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The sustainability-productivity tradeoff: Water supply vulnerabilities and adaptation opportunities in California’s coupled agricultural and energy sectors

The interdependence of water availability, agricultural production, and electric power generation is well established, yet significant challenges remain for understanding how decisions or resource disruptions in any one of these sectors impact the system as a whole. Nowhere is this challenge more pressing than California, which, despite chronic water scarcity, continues to lead the nation in agricultural production by a factor of two.

Primary Investigators:

NSF Organization:

Division of Computer and Network Systems

Program Manager:

David Corman

Sponsor:

University of North Carolina at Chapel Hill

Abstract:

The interdependence of water availability, agricultural production, and electric power generation is well established, yet significant challenges remain for understanding how decisions or resource disruptions in any one of these sectors impact the system as a whole. Nowhere is this challenge more pressing than California, which, despite chronic water scarcity, continues to lead the nation in agricultural production by a factor of two. In California, nonstationary climate is expected to increase the frequency and severity of drought, with highly uncertain impacts on the availability of surface water. The subsequent effects on statewide electricity generation and agriculture in California’s Central Valley will be closely linked. Surface water availability in the Valley is largely driven by snowmelt from the Sierra Nevada, which is stored and distributed to irrigation districts for food production. During drought, however, irrigators must pump groundwater to compensate for scarce surface water. As a result, electricity demand from groundwater pumping rises by up to 33%, primarily during summer months when urban electricity demands also peak. Reduced runoff during drought also translates to less hydro-power generation (which accounts for ~20% of California’s capacity), forcing electric utilities to rely on more expensive natural gas generation. The combination of higher electricity demand and increased reliance on natural gas leads to higher electricity prices. Thus water scarcity drives irrigators to pump significantly more groundwater when electricity prices are highest, an activity that becomes still more expensive if groundwater levels continue their historical decline. These issues illustrate the coupled challenges facing California’s food-energy-water (FEW) systems, encompassing multiple scales of governance, from statewide planning and management of infrastructure to local irrigation district and farm-level decisions.

The overarching contribution of this research is the design and integration of an open source modeling- simulation framework for the California FEW systems (CalFEW), with interactive visualization, sensitivity analysis, and multi-objective optimization tools to discover key vulnerabilities and tradeoffs across sectors. This new decision support framework will achieve four major scientific objectives. First, it will determine the impacts of climate change-induced variability on the amount, timing, and location of precipitation and runoff in the Sierra Nevada range. Second, this knowledge will be integrated into CalFEW to improve understanding of how the coupled systems will respond to future shocks in the form of water scarcity, commodity price dynamics and regulatory change. Third, it will leverage CalFEW to develop a suite of novel tools for reducing supply/financial risk and incentivizing more sustainable water-electricity consumption in the agriculture sector. Finally, the project will design and test portfolios of risk management tools to balance near-term productivity and long-term robustness/resilience across sectors and spatial scales. All tasks will rely on collaboration with a diverse group of decision-makers to understand how their perspectives on future risks, candidate policy actions, and preferred measures of system performance will affect the adoption of new, more coordinated management approaches.

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