National inventory of river and sea dykes - the state of advancement of the operation, primary results and perspectives

Abstract

In 1999, the French Minister of the Environment issued a national inventory of river and sea dykes using the software database "DYKES". The tragic floods of September 2002 in the Gard confirmed the importance of this inventory operation which aims to evaluate the issues involving the safety of dykes protecting flooded areas. After recalling the characteristic principals of the operation, the present article outlines its state of advancement and the primary extrapolations that can be made, displaying in detail the obtained results for the river and sea dykes of the Aquitaine region and, finally, describing the perspectives for the continuation of the inventory. At the end of 2002, the inventory had been completed for four administrative regions (Alsace, Aquitaine, Haute-Normandie and Nord Pas-de-Calais). A rough extrapolation of the results allows the primary estimation of the magnitude of national park of dykes (between 7 500 and 12 000 km of work) and confirms the spectacular amount and diversity of managers, who number about a thousand. Choose for example the Aquitaine region, counting some 840 km of dykes, spread out for the most part between Garonne, Dordogne and Adour rivers, and the Estuary of Gironde. More than two thirds of these dykes raise concern, often because their real state is unknown or their management is not identifiable. A new version, accessible via the Internet, of the database DYKES has just been completed. It must allow to finish the inventory of work under the best conditions so as to indentify the dykes that need reinforcement most urgently.