This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Irrigation canals form a sort of circulatory system for global agriculture. Across the world, millions of kilometers of human-made canals carry water from lakes, rivers and reservoirs downhill to farmland.
Canals are vitally important to human food production, yet many agricultural areas lack the means to monitor the ebb and flow of water through these waterways. This forces farmers and water managers to rely on scattered gauges, inspections and local reports to make decisions about water use. A new study from the University of Washington suggests, however, that the tools needed for more comprehensive monitoring may already exist.
In the study, researchers analyzed data from a NASA satellite built to track the water levels of oceans, lakes, rivers and other large bodies of water over time. That project was never designed to track smaller bodies like canals. Yet, when the researchers looked at roughly 800,000 kilometers (497,000 miles) of canals in Asia, they found that the satellite could measure water levels with moderate to high confidence at more than 85% of locations.
The discovery could give farmers around the world a powerful new tool to manage precious water resources, prepare for droughts and improve food security in their communities. "What we are seeing is not simply a new satellite capability," said co-author Faisal Hossain, a UW professor of civil and environmental engineering. "It may represent a fundamentally new way of managing the water conveyance systems that sustain modern agriculture." The study was published Sept. 30 in Geophysical Research Letters.
The satellite at the center of the study, the Surface Water and Ocean Topography (SWOT) mission, is a joint effort of NASA and international partners. In orbit since December 2022, the satellite monitors Earth's surface water at least once every three weeks using a tool called interferometric radar, which compares multiple radar scans over time to detect elevation changes. Oceans, lakes and other large bodies of water are relatively straightforward to track in this manner.
Irrigation canals, on the other hand, are frequently narrower than 20 meters (66 feet), which puts them at the extreme low end of the satellite's observation power. The project's architects assumed that fluctuations within small canals would be invisible to the satellite. In 2025, he and collaborators published the Global Registry of Agricultural Irrigation Networks (GRAIN), a global dataset that used open-source mapping data and machine learning to chart 3.8 million kilometers (2.4 million miles) of canal networks.
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