Inspecting Dams: How Satellites and Drones Help Avoid Catastrophes

January 28, 2025

A dam’s surface might appear calm and unyielding. But looks can be deceiving.

That’s why governments around the world require dams to be inspected periodically. It’s a complex process that looks for tiny shifts in the earth around the dam, the appearance of hairline cracks or other evidence that the structure is under stress.

Many of the world’s 70,000 dams, however, are located in remote areas that make regular inspections difficult.

That’s why, increasingly, the data for dam inspections is being captured from the sky, where drones and satellites keep a watchful eye.

“Drones and satellites have revolutionized dam inspection by providing access to previously unreachable areas and offering new, more affordable ways to monitor the entire structure,” said Raul Colcher, IEEE Life Senior Member.

Emerging Threats to Dams

While rare, dams do occasionally fail. The International Commission on Large Dams, which tracks the largest dams in the world, said that about 300 of the 36,000 dams in its database have ever failed. These incidents have caused major loss of life and property damage. The commission points out that though the failure rate has historically stood at around 1%, the rate has dropped dramatically in recent years.

“Generally speaking, the main causes are natural — like erosion, extreme weather or seismic activity, and human factors —bad projects, execution errors, inadequate maintenance and aging,” Colcher said.

Some experts see climate change as emerging threats to dams, because it increases the likelihood of massive rain events.

“Climate change is resulting in increased water behind dams, which in turn results in increased pressure on the structure,” said IEEE Senior Member Paul Kostek. “This highlights the need for increased inspections and the use of technology to expand the reach of inspectors.”

Emergence of SAR

In recent years, the most valuable satellite-based inspection tool has emerged: SAR, or synthetic aperture radar. This tool uses microwave pulses to map the ground, collecting the reflection of those pulses as they are bounced back from Earth. One advantage of SAR technology is that it can peer through clouds as it creates highly detailed three-dimensional models of objects on earth.

Over the years, a number of SAR satellites have been launched, and these satellites take continuous measurements of the planet. One constellation of SAR satellites passes over the same location on Earth once every 12 days. That continuous measurement has led to another capability, known as InSAR or Inferometric Synthetic Aperture Radar, which compares two SAR images to detect tiny changes, as small as one millimeter, in a dam’s surface, from space.

SAR systems can also be mounted on drones, Kostek said, allowing for other perspectives.

“Using unmanned aerial vehicles or satellites allows inspections to be done without travel and when needed, prioritizing those dams that need a visit,” Kostek said.

Get Involved: On a worldwide basis, electric power generation is one of the largest categories of water consumption. The IEEE Standards Association is bringing together sustainability advocates, electric utilities and community water users to identify strategies to impact the water-energy nexus. Check it out.