Editorial

The 11th National Symposium on Coastal and Civil Engineering (Journées Nationales Génie Côtier – Génie Civil; JNGCGC), with foreign participation, was held in Sables d’Olonne in the south of Nantes (France) on 22–25 June 2010, planned by the Centre Français du Littoral (CFL) association.

This conference follows up the preceding JNGCGC National Symposium, whose objectives are up-to-date knowledge acquisition in coastal and civil engineering, and presentation of new materials, techniques and documents (in exhibition stands), allowing exchange of ideas between specialists, researchers and experts in coastal engineering. In addition academic information is diffused on pedagogical activities, research and training in both undergraduate and postgraduate coastal and civil engineering in relation with the industrial activities and developments. Actors in the field of coastal engineering, with diverse competences, understand the value of this conference: a place of exchanges, debates and future collaborations. The utility of the conference is demonstrated by the number and the quality of both the French and foreign contributions.

The European Journal of Environmental and Civil Engineering therefore devotes a sixth special issue to the best contributions of the conference, respecting the diversity of the proposed themes, and thus confirming the multi-field character of coastal engineering. This volume gathers together the communications selected during the conference by a scientific committee, with the opinion of the reading panel and referring to the comments of two experts. Their authors agreed to extend and complete their contributions in more detail. Like the conference, this special issue examines the five following topics:

•	sedimentary dynamics and transport of particles;
•	sustainable management of sediments;
•	coastal, harbour and offshore works and structure design;
•	coastline vulnerability; and
•	coastal hydrodynamics.

The first theme gave rise to many communications at the conference. These deal with problems concerning the movement and/or stability of sedimentary zones, using observational methods, experimental measurements and/or numerical simulations. The only selected paper relates to simultaneous and very detailed measurements of velocity profiles, sediment concentration, pore pressure and sheet flow layer dynamics, which are analysed in order to better assess the relative importance of the processes that lead to bed destabilisation in both the laboratory and in the field. The originality of this work, by Berni, Michallet, and Barthélemy (2012) consists mainly in the implementation of combined and updated experimental techniques in the field of sedimentary transport (Acoustic Doppler Velocity Profiler [ADVP] and optical fibres), allowing access to an extremely fine description of the boundary layer and suspended materials, e.g. the thickness of the layer of sheet flow.

Two communications were selected for the second topic. As for the sustainable marine sediments management, this imposes a storage on ground of the non-or contaminated sediments and requires the development of processes of treatment and of reuse. The first paper, written by Limeira, Agulló, and Exteberria (2012), discusses a very important topic, which is the problem of dredged sediments. This work deals with the study of dredged marine sand from the Port of Sant Carles de la Ràpita (Tarragona, Spain) as construction material. The methodology is described in detail. The results presented are interesting and have led to a pilot study carried out with harbour concrete pavements produced at an industrial scale. Finally the authors prove that a beneficial use of dredged marine sand in construction material is possible when it is incorporated into concrete as granular corrector. The second contribution by Obana, Levacher, and Dhervilly (2012) concerns the Mont-Saint-Michel project to restore the maritime characteristics that existed before 1995. Attempts have been made to reuse excavated marine sediments, e.g. in the construction of pavements and driveways. The authors propose an experimental methodology and provide interesting findings in relation to possible alternatives for the use of sediments analysed in pavements and roads. A new approach to sediment stabilisation is proposed by using pozzolan and alkali-activated binders.

The design of marine structures is often compromised due to the lack of prediction methods for wave–structure interactions. The paper, by Oumeraci, Staal, Pförtner, and Ludwigs (2012), related to the third theme is dedicated to large-scale innovative experimentations in the Large Wave Flume (GWK) of Hanover/Germany. Tests are run on polyurethane bonded aggregate (PBA) coatings, which are highly porous and sustainable structures made with crushed stones and elastically bonded by polyurethane (PU). The major contribution is to improve the understanding of the processes involved in the interaction between wave, coating and foundation and to develop the missing design formulae for a broad range of wave conditions.

Extreme events occur and can cause damage to coastlines. For example, during the night of 27–28 February 2010, Cyclone Xynthia crossed France and damaged part of the Atlantic coast. The paper of Pineau-Guillou, Lathuiliere, Magne, Louazel, Corman, and Perherin (2012) has been chosen for its pertinent analysis of the recordings of the buoys of the French Hydrographical and Oceanographic Service (SHOM, Brest, France) and for the quality of the associated digital processing. Sea level return periods during the storm along the Atlantic and Channel French coasts are estimated using sea level measurement analysis and statistically computed extreme sea levels. Numerical simulation (WAVEWATCH III and HYCOM) are performed to model surges in La Rochelle, from 20 February to 1 March, and compared with observed surges in La Rochelle during the same period in order to evaluate their accuracy.

As noted above, observation remains an important asset for validating and developing models, and this requires on-site measurements. This is relevant to all topics in coastal engineering. The final paper (by Teles, Pires-Silva, & Belo-Pereira (2012)) in coastal hydrodynamics confirms this point. The SWAN model is used to estimate the wave field on an open sandy beach on the west coast of Portugal, considering different parameters and their effects. Wave measurements were taken during a stormy period and are used to model comparisons. The results improve the knowledge on the appropriate settings for the SWAN model. From this combination of numerical and site data, practical conclusions are drawn which may be useful for users of wave models, and in coastal hydrodynamics and coastal engineering.

Reading this special issue reveals the breadth of scientific knowledge necessary to solve the complex problems in coastal engineering; and from this, the significance of the term coastal engineering. In addition, the necessity of integrated coastal zone management is demonstrated. Other concepts related to the human, economic, political and legal aspects are fundamental. Difficulties remain but the importance of the results presented in the different contributions justifies the gathering, every two years, in a JNGCGC conference, of the various actors in coastal engineering. Warm thanks are due to the scientific and reading committees, as well as to the Chairmen of each topic who have, from their high quality work, contributed to the high scientific and technical level of this Symposium.