As residents of Michigan’s Midland county scramble to recover from devastating floods, a video has emerged showing the critical moment when Eden dam collapsed, in a failure experts are attributing to shoddy maintenance and climate change.
Two dams failed in Michigan this week, the first in Edenville on Tuesday, and the second in Sanford, which collapsed a few hours later as a result of the first failure upstream. The flooding resulted in the mandatory evacuation of 10,000 Midland county residents at a time when physical distancing measures are needed to curb the spread of covid-19.
Excessive rainfall over the past week caused water levels to rise in the reservoir behind Edenville Dam, but the failure itself is being attributed to deregulation and lack of upkeep. That Edenville dam collapsed this week should hardly be a surprise, given warnings that appeared as early as the 1990s.
A remarkable video captured by Michigan resident Lynn Coleman shows the moment when Eden collapsed, when the earthfill embankment dam could no longer hold back rising floodwaters.
“This video is going to be a classic in the teaching of geotechnical failures, but it also clarifies the events that led to the Edenville Dam failure,” explained Dave Petley, a geologist at the University of Sheffield, at the AGU’s Landslide Blog.
During the initial stages of the failure, spill water can be seen trickling down from the top, but the crest starts to degrade and deform. At the same time, a disturbing bulge appears near the bottom. Then, the entire thing collapses in what can looks like a fast-moving landslide.
The floodwater doesn’t immediately pour out, likely because unseen portions of the dam are still collapsing. But then the water starts to flow. And flow and flow and flow. At its peak, the Tittabawassee River crested at a height just over 35 feet (11 meters).
The exact physical reason for the failure is still not known, but in a subsequent blog post, Petley said a lack of upkeep, along with pressures imposed by climate change, might have something to do with it:
“[E]arthfill embankment dams are not unusual and, when well designed and maintained, they are not unsafe. This dam was completed in 1924. However, these structures do require maintenance—would you expect a train built in 1924 to still work without extensive restoration—and they were designed for a time when rainfall levels were different. Climate change—global heating—is driving increases in rainfall intensities and durations, meaning that the Probable Maximum Flood is increasing in very many places.
I always get howls of protest when I say that climate change is important, but it is the case. These structures, worldwide, are going to need a substantial upgrade to cope with that increase in rainfall, and that’s going to be very expensive. In the interim we will see more failures of this type.”
Wow, that’s as upsetting as it is alarming.
Climate change is bad enough as it is, but this incident potentially demonstrates the degree to which our existing infrastructure, without ongoing maintenance and improvements, isn’t ready to withstand the demands imposed by global warming. And given the Trump administration’s deregulatory agenda, it’s not a problem that will be fixed anytime soon.