Deadly Dam Failures: Cause, Effect, and Prevention
Buttress dams are similar to gravity dams in their shape, but they require less concrete. The forces of the water are diverted down to the foundation of the dam along sloping buttresses.
Arch dams look like a semi-circle or ellipse from above. The wall, which tends to be constructed with vertical slabs of concrete, can be relatively thin. The pressure of the water is carried sideways into abutments.
Dams can also be made with steel and timber.
How Do You Stop Dams from Overflowing?
That’s the thing — sometimes dams do break and overflow, causing massive flooding, destruction and death. It can wipe out access to roads, food and vital services.
But it is possible to control “overtopped” dams, with outlet works and spillways.
Outlet works can allow a constant stream of water into a river below the dam, for instance, or into a hydroelectric power system, or release it for farm irrigation.
Spillways, meanwhile, are often open chutes or shafts where the water flows out when its level gets high enough to enter an opening.
Why Do Dams Fail?
One of the most common causes for dam failure — that’s when the dam breaks in an uncontrolled way — is their age.
In 2021, the United Nations University published a report indicating that “tens of thousands of existing large dams have reached or exceeded an ‘alert’ age threshold of 50 years, and many others will soon approach 100 years.”
The Brumadinho dam at Minas Gerais was built in 1976, which means it was approaching the end of its lifespan. And Libya’s Abu Mansour and Derna dams were also built in the 1970s — so, while Storm Daniel triggered their failure, they may have been ready to fail, anyway.
But dams also fail due to poor design and irregular maintenance.
Overtopping can occur if a spillway design is inadequate and can’t cope when there’s heavy rainfall. The spillway may get blocked over time, too.
The older a dam gets, the more its foundation can experience a natural process called settling. Slopes surrounding the dam can become unstable, and if the original construction materials start to erode, it can cause seepage.
There are other natural causes of dam failure, including earthquakes, floods, extreme weather and landslides.
And then there are the effects of war — bombings and intentional sabotage.
How Do You Prevent Dam Failure?
Here’s the long answer: ensure regular maintenance and apply engineering advice and recommendations, but also design a good emergency strategy for the event of a dam failure in your area and make sure everyone knows about it.
Because, and this is the short answer as the US Federal Emergency Management Agency (FEMA) puts it, “no dam is flood-proof.”
Zulfikar Abbany is a Senior Science Editor and multimedia journalist DW. This article was edited by Carla Bleiker, and it is published courtesy of Deutsche Welle (DW).
