GROUNDWATER BANKING – AN AGRICULTURAL SYSTEMS APPROACH FOR WATER SECURITY IN CALIFORNIA

Helen Dahlke Assistant Professor in Integrated Hydrologic Sciences LAWR, UC Davis

FEBRUARY 13, 2015 EMAIL: [email protected] Signs of a 3-year droughtAGRICULTURAL – NOAA drought index BANKING Jan 2013 Aug 2013 Jan 2014 May 2014 Aug 2014 Feb 2015

Source: www.watereducation.org AGRICULTURAL GROUNDWATER BANKING

How did we get here?

The California Water Budget Evapotranspiration Precipitation ~ 125 MAF ~ 200 MAF

3 Storages in California

SNOW

RESERVOIRS? Water available as runoff ~ 75 MAF GROUNDWATER AGRICULTURAL GROUNDWATER BANKING

Changes in cropping patterns in the Sacramento Valley

Average values (in acres) for five northern Sacramento Valley counties. Crop 2003‐05 2009‐12 Change Need Deciduous Nuts & Fruits 219,182 258,113 38,931 reliable Olive & Citrus 28,997 37,002 8,005 water Vineyard 4,000 3,676 ‐324 supply! Rice 348,389 350,316 1,927 Pasture 112,623 127,528 14,905 Grain & Hay 71,774 61,434 ‐10,340 Field Crops 58,440 37,874 ‐20,566 Truck Crops 33,788 33,594 ‐194 Idle Land 32,204 26,609 ‐5,595 Total 909,397 936,146 26,749 Source: Northern Region, Land Use Section, 2012 AGRICULTURAL GROUNDWATER BANKING

Changes in irrigation methods in the Sacramento Valley

Average values (in acres) for five northern Sacramento Valley counties. Irrigation Method 2003‐05 2009‐12 Change

Basin Flood 353,691 354, 238 547

Surface Drip 60,232 83,393 23,161

Micro Sprinkler 46,725 88,390 41,665

Border Strip 117,521 76,581 ‐40,940

Furrow 87,912 59,392 ‐28,520

Hand Move Sprinkler 24,704 19,609 ‐5,095

Buried Drip 600 2,515 1,915

Solid Set Sprinkler 1,624 1,588 ‐36 Source: Northern Region, Land Use Section, 2012 AGRICULTURAL GROUNDWATER BANKING

Farm level decisions impact on groundwater resources

Advantages: Consequences: • Reduced crop stress, more efficient • Less crop fertilization • Irrigation “inefficiency” is a major • Increased yields, improved crop source of groundwater recharge! quality • More food grown per unit of water • More reliance on groundwater and land than for drip/micro- irrigation (timing, sediment) AGRICULTURAL GROUNDWATER BANKING

What is groundwater banking? • …is the active and intentional recharge of groundwater during years when rainfall is abundant to increase water supply reliability during drought years Agricultural groundwater banking: • Infiltrate/percolate water on agricultural fields to recharge groundwater … but possibly not in the form we might first envision. AGRICULTURAL GROUNDWATER BANKING

Feasibility study of agricultural groundwater banking • Surface water source and conveyance • Suitable cropping system • “Clean” recharge and effective retention • Cost-benefit, legal constraints ? ?

Figure: Faunt, 2009, p. 22 AGRICULTURAL GROUNDWATER BANKING

UC Davis groundwater banking project team

Helen E. Dahlke, Samuel Sandoval Thomas Harter, Toby O’Geen, Prof. Daniele Zaccaria, Asst. Prof. in Solis, Asst. Prof. and Prof. and CE and CE Resources Asst. Prof. and CE Integrated CE Specialist in Water Specialist in Specialist, UC Davis Specialist in Hydrologic Sciences, Management, UC Davis Groundwater Agricultural Water UC Davis , UC Davis Management, UC Davis

Daniel Putnam, Steve Orloff, CE Allan Fulton, CE Mark Lundy, CE Josué Medellín- CE Agronomist County Director Irrigation and Water Agronomy Azuara, Professional and Forage and Farm Advisor, Resources Advisor, Advisor, Colusa Researcher in Hydro- Specialist, UC Siskiyou County Tehama County County economic modeling, UC Davis Davis AGRICULTURAL GROUNDWATER BANKING

Begin with emphasis on agricultural systems growing alfalfa and irrigated pasture. Why? • Large acreage in CA (~ 1.5 million acres)  higher probability to find land parcels with the right and suitable groundwater aquifers for banking

• Relatively low use of fertilizers, pesticides  low risk for leaching

• Flood irrigation with surface water more common  suitable conveyance system for banking

• Preliminary assessment suggests Costs/Benefits more favorable than other crops

• But we are also interested in other annual low- value, low-nutrient crops and possibly tree crops AGRICULTURAL GROUNDWATER BANKING

Current status of project? 1. Experimental sites (Team Orloff, Harter, Putnam, Fulton, Dahlke) • Scott Valley Irrigation District (recharge experiments under way!) • Orland-Artois Water District (OAWD) – (GIS analysis, modeling)

2. Economic Model (Team: Sandoval, Medellin, Rodriquez, Dahlke) • Model for farm and district level, will be tested for OAWD

3. Alfalfa Flooding Tolerance (Team Putnam, Orloff, O’Geen, Dahlke) • Randomized Complete Block Design, 21 alfalfa plots (Campbell Tract, UCD) Scott Valley AGRICULTURAL GROUNDWATER BANKING

Scott Valley Scott Valley AGRICULTURAL GROUNDWATER BANKING

How much water can be recharged in a conventional alfalfa field?

Experimental Recharge Site

5 cm 15 cm

25 cm Glenn County, Target Work Area - Groundwater elevation change from Spring 2004 through Spring 2014 almond alfalfa

grapes Hydro-economic model for cost-benefit analysis AGRICULTURAL GROUNDWATER BANKING

Rodriguez Arellano et al. 2015 AGRICULTURAL GROUNDWATER BANKING

Flooding tolerance of alfalfa

How much and at what time during the winter can alfalfa tolerate high water application rates?

21 test plots with 4-yr old alfalfa Alfalfa immediately prior to last cutting of Nov. 2014

Location

West side of UCD campus AGRICULTURAL GROUNDWATER BANKING

Flooding tolerance of alfalfa

Block 1 Block 2 Block 3

Randomized Complete Block Design • 3 blocks, 7 plots each – along 1 alfalfa check (4-yr stand) • Factorial: Three “timing” and two “intensity” treatments • Plus control • Dimensions: 20 ft. by 50 ft = 1000 sq. ft. • Measured plant parameters: initial stand density, plant and stem count, yield • Measured physical parameters: Soil moisture, soil, air, water temperature, redox potential, control volume AGRICULTURAL GROUNDWATER BANKING

Flooding tolerance of alfalfa Week #1: 4 acre-feet on Week #2: 2+ acre-feet on High Low and High “January” plots “January” Plots • 1/26 – 2 acre-feet – 6 hours • 2/4 – 1 acre-foot – 1 hour • 1/28 – 1 acre-foot – 2 hours • 2/5 – 1 acre-foot – 1 hour • 2/6 to 2/8 – rainfall (~3 in.) • 1/30 – 1 acre-foot – 2 hours

Low Treatment High Treatment AGRICULTURAL GROUNDWATER BANKING

Anticipated Outcomes and next steps

• Assess site specific feasibility for groundwater banking based on a farm’s soils, climatic, water supply and water-infrastructure • Estimate production risks with flooding specific crops • Provide crop-specific and soil-landscape specific management guidelines to minimize risk to crop while banking groundwater • Give a holistic estimate of on-farm costs of groundwater banking: • costs associated with yield, reduction in crop quality, water, labor, permits, and other management practices) AGRICULTURAL GROUNDWATER BANKING

Thank you! Questions?