Flooded South: the consequences of blowing up the Kakhovka dam (in brief)

This article was written and released in Ukrainian in October 2022. On 6 June 2023, the Russian occupiers blew up a dam at the Kakhovka Reservoir. The following text is the English version of the article.

On 20 October 2022, President Volodymyr Zelenskyy stated that the Russians were planning to blow up the dam of the Kakhovka Hydroelectric Power Plant on the territory of occupied Kherson Oblast. And the main thing was, they planned to accuse Ukraine of doing it. 

This statement was a response to a remark made by Sergey Surovikin, then the new commander of the Russian army in Ukraine, regarding "preparations for a missile strike by the Armed Forces of Ukraine on Kherson and the dam of the Kakhovka Hydroelectric Power Plant."

Surovikin announced a "strike by the Ukrainian Armed Forces", commenting on the difficult military situation for the occupiers in Kherson Oblast. He admitted that the Ukrainian army was breaking through the Russian defences.

According to Ukraine's Defence Intelligence, the occupiers did most of the work on mining the dam in April. Over the past few days, the locks and supports of the Kakhovka HPP were mined.

However, in an interview with UP, Kyrylo Budanov, the chief of Defence Intelligence of the Ministry of Defence of Ukraine, said it would be extremely difficult to undermine such a structure.

"To destroy a structure of this size, you need dozens of tonnes of explosives, correctly placed. You can't put a KaMAZ [a large Russian-made truck – ed.] somewhere nearby, it won't help," Budanov said.

At the same time, experts began to discuss the real consequences of blowing up the dam, from the partial halt of the Ukrainian army's counteroffensive in the south to the flooding of much of the left bank of occupied Kherson Oblast.

Some experts whom UP contacted for an interview noted that there is currently too little input data to assess the real consequences of the Dnipro flooding.

What functions does the Kakhovka dam perform, what could happen in the event of its complete destruction, and how will it affect combat operations, in particular, the Ukrainian army’s counteroffensive operation in the south? Ukrainska Pravda presents a brief summary for our readers.

UP answered these questions with the help of:

• Mykhailo Yatsiuk – Head of the Institute of Water Problems and Land Development of the National Academy of Sciences of Ukraine;
• Volodymyr Kovalenko – Mayor of Nova Kakhovka, which lies five kilometres from the Kakhovka HPP; 
• Yurii Sobolevsky – Deputy Head of Kherson Oblast Council;
• Vasyl Opanasyuk – an explosive ordnance engineer;
• Roman Kostenko – an MP and a military man who is familiar with the course of hostilities in Ukraine's south.

The Kakhovka Dam is part of the Kakhovka hydroelectric power plant (HPP), built in the 1950s and 1960s in Kherson Oblast. The Kakhovka HPP is the last and lowest rung of the Dnipro cascade of power plants.

One of the tasks of the HPP is to provide water to Ukraine's arid south by accumulating and redistributing water resources.

The station's power output is not particularly high, amounting to 334.8 MW (for comparison: the capacity of the Kyiv HPP is 440 MW and that of the Dnipro HPP is 1,577 MW).

Since the first few hours of the full-scale invasion, the Kakhovka HPP and the North Crimean Canal, fed by the Kakhovka Reservoir, have been under the control of the occupiers. Water from the Dnipro river was being supplied to occupied Crimea again.

Ukrainian employees of the HPP are currently not allowed to work. "Safety measures" have been strengthened at the HPP.

Why the Kakhovka dam is important

The Kakhovka dam performs several functions at the same time. First, it "props up" the Dnipro and allows up to 18 cubic kilometres of water to be stored in the Kakhovka reservoir (the largest full volume of all reservoirs on the Dnipro).

Secondly, it helps regulate the accumulated volume of water to provide water to even the driest regions of Ukraine's south. Two giant canals depend on the water from the Kakhovka Reservoir – the Kakhovka and North Crimea canals, as well as irrigation systems in the Zaporizhzhia and Dnipropetrovsk oblasts.

Thirdly, the dam of the Kakhovka HPP is an energy facility, as the hydropower units installed on it generate electricity, mostly to balance the power system and cover peak consumption hours.

"During peak load hours, the Kakhovka HPP, which generates a considerable amount of electricity, acts as a kind of stabiliser of the power system. That is, it protects us from destruction and blackouts," Volodymyr Kovalenko, the Mayor of Nova Kakhovka, explains. 

Fourthly, there's another bridge along the dam between the two banks of the Dnipro River in Kherson Oblast. It is almost four kilometres long. The occupiers make a great deal of use of the dam to transport their equipment and manpower, even after precision missile strikes.

Is it even realistic to blow up the dam?

Not only Ukraine’s Defence Intelligence chief but also the military and local authorities speak cautiously about the possibility of the destruction of such a huge reinforced concrete structure as the Kakhovka Dam.

In favour of its strength, the dam structure is still standing after several missile strikes on the Kakhovka Bridge, launched by Ukrainian forces [so as to make the Russian troops withdraw from the area – ed.], and the bridge is still being used by the occupiers.

"The dam is really built with military actions in mind – it is a capital structure with a margin of safety. It is very difficult to destroy it from the outside, it would probably be necessary to use tactical nuclear weapons to do it. But if there is access to this infrastructure, which is the case with the Russian troops, then it could be undermined from the inside.

The weapons currently used by the Ukrainian military [i.e. destroying bridges and crossings in the occupied territories – UP] are not enough," says Yurii Sobolevsky, Deputy Head of Kherson Oblast Council.

Vasyl Opanasyuk, an explosive ordnance engineer, notes that if 5-6 tonnes of TNT (which fits in one truck) was detonated, it would only create a five-metre large hole in the dam. Water would simply flow through it.

It would take at least ten such trucks to damage the dam seriously. After that, the structure may begin to collapse under the pressure of the water.

There has already been a similar case in Ukraine’s history.

In 1941, the Soviet army blew up the Dnipro HPP dam to stop the advance of German troops. To be more precise, part of it was blown up, 175 metres out of more than 600. As a result of the explosion, a huge hole was formed in the dam, through which water flowed rapidly.

"When the explosion occurred, the speed of the current accelerated much faster. The water [level] could have risen to 5 metres. But it was unlikely to be a one-time wave. The water rose sharply and flowed very quickly for about 2–3 days. And then everything returned to normal," Volodymyr Linkov, Zaporizhia historian, told Radio Liberty a year ago.

What happens if the dam is blown up?

If the dam is severely damaged or destroyed, the water will flow down the Dnipro riverbed at a tremendous speed. Experts call this phenomenon a hydrodynamic accident. 

"There will be an artificial, uncontrolled flood, accompanied by the inundation of settlements and destruction of downstream facilities. This will pose a huge threat to the lives of the local population," explains Mykhailo Yatsiuk, Director of the Institute of Water Problems and Land Development of the National Academy of Sciences of Ukraine.

"The spill area will also depend on the water level at the time of the explosion. Now, the Russians seem to be trying to drain the water there," adds Yurii Sobolevskyi.

In the event of an explosion, the Dnipro will spill over onto both banks – both the right bank, where Kherson is located, and the left bank, where Nova Kakhovka is located. However, the left bank of Kherson Oblast will be hit harder, as it is lower than the right bank.

First of all, floodplain areas and floodplain terraces will be affected. 

Volodymyr Kovalenko predicts that a 12-metre-high water pillar will rise after the dam is blown up.

"According to Soviet calculations, this pillar of water will reach its peak during the tenth hour [after the explosion – ed.], at which time Dniprovskyi Avenue, Istorychna and Heroiv Ukrainy streets in Nova Kakhovka will be flooded. These streets are located along the Dnipro River [500 metres from the bank – ed.]," Kovalenko added.

He said that the water level on the coastal streets could be a metre and a half. It will begin to subside only seven days after the explosion.

The scale of the consequences

The greatest damage from the dam's destruction and the breakthrough of a huge water flow will be the flooding of settlements located downstream of the Dnipro.

According to President Zelenskyy’s estimates, more than 80 settlements, including Kherson, will be in the zone of rapid flooding.

There is no accurate data or modelling of the flood zone at the moment. Several Russian and German media outlets, as well as propaganda Telegram channels, have distributed a map (with reference to 2004 data) which shows Kherson, Oleshky and Hola Prystan as potentially flooded cities. 

However, some hydrologists have pointed out that the flooding of Oleshky and Hola Prystan is a situation from the realm of fantasy.

Meanwhile, residents of Kherson and nearby villages living near the Dnipro River and the Koshova River are being advised to temporarily move to streets on higher ground in their neighbourhoods. By doing so, they will have moved to a distance of 1,400 metres from the Dnipro bank.

At the same time, the Kakhovka Canal, which supplies water to occupied Berdiansk and most of the settlements in Zaporizhzhia Oblast, is at risk of running out of water.

"This humanitarian catastrophe will affect hundreds of thousands of people, if not a million," explains Mykhailo Yatsiuk.

The problem with the irrigation system in Ukraine's south will also add to the humanitarian disaster. It is not only a matter of next year's harvest shortfall but also soil degradation, changes in flora and fauna, etc. 

"This will affect both Crimea and the entire south of the Kherson Oblast. This includes the Krasnoznamianka Canal and rice irrigation systems in Kalanchak district. This will have huge negative consequences for agriculture in the entire region," adds Yatsiuk.

If the Kakhovka dam is blown up and the Kakhovka reservoir is emptied, Ukraine will only be able to restore its reserves in the spring of 2023 (provided that the plant is repaired). Transferring water from other reservoirs is quite unlikely.

The devastation, or at least reduction, of the water level in the Kakhovka reservoir is another extremely negative consequence of the dam's explosion – a threat to the operation of the Zaporizhzhia Nuclear Power Plant. After all, the ZNPP is cooled by water from the Kakhovka reservoir.

How will the dam being blown up affect the water supply to occupied Crimea?

In short, it will be negative for the residents of Crimea, as well as for the occupiers themselves. After all, if there is no water in the Kakhovka reservoir or its level is insufficient (less than the current 16.4 metres), water will simply not flow into the North Crimean Canal.

Oleksii Danilov, Secretary of the National Security and Defence Council of Ukraine, has said that if the hydroelectric power station is blown up, Crimea could be left without water for 10-15 years, possibly forever.

Why would the Russians blow up the dam?

The experts interviewed by Ukrainska Pravda suggest two reasons.

The first is that the Russians want to prevent the Ukrainian army from crossing to the left bank of the Dnipro River. 

However, Roman Kostenko, an MP and military officer, explains that this goal could be achieved much more easily – it would be sufficient to cut off the roadways and railway lines at the Kakhovka dam and keep it under constant fire. That is, there is no military expediency in blowing it up.

In addition, a huge water flow would rush to the left bank, which is currently occupied.

"As long as the Russians expect to stay on the left bank, I don’t think they will blow up the dam. If we push them out of the left bank, this issue may arise again," Kostenko says.

The second reason for a possible explosion is the continuation of Russia's tactics to destroy Ukraine's critical infrastructure. 

"This hydroelectric power plant is very important for the power sector. Given the volume of water, the potential of the units that are concentrated there... The enemy knows this, they want to destroy it and thus do damage to our economy," explains Mykhailo Yatsiuk. 

It is impossible to rebuild a damaged dam under the ongoing combat actions. In peacetime, it would take at least a year.

How will the dam being blown up affect the Ukrainian army's counter-offensive in the south?

Purely theoretically, the flooding of the Dnipro (provided that the Russians retreat to the left bank) will certainly complicate the Ukrainian army's access to the areas currently held by the occupiers. The widening of the river will mean an increase in the distance to the invaders.

However, Roman Kostenko believes that after the liberation of the right bank of the Dnipro (in Kherson), the Ukrainian army will have to entrench itself there and still launch a counter-offensive to the north, on the Zaporizhzhia front: "Conducting a forced crossing of the Dnipro River if the enemy is on the left bank means taking a big risk – there could be a lot of casualties."

Olha Kyrylenko, Ukrainska Pravda

Edited by Ivan Zhezhera and Teresa Pearce 

Translated by Sofiia Kohut and Myroslava Zavadska