by Geoffroy Caude, High Council for environment and sustainable development(HCESD)-Ministry of transport-France -geoffroy.caude@developpement-durable.gouv.fr
Safety issues for hydraulic structures have been implemented with new rules since 2006 in France for all sorts of hydraulic structures (hydroelectricity dams, dams for water supply for agriculture, hydraulic structures for navigation purposes as well). For the navigable waterways they apply to most dams used for water supply in artificial waterways, for dykes and levees with special cases when those dykes are also useful for flood protection. To a lesser extent navigation dams crossing the rivers are also concerned but safety issues are not as high as for the water supply dams.
Recently in May 2016, major floods occurred in the middle reaches of the rivers Seine and Loire and their tributaries, such as the river Loing generating very high damages: the highway A10 was closed to the traffic for several weeks, which hadn’t happened since its building in the 1970s and the dykes of the canal de Briare failed.
After those events, Voies Navigables de France, public authority responsible for the main navigable waterways set up a large maintenance program of about 900 M€ concerning the whole navigable network.
Considering the fact that with limited financial resources priorization is needed to determine where the main risks are, our High Council was commissioned to help VNF in making the right choices.
Three key issues have to be addressed.
The first relates to the implementation of the safety regulations which tend to consider navigation dams as hydroelectricity dams and canal reaches as whole dams, where the risks may be different.
The second examines how to balance the three main safety issues which have to be considered: riverine people, waterways navigation users, waterways operation workers.
The third one is to determine the best way to deal with with aging canals from the 19th century where the freight traffic has disappeared and with very little recreational navigation as well.
The article will describe how the mission from HECSD suggested a new method and introduced recommendations to VNF in order to improve the management of those safety issues.