Morphological restoration for sustainable enhancement of natural dynamic Loire river

Introduction

River regulation works and aggregate extraction have led to an incision of the Loire River bed in its upstream section, particularly in the Forez plain. Today, the sediment deficit downstream of the Grangent dam is estimated at 15,000 m³ per year.

Impact on Ecosystems

The water line is lowering, resulting in a disconnection between the river and its ecologically important riverbanks and its riparian vegetation. The riparian HICs, which are highly dependent on fluctuations in water levels, are directly affected.

Project Objectives

The first objective of the LIFE Loire en Forez project is to return nearly 60,000 m³ of sediment to the river over the life of the project. This restoration will be carried out through:

1. Proactive measures (by paving the bed and scarifying the islands)
2. Gradual measures (by facilitating lateral erosion)

This will allow a sustainable reconstitution, over a 30 km stretch, of the alluvial mattress essential for the proper functioning of all the ecosystems linked to the river.

Biodiversity Restoration

The induced renewal of pioneer HICs (3130, 3270, 8230, 6430 and also 91E0*), associated with the reconnection of 4 river annexes, is thus fully in line with the objectives of the Natura 2000 SCI FR8201765.

Some species of the SPAs FR8212002 and FR8212024 will also see their habitats restored, including:

• Sterna hirundo
• Alcedo atthis
• Charadrius dubius
• Actitis hypoleucos
• Merops apiaster

Compliance with Regulations

This project is now also essential for achieving the WFD objectives for the priority water bodies of the Loire FRGR0003c and FRGR0004a.

Innovative Approach

The innovative approach chosen for the Loire Forézienne, combining various methods of intervention, is intended to be highly reproducible. It will enable us to improve our knowledge of the dynamics of the river and its links with the habitats and species it supports.

Monitoring and Communication

Hydromorphological and naturalist monitoring will be implemented to identify and evaluate these interactions very precisely. Extensive public communication will also be set up to ensure the widest possible dissemination of results.