How technology can cut the risks of flooding

The first half of September 2024 saw devastating floods in Nigeria, Myanmar, the Czech Republic, Budapest and other parts Central Europe after heavy rainfall.

In August, floods hit Bangladesh and left more than 500,000 people without clean water, sanitation, dry clothes and other basics like medication.

With experts tending to attribute these extreme weather events to climate change, governments and communities are looking towards mitigation and adaptation strategies.

For instance, investment in grey infrastructure projects, using concrete and steel, and natural green initiatives could help to prevent the very worst impacts of more frequent and severe flood events.

Mobile flood barriers in Venice

Venice, one of the world's most iconic European cities, faces a double-whammy existential crisis: a combination of climate-driven sea level rise and the city's slowly sinking into the muddy foundations upon which it was built.

It's calculated to be sinking at about 2.5mm per year on average, and that for the past 150 years. Some studies suggest much of the city could be under water by the middle of the next century — a modern-day Atlantis.

But the more immediate challenge is flooding.

Planning for flood-prevention systems in Venice stretches back to the 1980s. In 2003, construction of the MOSE system began.

MOSE features four mobile inlet barriers at points along the lagoon that separate the city from the sea.

Each barrier consists of a series of gates that can be raised to separate the lagoon from the surrounding ocean during high flood tides.

Flow-through, flood control and 'dry' dams in Japan, US

Typically, dams are used to block a river as a means of water storage.

But flow-through dams are designed to allow water to move during normal conditions. Rather than storing water in dry periods, they come into action during severe weather: They close up and store the floodwaters on an upper floodplain, and protect land on the other side of the structure.

Water is then released back into the lower part of the river system once the floods have subsided.

Such dams have been constructed in Ohio, in the US, and in Japan, along the Masudagawa and Hata rivers. Another is being built along the Asuwa river. 

House stilts, breakaway walls and self-elevating homes

Stilts have long been used to support freestanding homes and protect them against flooding. But the idea is becoming popular in areas that are only now having to adjust to extreme weather and flooding.

While stilted houses have been commonly used in small island nations, where sea levels are rapidly rising, as well as floodplains in Asia and Africa, other nations are increasingly looking towards such techniques as a means of improving housing.

In the US, regulations stipulate that stilt supports need to be strong enough to withstand flooding and wind forces, while elevating buildings high enough to withstand a "once in a century" flood.

In the United Kingdom, a mechanical jack system has been developed by a company called FloodJack. It detect rising waters and activates a foundational elevation system to protect homes from water damage.

But for some nations, not even raised houses are enough anymore. In the wake of disastrous flooding events on the US Gulf Coast and in Australia, for instance, some governments have imposed restrictions on where homes can be rebuilt.

While these aren't technological innovations, policy initiatives such as these are increasingly being looked upon as effective ways of reducing loss and damage.

Barrier technology from Netherlands to Africa

Building temporary barricades against rising floodwaters — an idea developed by a Dutch company called SLAMDAM — has proved just as effective in African countries as it has in the Netherlands.

The SLAMDAM is made of tubes that fill with water to create a temporary wall or barricade that pushes flood waters back.

It has been utilized by communities in Burundi, Nigeria and Kenya. Communities have also used the stored water during dry periods for irrigation.

'Nature based' flood mitigation — an opportunity for Asia?

It's not just technological innovation that could help communities solve the problem of hazardous flooding. Some regions are turning towards environmental interventions. These are sometimes called "nature based solutions". 

For flood mitigation, they could include the management of the flow of water between rivers and floodplains, or the restoration of agricultural regions with native vegetation to encourage more effective stormwater storage.

Other ideas include reestablishing sand dunes and mangrove forests to provide natural barricades to flooding.

Such initiatives are considered "green infrastructure" and are being deployed across the globe.

Edited by: Zulfikar Abbany

Select sources:

MOSE System, Venice https://www.mosevenezia.eu/project/?lang=en

Portable dams in Africa / SLAMDAM https://www.unep.org/news-and-stories/story/can-portable-dam-help-africa-counter-rising-waters

Nature-based solutions for flood management in Asia and the Pacific, OECD (March 2024) https://doi.org/10.1787/18151949