Home - Themes - Diagnose physical alterations in rivers - Encouraging the physical restoration of rivers


    -Serge Lepeltier \ Loire-Brittany basin committee
    "In the Loire-Brittany basin, restoration of rivers and the reduction of diffuse pollution constitute major challenges in achieving good water status..."

    -Gilles Petel \ Board managing the Veyre and Auzon valleys
    "The work to recreate meanders in the Veyre river started in the fall of 2010..."
  • Evaluating risks of hydromorphological alterations

    In a partnership with the Water agencies and with scientific and technical support from its joint hydroecology centre with Cemagref in Lyon, Onema is currently mapping zones at risk of hydromorphological alteration that could result in failure to achieve good ecological status.

Encouraging the physical restoration of rivers

Changes in the morphology of rivers are one of the main obstacles to achieving good ecological status of aquatic environments. That is why it is necessary to launch operations to physically restore aquatic environments, based on good ecological-engineering practices and managed by local entities. Given the approaching 2015 deadline for good water status and the amount of work required, it is important to accelerate dissemination of known good practices, improve restoration techniques and encourage more ambitious projects. In 2010, Onema mobilised and informed water stakeholders and managed a project to devise a monitoring system for restoration operations.

Whether recreating meanders, replacing a river in its original bed, eliminating protection systems on banks, uncovering buried sections, etc., many projects to restore hydromorphological processes in rivers have been undertaken over the past few years and involved an array of stakeholders. These projects have multiple goals, including reducing flood risks, facilitating sediment transport, restoring continuity for aquatic species, reinstating hydraulic connections and habitats, improving water quality and living conditions, and creating recreational areas.


2 500 feedback compendiums distributed to water stakeholders

To achieve good ecological status, there must be many more such projects. To raise awareness on the part of local governments, elected officials, river boards, regional nature parks and managers of public land concerning the need to restore the morphology of rivers and to launch ambitious restoration projects, Onema published a compendium containing feedback from hydromorphological projects. The document explains the advantages of restoration, provides technical data and techniques for procedures, and presents feedback on about 60 restoration projects carried out throughout France over the past 20 years. Over 2 500 copies were distributed to water stakeholders, including consumer and environmental groups. It is the result of a partnership between the Ecology ministry, the Water agencies and Onema, and will be expanded with feedback from new projects over time.

Toward standardised monitoring of restoration projects

Due to a lack of serious monitoring and enough experience, it is difficult to evaluate rigorously the environmental response and the ecological benefits of many projects targeting hydromorphological restoration.

Funding entities and project managers, confronted with this lack of knowledge, need a means to check the effectiveness and the success of restoration projects, thus enabling them to promote the projects to local stakeholders. That is why Onema led efforts to develop a standardised monitoring system with the nine Onema regional offices, the six Water agencies and the Ecology ministry.

What types of projects should be monitored? Which monitoring method should be used? What data should be collected? How often? On which spatial scale? An initial report, published by the Onema/Cemagref hydroecology centre, provides information on how to set up a minimal, scientific monitoring system to detect environmental response. The monitoring system covers the biological, physico-chemical and hydromorphological characteristics of the restored environment.

A document to assist in defining a monitoring programme is now available for both the initial status report and for post-restoration monitoring. Tests are currently underway on a dozen restoration projects to assess their practical implementation and how they are handled, including political support, project management, acceptance by owners and funding. However, the feedback from the monitored projects will not be available for years due to the time required to assess environmental response based on the supplied data.


Onema in the Auvergne-Limousin region : Monitoring the remeandering of the Veyre river

In the Puy-de-Dôme department, the remeandering project on the Veyre river, which was heavily rectified in the 1960s, was monitored to determine the response of the aquatic environment and assess the success of the operation. The work started during the summer of 2010 under the responsibility of the board for the Veyre and Auzon valleys. The goal was to turn 1 100 metres of river into 1 750 metres. Prior to starting the work, the Onema regional office produced a baseline report with the Loire-Brittany water agency, the Auvergne DREAL and the Puy-de-Dôme fishing federation. Onema personnel measured in four stations (two for control purposes) the physical characteristics of the river, i.e. its width, depth, flow rate, granulometry, fine-sediment deposition, type and structure of banks and of riparian vegetation. They also located potential spawning grounds and shelters. The fishing federation carried out electric fishing to analyse fish populations while DREAL monitored invertebrates. Hydromorphological measurements and electric fishing will be resumed during the summer of 2011 to assess the short-term response of the environment.

All the monitoring work will be repeated three, four and five years after the end of the work. This project is part of the study undertaken to standardise national monitoring techniques. The study will first assess the practical implementation of monitoring protocols and techniques, then after a number of years, the relevance of the analyses made possible by the constituted data.

Contact : - Onema Auvergne-Limousin regional office