The climatic and physiographic settings of the Iberian Peninsula mean that recurrent flooding episodes and extended droughts are common hydrological phenomena that societies there have to contend with. The Fourth Assessment Report of the IPCC (Trenberth et al. , 2007) drew attention to the fact that many world regions are likely to experience an increase in the number of heavy precipitation events (e.g. 95th percentile), including those areas where a trend towards a decrease in the annual rainfall has been observed, such as the west ern Mediterranean. Earlier reports of global warming effects on the hydroclimatological regimes of the Iberian Peninsula also give accounts of change in the seasonal pattern of rainfall, which may further add to modification of flood patterns (Benito et al. , 2005). However, quantitative estimations of projected flood frequency in the Iberian Peninsula, based on downscaled climatic models, show conflicting results among the different models (e.g. Lehner et al. , 2006), and even contradict precipitation scenar ios obtained from some regional dynamic models (AEMET, 2008). This Chapter aims to: (a) describe the causes, timing and magnitudes of large floods in Iberian rivers; (b) describe changes in flood-related drivers, including extreme precipitation patterns and land-use change; (c) provide data on maximum river flows and their trends; and finally (d) consider the evolution of reported flood damage and weigh up the role of physical phenomena (floods and/or extreme rainfall), and socio- economic components of flood risk (exposure and vulnerability).

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