The Tidal Garden concept: Numerical modelling of tidal stream turbines in channels for optimal energy extraction

Water Qualit

Restauration morpho-dynamique et redynamisation de la section court-circuitée du Rhin en aval du barrage de Kembs (projet INTERREG / EDF)

National audienceThe Upper Rhine River has been heavily impacted by channelization for flood protection and navigation, and then by damming for hydropower generation. In normal non flooding conditions, most of the flows are diverted in a canalized section whereas the regulated “old Rhine” bypassed reach runs a minimum flow. Between Huningue and Neuf-Brisach, engineering works induced simplification and stabilization of the channel pattern from a formerly braiding sector to a single incised channel, hydrological modifications, bottom armouring due to bedload decrease, and thus ecological alterations. Two complementary and interdisciplinary projects have been initiated to restore alluvial morphodynamics: i) the international “INTERREG IV - Redynamisation of the old Rhine” project (2009-2012) coordinated by the Alsace region, France; ii) the left bank “controlled erosion” project launched by Electricité de France (EDF) within Kembs hydroelectric station relicensing process since 2003-2004. The purpose of these projects is to evaluate the feasibility of an important hydro-morphological and ecological restoration plan on a 45 km long reach, through both field testing of bank erosion techniques at favourable locations, and artificial sediments input from right bank excavations. This will help define possible long term prospective scenarios, in order to restore sustainable sediment transport, morphodynamics variability and associated ecological functions. The study will involve historical analysis, hydro-morphological / hydraulic physical and numerical modelling, physical and ecological monitoring, and sociological aspectsLe Rhin alsacien-allemand a enregistré de profondes modifications morphologiques et hydrologiques à la suite de sa correction et de sa régularisation pour la protection contre les crues et la navigation, puis après la construction de barrages hydro-électriques. Les aménagements réalisés entre Huningue et Neuf-Brisach ont engendré une simplification et une stabilisation du style fluvial. Un fleuve en tresses a cédé la place à un chenal unique incisé. Le fond de chenal est devenu pavé à cause d’une diminution des apports de charge de fond et des altérations écologiques ont été observées (simplification des habitats aquatiques et riverains). Deux projets complémentaires et interdisciplinaires ont été engagés afin de restaurer une dynamique des formes alluviales : i) le projet international INTERREG IV – Redynamisation du Vieux Rhin (2009-2012) sous l’impulsion de la région Alsace ; ii) le projet d’érosion maitrisée des berges de la rive gauche conduit par Electricité de France (EDF) dans le cadre du renouvellement de la concession de l’aménagement de Kembs. L’objectif des deux projets est de définir un plan de restauration hydro-morphologique et écologique conduisant à la redynamisation d’un tronçon de 45 km. L’étude repose sur une analyse historique, l’exploitation de modèles à la fois physiques et numériques, et les suivis morphologiques in situ d’une recharge artificielle en sédiments et d’érosions de berge contrôlées. Ces études de faisabilité sont complétées par des analyses écologique et sociologique pour apprécier l’impact socio-environnemental de ces projets

Infinitive Wh-relatives in romance : consequences for the truncation-versus-intervention debate

Romance clitic left dislocation is widespread across all kinds of nonroot contexts, but it is forbidden in infinitive wh-relatives. This article investigates the extent and nature of this restriction and the consequences it raises for the truncation and intervention analyses of the left periphery of embedded sentences. We will show that current proposals cannot account for the whole gamut of data. In consequence, we will propose that infinitive wh-relatives display a maximally syncretic left periphery, whereas infinitive wh-interrogatives have a full-fledged left periphery, crucially involving ForceP, because they are selected by a higher predicate. This crucial difference between infinitive relatives and interrogatives will also be shown to be consistent with the existence of specialized complementizers for the former but not the latte

‘Fourth places’: the Contemporary Public Settings for Informal Social Interaction among Strangers.

This paper introduces ‘fourth places’ as an additional category of informal social settings alongside ‘third places’ (Oldenburg 1989). Through extensive empirical fieldwork on where and how social interaction among strangers occurs in the public and semi-public spaces of a contemporary masterplanned neighbourhood, this paper reveals that ‘fourth places’ are closely related to ‘third places’ in terms of social and behavioural characteristics, involving a radical departure from the routines of home and work, inclusivity, and social comfort. However, the activities, users, locations and spatial conditions that support them are very different. They are characterized by ‘in-betweenness’ in terms of spaces, activities, time and management, as well as a great sense of publicness. This paper will demonstrate that the latter conditions are effective in breaking the ‘placelessness’ and ‘fortress’ designs of newly designed urban public spaces and that, by doing so, they make ‘fourth places’ sociologically more open in order to bring strangers together. The recognition of these findings problematizes well-established urban design theories and redefines several spatial concepts for designing public space. Ultimately, the findings also bring optimism to urban design practice, offering new insights into how to design more lively and inclusive public spaces. Keywords: ‘Fourth places’, Informal Public Social Settings, Social Interaction, Strangers, Public Space Design

Conviviality by design : the socio-spatial qualities of spaces of intercultural urban encounters

This paper presents findings from a mixed-method research project which explored use of outdoor spaces and social connections in Bradford, a post-industrial city in the north of England with a highly ethnically diverse population. Data was collected through micro-scale behavioural mapping of public spaces (analysed using GIS) and both on-site and in-depth interviews. The integration of these methods allows a focus on intersectional identities and social values for everyday conviviality situated in different typologies of public open spaces (parks, squares, streets) in city centre and suburban neighbourhoods. The analysis offers nuanced insights into the socio-spatial aspects of conviviality: patterns of activity by diverse users, situations in which encounters are prompted, and the implications of negotiating differences in relation to perceptions of self, others, and the environment. We discuss the relevance of the urban public realm for shared understandings of diversity, qualities of visibility, lingering and playfulness, and the importance of threshold spaces. We explore racialised and excluding experiences and how these relate to mobility and territorial patterns of use, specifically with relation to gender. The paper highlights connections between intercultural encounters and urban design practice, with implications for well-being and integration in ethnically diverse urban areas

Physical model experiments for sediment supply to the old Rhine through induced bank erosion

International audienceA mobile-bed, undistorted physical model (1: 40) has been used to investigate different sediment supply strategies to the Old Rhine through bank protection removal and modifications of groyne dimensions and configuration, which cause bank erosion. This trained channel was previously the main bed of the upper Rhine downstream of Basel (Switzerland), but it has an artificially low flow regime since the construction of the Grand Canal d'Alsace, a navigation canal, and a flow control dam at Kembs (France). Training works and subsequent channel incision have also greatly reduced sediment transport rates and created a heavily armoured bed. The modelled pilot site has a groyne field on the left bank. Results show that the currently existing groynes at the site are not effective in creating high bank-side velocities conducive to bank erosion, even for flow rates significantly higher than the mean annual flow rate. The river bank has also proved to be more resistant than previously thought, allowing long stretches of bank protection to be safely removed. The physical model testing process has produced a new configuration for the groyne field, where two higher, larger island groynes are placed further apart than the three existing attached groynes. This innovative approach has proved effective, causing bank erosion for flow rates below the mean annual flow rate, with consistent erosion being observed. It has also been found that such a configuration does not pose a hazard for the Grand Canal d'Alsace, which is situated next to the Old Rhine, through excessive bank erosion during high flow events

Dimensionnement des évacuateurs de crue de barrage par les dommages incrémentaux ou différentiels. Recommandations provisoires

At the end of 2013, the French Committee on Dams and Reservoirs (CFBR or French-COLD) launched a new Working Group (WG) with the objective of developing an incremental damage-based analysis framework for the safe design of dam spillways in France, and testing the method on real-life cases if possible. Present guidelines gather the results of this WG through the proposition of recommendations and methodological steps. The method is based on the comparison between two dam spillway design configurations (D0 : present design ; D_reg : updated design in compliance with new criteria), and on differential accounting of damages between these two design conditions, covering the full range of flood occurrence probability. The main steps of the methods are described, with an emphasis on the use of pre-existing guidelines and state-of-the-art practice, specifically on cost-benefit analysis approaches in a safety context. Three pilot case studies have been performed to test the applicability of the method, and the conclusions are drawn in the present guide as well. Some possible acceptability / tolerability criteria have been advanced, that would reflect the balance or unbalance between spillway upgrade investment costs on one hand, versus real gain on safety conditions on the other hand. The profession is invited to practice and use these guidelines, and to test the method on other real-life case studies. CFBR plans to get lessons learned from an extended practice, before issuing an update of the present guidelines in a revised version in the next few years.Fin 2013, le Comité Français des Barrages et Réservoirs (CFBR) a lancé un nouveau Groupe de Travail (GT) avec pour objectif de développer et, si possible, tester une méthode transposant le concept des « dommages incrémentaux » dans le contexte Français pour le dimensionnement ou la vérification des évacuateurs de crue de barrages. Le présent guide de recommandations constitue la proposition méthodologique traduisant concrètement cet objectif. La méthode repose sur la comparaison de deux situations de dimensionnement (D0 : dimensionnement actuel ; D_reg : dimensionnement de mise en conformité à des critères de référence), et sur le comptage différentiel, intégré sur l'échelle de probabilité, des dommages entre ces deux situations. Cela a conduit le CFBR à introduire le vocable de dommages « différentiels » pour décrire cette méthode. Les principales étapes méthodologiques sont décrites, en insistant sur la référence à des guides, référentiels ou pratiques déjà existants, notamment en matière d'analyses coûts-bénéfices et d'évaluation de la proportionnalité des coûts. Trois études pilotes ont permis de tester les options méthodologiques et d'en démontrer le caractère opératoire. Les bases de possibles critères d'acceptabilité, permettant de démontrer le caractère proportionné ou disproportionné d'un investissement au regard du gain en sûreté réellement apporté, sont posées. La profession est invitée à s'approprier, tester et éprouver ces recommandations sur d'autres cas d'application. Le CFBR prévoit dans quelques années (3 à 4 ans), et sur la base du retour d'expériences et de la pratique de la profession, de transformer ce guide en recommandations définitives