Before (June 3, 2019) and after Edenville dam collapse (May 20, 2020) near Midland, Mich. (NASA)
Torrential rains early this week proved too much for two major dams upstream of Midland, Michigan, a city of 40,000 people, to handle. On Tuesday, the Edenville dam collapsed while the downstream Sanford dam was overwhelmed, unleashing a gushing, record-setting surge of water into the city.
Ten thousand residents of Midland were told to evacuate after the Edenville dam failed and Michigan Gov. Gretchen Whitmer (D) declared a state of emergency.
Satellite imagery from NASA and Maxar captured before and after this disaster shows the dramatic effects of the compromised dams and how the floodwaters transformed the landscape. Vast areas, including homes, businesses, ball fields, roadways, and bridges were engulfed.
The Tittabawassee River, which the Edenville and Sanford dams help control, crested at 35 feet in Midland, its highest level on record, more than a foot above the previous high mark in 1986.
[Mich. governor says state will seek ‘legal recourse’ over failed dam]
The Maxar before and after scene below, shows the radical change at the Edenville dam after it collapsed:
Before and after Edenville dam collapse (Satellite image ©2020 Maxar Technologies)
Here’s a YouTube clip of the on-the-ground footage of the dam’s disintegration:
The dam’s demise is swift.
“The slope [of the dam] fails rapidly, initially forming a large toe bulge and there is major deformation at the crest,” writes landslide expert Dave Petley on the American Geophysical Union’s landslide blog, “The failure is rapid and mobile.”
NASA imagery (below) reveals how the collapse of Edenville dam emptied the lake it protected upstream. Wixom Lake, once a local playground for boaters, is now essentially a giant beach.
NASA imagery shows waterways before and after the Edenville dam collapsed and the Sanford dam was overtopped Tuesday. (NASA)
Notice how lake water, colored dark brown, is present upstream of the dam in the panel on the left (in the above image) before the dam is breached. But, on the panel on the right, the lake area is replaced by an earthy tone, indicative of sand, after the dam disintegrates.
The drone footage below, captured by Midland resident Peter Sinclair, provides a close-up and stark view of what’s left of Wixom Lake along with the flooding of nearby areas. Small ponds of water linger on the lake, but mostly just silt, sand, and mud remain:
While muddy, Sanford Lake, which sits above Sanford dam, was not drained. That dam was overrun, but did not collapse.
Here’s a scene before and during the time the Sanford dam was overrun, from Maxar:
Before and during time Sanford dam was overrun by floodwaters. (Satellite image ©2020 Maxar Technologies)
In the second frame in the above animation, you can see that while the dam is completely overwhelmed and surrounded by water, its basic structure is still intact.
The floodwaters along the Tittabawassee River river are now receding, but considering the huge amount of storm debris left behind around Midland, the cleanup effort has only just begun.
This imagery is a sobering reminder of the vulnerability of aging dam infrastructure in many parts of the U.S., especially as it is tested by extreme precipitation events intensified by climate change.
