Experts Predict Bigger Swings Between Wet and Dry Years in California

Investing in infrastructure and management techniques can help olive growers protect crops from flooding and save water for droughts.
By Thomas Sechehaye
Jan. 29, 2024 18:48 UTC

There is no such thing as a nor­mal” weather year in California any­more. Olive pro­duc­ers have to be ready for any­thing at any time. As Golden State farm­ers wrap up their 2023 har­vest and begin a new year, the water out­look is as uncer­tain as ever.

Predictions from the California Water Blog note that the main les­son of the wild 2023 water year is that California’s water sit­u­a­tion is highly vari­able, aver­ages are unre­li­able and improve­ments are needed to adapt to a con­stel­la­tion of inter­act­ing changes.

Olive grow­ers should be think­ing about alter­na­tive ways to take water dur­ing high-flow events, whether that’s build­ing a multi-use recharge basin or hav­ing a plan to divert water to more tol­er­ant crops on their acreage.- Caitlin Peterson, asso­ciate cen­ter direc­tor, PPIC Water Policy Center

Anxiety and worry are often devoted to drought and water scarcity in California. Still, a new report from the State of California Department of Water Resources empha­sizes that grow­ers must not lose sight of the less fre­quent and shorter wet years.

The real key here is long-term plan­ning. Seasonal fore­casts often get it wrong and aren’t yet equipped to deal with the next-gen­er­a­tion weather that we’re expe­ri­enc­ing,” Caitlin Peterson, the asso­ciate cen­ter direc­tor and research fel­low at the Public Policy Institute of California (PPIC) Water Policy Center, told Olive Oil Times.

See Also:Corto Bets on Olives as Crop of The Future in Changing Sacramento Valley

That means grow­ers must be ready for every­thing all at once,” she added. They have to plan for the next extreme while in the cur­rent extreme.”

The PPIC Water Policy Center con­nects non­par­ti­san, objec­tive research to real-world water man­age­ment debates. Their work is designed to pre­pare for chang­ing con­di­tions and aims to improve cur­rent and develop future water man­age­ment prac­tices.

We’ve seen in the past how the impacts of a given wet or dry cycle can vary across the state,” Peterson said. Sometimes, this is a ran­dom vari­a­tion in weather pat­terns.”

For exam­ple, the drought that impacted the state from 2020 to 2022 ini­tially hit north­ern California the hard­est; by 2021, the impacts became more wide­spread.

Other times, the PPIC said this could reflect dif­fer­ences in plan­ning and coor­di­na­tion struc­tures across local and regional enti­ties, as with the dis­parate readi­ness lev­els for the 2023 floods seen across local gov­ern­ments.

The PPIC brief on drought and California agri­cul­ture out­lines this as a dynamic sit­u­a­tion of a fast-paced drought pro­pelled by cli­mate change, and the impact of new rules is reduc­ing water avail­abil­ity and increas­ing crop water demands. The volatile sit­u­a­tion includes dra­matic swings between pre­cip­i­ta­tion whiplash and megadrought.

The north­ern half of the state is blessed with more abun­dant sur­face water and a smaller deficit in ground­wa­ter than the south­ern half of the state,” Peterson said. Growers in the north may have more of a buffer and more man­age­ment options when deal­ing with weather whiplash. But there will still be chal­lenges, and grow­ers statewide should be think­ing about how to build their resilience.”

Peterson under­scored the reduc­tion of water sup­plies. It’s impor­tant to keep in mind that grow­ers will have sig­nif­i­cantly less irri­ga­tion water to work with in the com­ing years, espe­cially in the San Joaquin Valley, where we esti­mate a 20 per­cent reduc­tion in sup­plies by 2040.”

A 2023 PPIC pol­icy report empha­sizes crit­i­cal issues for the future of agri­cul­ture in California’s San Joaquin Valley and the impend­ing reduc­tion in avail­able water.

Much of that reduc­tion is due to new rules designed to make ground­wa­ter extrac­tion sus­tain­able. This is con­sid­ered a vital facet of secur­ing a reli­able water sup­ply into the future.

We esti­mate that at least half a mil­lion acres of agri­cul­ture land will come out of irri­gated pro­duc­tion by 2040 in the San Joaquin Valley,” Peterson said. That means that regard­less of what the weather is doing in a par­tic­u­lar year, scarcity con­di­tions or sur­plus con­di­tions, on aver­age, grow­ers can count on less water.”

PPIC research on drought in California high­lights the vital imper­a­tive for agri­cul­ture to adapt, whether by find­ing ways to har­vest more water in wet years or by rethink­ing crop port­fo­lios and crop­ping sys­tems.


Wet con­di­tions can be highly costly to agri­cul­ture due to flood­ing, crop loss and dam­age to infra­struc­ture, yet farm­ers count on the wet years to get through the next dry years.

California’s farm­ers and olive grow­ers seek prac­ti­cal actions to respond effec­tively to the mer­cu­r­ial con­di­tions and seem­ingly non-stop del­uge of extremes. Peterson out­lined sev­eral actions for build­ing resilience by keep­ing all man­age­ment options on the table where pos­si­ble.

See Also:Researchers Develop Algorithm to Predict Harvest Potential from Climate Data

Olive grow­ers could upgrade their irri­ga­tion sys­tems to high-effi­ciency drip sys­tems. At the same time, grow­ers might also con­sider how to build sys­tems that quickly move large quan­ti­ties of water to fill an on-farm recharge basin with flood flows. A basin might sit idle for nine years out of 10 but must be imme­di­ately oper­a­tional before a high-flow event is under­way.

Irrigation sys­tems can be costly, but the hope is that well-main­tained sys­tems pay div­i­dends as part of a farm-wide water resilience strat­egy. Taking bet­ter advan­tage of the wet years in this way is a cru­cial strat­egy to help grow­ers get through the dry years.

To com­pound the issue, last year’s wet win­ter and flood­ing in California raised the pro­file of flood-MAR, or spread­ing excess water on agri­cul­tural lands to per­co­late into aquifers.

This is putting money into our col­lec­tive ground­wa­ter sav­ings account,” Peterson said. This ben­e­fits the grower directly when they can claim a por­tion of the water they recharged for later use, and it ben­e­fits the basin when ground­wa­ter lev­els improve.”

Olives have not been specif­i­cally stud­ied to gauge their tol­er­ance for short-term inun­da­tion, but it is pop­u­larly known that olive trees need good drainage.

To pre­pare for this, olive grow­ers should be think­ing about alter­na­tive ways to take water dur­ing high-flow events, whether that’s build­ing a multi-use recharge basin or hav­ing a plan to divert water to more tol­er­ant crops on their acreage,” Peterson said. Keeping some acres in annu­als is one way to do this, so you can have some flex­i­bil­ity on whether to plant or recharge.”

California olive grow­ers may need to adopt a new role, defin­ing them­selves as water har­vesters and look­ing for ways to store more water under­ground as a crit­i­cal facet of resilience to weather whiplash.

The PPIC noted that it is get­ting eas­ier for grow­ers to divert flood flows for on-farm recharge, yet many kinks still exist.

Several pol­icy changes could help California olive farm­ers adapt to the chang­ing cli­mate and ease the tran­si­tion to ground­wa­ter sus­tain­abil­ity.

According to the PPIC, the best thing grow­ers can do is be pre­pared, be informed on the per­mit­ting options and reg­u­la­tions and seek gov­ern­ment incen­tives where they are avail­able to help sup­port the kinds of invest­ments needed.

California’s chang­ing cli­mate con­di­tions con­tinue mak­ing head­lines, with grow­ers eval­u­at­ing how to best respond to loom­ing weather chal­lenges, from droughts to floods.

I think peo­ple often assume that weather whiplash is a new phe­nom­e­non,” Peterson said. On the con­trary, California has always had a pen­du­lum-style cli­mate that swings from wet to dry on a more-or-less 10-year cycle.”

The dif­fer­ence now is that the swings are get­ting big­ger,” she added. Dry years are get­ting hot­ter and drier. The jury is still out on whether wet years are get­ting wet­ter, but there’s some evi­dence to that effect.”

We’re see­ing more of our annual pre­cip­i­ta­tion fall as rain rather than snow, which presents many chal­lenges from a statewide water stor­age and dis­tri­b­u­tion per­spec­tive,” Peterson con­cluded. I think agri­cul­ture will con­tinue to sur­vive and thrive in California – but it might look a lot dif­fer­ent in 20 years than it does now.”


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