:

▪ -0.16 to -0.13 AF/acre

ET / Runoff

0.17

0.20

0.20 0.01 to 0.04

0.16 to 0.13

0.21 to 0.24

0.37

-0.16 to -0.13

Balance of Use vs Return

Percolation Factor

6% to 24%)

DRAFT

Conclusions

▪ Model assumptions and data sets are reasonably complete

▪ Additional calibration refinement may be warranted once data from following are received:▪ CalAm Water Company

▪ EGWD

▪ Mather Air Reserve Base

▪ Given the limitations on the data and physical understanding of the Subbasin, the model calibration is reasonable for use in the GSP for:▪ Water Budget Analysis

▪ Development of the Current and Projected Baselines

▪ Use for Sustainable Yield Estimation

▪ Use for Sustainable Management Criteria

40

DRAFT

Assumptions are to be confirmed

Work to be completed by November GSPWG Meeting

Baseline Assumptions

41

Water Budgets: Defining Time Frames

Historical Conditions

Historical

* Land use

* Water use

* Hydrology

Current Conditions

Current

* Land use

* Water use

Historical

* Hydrology

Projected Conditions

Projected

* Land use

* Water use

Historical

* Hydrology

Projected with Climate

Change

Projected

* Land use

* Water use

Projected

* Hydrology

Historical & Baseline Hydrologic Period

43

Calibration Period

Historical & Baseline Hydrologic Period

44

Historical Conditions Water Budget

▪ Historical conditions are covered under the historical calibration model.

▪ Work complete, pending QC

▪ Time period and details of budget to be determined

COMMITMENT & INTEGRITY DRIVE RESULTS

Current Conditions Baseline (CCBL)

Current Conditions Baseline Assumptions

▪ Hydrologic Conditions▪ 50 years of hydrology (WY 1970-2019)

▪ Land Use and Cropping Pattern▪ 2015 Sacramento County Survey

▪ Urban Demand▪ Existing urban water demand (Approx. 2018, per the UWMP)

▪ Ag Demand▪ Ag demand reflective of most current land use (2015 survey)

Current Conditions Baseline Assumptions

▪ Municipal / Remediation Pumping▪ Existing wells and GW infrastructure for each purveyor

▪ Current remediation and GW supply pumping rates

▪ Surface Water Deliveries: Current level of SW deliveries

▪ Agricultural Groundwater Substitution Transfers: None

▪ Municipal Groundwater Substitution Transfers:▪ City of Sacramento

▪ Golden State Water Company

▪ Sacramento County Water Agency

Need for Stakeholder Input

▪ Wherever recent historical conditions are different from current or

near-term practices➢ Diversions

➢ Pumping

➢ Water supplies

➢ Demands

➢ Water transfers

COMMITMENT & INTEGRITY DRIVE RESULTS

Projected Conditions Baseline (PCBL)

Projected Conditions Baseline Assumptions

▪ Hydrologic Conditions▪ 50 years of hydrology (WY 1970-2019)

▪ Land Use and Cropping Pattern▪ Urban sphere of influence for 2035-2040 or buildout conditions

▪ Urban Demand▪ Urban water demand reflective of 2035-2040 conditions (purveyors, UWMPs)

▪ Demand met by groundwater except where surface water is planned or required

▪ Ag Demand▪ Ag demand reflective of most current land use (2015 survey)

Projected Conditions Baseline Assumptions

▪ Municipal / Remediation Pumping▪ Existing wells and GW infrastructure for each purveyor, unless reported by specific purveyor

▪ Current remediation and GW supply pumping rates, unless reported by the remediation entities

▪ Surface Water Deliveries: Current level of SW deliveries

▪ Recycled Water Deliveries: None for Baseline

▪ Agricultural Groundwater Substitution Transfers: None

▪ Municipal Groundwater Substitution Transfers:▪ City of Sacramento

▪ Golden State Water Company

▪ Sacramento County Water Agency

Needs for Stakeholder Input – Demand/Supply

▪ Assumption of continued cropping patterns

▪ Locations for potential new well facilities

▪ Potential for decreased remediation pumping

Needs for Stakeholder Input – Major Projects

▪ Harvest Water (formerly South County Ag)

▪ City of Sacramento Groundwater Master Plan

▪ Regional Water Banking

▪ OHWD Recharge/Water Banking

▪ SAFCA Recharge/Water Banking

▪ Development Projects (next slide)

▪ Others?

Needs for Stakeholder InputMajor Development Projects

▪ Many entitled projects

▪ Will align proposed developments with UWMP assumptions

Needs for Input – Projected Water Supply for Major Developments

▪ Many project have complex water supply proposals or requirements

▪ Identify water supply sources to meet anticipated urban growth under proposed developments

▪ Surface water

▪ Groundwater

▪ Recycled water

▪ Identify new pumping wells under proposed developments

Next Meeting - Calibration Process

November 2020: Baseline Conditions

December 2020: Subbasin Yield Estimates

57