Satellite offers a flood warning breakthrough

Scientists from the University of Glasgow say they have established a new method to measure water behaviour by analysing sensor data relayed from the orbit.

A team from the School of Geographical & Earth Sciences describes in Geophysical Research Letters how the method might boost or even replace current tools employed for environmental reporting.

With climate change contributing to more frequently unpredictable weather events, the technique could offer a more efficient and timely response, they say. 

Standard practice for measuring river flow relies on stream gauges, that note discharge – the volume of water flowing past a particular point in a river second by. The method however can be both difficult and costly to implement and maintain, given that many sites are geographically remote. 

Satellites mounted with video sensors present an image of much larger areas of land, to provide better information on developing floods. But only in 2022 was the technique been perfected by the researchers, using footage from a Chinese satellite to chart flooding on a 12-mile section of the Darling River in Tilpa, Australia. 

By following the movement of visible surface features between frames in the video, the scientists were able to estimate the speed of the flow of the water.  

They paired the flow estimates with elevation maps of the flooded area, to estimate the flow discharge to within 15% of the local stream gauge measures in place along the site.  

Corresponding author and PhD student Christopher Masafu, said that while almost a third of the world’s population is exposed to flood risk and fresh water availability threats, the lack of stream gauges and other instruments limited knowledge of flows and any potential risks during heavy rains. 

“Satellites can be deployed anywhere around the world relatively cheaply and easily compared to the cost and effort of physically gauging all of those unmonitored rivers. However, their potential to measure river flows hasn’t been fully shown until this research, which is a really exciting breakthrough,” he commented. 

Masafu’s supervisor professor and co-author Richard Williams said satellite offered the opportunity for real-time monitoring and high vantage points, with obvious benefits in emergencies.  

He added: “What this technology allows us to do is mine that real-time video monitoring for even more useful information. That could help provide improved forecasts and warnings to help with on-the-ground planning during challenging situations.”

Dr Martin Hurst, co-supervisor and the third co-author cautioned that the technique had its limitations, notably that it can only be applied to footage ds without cloud cover. 

“However, it’s a big step towards making satellite footage a valuable tool for measuring the discharge of rivers around the world in addition to traditional stream gauges. We’re looking forward to developing the technique further in future research,” he stated.

Pic: Tobias Bjørkli