| Résumé: |
The 16th of June 1818 saw the break up of the ice cone of the Giétro glacier causing an outburst flood (GLOFs) with about 20 million m3 of water and which ravaged the Bagnes valley (Switzerland). Besides the catastrophic consequences for the population and the economy of the valley, the flood also caused major impacts on the landscape. Considered today as testimony to the Giétro tragedy, these geomorphological features, under the heading “palaeoevidence”, can be interpreted via the use of palaeohydrology and palaeohydraulics in order to reconstruct the characteristics of the historical flood. This mémoire uses palaeohydrological and palaeohydraulic investigations in order (1) to reconstruct the spatial extension of the Giétro outburst flood, (2) to estimate the uncertainties related to the approach and (3) to evaluate the potential of paleohydrology and palaeohydraulics in the reconstruction of past flood events. The research develops a framework for estimating the water depths and velocities reached by the flood via the interpretation of the palaeoevidence identified in the field. The resulting water stages are then mapped in order to reconstruct the spatial extension of the outburst flood. On a more extensive level, this research stress importance of a multidisciplinary approach in order to obtain more comprehensive investigations about natural disasters but also reveals the complex character of data combination and sharing. The results show that, despite palaeohydrology and palaeohydraulics being a suitable approach for the reconstruction of past outburst flood, they need to be combined with other disciplines in order to give satisfactory outcomes and reduce uncertainties. The users of such data need to work more closely with the producers of such data if data misinterpretation is to be avoided.
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