Water levels were expected to rise by another meter (about 3 feet) by Thursday following the destruction of the Kakhovka dam, Ukrainian authorities predicted.
While the flood's force was expected to ease on Wednesday, the rise in water levels would engulf more downstream areas along the banks of the Dnieper.
Russian state media has reported that flooding could last up to 10 days in the Kherson region.
The Kakhovka dam collapsed on Tuesday. It remained unclear what caused it.
Ukrainian President Volodymyr Zelenskyy has accused Russia of deliberately destroying the dam, while the Kremlin has blamed Kyiv's shelling for the breach.
"The destruction of one of the largest water reservoirs in Ukraine is absolutely deliberate ... Hundreds of thousands of people have been left without normal access to drinking water," Zelenskyy wrote on the Telegram messaging app.
Zelenskyy said international aid groups must take immediate action to tackle the disastrous effects of the dam's destruction and that groups not on hand to help were incapable.
"It is necessary for international organizations, like the International Committee of the Red Cross, to get immediately involved in the rescue operation and help people in the occupied part of Kherson region," Zelenskyy said in his daily video address.
"If an international organization is not present in the disaster zone, it means it does not exist at all or is incapable."
Moscow-installed authorities have imposed a state of emergency in the Russian-annexed part of the region.
In the Ukrainian-controlled side of Kherson, at least 1,582 houses have been flooded, and some 1,457 people have been evacuated overnight, governor, Oleksandr Prokudin, said.
Officials from Russia, Ukraine, and the UN have said that the damage will take days to assess and warned of a lengthy recovery period.
UN aid chief Martin Griffiths told the Security Council that the dam breach "will have grave and far-reaching consequences for thousands of people in southern Ukraine on both sides of the front line through the loss of homes, food, safe water, and livelihoods."
"The sheer magnitude of the catastrophe will only become fully realized in the coming days," he said.
Here are some of the other developments concerning Russia's war in Ukraine on Wednesday, June 7:
NATO to host emergency meeting on dam destruction
The NATO alliance is hosting an emergency meeting on Thursday to discuss the "outrageous destruction" of the Kakhovka dam, the alliance's Secretary General Jens Stoltenberg said.
He added that he spoke to Ukrainian Foreign Minister Dmytro Kuleba, who would take part in the meeting by video link.
Stoltenberg condemned the dam's destruction for "displacing thousands of people & causing an ecological catastrophe in Ukraine."
In a series of tweets announcing the NATO meeting, Kuleba reiterated again Kyiv's calls upon the alliance to set a clear path to Ukraine's eventual accession after the end of the war.
"We are not seeking NATO troops on the ground to end this war," he said. "We are seeking the best guarantee to avert future wars."
ICRC says dam destruction caused 'quite severe' consequences
The humanitarian consequences of the floods resulting from the destruction of the Kakhovka dam are "already quite severe," said Achille Després, a Spokesperson at the International Committee of the Red Cross.
Despres told DW on Wednesday that ICRC personnel were on the ground since the day before, to help evacuate those affected by the floods. Already 800 civilians were evacuated on Tuesday, with over 50 more on Wednesday.
Despres added that the difficult situation on the ground adds to the "already dire humanitarian situation following more than 15 months of military hostilities and active armed conflict in the immediate vicinity of these areas."
He noted that the ICRC teams on the ground were facing an even harder time due to the location of the dam, which has affected both Ukrainian and Russian-controlled parts. ICRC personnel were particularly facing difficulty in accessing the Russian side.
"This highlights the fact that in humanitarian crises it's paramount that humanitarian actors, neutral humanitarian actors can have access to population, to communities in need."
For 160 years since its establishment, the ICRC has prided itself on its neutrality, working hand in hand with authorities often branded as aggressors by the international community to reach civilians in need of assistance.
Russian, Ukrainian authorities evacuate some 6,000 after flooding
Around 6,000 individuals have been evacuated from areas of the Dnieper River flooded due to the Kakhovka dam's destruction, Russian and Ukrainian authorities have said.
Ukrainian Interior Minister Oleg Klymenko said in televised remarks that 1,894 citizens have been evacuated in Ukrainian-controlled areas. He added that rescuers, police and volunteers continued the evacuation efforts in the Kherson region.
Meanwhile, the Moscow-installed head of the region Vladimir Saldo said on Telegram that over 4,000 people were evacuated in the part of Kherson occupied by Russia.
"It is a bit premature to talk about going back," Saldo said, advising people to wait in centers for the displaced.
'No critical risk to Zaporizhzhia plant now', nuclear researcher says
The destruction of the Kakhovka dam has thus far not posed an "imminent or critical risk" to the Zaporizhzhia nuclear power plant, nuclear researcher Mariana Budjeryn said.
Speaking to DW on Wednesday, the senior research associate at the Harvard Kennedy School Belfer Center said the UN Atomic Energy Agency and Ukraine's nuclear operator both confirmed there was not yet any risk.
She warned, however, that for a nuclear power plant to safely and securely operate, it needed a constant and reliable water supply.
Budjeryn noted that the destruction of the dam has led to a dramatic drop in the reservoir levels, which after a certain level, could mean the plant's pumping system would fall short.
Though the plant was designed with backup systems, the researcher reminded that "nuclear power plants are not designed to operate in a war zone and they're not designed to operate in constantly responding to these very critical and drastic changes in conditions."
"And my concern is the state of the operating staff that is constantly put in a position to respond to the situation. And they're already working under really difficult conditions of occupation by the Russian forces."
Ukraine's health ministry warns of diseases, fish die-off in Kherson
Ukraine's Health Ministry has issued a warning on the spread of diseases and mass fish die-offs that could be caused by the destruction of the Kakhovka dam.
The ministry said that chemicals and pathogens could enter wells and water bodies in the southern Kherson region due to flooding.
It said that ministry experts were analyzing water samples.
Ukraine's Health Ministry said that there will be mass fish die-offs once floodwaters recede.
The ministry announced that antibiotics stocks in the region would be increased.
Fish consumption has also been banned to minimize the risk of botulism.
Erdogan suggests probe into dam breach
Turkish President Recep Tayyip Erdogan has proposed the establishment of an international commission tasked with examining the destruction of Ukraine's Kakhovka dam.
He made the comments in calls with Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskyy, Erdogan's office said.
Erdogan said that "a commission could be established with the participation of experts from the warring parties, the United Nations and the international community, including Turkey, for a detailed investigation into the explosion."
Turkey's president told Putin that "it is important to carry out a comprehensive investigation into the explosion at the Kakhovka dam in a way that leaves no room for suspicion."
Meanwhile, Zelenskyy said that he spoke of the "humanitarian and environmental consequences" of the destruction of the dam in his call with Erdogan.
Similarly, Putin told Erdogan the incident had led to a "large-scale environmental and humanitarian catastrophe" and called the breach a "barbaric act."
War in Ukraine and Ethiopia guarantees grim record in 2022
The number of people killed in wars and conflicts reached the highest number since the Rwandan genocide, the Uppsala Conflict Data Program found.
Researchers of the program at the University of Uppsala in Sweden said at least 237,000 people were killed in military conflicts in 2022.
Most fatalities were in Ukraine and Ethiopia, where at least 181,000 combat-related deaths were recorded.
Ukraine might have featured in headlines more but the civil war in Ethiopia between the Tigray People's Liberation Front and the government was the bloodiest conflict of 2022.
More than 100,000 people were killed in Ethiopia in 2022, and more than 81,000 in Ukraine.
Russia to boost security at Zaporizhzhia for IAEA visit
Russian state-owned news agency TASS reported Moscow would take extensive security measures at the Zaporizhzhia nuclear power plant in Ukraine during a visit by International Atomic Energy Agency chief Rafael Grossi next week.
Grossi said he would travel to the plant following an attack on the Kakhovka hydroelectric dam.
The Kakhovka dam feeds a reservoir providing cooling water for the Russian-occupied Zaporizhzhia nuclear power station.
The IAEA said it saw "no short-term risk to nuclear safety and security" as "back-up options" were available.
UK Intelligence doesn't foresee threat to Zaporizhzhia due to flooding
The Zaporizhzhia nuclear power plant is "highly unlikely to face immediate additional safety issues" due to the damage caused to the Kakhovka dam, the United Kingdom's defense ministry said.
In their latest intelligence briefing on Twitter, the ministry said the dam's structure would likely deteriorate further over the next few days, causing additional flooding.
The intelligence update stated water levels in the Kakhovka Reservoir were at a record high before the collapse.
China trade with Russia hits highest level since start of the war
China's trade with Russia reached an all-time high of $20.5 billion (€19.2 billion) in May.
China has become Russia's biggest export market and an important source of manufactured goods.
It has boosted its imports, especially energy, from Russia by 10% to $11.3 billion as Beijing capitalizes on price cuts.
Chinese exports to Russia surged 114% to $9.3 billion.
During a summit in March, Chinese President Xi Jinping and Russian leader Vladimir Putin pledged to boost trade to $200 billion in 2023 as they hailed their "no limits" partnership.
Western nations have criticized Beijing for not condemning Russia's actions in Ukraine and for indirectly supporting its sanctions-hit ally.
Two Russian towns lose power in attack
Two towns in Russia's western Kursk region lost electricity in an overnight attack, Roman Starovoy, the regional governor, said.
He claimed Ukraine dropped explosives on an electricity substation situated near the border.
"One of the workers received shrapnel wounds while restoring power supply. He is in the central district hospital, and doctors are giving him all necessary treatment," Starovoy told the Reuters news agency.
Zelenskyy says Ukraine will not be stopped by Russia's explosion of dam
Ukraine will not let the explosion of the Kakhovka dam stop it from reclaiming occupied territories, President Volodymyr Zelenskyy has said.
"The disaster caused by Russian terrorists at the Kakhovka hydroelectric power plant will not stop Ukraine and Ukrainians," Zelenskyy said in his evening video message late on Tuesday. At the same time, he promised help to those affected in the flooded region.
According to Zelenskyy's account, the blowing up of the dam was intended to slow down the Ukrainian counteroffensive. "We will still liberate our entire country," he said. Such attacks could not prevent Russia's defeat, he said, but would only lead to Moscow having to pay higher damages in the end.
The Ukrainian prosecutor general had already turned to the International Criminal Court (ICC) with a request for an investigation into the explosion, he said.
Meanwhile, Zelenskyy said the government was doing everything it could to rescue flood victims and provide the population with drinking water.
Russian forces shell ammonia pipeline in Ukraine's Kharkiv region
Russian forces repeatedly fired at an ammonia pipeline in Ukraine's Kharkiv region, a local governor said on Tuesday, a conduit potentially crucial for the extension of a deal allowing the safe export of grains and fertilizers from Black Sea ports.
The extension next month of the Black Sea Grain initiative, a pact struck in July 2022 to help stop global food prices rising, could hinge on the reopening of the pipeline.
The ammonia pipeline, the world's longest, stretches about 2,470 kilometers (1,534 miles) from Russia's Togliatti on the Volga River to three Black Sea ports. It has been shut down since Moscow's invasion of Ukraine in February 2022.
There was no recorded leakage from the late Tuesday shelling that hit the pipeline near the village of Masiutivka and an overnight shelling near the village of Zapadne, said Oleh Syniehubov, the governor of Ukraine's Kharkiv region.
lo,dh/msh (AP, AFP, dpa, Reuters)