As emergency managers in southern Ukraine evacuate people there from disastrous flooding caused by this week’s mysterious breach of a major dam, conservation scientists are pondering the effects on the region’s plants and animals. The collapse of a section of the Kakhovka hydroelectric dam has released a torrent that is only beginning to subside, leaving downstream nature reserves underwater and vast mudflats emerging from an emptying reservoir.
The dam has been occupied by Russian troops since soon after President Vladimir Putin launched the Ukraine invasion last year. On 6 June, in the middle of the night, Ukrainian and Russian soldiers on both sides of the Dnipro River heard explosions in its power plant. The reservoir’s 19 cubic kilometers of water—more than is currently stored behind the major dams of the Colorado River—began to spill through a breach in the dam. Both sides blame the other for the catastrophe.
The flooding has reached 80 settlements in Ukraine-controlled territory, Oleksandr Krasnolutskiy, Ukraine’s first deputy minister of environmental protection and natural resources, said at a media briefing yesterday. That’s only about 40% of the flooded zone, he noted; the remainder is now controlled by Russia. Evacuations from Ukrainian-controlled villages has been complicated by Russian shelling, Krasnolutskiy said.
There are long-term concerns about the loss of the reservoir, the second largest in Ukraine at 2155 square kilometers. It provided water for drinking and irrigation—the production of about 80% of Ukraine’s fruits and vegetables relied on water moved through a network of canals, mostly in Russian-occupied areas. Late last year, the pumping station of the Kakhovka main canal was damaged, according to media reports. Downstream agriculture could be compromised as well; Krasnolutskiy said the flooding has washed topsoil from tens of thousands of hectares of farmland.
Numerous ecosystems are likely to be altered by the disaster, the Ukrainian Nature Conservation Group (UNCG) said in a report released on 7 June. The draining of the reservoir has destroyed the spawning grounds of fish. As much as 2600 tons of 20 species have been commercially harvested in recent years. The receding waters also have exposed bird habitat on islands in the reservoir to predators, which could jeopardize the nests of yellow bittern (Ardeola ralloides) and other rare species. Important wetlands along the reservoir, including the Velyki and Mali Kuchuhury archipelago, will suffer from desiccation, and ecologists are concerned that invasive plants, such as ragweed and goldenrod, will colonize newly exposed sediment.
Downstream, the flooding could wipe out rare species, such as the ant Liometopum microcephalum, and hammer populations of Nordmann’s birch mouse (Sicista loriger) and other endemic mammals. “There is a risk we will lose these species forever,” Krasnolutskiy said. Biologists with UNCG also expect large losses of endemic plants and important species such as giant oaks.
Contamination is a concern, too. About 150 tons of oil have been released this week from the hydroelectric plant. And sediment flowing from the reservoir is laced with heavy metals and other toxic chemicals from decades of industrial pollution. Krasnolutskiy said his agency has taken water samples for analysis and expects preliminary results today. But fieldwork has been complicated by the fact the river sits in the middle of a war zone. Russian land mines, for example, have been washed into the river and deposited in unexpected places. “It’s very dangerous to go into the affected area because mines can be everywhere,” Krasnolutskiy says.
“We will be able to do any research only when the Ukrainian army liberates the territories occupied by the Russians,” says Oleksii Vasyliuk, an environmentalist who leads UNCG. The group hopes to update some information after the flooding subsides. Krasnolutskiy said yesterday that 11 cubic kilometers of water remain in the reservoir. It’s expected to flow through the breached dam in the coming days, with the lowermost reaches of the Dnipro River returning to a narrower channel unseen since the dam was built in the 1950s.
