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Thematic issues

Towards the restoration of rivers and aquatic environments
A collection of river hydromorphology restoration examples

Five new examples of river hydromorphology restoration have been published Read more

The collection presents more than 60 examples of river hydromorphology restoration undertaken over the past 20 years throughout France. These actions aim to preserve river hydromorphology or to re-establish hydromorphological processes of rivers.
The first part of this publication provides basic information on the benefits of restoration, given that river dynamics lie at the origin of biodiversity and good ecological conditions, and the fact that aquatic environments have much to offer society, etc.

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Why restore river continuity?


In France, more than 60 000 structures - dams, locks, weirs and mills - have been listed on rivers and are potential obstacles to river continuity. The European Water framework directive (WFD), the French Water law of December 2006, the French National Eel Management Plan and now the Grenelle 2009 law with its objective of implementing an ecological network (French green and blue network), all focus on biological continuity between major natural sites and within aquatic environments. In practical terms, these regulatory texts lead us to increase our collective efforts and actions in favour of restoring river continuity. The ambitious aim is to restore two-thirds of water bodies to good ecological status by 2015.

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Onema Meetings

  A hardcopy of the documents may be requested as long as stocks last. Please justify your request when writing to veronique.barre@onema.fr.

Accompanying implementation of French ecological networks dans les territoires


The symposium titled “Mobilising public entities for ecological networks” took place in March 2015 in Paris. The daylong meeting, with an array of speakers, enabled researchers, elected officials, local governments, State services, developers, managers of natural areas and associations to trade thoughts on the issues, techniques and measures involved in promoting biodiversity and ecological continuity. The operational phase in network implementation has raised a number of questions.
Symposium organised by the Ecology ministry and the Agriculture and forestry ministry, with support from Irstea and Onema, members of the TVB resource centre.

Meetings N°35, October 2015

River restoration and Natural Water Retention Measures


Natural Water Retention Measures as well as aquatic ecosystems’ restoration and preservation provide means to achieve good water status as required by the Water Framework Directive (WFD). In order to make progress on that topic, the workshop aimed to promote a better integration of European directives and policies through river restoration and natural water retention measures. The workshop was also focusing on the ways to improve local communities’ engagement in aquatic ecosystem restoration projects. These exchanges enabled to draw conclusions and make recommendations that may be integrated in the future WFD cycles.
A workshop co-organised by Onema and the International Office for Water in Bucharest - Romania - 12 November 2014, and held jointly with the Europe-INBO annual conference on 12-14 November 2014

Meetings N°33, September 2015

Reinforcing coproduction and brokering of research, development and innovation results for water and aquatic environments


How can operational needs be identified in order to steer RDI (research, development, innovation) policy toward the scientific and technical developments most useful for water managers? What forms of coproduction must be implemented to ensure that the intended persons can effectively use the results? And what transfer policy should be instituted so that the results are fully exploited?
A symposium organised by Onema in March and April 2015.

Meetings N°32, Avril 2015

The importance of the science-policy interface for water and climate


The symposium titled “Water and climate - Interaction between scientists and politicians for action” was held in Paris in February 2015. The purpose of the event, a forerunner to the 7th World water forum and the “Paris-Climat 2015” meeting (COP21), was to facilitate discussions between scientists and elected officials on the topic of water and climate change in view of jointly laying the groundwork for future improvements in the science-policy interface. These discussions are essential in order to transform scientific knowledge into actual water planning and management policy.

Meetings N°30, Avril 2015

A national specimen bank for continental aquatic environments?


Last November, several of the leading international experts on environmental specimen banks (ESB) met in Pau for two days of discussions that highlighted the value of these tools in meeting the challenges raised by pollution management and biodiversity conservation. The idea of creating an ESB for continental aquatic environments in France was floated.

Meetings N°29, March 2015

Overseas territories, the WFD and bioassessment


Over the past five years, the development of bioassessment tools suited to the overseas territories has made rapid progress. The symposium held on 20 and 21 March 2014 at the Porte-Dorée tropical aquarium in Paris was an occasion to report on the progress achieved and to assess the work that must still be undertaken for the upcoming management cycles of the Water framework directive (WFD). A review.

Meetings N°28, August 2014

Monitoring programmes: WFD requirements, their implementation and use of the results


The purpose of the workshop organised in Bulgaria in November 2013 was to facilitate discussions between European river basins on monitoring of water and aquatic environments, with the European commission and the European environment agency on hand, and to enhance the common implementation strategy for the WFD. The workshop was an occasion to discuss monitoring results and the impact of monitoring on implementation of management plans and programmes of measures in three main fields, namely the purposes of the monitoring programmes, stakeholder organisation and roles, and monitoring strategies. The conclusions drawn and recommendations made may be integrated in the future WFD cycles.

Meetings N°27, July 2014

Methods and tools to control agricultural nonpoint-source pollution for managers of water resources


Local governments are frequently confronted with the problem of managing agricultural nonpoint-source pollution. This type of pollution is one of the main causes of the degradation of water bodies in France and Europe. How can its management be improved and its impacts reduced? What are the tools and methods now available to water managers to effectively counter the pollution? The first edition of the national PollDiff’Eau symposium, held in Paris from 18 to 20 September 2013, was an occasion to present to some 260 participants the tools and methods developed by publicly funded research programmes.

Meetings N°26, April 2014

Bringing wetland research in line with operational needs


The objective of the meeting, based on an analysis of wetland research over the past ten years, was to set guidelines for scientific policy on wetlands better suited to the needs expressed in the field. This document reports on that meeting.

Meetings N°25, March 2014



Reducing chemical contamination of aquatic environments: five years of progress and results

The national symposium on monitoring and reducing chemical contamination of aquatic environments, held in Paris on 17 and 18 June 2013, brought together almost 200 participants, including water managers, stakeholders and scientists. An array of results and techniques, produced over five years of intensive efforts by BRGM, Ifremer, Ineris and Irstea, were presented.

Meetings N°23, December 2013


Invasive exotic crayfish: present situation and management approaches

Two days devoted to information and debate, organised by the INRA, the “Parc naturel régional de Brière”, the “Forum des marais atlantiques”, the Onema and the CNRS.

Meetings N°22, September 2013






Diagnosing and restoring aquatic biodiversity

The national symposium on «The outlook for managing aquatic biodiversity in rivers and lakes» was an occasion to report on some 30 partnership-research projects in the field of aquatic biodiversity. The two days of discussions between scientists and managers brought together over 200 participants, including research labs, the Ecology ministry, local governments, companies, environmental-protection groups and NGOs. Following a status report on biodiversity in aquatic environments in France, the meeting went on to present a range of innovative tools for monitoring and restoring biodiversity in a context of global climate change.

Meetings N°21, April 2013

Lessons from the national PCB action plan

Polychlorinated biphenyls (PCB) have been forbidden for 25 years, but are still present at the bottom of many French rivers and... in the fl esh of the animals living there. A spotlight was thrown on this long-standing pollution in 2006 when the EU adopted new health standards concerning the consumption of freshwater fi sh. France subsequently launched an action plan that produced, thanks to three years of research, considerable progress in our understanding of PCB transfers from sediment to fi sh and of the degree to which humans are exposed. The goals of the plan were met, notably concerning the establishment of thresholds for PCB contamination of sediment, above which fi sh are no longer suitable for consumption. These results raise the question of the lessons to be drawn from this situation for «emerging» contaminants. That was one of the main topics of the feedback symposium for the action plan, organised by Onema, the Ecology ministry and the University of Bordeaux 1, in a partnership with the Agriculture and Health ministries, and held on 31 May in Bordeaux. This document reports on that meeting.

Meetings N°18, October 2012

Research update on climate change
and low-flow conditions in France


A forward-looking meeting on quantitative hydrology was organised by Onema (national agency for water and aquatic environments) on 19 and 20 March in Paris. Approximately 20 past, current and future projects funded by Onema were presented. Scientists and water managers discussed the current directions taken by the quantitative hydrology research in France. The discussions addressed in depth the linked issues of climate change and the management of low-flow conditions, a major social and ecological issue. This document reports on progress in research and on the remaining issues.

Meetings N°17, September 2012

Engineering the water continuum

Water is an environment and a resource that has structured life from its inception and served as a vital support for biodiversity. It can be used in many ways, but it has also become a vector and receptacle for pollutants. The notion of an aquatic continuum has become critical to understanding aquatic ecosystems in that it emphasises the need for an integrative approach, spanning both the spatial and temporal scales, to water management. Incorporating this concept in ecosystem engineering is a major challenge. In addition to mobilising integrated, multi-disciplinary scientific methods, this approach must take into account not only the fact that human uses of water are highly diverse and interconnected, but the many stakeholders as well. Gaié and Onema examined the position of ecological engineering in sustainable water management during the symposium organised in the partnership with the Paris region, the French limnology association and Parisian universities.

Meetings N°16, August 2012

Management plan to save the eel. Optimising the design and management of installations

The Eels & Installations R&D programme is the result of a partnership between Onema, Ademe and five hydroelectric companies. Over the past three years, the programme launched 18 research projects to optimise the design and management of installations to protect migrating eels. On 28 and 29 November 2011, the feedback symposium brought together 160 persons, including researchers, water managers, associations and hydroelectric companies, in the conference room of the Porte Dorée aquarium in Paris. This key event in the French eel-management plan sketched a panorama of the results achieved in a series of presentations addressing the operational aspects of issues. The presented solutions and tools pave the way for a collaborative response by the economic participants to the challenge of restoring the species.

Meetings N°15, August 2012

Water status and the Water framework directive. A review of assessment methods

In view of the second management cycle of the Water Framework Directive (WFD), 2011 constituted a key year for developing and ensuring the compliance of water status assessment methods. In this context, the French Ministry for Sustainable Development and ONEMA (French National Agency for Water and Aquatic Environments) invited over 200 experts and managers to attend a series of meeting held from 19 to 22 April 2011. Participants included the Ministry, Water Agencies, DREAL (Regional Directorates for the Environment, Planning and Housing), ONEMA, research establishments and technical institutes, etc. These meetings were organised with the support of the International Offi ce for Water (IOWater). Two scientifi c information days focusing on bioindication were followed by two days of discussions in order to review the progress made, the prospects for the development of methods used for assessing water status in France, and the tools of the Water Status Assessment System (Système d’évaluation de l’état des eaux - SEEE).

Meetings N°13, December 2011

Treatment of wastewater, sludge and septage in small to mid-sized towns

The main goal of the symposium organised in Lyon, on 2 December 2010 during the Pollutec trade show, was to provide the French sanitation sector with operational tools to assist in meeting regulatory requirements and protect aquatic environments. The meeting was also an occasion to hold a debate on priorities for research and future developments, taking into account operational needs.

Meetings N°11, October 2011


Drinking-water abstractions and nonpoint-source pollution

Protection of drinking-water abstractions from nonpoint-source agricultural pollution was already a major health issue 30 years ago and has today become an urgent regulatory problem. In parallel with the Water framework directive, which set goals for good water status by 2015, the Grenelle environmental agreement identifi ed 500 «priority» abstractions for which action plans must be set up by 2012. To that end, over 200 professionals from the water sector, including research, agriculture, water management and local governments, attended the symposium held on 3 February 2011. The wide-ranging discussions produced a vast array of information on people’s experiences, technical solutions, opinions and questions. A review.

Meetings N°10, June 2011

How should invasive species be managed in aquatic environments?

Exotic crayfi sh, bullfrogs, Japanese knotweed, primrose willows… invasive species are one of the main pressures that ecosystems are subjected to, just like the destruction of natural habitats, pollution and overusing resources. Onema and Cemagref organised a seminar in Paris on the management of these species in aquatic environments, bringing together more than 130 researchers and managers of aquatic environments. Its objective? Provide three days for exchanging between the various stakeholders involved with these species, while also providing scientific and technical knowledge that can improve management practices.

Meetings N°9, May 2011

Good status of aquatic environments based on the scientific concepts of ecological engineering

The goal of the meeting, held during the international congress titled Ecological engineering, from concepts to application (CNRS, Paris, 2-4 December 2009) for the scientifi c community working in ecological engineering, was to shed new light on the issues involved in maintaining and restoring the quality of aquatic environments. The point was to take a new look at attaining good ecological status as defi ned by the European water framework directive (WFD) on the basis of ecological-engineering concepts, without undertaking a complete review of the methods used in this fi eld.

Meetings N°8, December 2010

Mesocosms, Their value as tools for managing the quality of aquatic environments

Mesocosms are artifi cial ecosystems used by researchers and industrial companies to study the long-term effects of chemical substances on the structure and operation of natural aquatic ecosystems. Could these experimental platforms be useful for managing the functioning of natural environments, notably for establishing environmental quality standards and developing monitoring tools? Are they suffi ciently representative for use in setting regulations? To discuss these issues, Onema and INRA, in conjunction with Total and Ineris, organised a symposium at Le Croisic from 14 to 16 October 2009.

Meetings N°7, October 2010

Climate change, impacts on aquatic environments and consequences for management

Building, on a national scale, sustainable dialogue between scientists and water managers in order to address the recognised climate change, that is the objective of the seminar organised by Onema and the Management and Impacts of Climate Change (GICC) programme of the ministry in charge of ecology, on 29-30 June 2009 in Paris. This seminar, entitled «Climate change, impacts on aquatic environments and consequences for management», brought together more than 120 scientists, experts, managers, and representatives of NGOS and companies. This dossier provides an overview of the current knowledge that was presented, the points of view expressed, and the questions raised over these two days.

Meetings N°2, January 2010

Drug residues in aquatic environments. Needs and tools for monitoring and risk evaluation

Monitoring drug residues in our aquatic environments and evaluating the risk for the environment and human health was at the core of the seminar organised by Onema on 25-26 May in Paris. Nearly 80 health and environment specialists came to share their expertise. The objective? Set down the basics for a joint effort programme to increase knowledge and contribute in developing the national inter-ministerial plan on drug residues in water.

Meetings N°1, December 2009

 

Onema Meetings (recap)

  This series is intended for technicians and interested persons. It presents the main elements of technical meetings organised by Onema and its partners. A hardcopy of each document may be requested as long as stocks last.
Please justify your request when writing to veronique.barre@onema.fr.

Chemical contamination of aquatic environments :Tools and methods for assessment and action
Confronted with the vast array of polluting substances and the complexity of their effects on both ecosystems and lifeforms, water managers and stakeholders have expressed growing needs for operational knowledge, tools and methods. How can the sources of pollutants be better identified and how can emissions be reduced? How can the presence of pollutants be linked to the observed ecological impacts and how can the assessment of water status be improved? Finally, how can the “emerging compounds of most concern” be identified in order to start working immediately on regulating them and attenuating their impacts? Over the past five years in France, these questions were the focus of an unprecedented R&D effort in the framework of the national 2010-2013 Micropollutants plan and a number of more specific action plans targeting PCBs, plant-protection products, pharmaceutical residues, urban wastewater management, etc. The national symposium, organised by Onema and Ineris on 17 and 18 June 2013, was an occasion to review the work undertaken.

Exotic crayfish invasions, Ecological impacts and management approaches
The importance of the ecological and economic impacts induced by biological invasions is now broadly recognised. At a time when the recovery and the preservation of the good state of aquatic environments impose themselves as essential ecological and societal stakes, the issue of invasive crayfish constitutes a major concern for numerous water managers and stakeholders.
This document presents the results of the first National meetings on invasive exotic crayfish providing a description of present knowledge on invasive and native crayfish species in France, a better understanding of processes operating, the place of invasive crayfish in aquatic ecosystems and their effects on biodiversity, and lastly a presentation of management approaches investigated in the country.
Gathering nearly 120 professionals concerned by crayfish invasion – researchers, managers, administrations, professional fishermen, consultants for environment and environmental associations – these two days combining science and management objectives made it possible to establish for the first time such a broad dialogue about the subject on a national scale. The « first meetings » were organised by the INRA, the Parc naturel régional de Brière, the CNRS, the Onema and the Forum des marais atlantiques. They took place on the 19th and 20th of June, 2013 at Saint-Lyphard, at the heart of the Brière marshes.

Diagnosing and restoring aquatic biodiversity
In a context of global change, what is the actual status of biodiversity in France? How will current and future changes in the climate affect fish populations, plants and plankton communities? What will be the effects of biological invasions on aquatic biodiversity? What will be the consequences of changes in discharge regimes and in river hydromorphology? How can the managers of aquatic environments assess these impacts? And how can they work to limit the effects and to restore biodiversity, both now and in the future? The symposium in Paris titled "The outlook for managing aquatic biodiversity in rivers and lakes" brought together over 200 participants, including research units, State services, local governments, companies, environmental-protection groups and NGOs, to address these questions. The two days of discussions between scientists and water managers provided feedback on approximately 30 partnership research projects on aquatic biodiversity. The symposium titled "The outlook for managing aquatic biodiversity in rivers and lakes" was organised by Onema (National agency for water and aquatic environments), with assistance from IOWater (International office for water). The symposium was held in Paris, on 14-15 November 2012.


Water science meets policy: How to streamline knowledge to address WFD challenges?
The 3rd workshop " Water science meets policy" organized in the framework of the science-policy interface for WFD common implementation strategy (CIS-SPI) was organized in November 2012 by Onema, and DG Research and innovation of the European commission. It was titled " How to streamline knowledge to address WFD challenges?" and focused on demonstrating the added value of SPI at all geographical levels and proposing key aspects to implement a sustainable SPI activity in the CIS structure. The event aimed also to identify possible methods and tools for a successful future knowledge brokering in the CIS context. This document presents the main recommendations expressed by the participants regarding tools, methods and operational modalities for an efficient implementation and successful SPI in the WFD CIS context. It also summarises the presentations given during the event. Recap of the 3rd “Water Science meets Policy” event, Brussels, 14 & 15 November 2012


Optimising the design and management of installations in the framework of the management plan to save the eel
The symposium titled "Eels and ecological continuity. Optimising the design and management of installations" was organised by Onema (National agency for water and aquatic environments) and the steering committee of the Eels & Installations R&D programme. It was held on 28 and 29 November 2011 in the auditorium of the Palais de la Porte Dorée in Paris, thanks to a partnership with the Tropical Aquarium. In three sections, the document presents the results of the R&D programme to restore eel stocks. View the short version Symposium on the results of the Eels & Installations R&D programme 28-29 November 2011, Paris



Implementation of the Water Framework Directive. When ecosystem services come into play
The seminar titled "Implementation of the Water framework directive. When ecosystem services come into play" was organised in September 2011 by Onema, the French national agency for water and aquatic environments, and EC DG RTD (Research and innovation directorate of the European commission) in the framework of the science-politics interface for WFD implementation (CIS-SPI). This document presents the results of the seminar, i.e. the concept of ecosystem services, the application methods for integrated water management in Europe, recommendations for decision-makers and the fields where further research is required. It also contains summaries of the presentations made during the seminar. Recap of the 2nd “Water Science meets Policy” event, Brussels, 29 & 30 September 2011


Drinking-water abstractions and nonpoint-source pollution. Operational solutions for supply zones of priority water abstractions
Both drinking water and agriculture are essential to modern life. Protecting water abstractions from the nonpoint-source pollution released in large part by farming activities is a crucial challenge for our societies. The "Large-scale farming offering high economic and environmental performance" scientific group (GIS GC-HP2E), of which Onema is a member, brought together a number of participants on 3 February 2011 in Paris, including the agricultural and institutional sectors, representatives of local governments, industrial companies and scientists, to discuss these complex issues. This document recapitulates the projects presented, the viewpoints and the scientific contributions made during the meeting. Recap of the 2011 Meeting of the GC-HP2E scientific group (3 February 2011, in Paris



Economic instruments to support water policy in Europe: paving the way for research and future development
The meeting was organised by Onema, with assistance from ACTéon, in December 2009. Participants included over 120 economists, hydraulics engineers, water-sector decision makers and representatives, EU representatives, scientists and politicians from 11 EU countries, the U.S. and Australia. Recap of the meeting held in Paris, 9 & 10 December 2009


Mesocosms.Their value as tools for managing the quality of aquatic environments
Onema and INRA, in a partnership with Total and Ineris, organised the national symposium on ecotoxicology at Le Croisic, on the Atlantic coast in France, from 14 to 16 October 2009. The meeting brought together over 30 scientists, experts, managers and stakeholders from the water sector. This document is the result of the two days of discussions between the various groups present. It reviews the advantages of mesocosms for ecology and ecotoxicology studies, presents the needs and expectations of water managers concerning toxic micropollutants, and finally proposes a number of ideas on the use of mesocosms in meeting the challenges involved in ensuring the quality of aquatic environments.
Recap of the Ecotoxicology symposium,14 - 16 october 2009 in Le Croisic


Climate change. Impacts on aquatic environments and consequences for management
This document sums up the data presented, the viewpoints expressed and the questions raised during the seminar, held on 29-30 June 2009 and organised by Onema and the Climate-change impacts and management programme (GICC) at the Ecology ministry, with assistance from GIP-Ecofor. Recap of the 29-30 June 2009 symposium, Paris


Knowledge for action

  The Knowledge for action series provides professionals in the water and aquatic-environment sector (instructors, students, scientists, engineers, managers, etc.) with information on recent research and science-advice work.

A hardcopy of each document may be requested as long as stocks last.
Please justify your request when writing to veronique.barre@onema.fr.


   Contributions of hydro-economic models to water management in France

Economic analysis plays an increasingly important role in managing water resources and aquatic environments. For example, it can assist water managers in determining the economic value produced by various water uses in a river basin. It can also contribute to identifying the most cost-effective programmes of measures in view of reaching good status of water bodies. Unfortunately, economic studies are often carried out in parallel to hydrological studies, i.e. the hydrological functioning of the basin and the dependant socio-economic processes are not analysed in an integrated manner...
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   Economic analysis for managment of water and aquatic environments

Whether the goal is to characterise in social-economic terms how water is used in a given area or to assess the costs and environmental impacts of a programme of measures or a project, economic analysis is now an integral part of the preparatory and formulation processes of public policy. Whatever the size of the project, cost-recovery analysis, cost-effectiveness analysis and cost-benefit analysis are all assessment techniques that water specialists must use to comply with regulations and implement water-management policy in their area.
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   Freshwater fish and climate change. Current situation and adaptation strategies

Aquatic environments constitute ecological treasure houses, represent a unique cultural heritage and provide society with important economic resources. What will be the consequences of climate change on the hydrology of aquatic environments? How will aquatic ecosystems and organisms react? What can be done to limit their vulnerability? Fish are emblematic life forms in rivers and an important resource for humans. They are one of the lifeforms that will potentially be impacted by climate change.
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   Assessing the passage of obstacles by fish. Concepts, design and application


Obstacles to flow in rivers constitute a major source of breaks in ecological continuity. Given the vast array of regulatory requirements, notably the Water framework directive, and the many environmental issues involved in restoring the ecological continuity of aquatic environments, Onema decided to create a "tool" to assess and quantify the impacts of hydraulic structures on the free movement of fish.
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   Designing ambitious projects for river restoration

The Water framework directive has made the physical restoration of aquatic environments an essential component in public water-management policies. Yet the initial feedback would indicate that technical excellence alone is not sufficient to guarantee effective implementation of river-restoration projects. To assist in solving this problem, the document presented here proposes a comprehensive framework with a description of the tools that may be used in an overall strategy designed to accompany stakeholders wishing to launch a hydromorphological-restoration project and ensure its success. It looks specifically at the conditions determining the legitimacy, both technical and political, of project promoters. The document discusses the means to ensure the social and territorial relevance of a project, as well as the means to demonstrate its technical and economic compatibility with the local social-economic context.
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   Structural characteristics of priority abstractions of use in designing protection systems

The first Grenelle environmental law, designed to reinforce WFD objectives, stipulates that "by 2012, action plans must be implemented to protect the 500 drinking-water abstractions in France, most threatened by nonpoint-source pollution, particularly by nitrates and phytosanitary products.
The goal is therefore to achieve specific results, i.e. protection of water resources, via an approach stressing preventive rather than curative measures.
The legal texts also stipulate that an action plan must be defined and implemented for priority abstractions with the local stakeholders. In this difficult situation, the local stakeholders, e.g. local State services, theWater agencies, local governments, Chambers of agriculture, water boards, etc., are all looking for effective, practical solutions in the field.
To assist in this work, a study covering the entire country was carried out to gain information on suitable strategies taking into account specific, local conditions.

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   Mapping techniques and hydrogeological models to characterise seawater intrusion in french coastal aquifers and asses the potential impact of sea-level rise
Coastal aquifers contain large quantities of groundwater essential for both human activities (drinking water, farming, industry and tourism) and for the environment (littoralwetlands, coastalmarshes and lagoons fed by coastal groundwater). Along the 5 500 kilometres of coastline in continental France, 95 superficial and 17 deep coastal aquifers have been identified. In the islands (French overseas territories), aquifers are generally all coastal. Partial intrusion of seawater into coastal aquifers is a natural phenomenon. The degree and range are variable and depend on the geologic features of the underground reservoirs. Intrusion may be amplified by pumping of freshwater and/or by a modification in the sea level, for example in response to climate change (Werner and Simmons, 2009). Natural seawater intrusion, whether coupled with an anthropogenic influence or not, risks contaminating the freshwater contained in the underground reservoirs. This document presents, via examples, a number of tools that can be used to qualify seawater intrusion and the potential impact of a sea-level rise on salinity levels in coastal aquifers.
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   Improving control over nutrients by restoring river hydromorphology
Increasing quantities of nutrients in rivers have led in many cases to significant eutrophication of environments. This complex process affects all ecosystem compartments via physical, chemical and biological disturbances and, more generally, it affects the use value of aquatic environments. The operation of hydrosystems contributes to regulating various ecological processes, including physical (water storage in floodplains, aquifer recharging and mitigation of low flows by wetlands), chemical and biological processes. Scientific research on the relations between hydromorphology and nutrient-transformation processes has increased over the past few years. This review of the literature presents the most noteworthy aspects of current knowledge and a number of examples.
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   Observed trends in river flow rates in France
On the whole, water resources in France are sufficient, however, there are significant differences between regions and times of year. Local shortages have increasingly led to restrictive measures on water usage. Why do water shortages occur? Are water resources in fact becoming more rare? Is this situation linked to excessive human usage or climate change? This document studies the fluctuations in water resources caused by climate factors in order to answer these questions. It presents the changes over the last 40 years in the hydrological regimes (high, mean and low flows) of rivers considered undisturbed or only slightly disturbed by human activities in continental France as well as in the overseas territories. The study is based on data from a selection of hydrometric stations in the French national network that is outstanding and of the upmost value due to its size and age.
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   River hydromorphology
A primer, written by Jean-René Malavoi and Jean-Paul Bravard in a very clear and instructive style, reveals the extraordinary complexity of the phenomena involved in "making" a river. The authors introduce us to river hydromorphology, a scientific discipline that has come of age, and explain the geomorphological characteristics of rivers, from the riverbed itself to the floodplain, that create the major types of habitat on which aquatic and terrestrial species depend. In the process, it becomes clear that the good ecological operation of rivers and their corridors depends on maintaining and restoring the natural geodynamic processes and the resulting geomorphological characteristics.
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   Assessing the ecological services of aquatic environments. Scientific, political and operational issues
In a context of climate change and biodiversity loss, the notion of ecological services has rapidly gained ground in political debates. The goal of good ecological status, set by the European water framework directive in 2000, has led to major efforts to preserve and restore aquatic environments. The ecological services provided by aquatic environments are now a topic of growing interest to water managers and, more generally, to all stakeholders in society interested in the quality and sustainable management of aquatic environments.
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The purpose of the national framework for water data (SNDE) is to improve the organisation of the water information system for France (WIS-F) on the national level. It was approved on 26 July 2010 by a national decree. The framework organises the various participants in WIS-F and structures its work.

Salmon are migratory fish that serve as indicators of river quality. Their current situation is not good. On the Dordogne river, the second river basin in France in terms of hydroelectric generation, local stakeholders have made major efforts in favour of salmon for 20 years, including releases of juveniles, population surveys and monitoring, modifications to obstacles in rivers, reductions in hydropeaking, etc.

Over the years, water stakeholders have produced vast quantities of data on water resources and aquatic environments. In France, public authorities have attempted to organise the sharing of the data, resulting in the progressive establishment of the French water information system (WIS-F). This complex, partnership-based system organises the production, collection, storage, use and dissemination of the data. The WIS-F is coordinated by Onema under the responsibility of the Ecology ministry.

 

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