Palaeoflood chronologies from seven Spanish river basins and floodplain aggradation chronologies from thirteen rivers are analysed. These fluvial records were divided in to two sub-sets, namely Atlantic (10 ka record) and Mediterranean (3 ka record) river basins, which represent distinct modern hydroclimatic conditions. In Atlantic basins floods result from intense, widespread rainfalls associated with Atlantic frontal systems transported by westerly airflow. Mediterranean river flooding is related to heavy rainfall induced by mesoscale convective systems (MCSs) during autumn months. Evidence from radiocarbon dates in slackwater flood deposits shows six periods of flood clusters at 10,750-10,240; 9550-9130; 4820-4440; 2865-2350; 960-790; and 520-290 cal BP. Despite the different flood-producing weather conditions in Atlantic and Mediterranean rivers, the radiocarbon sample clusters overlap and indicate changes in largescale atmospheric circulation and climatic conditions in the Iberian Peninsula. Comparison with proxy records of mean temperature for the Northern Hemisphere demonstrates a relationship between the period of slackwater flood deposition and cold climatic phases (e.g. the 2650 yr BP climatic event or AD 1590-1650 period of the Little Ice Age). Radiocarbon dates from aggraded floodplain sediments were clustered at 2710-2320, 2000-1830, and 910-500 cal BP. The first cluster period is in phase with the timing of slackwater deposition, whereas the third (910-500 cal BP) occurs in between two periods of increased flood frequency as indicated by the palaeoflood and documentary flood records. It is argued that the 910-500 cal BP floodplain aggradation period reflects the first post-Roman evidence of environmental change related to generalised land-use changes at the catchment scale, which produced high sediment load transported to overbank areas during high flows.

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Slackwater palaeoflood deposits were identified along two bedrock gorge study reaches of the Llobregat River, at Pont de Vilomara and Monistrol de Montserrat. The compiled palaeoflood record consists of two principal flood series: (a) a relatively complete record of low to high magnitude flood events from the last ca. 100 years and (b) evidence of the largest palaeoflood events that have occurred over the last ca. 2700 years. The longer term extreme palaeoflood record indicates that the discharge of the 1971 flood, the largest on record, was exceeded on at least eight occasions, with two periods of high magnitude flooding identified: (a) the Late Bronze Age (2500-2700 years ago) and (b) the Little Ice Age (AD 1500-1700). At Pont de Vilomara, palaeodischarge estimates of 3700-4300 m 3 /s compare to a discharge of 2300 m 3 /s for the 1971 event. Downstream at Monistrol, an estimate of 4680 m 3 /s for flood deposits dated as AD 1516-1642, and believed to be those of the AD 1617 flood, compared to 2500 m 3 /s for the 1971 flood. q

a b s t r a c t a r t i c l e i n f oThe Guadalentín River, located in southeast Spain, is considered one of the most torrential rivers in Spain, as indicated by catastrophic events such as the 1879 flood that caused 777 fatalities in the Murcia region. In this paper, flood frequency and magnitude of the upper Guadalentín River were reconstructed using geomorphological evidence, combined with one-dimensional hydraulic modelling and supported by records from documentary sources at Lorca in the lower Guadalentín catchment. Palaeoflood studies were conducted along a 2.5-km reach located at the confluence of the Rambla Mayor (162 km 2 ) and Caramel River (210 km 2 ). These tributaries join at the entrance of a narrow bedrock canyon, carved in Cretaceous limestone, which is 15-30 m wide and 40 m deep. Six stratigraphic profiles were described, the thickest and most complete corresponding to flood benches deposited upstream of the canyon constriction. The stratigraphic and documentary records identify five main phases of increased flood frequency. Phase 1, based on sedimentary palaeoflood evidence alone, occurred at c. AD 950-1200 with at least ten floods with minimum discharge estimates of 15-580 m 3 s − 1 . Phases 2-5, identified through combined sedimentary and documentary evidence occurred at: (a) AD 1648-1672, with eight documentary floods and two palaeofloods exceeding 580-680 m 3 s − 1 (most probably the AD 1651 and 1653 events); (b) AD 1769-1802, comprising seven documentary floods, of which at least two events (N 250 m 3 s − 1 ) are preserved in the sedimentary record; (c) AD 1830-1840, with four documentary floods, and at least two events recorded in the stratigraphy (760-1035 m 3 s − 1 ); and finally (d) the AD 1877-1900 period that witnessed seven documentary floods, with three palaeofloods exceeding 880 m 3 s − 1 .The palaeoflood and historical flood information indicate an anomalous increase in the frequency of large magnitude floods between AD 1830 and 1900, which can be attributed to climatic variability accentuated by intensive deforestation and land use practices during the first decades of the nineteenth century.

The Iberian Chain is a wide intraplate deformation zone formed by the tectonic inversion during the and basin evolution analysis, macrostructural Bouguer gravity anomaly analysis, detailed mapping and paleostress inversions have been used to prove the important role of strike slip deformation. In addition, we demonstrate that two main folding trends almost perpendicular (NE SW ID E W artd NW SE) were simultaneously active in a wide transpressive zone. The two fold trends were generated by different mechanical behaviour, induding buckling and bending under constrictive strain conditions. We propose that strain partitioning occurred with oblique compression and transpression during the Cenozoic.

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The Buntsandstein sequence of the central area of Spain ranges from a variety of fluvial facies, low in the succession, to tidal mudstones and carbonates in the youngest and most eastem areas. This paper is restricted to the conglomera tes in the lowest part of the fluvial sequence. These were deposited in bar and channel systems dominated by gravelly, low-sinuosity braided streams. Their distribution reflects both the pre-existing topography and synsedimentary tectonic movements.Six main facies have been distinguished (in order of decreasing abundance): sheets of massive conglomerates, channel-fill conglomera tes, coarse-medium sandstones, lateral accretion conglomera tes. tabular cross-stratified conglomera tes, fine-grained sediments.Sheets of gravels, formed as longitudinal bars, were by far the major feature of sediment accumulation. Units of lateral accretion, if not ver y frequent, are quite important as they probably represent modifications of bars during waning stage.Two big cycles may be seen in these conglomera tes. They correspond to different physiographic models. The lower cycle was mainly formed by smaller channels and bars than was the upper cycle. The lower cycle is mainly formed by channel deposits, whilst in contrast, the upper cycle is mainly made up of longitudinal bars.The change in sedimentation may be due to tectonic movements that occurred in the basin during Buntsandstein deposition.

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