The Yakima River Basin is a snow-dependent, agriculturally important region in Washington state, leading in production of many commodities and specialty crops. Nearly 50% of agricultural production in the Yakima Basin is irrigated, and is vulnerable to future expected temperature increases and severe droughts. Researchers at Cornell and Washington State Universities, led by Dr. Keyvan Malek, evaluated the impacts of changes in temperature, water availability, and atmospheric carbon dioxide concentrations on irrigated agriculture in this Basin and examined the effectiveness of potential strategies to mitigate the negative effects on crop yields.
The Yakima Basin receives most of its water supply from melting snowpack. A warmer climate reduces snowpack volume as more precipitation falls as rain. Higher temperatures also accelerate snowpack melting, causing water availability to shift towards earlier in the year, with less water available later in the irrigation season. Malek and colleagues modeled future water stress due to climate change in two time periods: around 2040 (2030 – 2060) and 2070 (2060 – 2090). Their results suggest that there will be an increase in the amount of unmet irrigation demand due to higher temperatures’ effect on snowpack. Specifically, significant droughts, defined in this study as unmet irrigation demand reaching greater than 30%, are expected to become more frequent and severe in both future time periods (Figure 1). Further, some drought events could reach greater than 65% unmet demand in the Yakima Basin, which has never occurred before in the historical record.
What could this mean for agricultural production in the Yakima Basin? Malek and colleagues focused on the ten top crops in the Basin, and grouped them into annuals (winter wheat, spring wheat, corn, and potatoes), multiple-cutting crops (alfalfa and pasture), and tree fruits (grapes, apples, cherries, and pears). They calculated impacts on yields for each group, and all three groups show possible reductions in average yields under future climates. The frequency of low-yield years–defined as years that produce under 60% of the fully irrigated yield–could also substantially increase with climate change. Interestingly, the year to year variation in yield is not necessarily expected to increase over time, likely due to expected decreases in the maximum yields. Smaller yield variations would allow predictions of yield loss to be more accurate.
So what can be done to prepare for what’s coming? One strategy that Malek and colleagues tested is using crop varieties that have longer growing seasons. Using these varieties increases average agricultural yield, but they remain vulnerable to more frequent and severe drought. In addition, the variability in yield also increases, meaning that both agricultural production and farmers’ revenue are likely to become more volatile: as crop varieties become more productive during years with adequate water supply, the gap between yields at full irrigation and during water-stressed conditions could increase.
The increase in yield variability could cause unintended costs such as the raising of insurance rates to cover the greater unpredictability in yields. Such costs are placed either on the public in the form of government-backed agricultural insurance programs, or on the farmers themselves if they pay for private insurance. To combat this issue, the potential productivity of crops could be improved with practices or varieties that emphasize making crops more resilient to variations in temperature and water supply.
Malek and colleagues discuss policy-related changes, such as the enhancement of water-related infrastructure and institutions to improve water availability, that would also be needed to ensure sustainable regional agricultural economies in snow-dominated regions under climate change. This could include building water storage facilities and adapting water rights so that unused water rights are relinquished. While they did not specifically model the outcomes of such improvements, they theorize that these changes will help mitigate the expected rises in unmet irrigation demand. In all likelihood, multiple strategies will be needed to adapt to the coming changes in water availability, and their implementation will require action by agencies that manage water projects and those involved in the relevant governance and regulatory frameworks, in addition to the growers themselves.
This and other work strongly suggest that climate change is likely to have a large impact on water supply in the Yakima Basin, which will have important consequences for irrigated agriculture. Growers will need to adapt to decreases and shifts in water supplies. In addition, there is an increasing trend in the consumption of fresh fruits and vegetables as the standard of living increases, which may also interplay with changes in supply. Water managers, policymakers, and those in the agricultural industry may need to work together to address climate change impacts and the increased volatility resulting from likely adaptation strategies, such as improving water-related infrastructure and institutions in addition to investing in increasing potential productivity of crops.
This article is also posted on AgClimate.net.
Reference
- Malek, K., Reed, P., Adam, J., Karimi, T. and Brady, M., 2020. Water rights shape crop yield and revenue volatility tradeoffs for adaptation in snow dependent systems. Nature Communications, 11(1), pp.1-10. https://www.nature.com/articles/s41467-020-17219-z
The work described in this article was supported jointly by the National Science Foundation under EAR grant #1639458 and the U.S. Department of Agriculture’s National Institute of Food and Agriculture under grant #2017-67004-26131, as well as the Washington State University Graduate School.
Comments
For context:
https://www.wcc.nrcs.usda.gov/ftpref/data/water/wcs/gis/maps/wa_swepctnormal_update.pdf
On my own one-acre homestead where in August every year water for irrigation is in short supply, I have been working toward water conservation and soil improvement to increase soil carbon, which seems to help with retaining soil moisture and soil microbial life as well as improving conditions for larger soil organisms such as earthworms. Here are some areas I am trying to work on: 1) Deep mulching of wood chips in fruit and nut orchard; 2) Use of annual non-bloating legumes such as Berseem Clover, which can hopefully provide significant forage similar to alfalfa in nutrient value, yet the growth pattern matches the seasonal precipitation pattern predicted in this report; 3) Planting drought adapted annuals such as Hopi Blue Corn, which I plant in the traditional way, as in: I make a 6″ deep trench with a large V shaped hoe, then at ten foot intervals I pierce the ground a foot deeper than the bottom of the trench with a special metal pole aka a glorified digging stick and insert up to ten seeds. The next row is ten feet over to the side and I try to alternate the holes on a diagonal. In the very hot weather of last summer while many of my berries and soft fruits were in essence cooked before harvest the corn emerged even from that depth and grew well. Once the corn is up and thriving, I push the edges of the trench back into the furrow, essentially hilling around the corn so the roots are in fact now eighteen inches deep. Traditional Hopi agriculturists break down enough of the plants to leave a corn stalk mulch around the remaining six or seven live stalks. The story I am told is the Corn roots will not only go deep in search of moisture but will spread out laterally up to ten feet. I also inoculate with Mycorrhizal fungi to help with moisture and nutrient extraction from the soil. The corn made not dry corn but soft eating corn for corn on the cob before frost, which my grandkids enjoyed. I am saving some cut juniper branches for making Piki bread from this years (hopefully) harvest of dried ears. The ashes of the burned juniper are mixed with the dried corn and hot water and a chemical reaction takes place which not only changes the color of the corn meal but allegedly increases the availability of niacin, an essential nutrient in the human diet. We can eat the seeds, but the animals can eat the rest of the plant as supplemental forage. I also grow Sorghum Sudan Grass which is also allegedly drought resistant and seems to provide some pretty decent gopher control and, if managed properly, some serious amount of forage in a small area. I also grow millet, which is also allegedly drought resistant. I was intending to use the grain to feed my poultry, but the birds didn’t leave much grain, however, the sheep eat the leaves and some of the stalks. 4) I am experimenting with perennial grasses and legumes which can be mowed planted between the garden rows. This helps with soil condition and is pleasant to walk on but also provides several cuttings of forage for poultry and sheep. 5) as funds allow, we are installing a drip irrigation system to use the water we have more effectively 6} a solar greenhouse for starting warm season plants so they can be set out when conditions are optimal. 7) Use of squash which can be planted in a hill where water and organic nutrients can be concentrated yet the vines can ramble to capture available sunlight even past the irrigated hill. A additional measure is harvesting drought resistant weedy annuals including Cheat grass, Foxtail Barley, Bulbous Bluegrass and Jim Hill Mustard and other forbs with the use of a scythe before they mature and become true weedy pests. When they are green and succulent they make pretty decent forage. If not harvested not only do they become true weedy pests but an extreme wildfire fuel risk. ( Why researchers aren’t using the beneficial qualities of these plants as major research possibilities to deal with drought is beyond me.) I harvested one small plot of foxtail barley and cheatgrass four times already this year as green feed for my poultry and sheep. The lambs grow well because their dams are providing plenty of milk; and the chickens lay very large eggs with deep orange yolks. it is simple but not easy to harvest by hand with a scythe or sickle or a human powered push reel mower and if need be a power mower although the sheep don’t really like it when I feed it to them all chopped up by the power mower. If I have time I have a manual baler powered by my manual labor so the young weedy annuals can be dried and baled for winter feed. With alfalfa hay being so high priced such forage options make financial sense to a small operator such as myself. With the weather we have had so far the weedy annuals are very dense and up to two feet tall in many places. ( Note: because there is enough exercise involved in scything and making hay from weedy annuals I don’t feel the need to go to the gym but focus on becoming farm strong) Also, commonly planted perennial range grasses such as Tall Wheatgrass and Crested Wheatgrass can be mowed just before they make heads and they make a great fresh forage but also a decent hay. Although they can certainly use supplemental irrigation they are well adapted to growing reasonably well just with natural precipitation. The deep roots they have are evidently a sound strategy to maximizing what soil moisture is available naturally. E.g.: a neighbor’s 40 acre field has not been irrigated for several years but was planted to Native Basin Wildrye grass. Pheasants and other wildlife abound therein. He has one horse that lives therein and I suspect the horse probably preferentially grazes on the young succulent weedy annuals helping keep them at bay. In summary we need to be adaptable and not just focused on propping up an irrigation system which may or may not be there for us in the future if the predictions in the report are true. As a side note I remember reading that Chukar Partridge consumed the seeds of the weedy annuals discussed. They should have plenty of seeds this year.
Hi James,
Thanks for your interest and for sharing your experience. It sounds like you are trying lots of interesting ideas!
Does this article take into consideration the Yakima Basin Integrated Water management plan? I’m curious if the plan there addresses some of the concerns written about in this article. Thanks!
Hi Laura,
Thanks for your question! The article does not specifically account for the Yakima Basin Integrated Water management plan as the model the researchers used is based off of current infrastructure and management regimes in the Yakima Basin. However, the authors do point out that some of the management plan’s key elements such as improvements in infrastructure, adding water storage, and increased water conservation could alleviate some of the expected impacts on water availability in a climate changed future. Therefore, it is likely the management plan will play a role in lessening future water stress and its impacts on crop production, but it is hard to say much more given that it’s not specifically addressed in the article.