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).

Levees, Diversion Canals or Flood Expansion Areas?

“…Rhône Plan, that was validated in 2006, poses the principle of protecting the most densely populated neighbourhoods, mainly in Arles, and to adjust the protection level between Tarascon and Arles, according to the flow capable of transiting through the Arles narrow river bed. To provide full protection against a 10 -3 yearly probability flood in the urban neighbourhoods of Arles, the Plan has defined a lower level of protection (though it is above the 10 -2 yearly probability flood) in neighbourhoods which have less at stake [8]. The municipality of Tarascon considered that protection offered in the Trébon area, which stretches on the left bank between Arles and Tarascon, is insufficient.…”

Is flood defense changing in nature? Shifts in the flood defense strategy in six European countries

“…The majority of the literature on flood defense consists of articles from fields such as civil engineering, geology, or physical geography and is essentially concerned with managing the hazard, the statistical analysis of the risk, or of the (non)robustness of infrastructure, etc. (Hu et al 2014, Cheetham et al 2015 From Alexander et al 2015, Ek et al 2015, Kaufmann et al 2015, Larrue et al 2015, Matczak et al 2015, Mees et al 2015. Veelen et al 2015).…”

Editorial

“…I believe we amply achieved this in this issue. With contributions from the USA (Deatrick, 2015), Thailand (Chinnarasri and Porkaew, 2015), The Netherlands (van Veelen et al, 2015), France (Balsells et al, 2015;Cheetham et al, 2015) as well as the UK (Connelly et al, 2015), this is also a truly international issue, demonstrating the wide-ranging topicality of flood resilience.van Veelen et al (2015) explore how flexible approaches to urban planning can help in coping with the long-term changes imposed by changing climates and increased urbanisation of waterfronts.They argue that methods such as the Adaptive Pathways (AP) (including the Adaptation Tipping Point concept) can contribute to more resilient urban waterfront development. Two areas of Rotterdam are presented as examples of application combining coastal and fluvial flood risk, where the AP was found to be an effective tool.…”

“…I believe we amply achieved this in this issue. With contributions from the USA (Deatrick, 2015), Thailand (Chinnarasri and Porkaew, 2015), The Netherlands (van Veelen et al, 2015), France (Balsells et al, 2015;Cheetham et al, 2015) as well as the UK (Connelly et al, 2015), this is also a truly international issue, demonstrating the wide-ranging topicality of flood resilience.…”

“…The authors suggest that harmonised European standards could help the route to market and encourage further innovation of these technologies. Cheetham et al (2015) take us to the Rhône River in southern France, which undergoes periodic flooding, leaving communities and vast areas of agricultural land inundated for significant periods of time. Levees and other flood-management structures have been constructed since the middle of the 19th century and were later raised and widened following flood events.…”