The 2020 Edenville and Sanford, MI Dam Failures: Geomorphic Change in Response to Catastrophic Flooding
Abstract
Catastrophic dam breaks are likely to become more common given the changing hydroclimate and aging dam infrastructure in the USA. However, virtually no data exist on river response to dam failure because catastrophic floods are unpredictable, can occur in remote locations, and introduce logistical challenges for fieldwork. On May 19th, 2020, a record flood in central Michigan caused the cascading failure of the Edenville (9 m) and Sanford (7 m) dams, resulting in an estimated >$200M in property damage and displacing 10,000 residents to shelters and hotels during the COVID-19 pandemic. Two weeks later, we collected UAV-mounted lidar data to quantitatively measure the intense scour and deposition that resulted from these events. Through comparison with pre-flood lidar surveys, we show both broad and localized several-meter erosional and depositional changes in vegetated, urban, and agricultural areas. A new channel formed downstream of the Edenville failure due to ~2 m of incision, and where this channel merges with the former river channel, a >3 m fan-shaped depositional wedge was created. The new channels along the floor of the former Edenville Lake host measurable knickpoints that arrest geomorphic change by delaying complete lake drainage. More than 8,000 m3 of agricultural topsoil were removed downstream of the initial dam break. Meter-scale fluvial bedforms were deposited on former baseball diamonds while houses, roads, and bridges were washed away. Further data collection over the following months and years allows investigation into how rivers and their surrounding landscapes respond to catastrophic floods. These surveys will form the basis for future tests of geomorphic transport and erosion models, which require critical evaluation to better prepare for the inevitable future failures of other aging dams in a changing world.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMEP016..10M
- Keywords:
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- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1826 Geomorphology: hillslope;
- HYDROLOGY