City on the edge: Paris faces yet another major flood

By Charles Baubion (charles.baubion@oecd.org), Directorate for Public Governance and expert in Risk Governance within the OECD High-Level Risk Forum and Bill Below of the OECD Directorates for Public Governance and Financial and Enterprise Affairs

“One Winter, I was staying in my dear Lutetia, the Gaul’s name for the town of Parisis… Only rarely does the river’s level rise or diminish… Yet, during that visit, the river was unusually violent, carrying off great blocks of ice that smashed into each other until they formed a bridge…”

In so describing Paris in the Winter of 357-358 CE, the future Roman Emperor Julien provided the first written record of the flooding of the Seine river basin—and through his surprise at what he saw, may have inadvertently evoked a bias that discounts the probability of inevitable but infrequently-occurring events.

Flooding is one of the most common, widespread and destructive natural perils, each year affecting approximately 250 million people and causing roughly forty billion USD of damage (OECD, 2016). But, beyond these abstract-sounding numbers is the heart-wrenching reality of lives and livelihoods lost or disrupted, often with severe, long-term consequences. Although floods are indiscriminate in their swath of destruction, as always, economically fragile populations face the greater burden of suffering and disruption. Yet, regardless of socio-economic standing, floods are emotional ordeals. After Katrina, the prevalence of Post-Traumatic Stress Disorder (PTSD) registered in Louisiana, Alabama and Mississippi rose from 15% a few months after the catastrophe to 21% a year later, according to research published in Nature.

Despite these enormous impacts, the political will to implement meaningful reforms in the wake of floods can be surprisingly short-lived. Political short termism surely plays a role. But also, disasters respect no administrative borders. The fragmented institutional and jurisdictional landscapes that characterise many risk zones can dampen initiative and discourage even the most resolute reformer. Paris is no different.

Avoiding a Katrina-style coordination disaster?

Since that frigid Winter in 357, Paris has expanded into a complex urban amalgam of municipalities and authorities, each with its own administration, budget and priorities. As a rule in France, mayors and prefects are responsible for managing risks, both with regard to prevention and crisis management. With 131 separate communes making up the recently established Grand Paris Metropolitan Authority, that requires a lot of coordination. The unique characteristics of Île-de-France–the region encompassing Paris–adds another layer of complexity to decision making.  While river basins and flood zones unite a broad number of stakeholders, the prospect of a future disaster can be a weak political link that is unable to overcome historically entrenched fragmentation. This is something that Paris set out to change.

paris floods 690x690Paris, 2016 

About one-third of France’s economic activity is concentrated in the Île-de-France region. In addition to being the seat of government, it is a large logistics hub for the entire French economy. Major disruptions would affect all of France, in addition to endangering a large part of the nation’s cultural heritage. But the rational and economic case for building resilient cities is always compelling—just not always sufficient.

Added momentum came from a number of sources. The EU Floods Directive was initiated in 2007 and designated 141 municipalities in the Paris/Île-de-France region as inhabiting a high-risk zone (TRI).  Concurrently, the ‘Grand Paris’ project, inaugurated in 2008, provided a catalyst for metropolitan Paris to ‘rethink’ itself in order to meet future economic, social and environmental demands. Also, the highly anticipated Paris Climate Agreement and the now-confirmed Olympic bid for 2024 offered the prospect of a global stage upon which Paris could showcase its forward-looking credentials.

OECD study commissioned

In 2014, the OECD was commissioned to assess the economic impacts of various flood scenarios based on the 100-year flood of 1910. Excluding Julian’s observations, detailed Seine flood records date back to 1649, with the worst flood occurring in 1658 where the level of the Seine attained 8.96 metres above its average level. In modern times, the 1910 flood, with a 100-year return period, reached 8.62 metres. Today, the 1910 flood serves as a benchmark. The OECD study concluded that a large-scale shock could have a significant macroeconomic impact in terms of GDP, with repercussions both on employment and on public finances. These could come under severe pressure with corresponding deterioration over a long period. According to flood scenarios, the damage from such a catastrophe is estimated to be between 3 and 30 billion euros for direct damage, together with a significant reduction in GDP which, over 5 years, could reach 1.5 to 58.5 billion euros. The resulting contraction in business activity could have a significant effect on the demand for labour; up to 400,000 jobs could be lost in the worst-case scenario.

690x500Paris, 1910

2016 floods: proof of concept

A little more than two years after the OECD delivered its report Parisians were once again watching the Seine rise to ominous levels.  From late May to early June 2016, the south-eastern half of Île de France – as well as the Centre region – witnessed episodes of intense and continuous rainfall over several days, with record-breaking totals locally, reaching more than 100 mm over four days. This led to serious, once-in-a-century flooding in the Loing Basin, as well as the other tributaries of the Seine and the Marne rivers, where known maximum levels were surpassed. In the Seine, the flood extended over one week, reaching 6.07 meters on the Austerlitz scale in the night of 3 June. These levels are equivalent to those of 1982, and 2.5 meters below the level reached in 1910. This caliber of flooding occurs roughly every 20 years. This episode of flooding caused the death of two people in Ile de France and injured a dozen (the same storm system caused 15 deaths and major flooding in southern Germany). Following this event, the OECD was asked to assess the progress made since its 2014 analysis, the results of which appear in the publication ‘Preventing the Flooding of the Seine in the Paris- Île de France Region, Progress Made and Future Challenges’ (OECD, 2018).

Takeaways

It is estimated that economic repercussions of the 2016 flood amounted to about 1.42 billion euros for the Loire and Seine Basins, a number consistent with 2014 estimates. In all, 545 communes in Ile-de-France were recognised as having undergone a natural disaster. Since 2014, the mechanisms aimed at improving public policies on flood risk management have enabled widespread mobilisation of public and private actors and led to the development of a dedicated strategy with an action programme. Important gaps remain, however, with respect to resilient urban development, flood protection infrastructure and prevention funding.

Conclusion

A perfect storm is brewing in many places around the world, through the combined forces of population growth, the accumulation of assets in flood-prone areas, population concentration in coastal areas and unpredictable weather events becoming the new normal (Houston, for example, has faced three 500-year weather events in the last three years). While Paris hasn’t resolved all of its challenges, it has taken important steps in thinking like a megacity, recasting many administrative processes and resources in accordance with a more holistic view of how to achieve resiliency and sustainability—a job that can only be accomplished over the long term. It’s a stark choice that many cities must face: be on the leading edge of this process or find oneself teetering on the edge of viability in facing the shocks that the future is guaranteed to bring.

Further reading:

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