Comment: key to preparing for intervention in the event of a flood


For many, 2021 was the year of the flood. From Canada to India, Western Europe and Australia, this year’s floods have claimed hundreds of lives, enormous financial costs and immeasurable suffering.

Research conducted by myself and others on flood risk around the world shows how changing our perspective on flooding can help us avoid disasters. No matter how much rain falls, catastrophic flooding happens because of decisions that put people and places at risk – and they can be avoided.

For example, the southern part of British Columbia has a long history of flooding and landslides. The November floods killed at least four people, washed away highways and forced towns to evacuate.

The excessive rains that caused this were likely exacerbated by human-induced climate change, but its effects were much worsened by widespread deforestation, as well as the construction of infrastructure in flood plains and even in a lake. dried up.

The 2018 floods in Kerala, southern India, were also linked to deforestation and poor urban planning, with increasing urban development contributing to flooding in the region this year.

And in Western Europe, many places affected by the rising sea levels in July 2021 – such as the town of Altena in Germany – were known to be at high risk of flooding thanks to flooding in recent decades and centuries. Despite a flood warning system predicting heavy rains in advance, this information was never translated into action.

Each of these tragic situations, however, could have been prevented from becoming a disaster by taking simple steps to reduce risk before storms hit: steps such as planning buildings on safer, higher land, l ‘improved forest and river management, poverty reduction and the provision of appropriate safety education. .

In 1970, a cyclone ravaged Bangladesh, killing hundreds of thousands. Another cyclone in 1991 killed more than 100,000 people. But over the following decades, concerted efforts by governments and local leaders focused on risk awareness, resilient livelihoods, and evacuation procedures – these measures reduced death tolls across the country. to only dozens when cyclones hit in 2020 and 2021.

Similar work saved thousands of people from hurricanes in Texas. In 1900, a hurricane passed through the town of Galveston left at least 6,000 bodies in its wake. But more recently, Tropical Storm Allison in 2001, Hurricane Rita in 2005, Hurricane Ike in 2008, and Hurricane Harvey in 2017 each claimed significantly fewer lives.

For Rita, more than 80% of the 119 deaths in Texas have been attributed to poorly managed evacuation procedures. Likewise, despite record-breaking rainfall during Harvey, the destruction of the hurricane was largely the result of Texans covering flood-prone areas with buildings, not preparing citizens for what to do when floods hit.

As climate change worsens, tropical cyclones – and the flooding they cause – are predicted to become less frequent but more intense. The consequences of future storms depend on our actions now. If fewer storms mean our preparation gets sloppy, then disasters will be worse.

We can see this phenomenon at work when people build structures related to flooding like dikes, dikes and dams. Since they create a barrier between water and flood-prone areas, people often assume that these areas are safe to build and that they don’t have to worry about the risk of flooding. Indeed, the works eliminate many small floods. But when great flooding inevitably occurs and a river or ocean reclaims its territories, devastation is just as inevitable.

The history of New Orleans provides a classic example. About half of the city is currently below sea level, and the city’s records of flooding from the Mississippi River go back more than 250 years. Additionally, New Orleans has always been prone to storms, dealing with Hurricane Betsy in 1965 and Hurricane Camille in 1969.

In July 2004, the Hurricane Pam training exercise for emergency responders demonstrated how unprepared the city was for a direct hurricane hit: especially when it came to evacuating hospitals. , search and rescue efforts, debris removal and temporary shelters. Tragically, this scenario was recreated in real life when Hurricane Katrina ravaged the city in 2005. Dikes broke, evacuation and accommodation systems were chaotic, and people drowned as they drowned. were on the phone while waiting for help.

Flood-prone cities are often “protected” by flood “defenses”, which have mainly served to encourage housing and business development in flood-prone lands such as London and Singapore. The two towns are located upstream of vast defenses which reduce the number of small floods, allowing the construction of huge financial centers on the flood plains.

But when, not if, a flood exceeds the capabilities of a defense, the lack of preparedness will be apparent in the disaster that follows. Warning systems, which are very capable of issuing accurate flood warnings, exist – but as with this year’s floods in Germany, they will not be effective without preparing people for evacuation.

Rather than building dams, the city of Toronto chose to move buildings out of floodplains after Hurricane Hazel cut a path through the city in 1954, killing at least 81 people.

Instead of rebuilding flood-ravaged residential streets, Toronto turned them into nature reserves to keep buildings out and water out. Town planners then integrated the reserves into the expanding city by creating walking and cycling trails alongside them. Now these have become recreational and commuting routes, environmental education sites, and a refuge for wildlife.

When Hurricanes Isabel in 2003 and Sandy in 2012 turned Toronto’s waterways into raging torrents again, its floodplains were devoid of buildings. Fallen trees littered the mud-covered paths, and transport and electricity were cut off. But there was only one death. Let us use this knowledge and wisdom to prepare other towns and villages for future flooding.

– Ilan Kelman is Professor of Disasters and Health at University College London.


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