Flash flood prediction for ungauged catchments
Garambois Pierre-André
PhD student, surface hydrology HYDROECO group,
Fluid Mechanics Institute of Toulouse (IMFT), UMR CNRS/INP-UPS 5502
Allée du Professeur Camille SOULA
31400 TOULOUSE, FRANCE
Abstract:
Flash flood is a very intense and quick hydrologic response of a catchment to rainfall. This
phenomenon has a high spatial-temporal variability as its generating storm, often hitting small
catchments (few km²).
Data collected by (Gaume et al. 2009) about 500 flash floods over the last 50 years showed that
they could occur everywhere in Europe and more often in the Mediterranean regions, Alpine
regions and continental Europe. HYMEX project is about such extreme events occurring in the
Mediterranean region. It aims at a better understanding and quantification of the hydrological cycle
and related processes in the Mediterranean with emphasis on high-impact weather events.
Given the small spatial-temporal scales and high variability of flash floods, their prediction remains
a hard exercise as the necessary data are often scarce. Flash flood prediction on ungauged
catchments is one of the challenges of hydrological modelling as defined by (Sivapalan et al. 2003).
Several studies have been headed up with the MARINE model (Modélisation de l’Anticipation du
Ruissellement et des Inondations pour des évèNements Extrêmes) for the Gard region (France),
(Braud et al. 2010), (Castaings et al. 2009). This physically based spatially distributed rainfall
runoff model is dedicated to flash flood prediction. This study aims at finding a methodology for
flash flood prediction at ungauged locations in the Cévennes-Vivarais region in particular.
The regionalization method is based on multiple calibrations on gauged catchments in order to
extract model structures (model + parameter values) for each catchment. Several mathematical
methods (multiple regressions, transfer functions, krigging…) will then be tested to calculate a
regional parameter set.
The study also investigates the usability of additional hydrologic indices at different time scales to
constrain model predictions from parameters obtained using these indices, and this independently of
the model considered. These hydrologic indices gather information on hydrograph shape or
catchment dynamic for instance. Results explaining global catchments behaviour are expected that
way.
In a multi scale point of view, regional characteristics about catchments geomorphology or rainfall
fields’ statistics should provide useful insight to find pertinent hydrologic response indices. These
considerations with physically based distributed modelling may bring better understanding on flash
floods generating mechanisms and catchment responses.
References:
Braud I., Roux H., Anquetin S., Maubourguet M.-M., Manus C., Viallet P., Dartus D. The use of
distributed hydrological models for the Gard 2002 Flash-Flood event. Analysis of associated
hydrological processes. Journal of Hydrology, Flash Flood special issue, accepted for publication
Castaings W., Dartus D., Le Dimet F.-X., Saulnier G.-M. 2009 Sensitivity analysis and parameter
estimation for distributed hydrological modeling: potential of variational methods. /Hydrol. Earth
Syst. Sci. J1 - HESS/ 13 (4), 503-517.
Gaume, E., Bain, V., Bernardara, P., Newinger, O., Barbuc, M., Bateman, A., Blaskovicová, L.,
Blöschl, G., Borga, M., Dumitrescu, A., Daliakopoulos, I., Garcia, J., Irimescu, A., Kohnova, S.,
Koutroulis, A., Marchi, L., Matreata, S., Medina, V., Preciso, E., Sempere-Torres, D., Stancalie, G.,
Szolgay, J., Tsanis, I., Velasco, D., and Viglione, A. "A compilation of data on European flash
floods." Journal of Hydrology, Volume 367, Issues 1-2, 30 March 2009, Pages 70-78.
Sivapalan, M., Takeuchi, K., Franks, S. W., Gupta, V. K., Karambiri, H., Lakshmi, V., Liang, X.,
McDonnell, J. J., Mendiodo, E. M., O'Connell, P. E., Oki, T., Pomery, J. W., Schertzer, D.,
Uhlenbrook, S., and Zehe, E. (2003). "IAHS Decade on Prediction in Ungauged Basins (PUB),
2003–2012: Shaping an exciting future for the hydrological sciences." Hydrological Sciences
Journal/Journal des Sciences Hydrologiques, 48(6), 857-880.
Corresponding author:
Garambois Pierre-andré, garamboi@imft.fr
Tel : 33 (0) 5 61 28 59 24
Fax : 33 (0) 5 61 28 59 95
Preference: Poster