Steadfast in the rising tides
A changing climate is intensifying flooding worldwide - posing significant threats to public infrastructure, coastal communities and their economies. Rising sea levels and increased rainfall, and the associated flooding, are forcing us to rethink how we design coastal infrastructure, and renew the existing built environment, to withstand such challenges. Currently, an estimated 680 million people live in low-lying coastal areas at risk of flooding.
That's 8.5% of the world's population!
By 2100, 250-400 million people will need to completely relocate as their built environment will be completely submerged. This means in less than 80 years we will succumb to an annual $14 trillion worth of GPD loss to rising sea levels.
As these are just projections it doesn't mean that we are destined for such devastation. By looking into the past and current stories of flooding we can learn and develop strategies to build more Resilient communities against flooding.
Treading water in Jakarta
Jakarta, Indonesia's capital, is home to 11.35 million people and is one of the world's most vulnerable cities for flooding. The city’s has a geographical disadvantage being situated on a low-lying delta and 40% of that being below sea level. This makes Jakarta highly vulnerable to both riverine and coastal flooding. Combine its geography with rising sea-levels, excessive groundwater extraction causing 5-10cm of annual sinking, and intense rainfall during the monsoon season, Jakarta is facing a watershed moment.
Heavy rainfall has caused three major floods since 2007 that has caused 194 deaths, totalled USD$2.85 billion in damages, and displaced 96 thousand people.
In 2020 alone, torrential rains triggered widespread flooding, evacuating over 400,000 people and claiming 67 lives. Damages have been estimated at USD$1.2 billion.
These floods have exposed the city's inadequate drainage systems, unregulated urban expansion, and poor flood management policies.
In response, Indonesia has proposed the construction of an 30km long giant sea wall called the National Capital Integrated Coastal Development (NCICD). It is colloquially known as the "Great Garuda" resembling the shape of the Hindu deity who, for Indonesians', symbolises sovereignty, strength, and protection.
Construction began in 2014 and is expected to be completed in 2027 and cost USD$40 billion. Inspired and co-developed by the Dutch, the NCICD will not just be a sea wall but also reside an airport, harbour, residential areas, green spaces, and industrial areas over its 4000 hectares.
Although the NCICD does not solve the issues of ground-sinking and poor drainage. Flooding from rainfall is still a large risk and will only be exacerbated through more intense and frequent rainfall during monsoon seasons. It is recommended that a holistic approach should be used with a combination of nature-based solutions, improved drainage systems, and stricter regulations on land use to enhance long-term Resilience.
The Netherlands: make room for the rivers
The first defenses the Dutch built to a rising sea was 800 years ago. They are experts in keeping the sea at bay as their existence relies on it.
God created the world, but the Dutch created The Netherlands
Unlike Jakarta, The Netherlands have implemented a holistic approach to flood-resilient infrastructure in managing its high risk floodplain areas. The Dutch have transformed their approach from purely defensive measures, such as dikes and levees, to an adaptive strategy known as the Ruimte voor de Rivier (or Room for the River) program.
Starting in 2007, the project's main goal is to manage higher water levels in rivers by lowering the levels of flood plains, creating water buffers, relocating levees, increasing the depth and width of channels, and the construction of flood bypasses.
Overall it aimed at reducing flood risks by creating space for natural water flow instead of constraining it.
The approach restored the river’s natural flood plain in places where it is least harmful to protect those areas that need to be defended.
With a capital cost of approximately €2.3 billion, the program has significantly reduced flood risk in key areas. One notable success of this initiative is in Nijmegen, where the Waal River’s floodplain was expanded by relocating a levee more inland. This allowed the river to carry excess water during heavy rains, reducing flood risks for the city and surrounding areas.
It is not clear what the direct economic savings are of this project, but some modelling and research suggests ROIs of up to 120 on flood mitigation projects.
A holistic approach
Jakarta's "Great Garuda" is only a part solution to their interconnected drainage and monsoon risks. Meanwhile, the Dutch have demonstrated the effectiveness of adaptive, forward-thinking infrastructure that works with nature rather than against it.
To build a flood-resilient future, cities worldwide must embrace a combination of engineering solutions and natural flood management. Investing in sustainable urban planning, restoring natural waterways, and adopting adaptive infrastructure strategies will be essential in mitigating climate-induced flooding challenges.
As floods become more frequent and more intense it is more important than ever to build Resiliency in our coastal communities.
Further Reading
Rising sea levels could cost the world $14 trillion a year by 2100
Room for the River Programme | Dutch Water Sector
Economically efficient flood protection standards for the Netherlands
