Research and Development Office

Scoping Methods for Evaluating and Computing Future Agricultural Water Needs

Project ID: 596
Principal Investigator: Jennifer Johnson
Research Topic: Agriculture Water Supplies
Priority Area Assignments: 2014 (Climate Change and Variability Research)
Funded Fiscal Years: 2014
Keywords: agricultural water needs, climate change, irrigation demands, socio-economic

Research Question

The largest consumptive use of water in the Western United States is for the production of irrigated agricultural. Thus, predicting how the demand for agricultural water will be affected by demographic, technological, and climate change is essential for understanding how the west's water resources can be sustainably managed in the future. Current methods for computing future agricultural water needs rely on methods that are primarily based on physical properties of the agro-hydrologic system. Two examples of this are: (1) develop a pattern of agricultural demands based on demands from a recent historical time period (i.e. the last 10 years); or (2) utilize an evapotranspiration (ET) calculator along with future temperature and precipitation projections to determine crop irrigation water requirements for an assumed crop mix. Method (1) assumes that irrigators are going to behave similarly to recent historical time periods in the future. Method (2) assumes crop mixes will not change and that the irrigators will behave just as the ET calculator behaves. Both of these approaches are limited in that neither method accounts for technological developments nor changes in agro-economic systems that can significantly impact the water needed to sustainably support irrigated agricultural systems.
To address these limitations and important question must first be answered; Is it possible to develop a method for evaluating future agricultural water needs that relies on more than just the physical factors and historical water use, but also includes the potential behavior of the irrigators under future conditions influenced by social, technological, economic, and institutional factors?

Need and Benefit

Reclamation is responsible for delivering water for irrigated agriculture in the western US. An important aspect of ensuring that water supplies remain viable into the future is understanding how the needs and demands of water users might change under possible future conditions . As mentioned in the Research Question section, current methods do not completely account for the impacts of potential changes to future demands. This scoping effort will help to determine if a more complete method can be developed.
This project could be used to address the following gaps as defined Addressing Climate Change in Long-Term Water Resources Planning and Management (Reclamation and USACE, 2011): 5.02 Understanding how socioeconomic factors may affect water and power delivery reliability, water allocation, as well as decisions on source of supply under a changing climate, 5.03 Understanding how institutional realities currently control socioeconomic responses to climate variability and could control socioeconomic responses under a changing climate, and 7.05 For each response on a socioeconomic system, uncertainty information on system science and associated ways of portraying this science in a system model and the observations used to customize a model for a specific system.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Scoping Methods for Evaluating and Computing Future Agricultural Water Needs (final, PDF, 363KB)
By Jennifer Johnson
Report completed on November 18, 2014

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