The Washington PostDemocracy Dies in Darkness

Satellite images show flooding north of Kyiv in possible sign of ‘hydraulic warfare’

3 min

In the early days of Russia’s invasion, Ukrainian soldiers and civilians scrambled to assemble their defenses, seeking to make moving through the country as difficult as possible for Moscow’s forces.

They blew up bridges, used buses as makeshift roadblocks and welded homemade “Czech hedgehogs” to repel Russian tanks. And, according to a new set of satellite images, they may have also used one of the world’s oldest methods of fortification: water.

Photographs from Planet Labs PBC, an American firm, and other researchers appear to show a large expanse of flooded land north of Kyiv, the Ukrainian capital. In a pair of before and after images, taken on Feb. 22 and Feb. 28, the swath of territory becomes significantly more sodden.

On Feb. 26, Ukraine’s ambassador to the United States said Russian forces had destroyed a dam in a water reservoir near Kyiv, creating a flood risk, but did not provide further details. It is not clear if that incident is related to the water seen on the satellite photos.

The Washington Post was not able to confirm that the flooding was intentional, but Planet Labs said it cited outside analysts who believe it was deliberate. If so, it would be the latest example of a centuries-old practice.

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“When you’re defending, you’re trying to use what you have,” said Marta Kepe, a senior defense analyst at the Rand Corp. “Throughout history, we have multiple examples where countries or military actors have built fortification lines — walls, trenches, fortresses and bunkers. But often we forget that rivers, marshes and water-based defense lines can also be used.”

If it is intentional, Kepe added, “that may be what Ukrainians are trying to do — use water to prevent Russian forces from getting close to Kyiv.”

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The inundated area is north of Kyiv on the bank of the Dnieper River, somewhat to the east of where a 40-mile convoy of Russian troops has been idling for days. U.S. officials have credited this stall-out in part to Ukrainian efforts to slow it down.

Deliberate flooding during combat — either to erect a barrier or destroy an area — is known as “hydraulic warfare,” and it has often been used to supplement a defensive strategy, Kepe said.

“Ukraine is mounting a defensive operation in its own territory,” she said. “Considering that, I would assume that they would be able to use their superior knowledge of the terrain to their advantage. Hydraulic operations would require such in-depth knowledge of the terrain.”

The Netherlands has been perhaps the most prolific employer of strategic, weaponized flooding. A 2015 research paper found that, from the years 1500 to 2000, about one-third of floods in the country’s southwest were deliberately caused during wartime. The tactic was often ineffective, the study found, and had far-reaching consequences for the land and local population.

Water was used elsewhere in Europe as a natural defense line during World War II, including in Finland and the Soviet Union. The most notorious example of strategic flooding occurred in 1938, when the Chinese military breached the dikes of the Yellow River to slow the advance of Japan’s troops during the Second Sino Japanese War. The flood devastated the area and became known as “the largest act of environmental warfare in history.”

The tactic can be “integrated into your national defense planning,” Kepe said, “but it can also be used as a last resort when you’re really trying to use any means possible for defense.”