Daily evaporation from 23 irrigated and rainfed crops worldwide from 2000 to 2025
This paper introduces CropET, a global dataset providing daily evaporation estimates for 23 irrigated and rainfed crops from 2000 to 2025 at 5 arc-minute resolution, which combines FAO-56 modeling with dynamic crop mapping and satellite data to offer a validated resource for analyzing agricultural impacts on the hydrological cycle.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
The water that falls from the sky and the water that rises back into the air form a continuous loop that sustains life on Earth. This cycle is not just about rain and rivers; it is deeply tied to the plants we grow to feed ourselves. When farmers plant crops, they change how water moves through the land. Some crops drink water from the soil, while others rely on irrigation systems that pump water from rivers or aquifers. As the global population grows and the climate warms, the way these crops use water is shifting. In some places, fields are expanding into new areas, while in others, rising heat is making the air thirstier, pulling more moisture from the soil. Understanding exactly how much water crops consume, and where that water comes from, is essential for managing food supplies and protecting the planet's fresh water reserves.
To solve this puzzle, researchers Akash Koppa and Sara Bonetti have created a new, detailed record of daily water loss from crops across the entire globe. They call this dataset CropET. It tracks the evaporation from twenty-three different types of crops, ranging from rice and wheat to soybeans and coffee, for every single day between the years 2000 and 2025. The map covers the Earth at a resolution fine enough to see individual fields, rather than just broad regions. By combining satellite data on rainfall and weather with updated maps of where crops are actually growing, the team built a picture of how agricultural water use has changed over time. This work moves beyond older estimates that treated crop areas as fixed and unchanging, offering instead a dynamic view that captures the real-world expansion of farming and the shifting climate.
The researchers found that the total amount of water evaporating from crops worldwide is immense. For the year 2000, their calculations showed that crops released about 5,814 cubic kilometers of water into the atmosphere. This figure aligns closely with other major studies, giving confidence that the new model is accurate. When they broke this number down, they saw that rice, wheat, and maize were the biggest consumers, together accounting for 40 percent of all crop evaporation. Rice stood out as the crop that relied most heavily on irrigation, drawing significant amounts of water from human-made sources. In contrast, crops like soybeans, cassava, and cocoa relied almost entirely on rain, showing little dependence on irrigation.
Over the two decades covered by the study, the pattern of water use shifted noticeably. In many parts of the world, particularly in India, eastern China, and Southeast Asia, the amount of water evaporating from crops increased. This rise was driven by two main forces: the physical expansion of farmland and the growing demand for water caused by warmer, drier air. In these regions, farmers planted more crops, and those crops drank more because the heat made them thirstier. The study highlighted that in China and India, both rain-fed and irrigated fields contributed to this increase. However, the story was different in other places. In the western United States and parts of South America, crop water use actually declined. In California's Central Valley, for instance, a severe drought and new water management laws led farmers to leave fields fallow, reducing the amount of water evaporating from the land.
The team also looked at how these changes played out over time and space. They discovered that the increase in water use was not uniform. In West Africa and the Brazilian savanna, the rise was almost entirely due to rain-fed crops expanding into new areas. In central India, however, the increase was driven mostly by irrigation. The researchers validated their numbers by comparing them to real-world measurements taken from towers that track water vapor rising from the ground. While their daily estimates were slightly lower than the tower measurements, the overall patterns matched well, confirming that the model captures the essential behavior of crops. The study also noted that for the years 2021 through 2025, the data relies on the crop areas recorded in 2020, as newer maps were not yet available, meaning the most recent years reflect a static view of farming rather than the latest expansions.
This new dataset offers a powerful tool for understanding the complex relationship between food production and the water cycle. By providing a daily, global view of how crops use water, it allows scientists and planners to see exactly where and when agricultural expansion is reshaping regional water budgets. It reveals that while some regions are seeing their crops drink more due to climate and growth, others are pulling back due to water scarcity. The work does not just count the water; it tells a story of how human choices and environmental changes are rewriting the rules of the Earth's hydrological cycle, one field at a time.
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