Over the past few years, research regarding urban heat islands has been published in many academic studies; however, high-resolution mapping for rural heat islands is sparse – yet critically important in the inland valley of southern California. Specifically, farmworkers in California’s Imperial Valley, who are on the frontlines of food production, are increasingly vulnerable to extreme heat. A new study by San Diego State University (SDSU) researchers – using U.S. National Science Foundation (NSF) ACCESS allocations on Expanse at the San Diego Supercomputer Center (SDSC), part of the UC San Diego School of Computing, Information and Data Sciences – revealed that irrigation, a crucial part of farming in the region, can both help and hurt workers’ exposure to heat stress.

“Our models on Expanse showed that irrigation lowers daytime temperatures in the summer by up to 1.3°C due to evaporative cooling,” said Fernando De Sales, an associate professor in the SDSU Department of Geography. “However, at night, the same irrigation practices increased heat stress, raising temperatures by as much as 1.3°C (equal to 34.34 degrees Fahrenheit).”

ACCESS allocations on Expanse at San Diego Supercomputer Center allowed us to complete our project in a resourceful manner – both time-wise and financially – without access to Expanse, we would not have been able to work so efficiently.

–Fernando De Sales, associate professor, San Diego State University Department of Geography

De Sales said that the added moisture in the air keeps temperatures from dropping, making it harder for workers to recover from extreme heat.

The SDSU study also showed that nearby urban and non-irrigated areas experience heightened heat stress due to moisture moving from irrigated fields.

“These findings highlight the need for policies that protect farmworkers from dangerous heat exposure, especially as temperatures continue to rise over the years,” De Sales said. “With the help of ACCESS allocations on supercomputers like Expanse, we are able to better understand and share mapping related to the extreme heat and the impact of increased irrigation.”

The study, entitled Impact of Irrigation on Farmworkers’ Heat Stress in California Differs by Season and During the Day and Night, was published in the Nature Communications Earth & Environment journal.

Resource Provider Institution(s): San Diego Supercomputer Center (SDSC)
Resources Used: Expanse
Affiliations: San Diego State University
Funding Agency: NSF
Grant or Allocation Number(s): EES240026

The science story featured here was enabled by the U.S. National Science Foundation’s ACCESS program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296.