California faces challenges in trying to produce so much of our food
By the USGS Earth Resources Observation and Science (EROS) Center
Groundwater is a crucial source of water for California, especially for its $59 billion agriculture industry.
But even when the water is underground, Landsat satellites that observe the Earth’s land surface can still help growers monitor it.
In just one example of the benefits of monitoring, growers in a 100,000-acre area of California—an area about the size of Bakersfield—saw a 13% reduction in groundwater pumping in the first year of using information derived from Landsat and other sources. That resulted in savings of roughly $40 million.
Supplies of groundwater for irrigation are more predictable than surface water, which can fluctuate with drought, but groundwater is not infinite. If too much groundwater is pumped out, wells can go dry and land can sink, leading to infrastructure issues. Monitoring groundwater use can help prevent problems like these.
‘Users of Landsat on a Daily Basis’
Many types of crops grow in California, which supplies more than a third of the country’s vegetables and three-fourths of its fruits and nuts, according to the California Department of Food and Agriculture.
Using remote sensing data like Landsat to map crops field by field reveals how many acres are growing. That lets various commodity boards such as the Almond Board of California and the California Walnut Board estimate the volume of crop that’s available to market to the world. And using remote sensing to know how much water those crops are using helps growers optimize groundwater use, management and regulatory compliance.
“We are significant users of Landsat on a daily basis,” said Joel Kimmelshue, founding partner and principal soil and agricultural scientist at Land IQ.
Land IQ maps more than 50 California crops on 15 million producing acres of land with a very high (97+%) degree of accuracy. The company also provides monthly crop water consumption estimates, with Landsat and other satellite information as a fundamental starting point coupled with data-driven models. An extensive ground data collection system helps calibrate and validate the satellite results.
Wanted: Fast Data
Nearly 40 groundwater sustainability agencies and irrigation districts use Land IQ’s crop water use estimates, including the Mid-Kaweah Groundwater Sustainability Agency (MKGSA) in the San Joaquin Valley.
Several years ago, MKGSA made the difficult decision to put restrictions on groundwater use in reaction to sustained drought and a new California state law. MKGSA needed a way to measure growers’ groundwater usage, but under a tight deadline, there wasn’t nearly enough time to install water meters to monitor 65,000 acres of irrigated cropland.
So MKGSA turned to Land IQ to estimate the total amount of water used by crops, which is based on evapotranspiration (ET), a combined loss of water through evaporation and plant transpiration.
MKGSA growers were initially given 2.5 acre-feet of groundwater per acre of land in 2022—enough to cover each acre with 2.5 feet of water—beyond precipitation or surface water that their crops also use. Every month, they can check their groundwater consumption for the previous month on a dashboard to see how their “water budget” is going and what they have left for the rest of the year. If they don’t use all their allocated groundwater in one year, the unused amount remains available for them in the future.
‘At the Core … Is the ET Data’
“Without the Land IQ data, farmers couldn’t plan. They were just doing what they used to do, what their grandfathers did, what their great-grandfathers did. And that wasn’t working. We were overdrafting the groundwater system. They had to make a change,” said Aaron Fukuda, interim general manager of the MKGSA and general manager of the Tulare Irrigation District, which is a member of the MKGSA.
“At the core of all of it is the ET data. Pull that out, and the heart of the system falls apart.” – Aaron Fukuda
MKGSA’s growers have four years of Land IQ data to look back on now. In addition to keeping track of their water budgets, they can find the average of how much water is used by a certain tree crop, like almonds, or another perennial crop. “They’re fine-tuning their irrigation to get to the optimum yields based on water availability, yields and commodity pricing,” Fukuda said.
For growers of annual crops such as corn or wheat, once they know how many acre-feet of groundwater each crop type needs, they can plan out what to plant in each field based on how much water they have to “spend.”
MKGSA’s plan, a revision from an earlier plan rejected by the state, is paying off. In a comparison of two drought years—2021 to 2022—groundwater pumping went down 13%, saving 20,000 acre-feet of water and roughly $40 million, based on a drought-year value of water at $2,000 per acre-foot, Fukuda said. In other words, that’s 6.5 billion gallons, enough water to supply a city like Santa Barbara for more than a year and a half.
Plus, because the revised plan met the state’s requirements, MKGSA is being considered to avoid a “probation” period in which the state would take over the sustainability planning. That would cost growers tens of millions of dollars in fees annually, Fukuda said.
“Because we’ve implemented the allocation system, because we’re cutting back, we’re making the hard decisions; because we’re monitoring and we are showing results, we are hoping to avoid probation.”
‘The Industry Standard’
One reason Landsat is so valuable to companies like Land IQ and customers like the MKGSA and its growers is because the data is offered to the public at no cost, said Diya Chowdhury, Land IQ spatial sciences team lead. “That allows us to pass that cost savings down to our clients. There’s a limited budget, and it allows us to work within that.”
Chowdhury estimates that overall, Land IQ includes Landsat data in 90 percent of its crop mapping and ET projects, which also include Arizona, Australia and Mexico.
Landsat’s annual value in 2023 was calculated to be $25.6 billion for myriad uses, including the agriculture industry. Landsat is a partnership that began between the U.S. Geological Survey (USGS) and NASA more than 50 years ago, by far the longest-running Earth observation satellite program in the world. The data are made available through the USGS.
Some Land IQ projects need to look at imagery from decades ago. “Landsat is considered to be the industry standard due to the historical record of data,” Chowdhury said.
The two current satellites collect fresh imagery of every spot of land on Earth every eight days, a benefit to Land IQ. “It gives us a time series of data to work with,” she added. “We’re looking at crops, which is a dynamic system. You need to consider how things are evolving and changing over time.”
The company uses artificial intelligence (AI) methods—specifically machine learning—to be able to incorporate all of the remote sensing and ground data into its work.
Looking ahead, Landsat’s role is expected to grow as technology evolves.
AI methods will continue to be useful as plans for the next generation of Landsat satellites include even more remote sensing data. A trio of satellites is planned to launch in late 2030/early 2031 as Landsat Next, capturing far more detail about features of the Earth’s surface more frequently than current Landsat satellites, including more information about crop conditions.
Landsat is crucial for Land IQ’s work, Kimmelshue said, and “for the people that use those ground-validated results. That’s the real critical part: for them to manage the short water that we have in many places in the western United States.”
