Lessons from the autumn 2014 flash floods in the city of Nîmes and its neighborhood (France): behavior of several mitigation dams and hydrological analysis

Testo completo

(1)E3S Web of Conferences 7, 16002 (2016) FLOODrisk 2016 - 3rd European Conference on Flood Risk Management. DOI: 10.1051/ e3sconf/2016 0716002. Lessons from the autumn 2014 flash floods in the city of Nîmes and its neighborhood (France): behavior of several mitigation dams and hydrological analysis 1,a. 1. 2. 3. Catherine Fouchier , Patrice Mériaux , Guillaume Pla2, Jean-Luc Nuel , Etienne Retailleau , Paul Royet. 1. 1.

(2) -en-Provence Cedex 5, France City of Nîmes, 152 avenue Robert Bompard, 30000 Nîmes, France 3 Gardon rivers SMAGE, 6 avenue du Général Leclerc, 30000 Nîmes, France 2. Abstract. The Languedoc area, in Southern France, is prone to autumnal flash floods which are characteristic of the Mediterranean climate. To cope with this threat, the local authorities have chosen to build several dams on the main dangerous rivers of the area. We have focused on the flood mitigation facilities of two operators: the City of Nîmes and the Gardons Rivers Managing authority. After the catastrophic flash flood of October 1988, the city of Nîmes built flood mitigation dams on many of its high-risk streams. These flood barriers worked several times during the intense rainfalls of autumn 2014. The on-site conclusions drawn from these floods and the computation carried out with hydrological models confirmed how well the dams functioned. In 2010, the Gardons Rivers Managing authority built a flood mitigation dam on the Esquielle River to protect the village of Saint-Geniès-de-Malgoirès. The spillway of this dam worked for the first time in the autumn of 2014. We analyzed one of the major floods monitored on that occasion at its outlet. The goals of this study are: (i) to evaluate dams efficiency and (ii) to test, on a catchment which was not used for its calibration, the AIGA flash flood warning method, which was developed by IRSTEA.. 1 Introduction

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