Diagnosing alterations in rivers

The state of aquatic ecosystems is based on parameters that determine their functioning characteristics. Several categories of parameters are generally distinguished:

  • Hydromorphological components - the hydromorphological status of watercourses takes into account different factors: the hydromorphological regime (water flow..), the river continuity (circulation capacity of aquatic species and sediment) and the morphological conditions (depth and width of the watercourse, structure of the bed or river banks, etc.)
  • Biological components, relating to the composition and abundance of aquatic flora and fauna;
  • Physico-chemical components: the WFD makes a distinction between chemical parameters, i.e. the content of different polluting substances (priority and toxic substances), and physico-chemical parameters supporting the biology, such as the oxygen balance, water temperature, or nutrient concentrations.


To ensure that the diagnosis is complete and all the alterations are identified, these three components have to be considered.

Various tools are available as supports for this diagnosis.


    EN - Inrae & OFB - 2023
    Online since:

    This guide gives insights on the method age estimation of Atlantic Salmon based on scale, illustrated by examples and focuses on the main difficulties currently encountered for interpreting scales.

    FR - OFB

    This page introduces the SYRAH-CE project, whose aim is to evaluate risks for water course physical alterations throught a geographical information system (GIS) hydromorphological pressures assessment.

    EN - OFB - 2021

    An adaptation of the Information on the Continuity of Ecosystem (ICE) method to the tropical islands of Guadeloupe, Martinique, Mayotte and Réunion.

    EN - Onema - 2013

    This document recapitulates the knowledge, methods and results presented during the meeting titled “The outlook for managing aquatic biodiversity in rivers and lakes”, held in Paris on 14-15 November 2012.

    EN - OFB - 2020

    A user manual for interpreting the scales and estimating the age of brown trout (Salmo trutta).

    EN - Onema - 2011

    This document is a report of two scientific information days followed by two days of discussions focusing on bioindication, organised in France from 19 to 22 April 2011.

    EN - Onema - 2014

    This document gives an overview of the current knowledge about observed and predicted changes of climate and hydrology, and about the impact of these changes on fish population.

    EN - Onema - 2010

    The authors introduce us to river hydromorphology and explain the geomorphological characteristics of rivers that create the habitat types on which aquatic and terrestrial species depend

    EN - Onema - 2015

    This document presents the issues involved in ecological continuity for fish species, the scientific principles underlying the development of this assessment method and the ICE protocol.

    Data and Maps

    FR - OFB - 2019

    Different graphic representations illustrating flow barriers data: obstacle types, height, uses…

    FR - OFB

    This webpage introduces the water quality monitoring programs developed in France, as a requirement of the WFD

    FR - OFB

    Tool for visualizing and exploiting a large number of data relating to water, aquatic environments and their uses in the form of maps, graphics or interactive tables.


    FR - Eaufrance

    This website, dedicated to wetlands, provides information about the functions and values of wetlands, their regulation... and inventories and maps at different scales.

    FR - AFB - 2018

    This participatory portal offers a centralized access to data on migratory fish in metropolitan France, as well as links to resources and to websites on migratory fish.

    FR - Eaufrance

    A national database for water levels and flows. HYDRO stores the water level measures from about 5 000 measuring stations. It calculates for each given station the instantaneous, daily or monthly flows.

    FR - AFB

    The national interface, Naïades, provides access to data from national monitoring of rivers and lakes. This data is targeted on biological, physicochemical, hydromorphological and temperature quality elements.


    Migratory fish control stations provides informations on the status of fish populations: Kerhamon, Châteaulin, Pont Scorff...   

    EN - Onema - 2015

    After giving some contextual elements about the water-status assessment system in France, some data and maps are proposed about the chemical and ecological status of surface waters and about the chemical and quantitative status of groundwater.

    FR - IGN / BRGM

    This website offers maps, aerial photographs and data concerning environment, spatial planning or public services in France.

    FR - Onema & Agences de l'Eau - 2016

    This new smartphone or tablet application allows to obtain information on the river status: "very good", "good" or "poor"; information of a given river’s water quality over the last 3 years and on fish species present in the watercourse.

    FR - Eaufrance

    A database listing the flow barriers present on French territory, combined with national homogeneous information (national code, localisation…). This fact sheet explains the reasons and the context of its creation.