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© Irstea

Water-related hazards and risks

In summary

In a word

  • 71 permanent staff including 59 researchers, engineers and technicians
  • 57 top-ranking publications per year on average

Three lines of scientific research

  • Understanding the processes related to the water cycle and associated materials, as well as comprehending how catchments function
  • Quantification of the risks related to water and its quality, predetermination and forecasting of extreme events, in a context of global change
  • Management of water resources and the necessary adaptation to a non-stationary environment and to changing needs

Editorial : water, between preservation and risk management

Vazken Andréassian, Directeur-adjoint scientifique de ARCEAU- © Irstea - M.-L. DegaudezWater, indispensable to life, is paradoxically the source of hazards that cause considerable damage to humans and property (floods, drought and pollution) every year. And yet, as powerful as such events may be, water remains a vulnerable resource profoundly impacted by ever-increasing competition for its usage and the uncertainty of global changes which, though acknowledged, are still poorly understood. The researchers involved in the research topic ARCEAU (Waterrelated hazards and risks) are working on both water resources management and the prevention of the associated risks. And this, against a backdrop of increasingly stringent national and European regulation on the need to preserve the quality of the aquatic environments and to protect humans and their facilities against floods.


From a scientific standpoint, challenges abound: how to store, analyse and utilize ever-increasing and widely-varying data? How to build models and guarantee their validity? How to predict the consequences, at varying scales of time and space, of the global changes associated with climatic and man-made phenomena? How to achieve enhanced identification and management of the risks related to diffuse pollution? How to anticipate extreme events – i.e. events that may occur beyond the century or even the millennium – when there is an acute lack of measured data?

These are all questions to which Irstea scientists are responding in the course of their research. They are acknowledged experts in the field of development and validation of hydrological models (flows) and hydraulic models (water speeds and levels), as well as in flood forecasting, notably through the use of two operational tools in France: GRP for the gauged rivers and AIGA for the non-instrumented rivers. Their expert knowledge is also highly valued at the national level in defining and limiting instances of pollution. They have also gained international recognition through the very high level of visibility of their work on hydrological extremes, their collaborative networks with the United States and Australia and the presence of a number of researchers as associate editors in refereed journals.

Although such advances are gradually extending the field of knowledge, their main purpose is to respond to the needs of the economic stakeholders and the political decision makers wishing to prepare practical adaptation strategies for both the present and the future.

Selected research projects

Flood risk : how can we estimate extreme flood levels?

Flood risks: forecasting floods to improve warning systems


Wetland buffer zones


Hydraulic facility: flooding in the laboratory

Interview with a partner

A platform facilitating anticipation

In January 2016, a web-based platform co-developed by Irstea was launched to offer local communities and state services of the Provence-Alpes-Côte d’Azur region real-time warnings of natural rainfall-related hazards.

This platform is proving particularly useful in the Department of the Hautes-Alpes, which has poor weather radar coverage. "Thanks to the highly accurate data, we can anticipate flood events and gain time to be able to evacuate camping sites along the river and stream banks, says Pierre-Yves Lecordix, deputy director of the departmental directorate of the territories (DDT) of the Hautes-Alpes region. Conscious of the value of these alerts, in 2011 we opted to be among the experimental users of the platform. It proved relatively easy to use it effectively and we have also been able to exchange information with other experimental users at meetings organised by Irstea".

In order to transition to the operational version, three days of information and training were given to risk prevention and crisis management actors (elected officials, technicians, state services agents). As for the future, the DDT of the Hautes-Alpes already has some expectations in mind. “If a distinction can be made between rain and snow, we could use the platform to manage winter risks, according to Pierre Lecordix. In addition, the integration of the Italian radar data could improve our anticipation of crossborder phenomenon.”

Scientific observatory

An observatory down the years
For more than fifty years, Irstea has been collecting hydrological and biogeochemical data thanks to the observatory, which is situated in the Paris region.
Consisting of the catchment areas of the Grand Morin, the Petit Morin and the Orgeval, ORACLE comprises a complete network of measures enabling Irstea researchers to monitor the long-term evolution of the critical zone in response to climate change and land-use (agricultural pollution, urbanization, etc.). Regularly subject to sudden and violent flooding, it also contributes to the validation of the models for forecasting extreme hydrological events.
The measurements collected (several million per month!) are recorded in the hydrology observatories database (BDOH), managed by Irstea.

Created in 1962 and consequently the oldest of France’s hydrological observatories, nonetheless ORACLE is looking to the future. For example, since 2015 it has had a laboratory devoted to high-frequency monitoring of water quality (every minute) and evapotranspiration measurement equipment acquired in the context of the CRITEX project. In addition, it will be integrated into the future research infrastructure of OZCAR and is one of the 18 study sites for the European long-term ecosystem research infrastructures project (eLTER).