Rediscovering Paris’ Underground River, La Bièvre

22.12.2023 - 15:35 / forbes.com / Anne Hidalgo / Napoleon Iii III (Iii)

Lots of our most beloved global cities have underground rivers, long forgotten by most. In London, there is the river Tyburn that runs under Buckingham Palace and the river Walbrook running under the Bank of England. New York has several, such as Minetta Brook in Manhattan, which can still give today's residents problems with flooded basements. In Sydney, there is Tank stream which is today an underground stormwater channel. Many of these streams became polluted by tanneries and other livelihoods of days gone by, serving eventually as sewers or drains, before being permanently diverted underground to make way for buildings and above ground life.

In Paris, everyone knows La Seine, the iconic waterway that itself is getting a new lease of life—channelling the buzz of preparations for the Olympic Games in Paris in 2024 there are plans for huge investment to clear the Seine of sewage and bacteria and to open it up for public open-water swimming in three sites by 2025.

There is another Parisian waterway getting increasing attention too. La Bièvre runs for 36 kilometres (22 miles) through Paris' suburbs before it runs into the Seine near the Austerlitz train station, south east of the city. Its name could have come from the Latin bivre referring to a local beaver that disappeared in the 13th century or from beber, meaning brown, like the color of the water. In the 15th century, the family Gobelin established a dyeing business on its banks and made their money by discovering a special kind of scarlett dye—the watercourse became a functional way to dispose of industry waste and it became very contaminated.

Under Baron Haussmann, Napoleon III's architect who created the modern boulevards that gives Paris its recognisable grandeur today, La Bièvre was canalised and then completely covered up. Now it is being carefully uncovered bit by bit in a restoration project that might help the city meet its climate objectives and greenify the city. Uncovering buried watercourses in places such as Paris can aid biodiversity, the water can absorb heat, evaporate and cool the surrounding air (useful in a city at risk of 40 degree summers in the near future) and it provides green space for residents. These uncovered streams can also help cities mitigate against flood risk, as when the water rises it is usually absorbed by natural flood plains.

Stretches in the suburbs of Arcueil and Gentilly have already been reopened and under Paris' mayor Anne Hidalgo, a section that can still be seen at Parc Kellerman will be opened up further—there is a small waterfall here before it heads underground into the city depths. After it is opened further, this section will have improved water quality and will help futureproof against flooding.