Building a resilient system of defence against flooding from the Rhône

Abstract

The River Rhône in the south of France is susceptible to periodic flooding, leaving communities and vast areas of agricultural land inundated for significant periods of time. Efforts to control flooding in the lower Rhône valley have been undertaken since the middle of the nineteenth century, notably through the construction of levees and other flood defence and river management structures. These have subsequently been raised and widened following each major flood event, making their capacity to resist floods difficult to evaluate. Recent flood events have resulted in numerous breaches in the existing system of protection. The recent introduction of a global strategy for flood management in the lower Rhône catchment (Plan Rhône) includes for major infrastructure improvements to enhance the resilience of existing flood defences. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. This paper examines the application of the Plan Rhône since its release, presenting case studies and, where appropriate, the collaborative work undertaken by the main actors involved. Details of the different approaches undertaken to evaluate the risks associated with the levees are provided, together with proposed solutions to enhance the resilience of the global system of protection against a flood with a probability of exceedance of 10−3 (1 in 1000 year return period).