Ukraine Dam Collapse: SAR reveals flooding extent

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The collapse of a major dam has unleashed profound concerns over the damage caused by widespread flooding, as the waters from the Dnipro River gush across southern Ukraine.

Mass evacuations are underway downriver from the Nova Kakhovka Dam, the largest reservoir in Ukraine, which sits about 20 miles (30 km) east of Kherson, a city with a pre-war population of approximately 300,000.

The situation upriver is perilous for different reasons. The reduction in water levels is raising safety issues involving the Zaporizhzhya nuclear power plant, which relies on the Dnipro River for cooling the facility’s reactors.

Tracking the extent of damage and the fallout across such a large area – which also happens to be a warzone – presents major challenges. 

Satellite imagery has played an important role during the conflict in Ukraine as a source of objective and timely information that can be used to assess the situation on the ground.

The synthetic aperture radar (SAR) images below were collected by our friends at Umbra, a leader in advanced space radar technology.

The first image shows the Nova Kakhovka Dam on June 6 (17:28 local time) after the collapse took place earlier that day.

Nova Kakhovka Dam - 06JUN23 - 17:28 (local time)

Prior to the blast, the dam stood 30 meters tall and held back a reservoir equal in volume to the Great Salt Lake in Utah. 

Massive flooding has inundated low-lying areas on either side of the Dnipro river.

Ursa Space created flood extent maps by applying an algorithm to SAR imagery that is designed to extract and classify water pixels. 

 

Nova Kakhovka on the river’s southern bank was quickly submerged after the dam’s collapse, as you can see in the flood extent map below, based on SAR imagery collected June 6 (17:28 local time).

Nova Kakhovka Dam - 06JUN23 - 17:28 (local time)
Flood analytic vectors and permanent water displayed

Residents have been fleeing the area in and around the downstream city of Kherson in southern Ukraine where floodwaters were expected to stop rising by the end of Wednesday (June 7). 

The flood map below is based on SAR imagery collected June 7 (10:33 local time). It shows the town of Kardashynka, just south of Kherson. 

Kardashynka - 07JUN23 - 10:33 (local time)
Flood analytic vectors and permanent water displayed

Unfortunately, the complete toll of the dam’s collapse won’t be fully revealed until long after the floodwaters have receded.

Agriculture production will almost certainly be impacted because of the collateral damage to the canal system that irrigates much of southern Ukraine.

Another potential fallout with serious consequences relates to the Zaporizhzhya facility, Europe’s largest nuclear power plant.

There is no immediate risk to the safety of the plant, even though there was a significant reduction in the level of the reservoir used to supply cooling water, International Atomic Energy Agency head Raphael Grossi said in a statement

An additional source of water is the large cooling pond next to the site, Grossi said. 

Still, the water levels at the reservoir and cooling pond will be closely watched for the foreseeable future. 

We have illustrated before how SAR-based analytics can be used to measure water levels at dam reservoirs.

 

Given the importance of this story, we will continue to monitor the situation and provide more updates as they become available.

Follow us on LinkedIn and Twitter for the latest. 

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