A Look at the Most Catastrophic Floods in History

Imagine losing your home and all of your possessions. Then, imagine catching a disease and nearly starving to death as there is no arable land to live and farm on or clean water to drink. These are just some of the dire consequences of a flood. 

Floods are one of the strongest forces of nature, and some researchers say flooding impacts more people than any other type of environmental disaster.

Floods have caused destruction throughout human history. Regions prone to floods have seen the loss of countless lives, and the destruction of infrastructure and properties over and over again. And the frequency of floods doesn't seem to be decreasing. In fact, it might be on the rise.

Why floods happen

Many factors contribute to flooding. Floods can occur because of:

1. Weather events, like heavy or prolonged rainfall, storm surges, and snowmelts
2. Human-driven causes, including poor management, deforestation, infrastructure failure, and over-development 
3. Land alteration such as urbanization, and paving land (making it impermeable)
4. Homes built on flood plains or in low-lying coastal regions
5. Global warming, which is invariably linked to weather events

Even though all of these elements can contribute to flooding, scientists primarily point the finger at global warming as the main culprit of increased flooding, saying we will see more and more devastation caused by an increasing number of floods every year.  

Even if our warming planet is not the direct cause of increasing floods, it exacerbates many of the factors that lead to floods.

As the Director of the United Nations Environment Programme’s (UNEP) Global Resource Information Database in Geneva, Pascal Peduzzi, said "While it is difficult to make a direct link between an individual extreme event and climate change, it is clear that we need to be prepared to face more intense and more frequent extreme hydro-meteorological events due to climate change."

Climate change has increased our global temperatures, and with hotter temperatures, Earth's weather system has more energy. A warmer atmosphere can hold more moisture, which leads to an increase in storms and rainfall intensity, duration, and frequency. It can also melt polar ice and glaciers and lead to rising sea and ocean levels, which in turn flood coastal regions. 

"Around 50 million extra people will be exposed to inundation."

And it's easy to see these climate changes. Quasi-stationary storms over Europe were once extremely rare. But, according to a study published in Geophysical Research Letters, in a worst-case scenario, such storms could, "become as much as 14 times more common in 2100 than they were at the start of this century."

Another study quoted by the BBC shows that the percentage of the global population at risk from flooding has risen by almost a quarter since the year 2000. By 2030, millions more will experience increased flooding due to climate and demographic change, according to the report's authors.

As Gilbert F. White, a geographer renowned for his work on flood plain management and a leader in natural hazards research, is famously known for saying "Floods are 'acts of God,' but flood losses are largely acts of man." And from the aforementioned information, it's easy to see where White was coming from.

Flooding repercussions

The direct effects of floods are disastrous: Infrastructure, homes, and land are upended or damaged, and loss of life can be high.

And the indirect effects of floods can be just as damaging: Contamination and disease can wreak havoc for months or years after the event. Floodwaters can carry raw sewage, toxic chemicals, and hazardous waste, leading to the spread of harmful diseases, contamination, and infections. Moreover, drinking water becomes polluted, further spreading the risk of illness.

On top of that, economic loss from the destruction of property, lost business, and rehousing entire communities can be devastating.

Needless to say, flooding — be it river flooding, coastal flooding, flash floods, or urban flooding — leaves its destructive mark on the world.

Some of the worst floods in history and their impact

That destructive mark is easily noticeable when we take a closer look at some of the most devastating floods in history.

• The Netherlands' "Great Drowning of Men"

A vicious North Sea tempest swept across regions of Europe in January 1362, and caused what's known as The Grote Mandrenke, or The Great Drowning of Men. The damage caused by the storm's winds in England was violent, but it was a catastrophic storm surge in the Netherlands, Germany, and Denmark that truly left its mark. 

The storm surge overran nearly every dike and levee it came across. Anywhere from 25,000 to 100,000 people drowned, and some 60 villages and towns in Denmark were "swallowed by the salt sea." Flood erosion was so strong that it permanently changed the coastline and caused entire islands to disappear. Along with other storms during the Middle Ages, the Grote Mandrenke contributed to the forming of a shallow North Sea bay in the Netherlands, called Zuiderzee.

• Mississippi flooding

Months and months of unrelenting rain in the spring of 1927 caused the lower Mississippi River to swell so much that it overran its levee system. The flood quickly spread over 16 million acres of land across seven states, with the brunt of the damage being felt in Arkansas, Mississippi, and Louisiana. In those states, the floodwater was so high that it created a shallow sea 75 miles (120 km) wide, and thousands of residents had to evacuate by boat.

It took many more months before the waters receded, by when 1 million people had been driven from their homes — approximately one percent of the entire American population at the time.

• China floods 

China has experienced a huge number of floods over the centuries. Some of its worst ones include the 1887 and the 1938 Yellow River floods that killed up to two million people and 800,000 people, respectively. There were also the Jiangsu-Anhui and the Yangtze River floods in 1911 that caused 100,000 deaths, and left some 370,000 people homeless. 

In the summer of 1931, the Yangtze, Yellow, and Huai Rivers burst through their badly managed dikes and flooded an area larger than the size of England. Thousands of people died from drowning, but even more died in the following months due to widespread famine and diseases which included cholera, typhoid fever, and dysentery. The total death toll may have been in the millions.

The river flooded again just three years later, in 1934, which caused millions of people to lose their homes, and the death of around 150,000 people.

In 2021, record-breaking rainfall caused Henan province to flood, displacing around 200,000 people and causing widespread disruptions. Several dams and reservoirs breached warning levels, and the area's transport systems came to a standstill.

• 2021: Germany, Belgium, Uganda, and Afghanistan

2021 saw a number of other floods. Overflowing rivers affected 30 villages in Uganda, and rising water levels of Lake Kyoga forced hundreds of households to evacuate.

In Afghanistan, heavy rainfall caused massive flash floods, destroying houses, submerging roads, causing people to go missing, and hundreds of people to die.

And in July, intense storms in western Germany and parts of Belgium dumped up to six inches (15 cm) of water in 24 hours, causing rivers and streams to swell, and to sweep houses and cars off the ground. The water caused massive landslides in both countries, and the deaths of hundreds of people. 

Even though the numbers of deaths and displaced people were much lower than in the past, they are not insignificant. 

"We should not be seeing this number of people dying in 2021 from floods. It just should not be happening," said Hannah Cloke, a hydrologist and flood forecaster at the University of Reading, in Science.

As we've seen, some of the wealthiest countries are facing the same issues as people living with more limited access to advanced flood control technology and techniques. Even though scientists were able to forecast this years' floods in Western Europe, they weren't able to protect enough people from their devastating impact.

So what is being done to prevent floods from happening, or to minimize their impact? 

Flood prevention

A few preventative measures include:

• Adding water-smart improvements to buildings
• Creating green infrastructure
• Improving forecasting systems
• Curbing climate change

And technology plays a major role in all of these precautions.

Flood forecasting systems that use satellite imagery are improving, which would make it easier to mitigate against the risks of flash flooding.

Big tech companies like Google have also been taking a role in flood forecasting by using AI-enabled systems. Google sent millions of notifications to people living in flood danger zones in India and Bangladesh in 2018 and 2019, for example, warning them of upcoming floods.

Robotics is also being used to investigate the causes of flooding in hard-to-reach areas. Mr. Nosey, for example, is a remote-controlled robot used by the U.K. Environment Agency to inspect underground tunnels and send real-time images to the surface. The agency then uses these images to determine the causes of damage and blockages. 

Along with better tech comes better infrastructure. Stronger storm surge barriers, like the Maeslant barrier in the Netherlands and the Thames River barrier in England, are popping up in more locations, to minimize danger or prevent floods from happening.

On a more local level, building permeable pavements and green roofs can improve drainage and avoid surface water flooding, explained Dr. Linda Speight, a flood expert at Reading University in the U.K. 

Dating from the 1970s, houses built into the earth also go hand in hand with permeable and green infrastructure, and they have the added benefit of curbing global warming. These earth homes reduce fossil fuel consumption as their indoor temperature remains more stable year-round. 

Going back to basics, the Netherlands has created policies that leave "room for the river" — they have widened and deepened river channels, and set aside land where floodwaters can spread out. 

And, of course, curbing global warming is also a major focus around the world. From renewable energy to better recycling methods, engineers, scientists, researchers, and more have been putting their heads together to invent and manage systems that minimize climate change. The end result: Fewer floods, and more lives saved.