Satellite-based river monitoring technique could provide early warning of flooding

Developed by researchers  from the university’s School of Geographical & Earth Sciences,  the technique, which measures the speed of river flows by analysing video footage captured from orbit, could replace or enhance the way governments and land managers currently monitor rivers, and improve the ways that floods are predicted.

Currently, river flows are most often measured using stream gauges, which directly take stock of the volume of water flowing past a particular point in a river every second – a measurement known as discharge. However, stream gauges are expensive to install and maintain, and difficult to place in remote areas.

While stream gauges provide detailed measurements of river discharge at specific points, satellites equipped with video sensors provide a much broader visual overview of large areas of land, making them useful for monitoring geographical changes over time and providing real-time information on the spread of floods.

To develop the technique the team used video footage from a Chinese satellite to measure the discharge of a February 2022 flood along a 12-mile section of the Darling River in Tilpa, Australia. By tracking and analysing the movement of visible surface features between frames in the video footage, they were able estimate the speed of the flow of the water, and by combining these estimates with detailed elevation maps of the flooded area, they were able to estimate the flow discharge to within 15% of real measurements taken by stream gauges on the river during the flood.

Commenting on the potential of the approach Professor Richard Williams said: “Satellites give us the ability to monitor rivers in real time from a high vantage point, and being able to watch them swell and flood during heavy rains can be very helpful in emergencies. 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.”

A paper on the research , titled ‘Satellite Video Remote Sensing for Estimation of River Discharge’, is published in Geophysical Research Letters.