Renaturation of the River Air

Atelier Descombes Rampini

Team of designers: Group Superpositions.
Architects: Georges Descombes and Atelier Descombes & Rampini.
Client : State of Geneva.
Location: River Air, State of Geneva, Switzerland.
Photographs: Superpositions, Fabio Chironi and Jacques Bethet.

Near Geneva, the Aire River flows through valleys historically devoted to farming. From the late 19th century, the river was progressively canalized. In 2001, the State of Geneva opened a competition with the idea of restoring the river to its original shape and meanders by destroying the canal. In our winning entry we instead proposed combining the clear territorial cut of the canal with a parallel new vast divagation space for the river. In the process, the canal became the pointer for the transformations, a reference line providing the possibility of understanding a before and an after, a becoming which superimposes both situations and accepts that something began which was already there.

DESIGNINGARIVERGARDEN | Renaturation of the River Air.

08_jacques-bethet_canal

The official justification for the competition brief was an ecological one, in which the legitimate necessities of environmental improvement neglected any design values or considerations: a clear opposition of nature and culture. Our project attempts to propose an alternative path, where the urgent ecological shifts are incorporated in a larger cultural change.

01_fabio-chironi_canal-and-river02_fabio-chironi_launching-pattern03_fabio-chironi_river_general-view

The complex organisation of the design associates the new river space and a linear set of gardens in the former canal. In reality, the whole design becomes a linear garden. The footprint of the canal is a key device for building the paradoxal blend of calm and questioning, of leisure and knowledge, without which there is no real garden. Facing the whole watershed, the original morphology of the mountains and the traces of human modifications, this long rivergarden organises the situations, the views, the confrontations, the presences in a true Einsensteinian montage, aimed at introducing questions, worries and hopes into this fragile and precious territory, through shocking juxtapositions renewing attention and emotion. The presence of the remnants of the canal in a new designed situation created a complex temporality: both very far away and very present. A collision of space and time. Of memory and desire.

a_superpositions_concept-scheme

Conceptual Scheme: the Existing Canal and the New River.

b_superpositions_aire_general-plan

General Plan.

This open-air laboratory character is at its maximum with the design of the new riverbed. There – conscious of the useless effort of designing a fixed river bed and well aware that a river loves to design itself freely – we instead risked a launching pattern, an initiating process whose form addresses the river flow and a prepared terrain. This diamond-shaped diagram, based on the percolation principle with dissipative forces, opens a complex web of undetermined channels for the flows. These channels were excavated along the entire new river bed, first by removing the humus layer and then digging the entire diagram, maintaining a precise control of the longitudinal profile of the river. The dimensions of these lozenge-shaped islands were configured in order to be able to accept the width of the former historical meanders.

c_superpositions_evolution-of-the-morphology

Study of the Evolution of the River Morphology.

04_superpositions_river_detail05_superpositions_river_detail

The result is spectacular and suggests a conceptual link with the work of many earthworks artists, affecting clearly artificial interventions in a natural situation, which are then left to the mercy of the natural forces of erosion. One year after the flows invaded the new river space, the results are beyond our most optimistic expectations: the river flows displace diverse materials, sediments, gravels, sands and the initial geometrical matrix of lozenges gives birth, with a very surprising path, to an extreme diversity in the fluvial geomorphology.

06_jacques-bethet_canal07_jacques-bethet_canal09_superpositions_water-gardens

The monitoring of the processes at work are now a key mission of the design team: to observe, measure and confront all the processes at work in the river bed – with the most advanced technological tools – in this huge laboratory. A first conclusion is that we have to accept this paradox: the more defined the launching grid given to the river, the more the river will be free to design itself.

11_jacques-bethet_dikes


Engineers: B+C Ingénieurs SA and ZS Ingénieurs civils SA.
Biology: Biotec SA.
Construction period: 2001-2016.
Surface area: 50 Ha.
Length : 5km.
Cost: 70,000,000 CHF.