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More and more floods occurred over the last two decades causing important damages. Moreover, levees are often not well maintained, so they hardly resist to major floods and can break easily. At French national scale, the length of levees and the lack of data complicate their management. In this frame, levee managers need approaches and tools to be helped in their maintenance decision. First, we have developed a Levee Geographic Information System. This GIS application allows collecting data necessary for managing a levee portfolio. Secondly, we have developed a SDSS to assist levee managers in their prioritizing maintenance activities. This SDSS is using Operational Safety methods to assess levee performance along their length. The SDSS is aggregating performance indicators with a rule-based multi-criteria assignment method. All these tools and methods are operational and now used by levee managers in their regular infrastructure portfolio maintenance. RÉSUMÉ. On assiste ces dernières années à de nombreuses crues dévastatrices. Les digues de protection contre les inondations, souvent mal entretenues, se sont rompues à plusieurs reprises. En France, le manque de données sur l'ensemble du parc de digues complique leur gestion. Dans ce contexte, les gestionnaires locaux ont besoin de méthodes et d'outils pour les aider dans leurs opérations de maintenance. Nous avons d'abord développé un système d'information géographique spécifique aux digues permettant de collecter les données utilesà la gestion des ouvrages. Ensuite nous avons développé un SDSS pour prioriser les actions de maintenance. Ce SDSS utilise des méthodes de Recherche Opérationnelle pour évaluer la performance des digues. Le SDSS agrège des indicateurs de performance à l'aide d'une Downloaded by [Simon Fraser University] at 14:30 02 February 2015 348 Journal of Decision Systems. Volume 18 -No. 3/2009 méthode d'agrégation à base de règles. Ces outils et méthodes sont opérationnels et désormais utilisés par des gestionnaires de digues.

Deteriorating levees and recent well-publicised severe flood events have led to international concern about levee performance and failure. This has stimulated the production of the International Levee Handbook. A key starting point for the international authorship team was the acceptance that the issue of failure modes would pervade the entire handbook; a clear, concise and consistent classification and treatment of deterioration and damage mechanisms has therefore been developed with explanations of the ways these can link to generate breach scenarios. The ILH team has also established a relationship between levee form and function and the modes of failure that must be addressed to describe, design and manage a levee system. The team is currently developing methods for the analysis of these failure scenarios and their component mechanisms and the relation of these to the performance and reliability of the levee structure. When complete, the ILH will provide levee practitioners with a comprehensive and definitive guide which will facilitate sustainable design, construction and management practices.

Although hydraulic infrastructure such as levees remain important for flood risk management in the USA, France, and Quebec (Canada), there is increasing emphasis on nonstructural measures, such as regulatory flood maps, to reduce exposure and vulnerability, for example, preventing people from building in high hazard areas. One key concept related to areas protected by levees is that of “residual risk”, that is, the risk from floods greater than the design standard of the levees (levee overtopping) and from levee breach. In this article, we review the legislative framework for regulatory flood maps in the USA, France, and Quebec (Canada) and compare how residual risk behind protective structures is taken into account (or not) in regulatory flood maps. We find big differences in how the USA, France and Canada manage residual risk behind the levees. While in France the area behind levees is part of the regulatory flood prone area, and land use restrictions, building codes, emergency measures and risk communication are mandatory, in the USA the area behind levees is only shown as part of the regulatory flood prone area if the levee is not accredited. In Quebec, regulatory flood maps in general follow the French approach with a few exceptions.

The River Rhône in the south of France is susceptible to periodic flooding, leaving communities and vast areas of agricultural land inundated for significant periods of time. Efforts to control flooding in the lower Rhône valley have been undertaken since the middle of the nineteenth century, notably through the construction of levees and other flood defence and river management structures. These have subsequently been raised and widened following each major flood event, making their capacity to resist floods difficult to evaluate. Recent flood events have resulted in numerous breaches in the existing system of protection. The recent introduction of a global strategy for flood management in the lower Rhône catchment (Plan Rhône) includes for major infrastructure improvements to enhance the resilience of existing flood defences. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. Details of the different approaches undertaken to evaluate the risks associated with the levees are provided, together with proposed solutions to enhance the resilience of the global system of protection against a flood with a probability of exceedance of 10−3 (1 in 1000 year return period).

France and other regions around the world frequently undergo devastating flood events. Any failure of a flood protection structure can lead to human casualties and material damage. Unfortunately, such long linear structures are often poorly maintained and have shown repeated signs of weakness. Therefore, river levee management raises a number of substantial issues for the decision-makers responsible for ensuring maximum safety for the surrounding population at a reasonable management cost. The aim of the Digsure project is to provide levee managers with scientific methods and information technology (IT) tools for levee management. The Digsure method is a levee assessment method based on a probabilistic pattern. It produces levee performance indicators and integrates data and the uncertainty on results. Digsure is a geographic information system tool that implements the Digsure method. It estimates and displays levee performance and associated uncertainty intervals throughout levee assessments.

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Abstract. Risk Flood protection involves works which reduce the hydraulic hazard in protected areas in terms of frequency, duration, water level, water velocity or flood arrival time. These works are parts of protection systems. In this paper, we discuss and compare three structure-based solutions that contribute to flood protection but seem to oppose one another in the mind of general opinion: levees based protection systems, whose purpose is to prevent water from spreading in protected areas; diversion channels that aim to decrease the flow at their downstream; flood expansion areas, whose purpose is to temporary store water, reduce flood peak and spread flow duration. The article also deals with weirs which can be found in addition to dikes in the three types of solutions on which the paper focuses. For each type of these flood protection solutions, the paper describes their functions and limits, details how these solutions are similar, opposite or complementary, and in the end shows that they are globally complementary and not mutually exclusive. It also demonstrates the interest of a multi-scale analysis and of an integrated design and management of these arrangements, taking into account flood risk, morphological changes and associated environmental objectives.