20 May 2020
Edenville dam: a major dam collapse in Michigan
In Midland County, Michigan, USA a dam collapse is underway, driven by heavy rainfall. CNBC has a good article about the ongoing accident, which is causing extensive flooding. Unfortunately, as I write, reports are coming in that a second dam, at Sanford in the same area, has also breached.
The Edenville Dam is located at 43.813, -84.376. MLive has excellent aerial footage of the breach, and the extensive downstream flooding:
The town of Edenville is located about 1 km downstream of the dam:-
At the moment the cause / mechanism of the failure is not clear. ABC12 has a report from 2018 that the licence for the dam had been withdrawn by the Federal Energy Regulatory Commission because the structure had insufficient capacity to handle the Probable Maximum Flood. The FERC ruling is available online, and states the following:
Of particular concern is the project’s inability to pass the Probable Maximum Flood (PMF) due to inadequate spillway capacity … Currently, spillway capacity at the Edenville Project can only pass about 50 percent of the PMF.
NBC25 reports that the designs for a remediation of the hazard were being prepared, with construction anticipated in the period 2021 to 2023.
On reflection 1: Cyclone Amphan
Cyclone Amphan will make landfall in a few hours from now in NE India; this remains an extremely dangerous storm. As I have noted previously, although we categorise tropical cyclones on the basis of wind strength, most of the damage is typically caused by water. India and Bangladesh have well-established systems for evacuating people exposed to storm surge (although in the time of Corona Virus these will be tested to the maximum), but this storm is likely to cause substantial levels of inland damage from flooding and landslides.
On reflection 2: submarine landslides in the Gulf of Mexico
New research, published in Geophysical Research Letters, has detected 85 previously unknown submarine landslides in the Gulf of Mexico. Most of these landslides were triggered by the passage of seismic waves from distant earthquakes. The study suggests higher than anticipated levels of hazard to both underwater infrastructure and coastal communities.