Articles | Volume 18, issue 9
Hydrol. Earth Syst. Sci., 18, 3733–3761, 2014

Special issue: Hydrological cycle in the Mediterranean (ACP/AMT/GMD/HESS/NHESS/OS...

Hydrol. Earth Syst. Sci., 18, 3733–3761, 2014

Research article 26 Sep 2014

Research article | 26 Sep 2014

Multi-scale hydrometeorological observation and modelling for flash flood understanding

I. Braud1, P.-A. Ayral2,3, C. Bouvier4, F. Branger1, G. Delrieu5, J. Le Coz1, G. Nord5, J.-P. Vandervaere5, S. Anquetin5, M. Adamovic1, J. Andrieu6, C. Batiot4, B. Boudevillain5, P. Brunet4, J. Carreau4, A. Confoland5, J.-F. Didon-Lescot3, J.-M. Domergue3, J. Douvinet7, G. Dramais1, R. Freydier4, S. Gérard5, J. Huza1,8, E. Leblois1, O. Le Bourgeois4, R. Le Boursicaud1, P. Marchand4, P. Martin7, L. Nottale9, N. Patris4, B. Renard1, J.-L. Seidel4, J.-D. Taupin4, O. Vannier5, B. Vincendon10, and A. Wijbrans5 I. Braud et al.
  • 1Irstea, UR HHLY, Hydrology-Hydraulics, Villeurbanne, France
  • 2Ecole des Mines d'Alès, Alès, France
  • 3ESPACE, UMR 7300 CNRS, "Antenne Cevenole", Université de Nice-Sophia-Antipolis, Université d'Avignon et des Pays de Vaucluse, France
  • 4Hydrosciences, UMR 5569 CNRS, IRD, Université de Montpellier II, Montpellier, France
  • 5LTHE, UMR 5564 CNRS, IRD, Université de Grenoble, Grenoble, France
  • 6ESPACE, UMR 7300 CNRS, Université de Nice, Nice, France
  • 7ESPACE, UMR 7300 CNRS, Université d'Avignon et du Pays de Vaucluse, Avignon, France
  • 8Centre for Water and Climate, Wageningen University, Wageningen, the Netherlands
  • 9Observatoire de Paris-Meudon, CNRS LUTH et Université de Paris Diderot, Meudon, France
  • 10CNRM-GAME, UMR 3589, Météo-France et CNRS, Toulouse, France

Abstract. This paper presents a coupled observation and modelling strategy aiming at improving the understanding of processes triggering flash floods. This strategy is illustrated for the Mediterranean area using two French catchments (Gard and Ardèche) larger than 2000 km2. The approach is based on the monitoring of nested spatial scales: (1) the hillslope scale, where processes influencing the runoff generation and its concentration can be tackled; (2) the small to medium catchment scale (1–100 km2), where the impact of the network structure and of the spatial variability of rainfall, landscape and initial soil moisture can be quantified; (3) the larger scale (100–1000 km2), where the river routing and flooding processes become important. These observations are part of the HyMeX (HYdrological cycle in the Mediterranean EXperiment) enhanced observation period (EOP), which will last 4 years (2012–2015). In terms of hydrological modelling, the objective is to set up regional-scale models, while addressing small and generally ungauged catchments, which represent the scale of interest for flood risk assessment. Top-down and bottom-up approaches are combined and the models are used as "hypothesis testing" tools by coupling model development with data analyses in order to incrementally evaluate the validity of model hypotheses. The paper first presents the rationale behind the experimental set-up and the instrumentation itself. Second, we discuss the associated modelling strategy. Results illustrate the potential of the approach in advancing our understanding of flash flood processes on various scales.