On October 21st, the integrated development project Isère Amont, for which Egis served as project manager, was awarded the Grand Prix National de l’Ingénierie in the “Adapting existing infrastructure to address the causes or effects of climate change” category. This prestigious national recognition highlights a pioneering initiative that redefines flood risk management.
Isère Amont: Shifting the paradigm by restoring the river’s place
The Grésivaudan Valley, an alpine corridor in southeastern France located upstream from the city of Grenoble, has long been shaped by agriculture and industry. Following major river engineering works—particularly after the 1859 flood—the valley’s natural fluvial dynamics were disrupted. Today, it faces a significant flood risk, threatening 300,000 residents and potentially causing damages estimated at over one billion euros.
Launched by the Syndicat Mixte de Bassins Hydrauliques de l’Isère (SYMBHI), with the support of its delegated contracting authority Elegia Territoires 38, the Isère Amont project rethinks flood risk management.
Egis, lead contractor for project management, alongside Artelia (upstream design) and Hydrétudes (environmental and ecological lead), have embraced a paradigm shift: giving the Isère more space and restoring its interactions with both natural and urban environments over a stretch of more than 40 km.
Following the initial study phases, the consortium led by Egis carried out the full scope of design and construction supervision over three successive contracts, spanning a period of 15 years from 2008 to 2023. The contracts included the missions defined by the French MOP law, as well as additional support services such as stakeholder engagement and assistance with the preparation of certain administrative files.
A new hydraulic planning strategy
Rather than confining the river, the project takes a controlled approach to freeing its channel and restoring its natural dynamics:
- 16 controlled flood expansion areas (CIC) across 3,600 hectares, with a storage capacity of 35 million m³
- 42 spillways and 4 mobile gates
- 17 km of containment dikes and 21 km of reinforced dikes
- An agricultural compensation protocol for flood-prone areas
Objective: to protect 29 municipalities from flooding, while promoting a more natural management of the river and its floodplain.
The project, spanning 18 years and backed by a budget of €135 million — 6% from AERMC, 43% from the French State, and 51% from SYMBHI via the Isère Department and local authorities (Grenoble Métropole and the Grésivaudan intermunicipal community) — was put to the test during the 2023 flood.
An ambitious ecological restoration strategy
From its inception, the project embraced an aquatic ecosystem management (GEMA) approach, including:
14 km of levees removed, 6 km of levees set back, and 300 hectares of alluvial forest reconnected
4 river side channels reopened, wetlands and gravel pits restored
Fish migration routes and ecological corridors reinforced
Landscape enhancements: soft mobility paths, green rest areas, and signage
These measures restore a mosaic of habitats that support biodiversity, including bioindicator species such as Typha minima (dwarf bulrush) and the beaver.
Designed with residents in mind, the project includes landscaped developments, cycling and walking paths, green rest areas, and educational signage. Delivered in 2023 after 18 years of consultation, design, and construction, Isère Amont showcases the power of engineering to combine public safety, territorial resilience, and ecological restoration.
A project aligned with Egis’s core climate commitments:
- Greenhouse gas emissions reduction by 2033: - 55% of total direct and travel emissions; -61% reduction in carbon intensity of other significant Scope 3 emissions. By 2050, 90% reduction in all emissions.
- Lower emissions from client projects and minimize their impact on biodiversity
- Carbon sequestration: restoration of natural ecosystems
- Enhance the resilience of territories to climate risks
- Business portfolio transformation: significantly increase the proportion of projects contributing to the ecological and energy transition by 2030.
