Comparative hazard analysis of processes leading to remarkable flash floods (France, 1930–1999)

Abstract

Article history: Available online xxxx Keywords: Historical hydrology Multidisciplinary approach Flash flood Remarkable flood Comparative analysis Cascade effects u m m a r y Flash flood events are responsible for large economic losses and lead to fatalities every year in France. This is especially the case in the Mediterranean and oversea territories/departments of France, characterized by extreme hydro-climatological features and with a large part of the population exposed to flood risks. The recurrence of remarkable flash flood events, associated with high hazard intensity, significant damage and socio-political consequences, therefore raises several issues for authorities and risk management policies. This study aims to improve our understanding of the hazard analysis process in the case of four remarkable flood eventsFirstly, we present the methodology used to define the remarkability score of a flood event. Then, to identify the factors leading to a remarkable flood event, we explore the main parameters of the hazard analysis process, such as the meteorological triggering conditions, the return period of the rainfall and peak discharge, as well as some additional factors (initial catchment state, flood chronology, cascade effects, etc.). The results contribute to understanding the complexity of the processes leading to flood hazard and highlight the importance for risk managers of taking additional factors into account.

Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

“…While stratiform rainfall plays an important role moistening the entire basin, convective rainfall generates considerable runoff, leading to flash flooding. Several authors have argued about the role of convective rainfall triggering flash floods (Doswell et al, 1996;Kahana et al, 2002;Schumacher and Johnson, 2005;Delrieu et al, 2005;Šálek et al, 2006;Milelli et al, 2006;Rozalis et al, 2010;Fragoso et al, 2012;Berne and Krajewski, 2013;Gochis et al, 2015;Bruni et al, 2015;Piper et al, 2016;Douinot et al, 2016;Llasat et al, 2016;Baltaci, 2017); however, to our knowledge no other study has tracked convective and stratiform water in a modeling setting to explore their relative role leading to flash flooding.…”

Detection and attribution of flood trends in Mediterranean basins

“…Nonetheless, the evolution of flood frequency and intensity is a key question for risk prevention. Flood-related mortality in the Mediterranean basin is conditioned both by hazard drivers (e.g., rainfall intensity, discharge) but also by social drivers (e.g., behaviors, characteristics of buildings) as shown in different studies (Ruin et al, 2008;Vinet, 2011;Boudou et al, 2016). Deeper knowledge in rainfall and flood trends must be crossed with exposure (e.g., population in flood prone zones) and vulnerability data (e.g., eldering of population in the future) to anticipate evolution in human mortality in relation to flash floods in the Mediterranean basin (Petrucci et al, 2019).…”

Detection and attribution of flood trends in mediterranean bassins

“…Nonetheless, the evolution of flood frequency and intensity is a key question for risk prevention. Flood related mortality in the Mediterranean basin is conditioned both by hazards drivers (rainfall intensity, discharge…) but also by social drivers (behaviors, characteristics of buildings…) as shown in different studies (Ruin et al, 2008, Vinet, 2011, Boudou et al, 2016. Deeper knowledge in rainfall and flood trends must be crossed with exposure (e.g.…”