As climate change drives unprecedented sea level rise, governments and citizens in vulnerable countries are looking for innovative ways to predict, prevent, adapt and insure against flooding.
The floods that hit West and Central Africa during the last two weeks have displaced more than 3.4 million peopleaccording to the United Nations Refugee Agency, marked by the worst floods in a decade in Nigeria, which killed hundreds and affected 2.8 million people.
Extreme floods have killed more than 1,300 people in Pakistan since June and are now threatening to trigger a food crisis.
Floods will become more frequent in the future. According to a United Nations report published last weekthe planet is on track to warm by 2.1°C to 2.9°C above pre-industrial levels by the end of the century, despite the measures taken by governments to combat climate change.
Vulnerable coastal megacities
As the world cannot cope with climate change in the short to medium term, countries must urgently find solutions to mitigate the devastating effects of extreme floods.
More than 1.8 billion people, approximately 23% of the world’s population, are at high risk of flooding. More than 1.2 billion of them are in South and East Asia, including 395 million in China and 390 million in India. Of the 170 million people at high risk of flooding and extreme poverty, 44% reside in sub-Saharan Africa.
These high figures reflect the simultaneous rise in sea level and urbanization, which makes the inhabitants of coastal megacities among the most vulnerable.
Traditional engineering solutions, such as flood walls and embankments, are helpful, but may be insufficient if drains or floodplains are missing, aging or blocked. In Nigeria, for example, government officials claim that the structures built along the drains contributed to the severity of the flooding in Lagos.
One such approach is that of sponge cities, which seek to grow and work with nature to absorb, clean up and use excess water during extreme floods. For example, the Chinese port city of Ningbo has transformed 3 kilometers of previously developed land that has fallen into disuse into an ecological corridor and public park.
Creating more sustainable ecosystems on the high seas is another approach to dealing with rising sea levels during severe storms. Certain countries of southern and eastern Africa are trying to build a “great blue wall” to protect coastal and marine areas stretching from Somalia to South Africa in the Indian Ocean.
Technology plays an important role in helping countries predict floods and warn people of danger.
With an estimated 20% flood risk of the country, Malaysia has become a world leader in the deployment of forecasting and monitoring technology.
By the end of 2022, the Department of Irrigation and Drainage (DID) Malaysia will implement its National Flood Forecasting and Warning System, which was developed with UK engineering consultancy HR Wallingford.
The system collects data from 700 observation gauges across the country, often located in difficult terrain, to create simulations and models to better prepare residents and officials.
Drones are increasingly being used to record accurate image data that planners can use to prevent and predict floods and assess damage afterwards.
The Malaysian Space Agency is using drones and two satellites, with a third scheduled to launch in 2025, to identify flood-prone areas before the onset of the rainy season. The agency’s integrated disaster management system and logistics system imagery-based information system known as eBanjir directly assists DID in its flood management initiatives.
Similarly, Brazil is leveraging the data through its waterproofing mobile phone app, developed locally in March 2022 in collaboration with researchers from Germany and the UK.
The app empowers community members to become citizen scientists by recording rainfall and flood impact assessments that can be used to plan or prevent severe flooding. The app is currently in use in 20 municipalities, and the research team behind the platform is looking to roll it out to other countries around the world.
Using larger and better volumes of data means that artificial intelligence can help predict when a flood might occur, allowing more targeted infrastructure to be built to withstand flooding. For example, researchers at Stanford University in the US are using machine learning to track atmospheric patterns and predict when rainfall will cause flooding.
Protect food from flooding
In addition to uprooting people, the floods jeopardize short-term food security by destroying infrastructure, agricultural land and livestock, and damaging water resources and sanitation in the months that follow.
To counter this, planting more resilient crops could help smallholder farmers who have lost an estimated $21 billion in agricultural produce and livestock to floods over the past decade, putting them second only to droughts.
Researchers are using genetic tools to generate the gene responsible for flood tolerance, called Sub1. The use of the flood resistant rice thus obtained, which produced 60% more rice than standard varieties in a controlled experiment, could go a long way towards reducing the 4 million tons of rice lost to floods each year.
Over the past decade, farmers in the Philippines have widely adopted underwater rice, a shred that does not die when submerged underwater for up to 14 days.
Other subsistence farmers are turning to an old practice of using floating farms to guarantee crop yields amid rising sea levels.
More than 6,000 farmers in the southwestern deltas of Bangladeshwho are already under water eight to ten months a year, compared to five months a year about 200 years ago, use this practice to grow fruits and vegetables on rafts made of invasive hyacinths.
Mexican farmers have also revived the use of chinampas (agricultural islands), long narrow strips of land on shallow lakes near Mexico City that are anchored to the lake bottom with native willow, to meet agricultural demand when traditional markets closed during the COVID-19 pandemic.
Developed by the Aztecs over 700 years ago, chinampas are very fertile agricultural fields which house a wide variety of produce, from fruits and vegetables to eggs and honey. They have the added benefit of being able to meet their water needs directly from the lakes themselves.