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TOPS Satellite Irrigation Management Support (SIMS)

The SIMS beta web interface is available here. For a brief tutorial, please see the help page.

SIMS Web Interface (beta) This interface is being made available for review and evaluation by California growers. Maps and data are currently available for 2010 to present. Please send questions and comments to

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A common approach to optimize irrigation scheduling is to calculate recent crop water loss by obtaining a measure of reference evapotranspiration (ETo) from an agricultural weather station and applying a crop coefficient (Kc) to calculate the crop evapotranspiration (ETc), a measure of crop water demand. The California Irrigation Management Information System (CIMIS), operated by the California Department of Water Resources (CDWR), currently provides daily estimates of reference evapotranspiration (ETo) on a 2 km (1.25 mi) statewide grid. However, prescriptive tables frequently used to estimate Kc values for conversion of ETo to ETc can be difficult to use, and do not readily account for such considerations as site specific conditions, year to year variations in weather or other growing conditions, maturity level of permanent crops, stand density or other cultural practices, and so can differ from actual crop conditions.

Recent research conducted by USDA and partners has demonstrated that direct relationships exist between satellite indices of vegetation conditions, fractional canopy cover in crops, and crop coefficients for multiple California crops. By using spectral indices that can be obtained from several satellite instruments, it is possible to map crop coefficients on an approximately weekly time step at a spatial resolution of 1/4 acre (30m), and thus provide information that is useful at the scale of individual farm fields. To date, however, lack of an operational system for real-time processing of the satellite data has presented a substantial barrier to use of this approach for irrigation management.

The Satellite Irrigation Management Support (SIMS) project is a NASA supported effort to apply publicly available data from earth observing satellites to map crop cover, crop coefficients and crop evapotranspiration, with the longer-term goal of developing information products and tools to provide decision-support for water managers and agricultural producers. The project is using the Terrestrial Observation and Prediction System (TOPS), a NASA modeling framework developed to monitor and forecast environmental conditions. The primary focus of the effort is to extend TOPS to provide the computing and data processing systems required to support the use of satellite data to provide rapid assessments of current crop conditions, and to translate the satellite data into formats that are useful to agricultural producers in irrigation scheduling and water management. The project has also developed functioning prototypes of web and mobile phone based reporting and data access systems to allow evaluation of data products by agricultural producers. The project has deployed wireless sensor networks in commercial fields across California to collect information on weather and soil moisture conditions to facilitate product evaluation.

Maps of crop cover and water demand are distributed via an on-line web interface for review and evaluation by California growers. The web interface allows users to browse and query specific locations of interest to obtain basal Kc and ETc data values to assess crop water requirements for individual fields. Participating growers will ultimately be able to create an account, draw or upload information to define a region of interest, and configure customized reports summarizing Kc and ETc values for fields or blocks of interest. The project will also test the use of mobile devices for distributing and exchanging data with growers who wish to further customize the system for their farming operation.

When complete, the NASA computing and data management infrastructure being developed will provide new capabilities to supplement existing tools used by agricultural producers and water resource managers striving to maximize the benefit of water supplies throughout California.

The effort was initiated as part of a larger project supported by the NASA Applied Sciences Program that focused on expanded use of satellite observations for water management in California and potentially other states, as a joint effort among NASA Ames Research Center (ARC), the Jet Propulsion Laboratory (JPL), and Marshall Space Flight Center (MSFC). Working with partners at the California Department of Water Resources (DWR), USDA Agricultural Research Service (ARS), USDA Natural Resource Conservation Service (NRCS), universities, water districts, irrigation consultants, and agricultural producers, the project is developing the data systems necessary to support a range of water management applications, from monitoring Sierra Nevada snowpack to tracking and forecasting irrigation demand in California's Central Valley and other key growing regions. The TOPS-SIMS irrigation forecasting project is led by NASA Ames Research Center and CSU Monterey Bay.

Additional information:

Guidelines for calculating crop water requirements (FAO-56 international practice standard)

California Irrigation Management Information System

Western Growers Association

USDA San Joaquin Valley Agricultural Sciences Center


Melton, F., L. Johnson, C. Lund, L. Pierce, A. Michaelis, S. Hiatt, A. Guzman, D. Adhikari, A. Purdy, C. Rosevelt, P. Votava, T. Trout, B. Temesgen, K. Frame, E. Sheffner, and R. Nemani, 2012. Satellite Irrigation Management Support with the Terrestrial Observation and Prediction System: An Operational Framework for Integration of Satellite and Surface Observations to Support Improvements in Agricultural Water Resource Management. IEEE J-STARS Special Issue Interoperability architectures and arrangements for multi-disciplinary Earth Observation systems and applications, 5(6), pp. 1709-1721, 5(6), pp. 1709-1721.

Johnson, L., F. Melton, A. Michaelis, L. Pierce, C. Lund, T. Trout, D. Wang and R. Nemani, 2011. Satellite irrigation management support with the Terrestrial Observation and Prediction System. Proceedings ASPRS 18th William T. Pecora Memorial Remote Sensing Symposium, 14-17 Nov., Washington DC (4 pp)

Johnson, L. and T. Trout, 2012. Satellite NDVI assisted monitoring of vegetable crop evapotranspiration in California’s San Joaquin Valley. Remote Sensing 4:439-455. doi:10.3390/rs4020439

Trout, T., L. Johnson, and J. Gartung, 2008. Remote sensing of canopy cover in horticultural crops. HortScience 43(2):333-337.

Nemani, R., P. Votava, A. Michaelis, F. Melton and C. Milesi, 2011. Collaborative supercomputing for global change science, Eos 92(13) 29 March 2011.

Nemani, R., H. Hashimoto, P. Votava, F. Melton, W. Wang, A. Michaelis, L. Mutch, C. Milesi, S. Hiatt and M. White, 2009. Monitoring and forecasting ecosystem dynamics using the Terrestrial Observation and Prediction System (TOPS), Remote Sensing of Environment 113:1497-1509.