Renaturation of the Aire — Geneva's 5 km River Revitalisation with 300-Year Flood Protection (Switzerland)

The Aire, canalised in 1896 and again in the 1940s, was the object of a 2001 design competition won by the Superpositions team (Georges Descombes with engineers and biologists). The canton's renaturation was built in four stages: a pilot stretch (2002–2006), the central stretch securing Certoux and Lully (2008–2010), the Lully–Marais stretch with a new diamond-pattern bed and a riverside promenade (2013–2016), and a fourth, final rural stage inaugurated on 13 March 2023.
The canton reports over 5 km of river revitalised in total; the fourth stage alone covered more than 1 km between Certoux and the French border, with more than 10,000 shrubs, reeds and other plantings and 125 trees, and the villages are now protected against a flood with a 300-year return period. Works are financed from the cantonal renaturation fund, fed mainly by hydropower taxes and fees.
The project won the LILA 2018 award for public landscapes. Rather than demolishing the old canal, the design kept it as a reference line alongside the new river space.
Caution: published materials are largely promotional or institutional. Reported cost figures differ between sources (a total near CHF 70 million appears in one), and no peer-reviewed before/after biodiversity monitoring was found, so ecological outcomes are asserted rather than quantified. Part of the programme, a reopening within the PAV urban district, remains only a possibility.

Read the full analysis: https://www.ge.ch/document/renaturation-aire-presentation-sa-4e-etape