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NASA Helps Growers During California's Drought
February 25, 2014

Water - it shapes our world in many ways. It has the power to cut through rock and turn stone into sand. We rely on it to trade goods, power our homes, grow our crops, quench our thirst. For these and many other reasons, water is precious to life on Earth and essential to sustaining life beyond. 

Astronauts orbiting the International Space Station have the unique vantage to see our world defined by oceans and the stretches of land between them. It also gives them the vantage to see the havoc water and its absence can cause for us on Earth: hurricanes, typhoons, fires, flood, drought.

Following two consecutive years of drought conditions, 2014 is shaping up to be one of the driest years on record in California. Tides ebb and flow, and so do levels of rain and snowpacks. But these low levels have reached a critical point. In January, Governor Edmund G. Brown Jr. declared a drought State of Emergency and directed state officials to take all necessary actions to prepare for water shortages.


If you don't already, why should you care about California's record-breaking drought? California’s 81,500 farms and ranches produced $43.5 billion in cash receipts in 2012, making it a major source of income and jobs in agricultural communities across the state. California's growers produce a spectacular diversity of specialty crops including half of the U.S. grown fruits, nuts and vegetables. These crops are in the produce stands across the U.S. and the world. Like other western states, California agriculture uses approximately 80 percent of the available water resources.

“California farmers and water managers are increasingly concerned about the long-term sustainability of our agricultural water supplies, and years like this underscore the challenges facing California’s farmers,” said Forrest Melton, a senior research scientist for California State University, Monterey Bay (CSUMB) and the Cooperative for Earth Science Research and Technology at NASA's Ames Research Center in Moffett Field, Calif. 

Since 1982, the California Department of Water Resources (CDWR) has operated more than 140 monitoring stations that provide daily measurements of agricultural weather conditions and the amount of water lost to the atmosphere by a well-watered grass surface. Data from this network is distributed through the California Irrigation Management Information System (CIMIS), operated by CDWR. To date, this information has been shown to have great value as a tool for irrigation managers to determine the water requirements for their crops.


Where does NASA come in?

“Our goal is to find new ways to make satellite and weather information both highly useful and easily available to growers in California and across the western U.S.,” Melton said. "We want to support farmers in improving on-farm water management and help water managers plan and mitigate the impacts of drought. One of the lowest cost solutions to our water management challenges is improving water use efficiency where it’s practical and cost-effective." 

NASA invested significant resources over the past 10 years in the development of new technologies including the Terrestrial Observation and Prediction System (TOPS) and a platform for scientific collaboration called NASA Earth Exchange (NEX), that can deploy the power of the Pleiades supercomputer at Ames' NASA Advanced Supercomputing facility to solve real-world problems by quickly processing and integrating data from a variety of sources including satellites such as Terra, Aqua, Landsat 7 and Landsat 8. 

“TOPS/NEX technologies now allow us to bring together the information needed to support efficient natural resources management in near-realtime, what we have been dreaming for decades,” said Rama Nemani, principal scientist for the NEX project at Ames.

Using these technologies, Melton and a team of scientists working on the Satellite Irrigation Management Support (SIMS) project are working closely with CDWR, partner growers and the Western Growers Association to develop a system for mapping crop conditions and crop water requirements across millions of acres of California farmland.

By combining NASA satellite data with information provided by CIMIS, the team is able to develop near real-time estimates of crop water requirements for every field in the state. This information is designed to help California growers better manage irrigation, monitor crop development, and improve on-farm water use efficiency. It also helps water managers improve estimates of agricultural water requirements.

"We are implementing web and mobile data interfaces to increase the ability of the agricultural community to access and use satellite data in irrigation management and crop monitoring," said Melton. 

The SIMS project team also is collaborating with CDWR and partner growers to conduct validation studies using wireless sensor networks. 


“Field assessment of the SIMS estimates of crop water requirements has been very encouraging and utilizes two independent validation methods," said Christopher Lund, research scientist with CSUMB and the Cooperative for Earth Science Research and Technology at Ames. "One requires the deployment of instruments to measure the surface energy balance while the other uses soil instrumentation to track the soil water balance.”

“The project also is providing students with technical applied science training using state of the art instrumentation," said Kirk Post, formerly a student on the project and now a research scientist with CSUMB and the Cooperative for Earth Science Research and Technology at Ames. "Students interested in the development and applications of these technologies are able to work collaboratively with researchers and California growers in developing information driven solutions.” 

Water managers, scientists and growers alike are highly encouraged by the results to date. Trials conducted on lettuce and broccoli crops in Salinas during 2012 and 2013 have demonstrated sustained yields while reducing the amount of water used by up to 33 percent relative to standard practice; saving water means saving money.

"These carefully controlled scientific experiments clearly showed the feasibility of matching water applications to the actual crop uptake pattern, and have proved useful in evaluating both ground- and satellite-based irrigation scheduling tools," said said Lee Johnson, a senior research scientist with CSUMB and the Cooperative for Earth Science Research and Technology at Ames.

Initial results also indicate benefits for water quality, including the potential to reduce the leaching of nitrates from the soil below the root zone into groundwater. This also means fertilizers are being used more efficiently with more nutrients staying in the soil to help future crops grow.   

The SIMS project team also is working with scientists at U.S. Geological Survey (USGS) and U.S. Department of Agriculture (USDA) this year to leverage the NEX capabilities for rapid satellite data processing to identify the change in fallowed land in California – cultivated land intentionally allowed to lie idle during growing season – due to the state's water shortage.  

"Shortage of water due to drought leads to an increase in the extent of fallowed land in the Central Valley because farmers are unable to fully irrigate crops, and will often prioritize use of the limited available agricultural water supplies to attempt to sustain perennial crops on their farms and ranches," said Melton. "Timely and accurate knowledge of the extent of fallowing can provide insights into the severity of drought impacts, and provide the basis for sound decisions for drought response. Such decisions can ensure efficient allocation of scarce available water for on-farm use, and authorize provision of emergency assistance." 

That's why NASA Ames, CDWR, USDA, USGS, and CSUMB have partnered together and demonstrated they can modify and apply the methods to produce the USDA's annual Cropland Data Layer (CDL) to support within-season mapping of fallowed agricultural lands based on the fallow/idle crop class in the CDL. The partnership also has demonstrated how new methods using time-series of data from NASA and USGS satellites – including Terra, Aqua, and Landsat – can be used to track the development of crop canopies, and can provide information on land fallowing and reductions in planted acreage early in the year.

"This capability can provide early identification of changes in fallowed acreage due to water shortage during drought, filling an important information gap and reducing ambiguity surrounding drought impact assessment and decision making for drought mitigation," said Jim Verdin at USGS.

The project team completed a one-year feasibility and validation study in 2013, and is currently preparing to produce data and maps of fallowed acreage for the Central Valley beginning in April 2014, to support monitoring of impacts of the ongoing drought in California. The NASA Applied Sciences Program and the NIDIS Program Office at NOAA support the project.


Also in April, NASA and CDWR will resume flights of NASA’s Airborne Snow Observatory to map the snowpack of the Tuolumne River Basin in the Sierra Nevada and Uncompahgre watershed in the Upper Colorado River Basin. The Tuolumne watershed is the primary water supply for 2.6 million San Francisco Bay Area residents. The airborne observatory measures how much water is in the snowpack and how much sunlight the snow absorbs, which affects how fast the snow melts. These data enable accurate estimates of how much water will flow out of a basin when the snow melts. Last year, observatory data helped water managers optimize reservoir filling and more efficiently allocate water between power generation, water supplies and ecological uses.

Another NASA project mapped significant areas of subsidence (ground sinking) in the San Joaquin Valley from 2007 to 2011 caused by decreased groundwater levels. Groundwater is increasingly important in water resource management, yet knowledge of groundwater levels is not uniformly available. Satellite- and airborne-based radar can monitor groundwater levels by measuring surface deformation due to the withdrawal and recharge of aquifers. 

NASA has produced regional maps of the rate and total amount of subsidence, along with animations and detailed histories of individual locations that can help deduce year-to-year changes in groundwater storage. Researchers hope to extend the data to the present day to give state water managers updates of how the subsidence has progressed during the drought and detect possible new areas of concern. The data can be used to focus on problem areas where too much water is being pumped. The maps also help managers of infrastructure that can be affected by subsidence, such as aqueducts, flood-control channels and the California High-Speed Rail Authority. 

NASA is teaming with CDWR; University of California, San Diego; and others to conduct airborne campaigns, satellite studies and analyses of weather and climate models to enhance understanding and improve forecasts of atmospheric rivers. These narrow, low-altitude, elongated corridors of water vapor account for most major flooding events, provide about 40 percent of California’s freshwater and are often “drought busters.” They help us understand and predict the global water cycle and its regional extremes.

NASA satellite data and modeling studies have contributed to a better description and understanding of the Madden-Julian Oscillation, a recurring pattern of tropical weather and climate that impacts weather in Earth’s mid-latitudes, including California. Weather forecast models now demonstrate the ability to forecast this pattern up to four weeks in advance, potentially providing new, long-lead precipitation forecast information for California. The NASA team is working with the global weather and climate forecast communities to enable and improve routine forecasts of this phenomenon.

NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

Three of the five new NASA Earth science missions scheduled to launch in 2014 will contribute to water cycle research and water-related policy decisions.

The Global Precipitation Measurement (GPM) Core Observatory, a joint satellite project with the Japan Aerospace Exploration Agency scheduled for launch Feb. 27, will inaugurate an unprecedented international satellite constellation that will produce the first nearly global observations of rainfall and snowfall. The new information will help answer questions about our planet's life-sustaining water cycle, and improve water resource management and weather forecasting.

ISS-RapidScat, scheduled to launch to the International Space Station in June, will extend the data record of ocean winds around the globe. The data are a key factor in climate research, weather and marine forecasting and tracking of storms and hurricanes.

Soil Moisture Active Passive (SMAP), launching in November, will inform water resource management decisions on water availability. SMAP data also will aid in predictions of plant growth and agricultural productivity, improve short-term weather forecasts and long-term climate change projections, and advance our ability to monitor droughts and predict floods and mitigate their related impacts on people’s lives. 

NASA also plans to launch four additional water-related satellites in the next seven years: The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2); Gravity Recovery and Climate Experiment (GRACE) Follow-on; Surface Water Ocean Topography mission; and the NASA-Indian Space Research Organisation Synthetic Aperture Radar mission. These satellite missions join more than a dozen NASA airborne sensors focused on regional-scale issues, understanding detailed Earth science processes and calibrating and validating NASA satellites.

“Over the past two decades, NASA has developed capabilities to measure and provide useful information for all components of Earth’s freshwater resources worldwide," said Michael Freilich, director of NASA’s Earth Science Division in Washington. "Working with partners like CDWR, we are leveraging NASA’s unique Earth monitoring tools and science expertise to help managers address the state's water management challenges.

Rachel Hoover
Ames Research Center, Moffett Field, Calif.

Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.

Folsom Lake, near Sacramento
The severity of California's drought is visible at Folsom Lake, near Sacramento. On July 20, 2011, the lake was at 97 percent of capacity; on Jan. 16, 2014, it was at 17 percent.
Image Credit: 
California Department of Water Resources
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One of the first complete views of the United States from Landsat 8
One of the first complete views of the United States from Landsat 8
Image Credit: 
NASA/David Roy
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Smartphone in a crop field
NASA is implementing web and mobile data interfaces to increase the ability of the agricultural community to access and use satellite data in irrigation management and crop monitoring.
Image Credit: 
NASA Ames/Cooperative for Earth Science Research Technology
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Before and After Images: 
Images captured in January 2011 and January 2014 by the Landsat satellite over the San Joaquin Valley in California. Areas with dense vegetation are shown in green. Yellow and brown indicate sparse vegetation or bare soil. These images illustrate the effect of the ongoing drought in California on both agricultural fields and the grasslands to the west.
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Page Last Updated: February 27th, 2014
Page Editor: Rachel Hoover