A Framework to Evaluate Irrigation Efficiency Impacts Under a Changing Climate

By Karie Boone, Center for Sustaining Agriculture & Natural Resources, Washington State University

For decades, federal agencies, practitioners and academics across the Northwest have promoted transitioning farmers to more efficient irrigation systems with the intent of reducing agricultural water withdrawals and making more water available for other uses such as municipal, industrial and flows for fish. More recently, climate change-related drought and water stress have provided even more momentum towards irrigation efficiencies that deliver water directly to the crop root zone, reduce field application water losses and potentially increase farm-level agricultural productivity. Indeed, ongoing and anticipated impacts of changes in temperature, water availability, and atmospheric carbon dioxide suggest that irrigated agriculture will experience an increase in the amount of unmet irrigation demand due to higher temperatures’ effect on snowpack as well as possible reductions in average yields under future climates (see my colleague Aaron Whittemore’s post on that). Whether investments in more costly but less labor-intensive sprinkler or drip systems can effectively help meet water demands across diverse user groups does not have a simple answer. Instead, decision-makers must evaluate region-specific hydrologic, ecological, and socio-economic conditions to better understand outcomes of efficiencies before this potential climate adaptation strategy is implemented.

Drip irrigation system on grave vines
Drip irrigation is a water efficient irrigation technology utilized to deliver water directly to the plant root zone. Credit: WSDE under CC BY-NC 2.0.

A recent interdisciplinary study from researchers at Cornell and Washington State Universities, led by Dr. Keyvan Malek, develops a framework to evaluate efficiencies using Washington State’s Yakima River Basin as a case study. The basin is a snow dependent, heavily irrigated agricultural region and thus particularly sensitive to climatic warming while also having a relatively low adoption of efficient irrigation technologies. The framework models context-specific scenarios to help decision makers evaluate the effects of irrigation efficiencies on water-dependent stakeholders, agricultural productivity, hydropower generation, and aquatic habitats. More specifically, the analysis uses an integrated modeling platform (VIC-CropSyst-YAKRW-ASEAP) to more holistically capture the numerous impacts of changing irrigation technology on irrigation water supply and demand, crop biomass production, return flow, and streamflow, as well as hydropower generation, farm-level energy demand, and instream flows to support fish species.

The authors develop scenarios for two future time periods (2030 – 2060 and 2060 – 2090) to demonstrate possible implications of irrigation efficiencies at the food-energy-water nexus, and found that changes to agricultural water use patterns are contingent on the myriad local climatic, institutional and infrastructural factors such as water rights, water law and reservoir storage capacity. Results suggest that farmers’ investments in more efficient irrigation systems affects the distribution of water, regional agricultural productivity, hydropower generation, and aquatic habitats within a basin.

Legend with historical, no_action, IPEV, and all_switched categories
Bar graphs depicting irrigation efficiencies
Figure 1 (modified from article) visualizes the impacts of irrigation efficiencies on diverse water-dependent sectors. 1. NoAction (black) is a status quo scenario, meaning that while climate changes, the irrigation system would not change in the future. 2. Irrigation Pattern based on Economic Viability (IPEV) (pink) scenario highlights which investment decision makes sense for farmers when they experience a certain climatic condition. 3. All_Switched (blue), in which all of the farmers with inefficient irrigation systems switch to more efficient technologies. This scenario is a way to explore the potential impacts if all farmers were to switch, and thus represents the highest possible impacts farmers’ adaptive irrigation decisions.

Scenarios that allowed for changes to water rights so that water conserved through efficiency upgrades were then applied to increased crop acreage elsewhere led to improved agricultural productivity but then had varying levels of negative outcomes (see color coded scenarios in Figure 1) for all other sectors including hydropower, and labor. It also had negative outcomes on mean annual and mean summer flows (MSF), indirectly indicating impacts to ecological indicators including fish populations (Figure 2).  Malek and colleagues demonstrate that regional institutions and infrastructures weigh heavily on the outcomes of efficiency improvements and, as such, that policy recommendations in this realm are perhaps not generalizable. And overall, increased efficiency may have positive impacts for agriculture but could have negative impacts on other water users and sectors where even a combination of large infrastructural investment such as new reservoir systems coupled with conservation measures can enhance conflicts among various users.

Figure of box and whisker plots of data
Figure 2 (modified from article): Mean Summer Flow (MSF) modeled over two future time periods where higher values indicate more stream flow and are more favorable. See Figure 1 for scenario/color descriptions.

In response to efficiency impacts at the inherently interconnected food-water-energy nexus, authors argue that policies should be considered under a “wicked problem” framework where there is no perfect or a final solution. And while recognizing the challenge of knowing which stakeholders should be included or excluded in the efficiency impact analysis, policies should nevertheless “incorporate various points of view, disciplines and knowledges, while incorporating awareness raising and capacity-building as part of the process.”


Malek, K., Adam, J., Yoder, J., Givens, J., Stockle, C., Brady, M., Karimi, T., Rajagopalan, K., Liu, M., & Reed, P. (2021). Impacts of irrigation efficiency on water-dependent sectors are heavily controlled by region-specific institutions and infrastructures. Journal of Environmental Management, 300, 113731. Online Access

This 5-year research and extension project (2018-2023) is led by Washington State University’s State of Washington Water Research Center (WRC) and is supported by USDA National Institute of Food and Agriculture, project #1016467. The full Technology for Trade project team, and more information about the project, is available at the WRC Technology for Trade page.