Devastating flood in Spain kills at least 95 in its worst natural disaster in recent decades

At least 95 people have been killed in possibly the deadliest flooding to hit Spain in its modern history after torrential rain battered the eastern region of Valencia, sweeping away bridges and buildings, local authorities said on Wednesday.

Residents in the worst-hit places described seeing people clambering onto the roofs of their cars as a churning tide of brown water gushed through the streets, uprooting trees and dragging away chunks of masonry from buildings.

"It's a river that came through," said Denis Hlavaty, who waited for rescue on a ledge in the petrol station where he works in the regional capital. "The doors were torn away and I spent the night there, surrounded by water that was two meters deep."

Defence Minister Margarita Robles told Cadena Ser radio station that a military unit specialised in rescue operations would on Thursday start combing through the mud and debris with sniffer dogs in the worst-hit areas.

Asked if the number of victims was likely to increase, she said: "Unfortunately we are not optimistic." The teams have brought with them 50 mobile morgues.

Prime Minister Pedro Sanchez promised to rebuild infrastructure that has been destroyed and said in a televised address: "For those who at this moment are still looking for their loved ones, the whole of Spain weeps with you."

Footage shot by emergency services from a helicopter showed bridges that had collapsed and cars and trucks piled on top of each other on highways between flooded fields outside the city of Valencia.

Trains to the cities of Madrid and Barcelona were cancelled due to the flooding, and schools and other essential services were suspended in the worst-hit areas, officials said.

Power company i-DE, owned by Europe's biggest utility, Iberdrola, said about 150,000 clients in Valencia had no electricity.

Emergency services in the region urged citizens to avoid all road travel and to follow further official advice.

Some parts of Valencia area such as the towns of Turis, Chiva or Bunol recorded more than 400 millimeter of rainfall, leading the state weather agency AEMET to declare a red alert on Tuesday. It was lowered to amber on Wednesday as the rain eased.

There was also flooding in other parts of the country, including the southern region of Andalusia, and forecasters warned of more bad weather ahead as the storm moved in a northeasterly direction.

"(The floodwaters) took away lots of dogs, lots of horses, they took away everything," said Antonio Carmona, a construction worker and resident of Alora in Andalusia.

What caused deadly floods in Spain?

The phenomenon is known locally as DANA, a Spanish acronym for high-altitude isolated depression, and unlike common storms or squalls it can form independently of polar or subtropical jet streams.

When cold air blows over warm Mediterranean waters it causes hotter air to rise quickly and form dense, water-laden clouds that can remain over the same area for many hours, raising their destructive potential. The event sometimes provokes large hail storms and tornadoes as seen this week, meteorologists say.

Eastern and Southern Spain are particularly susceptible to the phenomenon due to its position between the Atlantic Ocean and the Mediterranean Sea. Warm, humid air masses and cold fronts meet in a region where mountains favor the formation of storm clouds and rainfall.

This week's DANA was one of the three most intense such storms in the last century in the Valencia region, Ruben del Campo, spokesperson for the national weather agency Aemet, said.

"Forecasts were in line with what happened. But in an area between Utiel and Chiva, in the province of Valencia, rainfall exceeded 300 liters per square meter. In that area, storm systems formed and regenerated continuously," he explained.

While experts say it will take time to analyse all the data to determine if this particular DANA was caused by climate change, most agree that an increase in temperature of the Mediterranean and warmer and more humid atmospheric conditions contribute to producing more frequent extreme episodes.

"We're going to see more of these flash floods in the future. This has the fingerprints of climate change on it, these terribly heavy rainfalls, and these devastating floods," said Hannah Cloke, professor of hydrology at the University of Reading.