Le barrage de la Manzo (Antilles - France) est un ouvrage en remblai d’enrochements, de 27 m de hauteur, permettant le stockage de 8 Mm3 d’eau. Depuis 1980, il remédie au manque d’eau durant la saison sèche et permet essentiellement l’irrigation des terres du sud-est de la Martinique. Ainsi, il répond aux enjeux territoriaux majeurs de soutien d’une agriculture compétitive et de maintien de l’emploi. Au fil des années, la structure s’est intégrée au paysage des communes de Ducos, François et Saint-Esprit. L’article analyse la résilience et la capacité d’adaptation de l’ouvrage vis-à-vis de l’évolution des usages et du changement climatique à partir de l’année 2000. Les aléas naturels intenses (tempêtes, sécheresses, séismes), l’évolution des usages et les préoccupations relatives au réchauffement climatique exigent une plus grande résilience hydrologique. La Collectivité Territoriale de Martinique, en tant qu’exploitant du barrage se doit d’anticiper ces questions pour garantir des services de manière durable et économique tout en minimisant les impacts socio-environnementaux.
No abstract is provided for this article.
No abstract is provided for this article.
Les retenues d'altitude sont des ouvrages hydrauliques implantes dans les stations de loisirs de montagne destines a creer une reserve d’eau pour la production de neige de culture, d’eau potable, pour l’irrigation, etc. En raison de l’implantation de ces retenues, les difficultes techniques, reglementaires, environnementales et liees a la securite publique sont nombreuses et specifiques. Ce livre, veritable manuel integre, etablit les regles en matiere de conception, de realisation et de surveillance. Il repond aux questions d’evaluation des sites, d’analyse des aleas naturels et technologiques et d’etude d’onde de submersion. Enfin, il propose des elements d’aide a la decision pour les maitres d’ouvrage et leurs bureaux conseils quant a l’organisation d’un tel projet.
This paper reviews Cemagref (Centre national du machinisme agricole, du génie rural, des eaux et des forêts) research on assessment of hydraulic works, especially on their performance and safety. A generic functional model has been developed, using reliability methods, to represent the various mecanisms acting on different hydraulic works (gravity and embankment dams, fluvial dikes, etc.). Collecting and analyzing data on the failure of these works allowed us to define structural indicators and the rules for their assessment. Performance indicators for hydraulic works were created through multicriteria aggregation methods; various results were thus obtained. A database of knowledge relating to mechanisms and histories of dam ageing has been produced and constitutes a useful aid for consulting civil engineers. Methods and tools have been developed to assess the performance of fluvial dikes and to assist managers in planning maintenance operations. Similar research is under way on embankment dams and will provide a diagnosis tool for hydraulic works in operation.
RESUME – L'article presente a travers le recent guide de recommandations Retenues d’altitude la synthese d'un retour d’experience sur le comportement et la pathologie des dispositifs d’etancheite par geomembrane en altitude. Il donne les recommandations fortes du guide relatives a ces dispositifs, en particulier sur la structure support, le drainage inherent au DEG et la structure de recouvrement. Un descriptif general du guide termine l'article. Mots-cles : Retenues, altitude, etancheite, geomembrane, recommandations
. The experience feedback on a crisis that hit a city is frequently used as a "recollection" tool. To capitalize information about an experience feedback from the cities that have been affected by a natural hazard, the authors propose in this study a functional model to model scenarios of city crises. In this model, the city, considered as a complex system, was modelled using a functional analysis method. Based on such modelling, two risk analysis methods (Failure Mode and Effect Analysis and Event Tree Method) were deployed and adjusted. Lastly, a qualitative reasoning model was used for the scenario modelling of the urban crisis. By functional modelling performed on components of the cities, the objective of this model is to replicate the behaviour of a city affected by a crisis, highlighting the sequences of failure and non-failure modes that have operated during the crisis. This model constitutes a means of understanding the functional behaviour in a crisis of cities and capitalization of the experience feedback of the cities affected by crisis. Such functional modelling was deployed in a case study.
This paper presents the Cemagref work in the field of diagnosis aid applied to dam ageing. The context is a portfolio of 250 dams under the supervisory of the environment ministry and involving public safety. These dams are characterised by a relative heterogeneity in their conception, age and management modes. First, the paper presents this dam portfolio. Our approach proposes to capitalise on feedback and expert knowledge, in order to improve dam diagnosis. Our work has started with computer researches, in order to model expert’s process of reasoning by dam ageing scenarios. We have produced a decision making aid system for dam ageing diagnosis. This system is able to manage historic and ageing scenario databases. Then, we have developed with LERMES/CUST a dam degradation model in order to build up the scenarios. Our methodology is based on functional modelling and FMEA method. Our main goal is to build up a dam ageing scenario database and to manage this database with the decision making tools.
No abstract is provided for this article.
reservoirs are hydraulic structures in ski resorts in the mountains, used to store water in general for snowmaking. There are more than one hundred of them in France, most of them less than 10 years of age. Despite their modest volumes (5,000 to 400,000 m3) and dam heights of between 5 and 20m, these structures do induce potentially high risks for people and property situated downstream from them. They are located at altitudes between 1,200 and 2,700m, and often face difficult topographical, geological and geotechnical conditions, mountain-specific hazards, a very limited period for construction in the year, considerable pressure from ice and intense cold, the difficulty of surveillance in winter, etc. A survey conducted on about 70 of these mountain reservoirs provided considerable information, particularly on the behaviour and pathologies of these small dams at high altitudes. These reservoirs are generally entirely sealed by geomembranes (85% of cases). This feedback on experience served as a basis for writing a set of guidelines on studying, designing, constructing, monitoring and rehabilitating these mountain reservoirs [4]. This guideline has been supported by the French ministry of environment and it has been prepared by a working group lead by the Cemagref and with the contribution of EDF and ISL. The article presents, through the guideline Mountain reservoirs, a summary of the feedback on the behaviour and pathology of mountain reservoirs. It gives a general description of the guideline [4], and emphasis on the main key themes: environmental impacts, risks specific to the mountain, design of embankments and drainage system, monitoring and operation, and those aspects of the underlying layer, drainage and cover layer of the GSS that appear to be essential for the system to behave correctly.
No abstract is provided for this article.
Depuis vingt ans, le développement des retenues d’altitude destinées au stockage de l’eau pour la production de neige de culture a été spectaculaire sur l’ensemble des massifs français, pour des raisons tant climatiques que commerciales.Exposées à des aléas naturels spécifiques au milieu montagnard comme les avalanches ou les débordements torrentiels, la conception et la gestion de ces retenues posent toutefois des problèmes de réglementation et de sécurité publique. Cet article propose des recommandations en matière de conception, de réalisation et de surveillance.
Gabions are a common construction material in the African Sahel and elsewhere, especially for spillways. Stepped gabion spillways are structurally stable, resistant to water loads, and efficient energy dissipators, but there are no clear design rules to date. One‐fifth‐scale model tests representing 3–5 m high standard prototypes discharging up to 3m3⋅s-1⋅m-1 enabled us to establish quantified energy‐dissipation criteria and efficient stilling‐basin design rules, saving 10–30% on basin length as compared with current methods. The different types of flow over the stepped face are also described and analyzed: isolated nappe flow, partial nappe flow, and skimming flow. From a technical point of view, stepped gabion spillways can withstand flows up to 3m3⋅s-1⋅m-1 without great damage, if setting of gabions complies faithfully with the code of practice. Some advice is given on preventing gabion deformation.
