Water, the lifeblood of agriculture, is facing a global crisis as its finite resources continue to dwindle. In this challenging scenario, agricultural regions plagued by water scarcity are under pressure to make every drop of irrigation water count. Economic Irrigation Water Productivity (EIWP) is a path toward efficient agricultural water use, with the potential to significantly reshape policies and practices.
Transforming Metrics for Agricultural Water Management
Traditionally, the agricultural sector has assessed its success through the lens of crop yields per unit of land. Even in regions with scarce water resources, the drive for increased yields often overshadows concerns about water availability. However, this approach is transforming. Today, the focus is shifting towards economic water productivity, where the emphasis is on maximising economic output per unit of water used as highlighted by the Food and Agriculture Organisation (FAO) and the World Bank in their 2022 Investment Brief. It is a shift driven by the realisation that water availability directly impacts production costs, making EIWP a critical metric in informed policymaking for agricultural water management. The concept of EIWP is gaining traction in agricultural water policy circles, redefining the value of irrigation water, and inducing farmer behaviour changes in curbing water use increases.
Assessing Productivity in Economic Terms
The evaluation of EIWP considers factors like crop evapotranspiration (ET) and biomass, which can be estimated using remote sensing-based models. When combined with economic data, remote sensing has the potential to shape water policies and investments, fostering the development of more sustainable agrifood systems particularly in regions with limited water resources. The lack of ground-level measurements, adequate irrigation infrastructure, and water metering technologies is often a barrier to collecting data on changes in water use across wide areas. This data limitation poses a significant challenge to water-scarce basins, especially in cases where there is a dearth of data regarding the number and types of irrigation systems in use and their efficiency, water consumption and water availability, soil moisture, and river flow. This underscores the importance of regular satellite observations which generate estimates that are comparable to in-situ methods in terms of accuracy.
Crop Evapotranspiration Estimation for Managing Agricultural Water and Yields
As a key component of the water balance, evapotranspiration (ET) has long been the key factor for irrigation scheduling, crop yield estimation, and studying climate change because it involves energy and mass exchanges between the land surface and atmosphere.
Globally, approximately 60% of the annual precipitation that falls on land is sent back into the atmosphere through evapotranspiration (Jung et al., 2010). Estimation of ET ensures optimised use of available water resources. Satellite remote sensing has enabled significant progress in ET estimation methods, leading to its widespread adoption by the global scientific community, thanks to the comprehensive spatiotemporal coverage offered by satellite data.
Harnessing Earth Observation for Smart Agricultural Water Management Policies
Earth observation informs agricultural water management policies through different ways. By considering the economic returns per unit of water, local and regional water authorities as well as government bodies can prioritise the allocation of water to crops or regions where it is most productive. Remote sensing-backed policies can also encourage the adoption of water-efficient irrigation practices, conserving water resources for upcoming growing seasons and future generations. EIWP facilitates enhancing agricultural water use often through the provision of financial incentives or subsidies for crops that yield higher economic returns per unit of water, or the promotion of the adoption of smart irrigation scheduling technologies for economically profitable and water-efficient agricultural practices.
Depending solely on rainfall leaves farmers susceptible to climate change-induced droughts and floods. On the flip side, irrigation strains groundwater resources. While increasing EIWP in a world where every drop of water counts may not align with the specific goals of individual farmers in terms of net revenue or yield output, it remains essential in water-scarce regions where efficient irrigation management is of utmost importance. The time has come to promote the involvement in remotely sensed EIWP, driving the shift towards water-efficient farming.
About the Author
Rim Hazimeh is a GIS specialist and Project Coordinator at AgHive, at the American University of Beirut (AUB). She is actively engaged in diverse international research projects that focus on water resources management and climate change.