05/01/2023 1

Agricultural sensitivityto climate change and water

resources interactions in the San Joaquin Valley, Calif. and

system resilience offered by adaptation strategies

Presenter:Philip Bachand

Bachand & Associates530-758-1336

philip@bachandassociates.com

05/01/2023 2

Critically Overdrafted Groundwater Basins, 2016

Management Plan

Climate Change

Local Adaptation

Regional Adaptation

Reservoir Management

Rain / Snow

Runoff

Temp / Precipitation / ET / CO2

Land UseGroundwater Supplies

Surface Water

SuppliesWater Transfers

Conjunctive Use

Recharge and Withdrawals

ISNOBAL

CalSim

C2VSIM

WUE

NUE

CO2 fertilization

Ag Literature and Databases

Cultural Practices

Crop Yield

Water Resources Water Quality

Outcomes

Anthropogenic Feedback Mechanisms

Estimated NPV: Total and by groups and subwatersheds

Economic Model

WARMF

Land Use

Precip

SJV Stream flow and quality

Irrigation

Fertilization

Tetra TechSujoy Roy, pH.D., LeadTASK 3

Tetra Tech and UC Davis LAWRPhilip Bachand, pH.D., LeadTASK 5

UC Davis LAWR and Tetra TechDr. Lucas Silva, pH.D. Lead

TASK 1

Systech and Tetra Tech

Joel Herr, LeadTASK 3

UC Merced and Tetra TechProf Rob Rice, pH.D. LeadTASK 2

UCD AREDr Leslie Butler, Lead

TASK 4

05/01/2023 4

Key questions identified in the proposal• What magnitude of change is required in water management to

address changes in precipitation timing, frequency and type, and in snowpack water storage?

• What cropping strategies are likely to sustainably mitigate climate change pressures and how will those affect crop distribution in the SJV?

• How sensitive, robust and resilient are these cropping strategies to the evolving climate change / water paradigm?

• What are the economics behind adaptation strategies at the local and regional scale?

05/01/2023 5

Reservoir Operation - Today

Surface Water Supply Demand

Oct Nov Dec Jan Feb Mar Apr May Jun July Aug Sep

Reservoirs

• Surface Water Supply• From Sierra runoff

• Demand• Agricultural demand dominates

demand

• Reservoirs• Managed to mitigate floods and

meet demand curve

05/01/2023 6

Reservoir Operation - Today

Surface Water Supply

Oct Nov Dec Jan Feb Mar Apr May Jun July Aug Sep

Reservoirs

• Surface Water Supply• From Sierra runoff

• Demand• Agricultural demand dominates

demand

• Reservoirs• Managed to mitigate floods and

meet demand curve

Groundwater

Demand

05/01/2023 7

Watershed of the Sacramento-San

Joaquin Delta and Regions that Use

Delta WaterCVP Target--• Serves 2M Ac Irr. Ag • Delivers 7M Ac-ft

• 70% to Ag• 9% to Urban• 11% to wildlife

State Target --• Serves 0.75M Ac Irr. Ag • Delivers 3M Ac-ft

• 30% to Ag• 70% to Urban

Total SWP Annual Delivery (1000 Ac-FT), DWR 2015

05/01/2023 8

2014 Sustainable Groundwater Management Act (SGMA)

Sustainable Yields & Undesirable Results• “Sustainable yield,” according to the SGMA, means the maximum quantity of water

– calculated over a base period representative of long-term conditions in the basin that can be withdrawn annually from a groundwater supply without causing an undesirable result.

• Undesirable Results: Chronic lowering of groundwater levels (excluding reductions in groundwater levels during

drought if offset during other periods) Significant and unreasonable reductions in groundwater storage; …. seawater intrusion; …. degradation of water quality; …. land subsidence; and Surface water depletions that have significant and unreasonable adverse impacts on

beneficial uses.

05/01/2023 9

Conveyance and Exports in California’s Water Budget

1873 TODAY

Sacramento River

Sacramento River

San Joauqin River

San Joauqin River

CVP (Federal) and SWP (State)Diversions

05/01/2023 10

The San Joaquin Water Budget

Surface Transports

Surface Storage Use

Loss

F=

• Precipitation(t)= F(Climate = F(Climate Change)

• Infiltration(t) = F(Soils, Geology, etc…)

• Evapotranspiration(t) = F(Climate = F(Climate Change))

• Other(t)• Delta Flows and Mgmt

• Capacity(t)• Conveyance(t)• Management(t)• Inefficiencies(t)• Costs(t)

F=

• Demand of Sectors(t)= F[ ]

• Recycling(t)• Reuse(t)• Conservation• Hard Needs• Soft Needs =

F(Wealth, etc…)• Costs(t)

F=

(t)(t)

(t)

Groundwater Supply (? MAF Overdraft

Annually) (t)

Sierra Runoff

(t)

(t)

05/01/2023 11

Complying with the Biological Opinions to comply with Endangered Species Act

State and/or Federal Listing Status of Native Fish SpeciesCommon Name Scientific Name Listing StatusDelta smelt Hypomesus transpacificus FT, SElongfin smelt Spirinchus thaleichthys FC, STChinook salmon, Central Valley spring-run ESU

Onorhynchus tshawytscha FT, ST

Chinook salmon, Sacramento River winter-run ESU

Onorhynchus tshawytscha FE, SE

steelhead, Central Valley DPS

Onorhynchus mykiss FT

green sturgeon DPS Acipenser medirostris FT

F = Federally-listed under ESA | E = Endangered | C = Candidate Species for Listing| ESU = Evolutionary Significant Unit | S = State-listed under CESA | T = Threatened |DPS = Distinct Population Segment

The CVP/SWP operations are informed through a structured decision making

process designed to reduce the adverse effects on federally and state listed fish

species.

05/01/2023 12

SGMA Supply Augmentation – Water Available• Potential water sources

• Surface water• Recycled water• Conserved water• Brackish or saline water, Desalination• Transferred water• Other

• Aquifer replenishment• In lieu recharge• Direct recharge

• Uncertainties• Climate change• Institutional / regulatory

constraints• Regional and local challenges

and implementation strategies

• State Water Project and Central Valley Project

• System reoperation

05/01/2023 13

Future Opportunities and Considerations towards Supply Augmentation and Demand Reduction

• Sustainable Yield (SGMA)• WUE and NUE (Demand; Agriculture; Horwath, et al)• Estimating regional overdraft from cropping data (Demand; Agriculture; Bachand)

• Sierra Water Deliveries• Sierra Nevada Runoff Timing and its Variance (Supply; Water; Rice et al)• Sierra Nevada Runoff Annual Volume Reductions (Supply, Water; Rice et al)

• Augmenting Water Supplies• On-Farm Recharge and Agricultural Water Banking (Supply; Water; Bachand et al)• Reservoir and Water System Re-operation (Supply; Water, Bachand, Sujoy, et al)• Within and Outside Water Transfers (Supply; Water; Roy, Herr et al)

• Delta Management under Climate Change (Supply; Water, Roy, Herr et al)

• Economics• Land Fallowing and Retirement (Demand; Agriculture; Butler et al.)• Water Markets (Supply; Water; Butler et al.)

05/01/2023 14

NASSDatabase

*5

*

*

**WARMF Estimates

*

*

Silva, Maxwell, Horwath et al, 2016

Task 1. Quantify relationships between crop yields, farm practices, and possible environmental impacts.

Key Issue. Viability of agricultural efficiency depend upon crop response to changes in climate and atmospheric composition.

Specifically we want to know:

• What will be the net impact of climate change and rising CO2 on crop WUE and NUE?

• How will these changes affect yield quantity and quality of different crops?

• How will these impacts change water, carbon and nutrient cycles at the regional level?

Silva, Maxwell, Horwath et al, 2016

05/01/2023 16

Changes in irrigated land inputs from 2007 – 2012 (2012 USDA NASS Census Report)

Characteristics Units2012 2007 2012:2007 2012 2007 2012:2007

Land in farms acres 16,039,761 16,231,930 99% 9,529,240 9,132,765 104%Irrigated land acres 7,861,964 8,016,159 98% 167,332 0%Market value of agricultural products sold $1,000

37,327,971 29,586,599 126%5,299,501 4,298,465

123%

Total farm production expenses $1,000 30,233,225 23,015,562 131% 5222442 3,947,079 132%Fertilizer, lime, and soil conditioners purchased $1,000

1,793,731 1,294,928 139%12,331 19,247

64%

chemicals purchased $1,000 2,171,784 1,347,595 161% 18,889 21,537 88%

Gasoline, fuels, and oils purchased $1,000 1,402,954 998,021 141%

22,203 26,29684%

Utilities $1,000 1,571,566 1,132,624 139% 112,777 98,923 114%

Irrigated Farms, Any land irrigated Nonirrigated Farms

Understanding current water demand and trends based as cultural practices are changing

Task 1. Quantify relationships between crop yields, farm practices, and possible environmental impacts.

Key Issue. Changing cultural and irrigation practices have affected crop inputs, per acre efficiencies and per acre yields.Specifically we want to know:

• What effects do the changing practices have on crop distribution and regional inputs, including water demand?

• How are these factors affecting surface and ground- water demand?

Task 1 – Upcoming Steps• Viability of agricultural efficiency depend upon crop response to

changes in climate and atmospheric composition.• Silva, Maxwell, Horwath et al are assessing these effects.

• Assessing CO2 effects on WUE and NUE using available datasets and modeling based upon plant physiology.

• Inputting data into water quality model (ie. WARMF)

• The effects of changing agricultural practices on local and regional water use

• Bachand, Silva et al• Using available NASS, DWR and other data sets to assess how changes in

agriculture have affects water use and groundwater pumping

05/01/2023 18

05/01/2023 19

Future Opportunities and Considerations towards Supply Augmentation and Demand Reduction

• Sustainable Yield (SGMA)• WUE and NUE (Demand; Agriculture; Horwath, et al)• Estimating regional overdraft from cropping data (Demand; Agriculture; Bachand)

• Sierra Water Deliveries• Sierra Nevada Runoff Timing and its Variance (Supply; Water; Rice et al)• Sierra Nevada Runoff Annual Volume Reductions (Supply, Water; Rice et al)

• Augmenting Water Supplies• On-Farm Recharge and Agricultural Water Banking (Supply; Water; Bachand et al)• Reservoir and Water System Re-operation (Supply; Water, Bachand, Sujoy, et al)• Within and Outside Water Transfers (Supply; Water; Roy, Herr et al)

• Delta Management under Climate Change (Supply; Water, Roy, Herr et al)

• Economics• Land Fallowing and Retirement (Demand; Agriculture; Butler et al.)• Water Markets (Supply; Water; Butler et al.)

05/01/2023 20

On-Farm Flood CaptureDefinition and Vision

• Available = Physical, Legal

• Leveraging Private Lands

• Dual Use Farm and Flood

• Design into Farm Management

• Leveraging Community Resources

Capturing Available Flood Flows onto Farm Lands for Groundwater Recharge and to Mitigate Downstream Flood Risks

05/01/2023 21

Flood Flow Thru the James Bypass

Winter Flooding of Row Crop Fields

05/01/2023 22

Acreage needed to offset 1M ac-ft overdraft for different Periods and Rates of Infiltration

2 4 6 80

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

4812

Infiltration Rates (in/d)

Period (weeks)

Acre

s Req

uire

d

05/01/2023 23

Regional Considerations for On-Farm Flood Recharge

Opportunities for Recharge due to high precipitation

Reservoir / Water System Reoperation

Water Transfer Opportunities

Dahlke et al, 2016

Yield Potential

05/01/2023 24

Summary To Date• Project ranges across water, agriculture, economics and climate change• California’s regulatory climate (e.g. SGMA) is a main driver for potential solutions• Modeling tools that are being used to assess opportunities and scenarios include CA hydrologic

models, agricultural datasets and public databases, runoff models and economic models including the Statewide Agricultural Production Model.

• Collaborators from public and private groups• Scenarios being defined in conversations with stakeholders and in consideration of climate

changes and California’s regulatory response:• Augmenting water supplies (e.g. recharge, reservoir re-operation)• Changing crops and cropping practices (e.g. specialty/high value crops, fallowing, dry land farming)

• Will assess economic effects on agricultural production using SWAP model.