Assessment of flash floods taking into account climate change scenarios in the Llobregat River basin

M Velasco,P A Versini,A Cabello,A Barrera-Escoda

doi:10.5194/nhess-13-3145-2013

M Velasco, P A Versini + Show 2 more

Open Access

https://doi.org/10.5194/nhess-13-3145-2013

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Abstract

Abstract. Global change may imply important changes in the future occurrence and intensity of extreme events. Climate scenarios characterizing these plausible changes were previously obtained for the Llobregat River basin (NE Spain). This paper presents the implementation of these scenarios in the HBV (Hydrologiska Byråns Vattenbalansavdelning) hydrological model. Then, the expected changes in terms of flash flood occurrence and intensity are assessed for two different sub-basins: the Alt Llobregat and the Anoia (Llobregat River basin). The assessment of future flash floods has been done in terms of the intensity and occurrence of extreme events, using a peak over threshold (POT) analysis. For these two sub-basins, most of the simulated scenarios present an increase of the intensity of the peak discharge values. On the other hand, the future occurrence follows different trends in the two sub-basins: an increase is observed in Alt Llobregat but a decrease occurs in Anoia. Despite the uncertainties that appear in the whole process, the results obtained can shed some light on how future flash floods events may occur.

Highlights

Flash floods are caused by an intense rain event producing several hundreds of mm in a few hours (Collier, 2007; Younis et al, 2008; Versini, 2012)
Despite the uncertainties that appear in the whole process, the results obtained can shed some light on how future flash floods events may occur
A hydrological model has been used to study the future trends of flash floods

Summary

Introduction

Flash floods are caused by an intense rain event producing several hundreds of mm in a few hours (Collier, 2007; Younis et al, 2008; Versini, 2012). Such events typically occur in quick response basins characterized by (i) the small size of the catchments (under few hundreds km2), and (ii) flood flows that are essentially composed of surface runoff water or at least fast responding runoff processes (Creutin et al, 2009). In Marchi et al (2010), the response times of several European flash flood events were studied. The magnitude of European flash floods is more extreme in Mediterranean regions than in inland continental regions and flash floods often result in loss of life (which is not that common in lowland floods)

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