Search

Extreme floods are anticipated to become more frequent in a future warmer climate. However, the long-term alterations in flood patterns across different regions of Europe remain unclear. In this study, we present a 15,000-year record of extreme floods in the Duero River, located in the southwestern Atlantic region. We analysed slackwater flood sediments, quantified the discharge and timing of individual flood beds over millennial time scales, and identified their potential climate influences. The composite record includes at least 62 floods grouped into ten flood-rich periods (with an average duration of 230 years). A high-frequency phase of moderate-magnitude floods (>10 events) occurred at ∼11.6–11.5 ka, following a period of reduced flood activity during the Younger Dryas. Similar clusters of Early Holocene floods (10.8–10.3 ka, 9.5 ka) coincided with or preceded meltwater pulses from the North Atlantic. The absence of palaeoflood records with discharges exceeding 6100 m3/s during the Mid-Holocene suggests a decline in winter hydro-meteorological extremes. High flood magnitudes were recorded during transition periods toward cooler and wetter conditions at 4.4, 2.3, 0.5, and 0.11 ka with discharges ranging from 7600 to 10,000 m3/s. These periods were interpreted as indicative of a southward shift in cyclone tracks in Europe driven by negative phases of the North Atlantic Oscillation (NAO). Conversely, flood magnitudes decreased during past warmer climate conditions (1.7 ka, 0.9 ka, and the present), although flood frequency remained high. The current decline in flood frequency reflects an increase in flood regulation due to dams, but it is also consistent with the prevailing positive trend in the NAO observed over the last 40 years., Ministerio de Ciencia e Innovación (España), Dirección General del Agua, Fundación Biodiversidad, Union Europea, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

A sedimentary sequence covering the entire last glacial cycle (period between Terminations I and II) outcrops along the south-eastern coast of Formentera Island. A detailed geomorphological, geological and sedimentological study, supported by geochemical, soil and soil-morphology analyses, magnetic susceptibility, phytolite content and luminescence dating (TL, OSL) allowed to reconstruct the environmental evolution of this coastal setting, and to frame it within the evolutionary pattern of the North Atlantic climate variability. Three highstands of sea level are identified in this island for MIS 5e, and a fourth one is attributed to MIS5a. MIS5 – MIS4 transition is characterized by soil development under a moist-warm climate and a descending sea level scenario. Aeolian units (72 ± 7 ka BP) developed during MIS4 under prevailing northerly winds that persisted until the beginning of MIS3, when new aeolian dunes (54 ± 5 ka BP) developed after a major sea-level lowstand. A sudden shift in prevailing winds occur within MIS3, when aeolian units (51 ± 4 ka BP) grew under the influence of S-SW winds and moister climate, evidenced by a dense root bioturbation. The greater influence of northerly winds is attributed to the weakening of Atlantic Meridional Overturning Current (AMOC) in North Atlantic, and enhancement of westerlies in NW Europe during colder periods. Periods of prevailing southerly winds and moister climate correlate well with warm Greenland Interstadials, and reinforcement of AMOC. Between 50 and 40ka, alluvial/colluvial sedimentary units punctuated by soil and calcrete development, witness the climatic variability recorded along this period in the North Atlantic. A sedimentary hiatus with erosion and calcrete development characterizes the transit between MIS3 and MIS2. Finally, a reddish alluvial sedimentary unit records a short span of humid and warm climate (soil development, peak in magnetic susceptibility, phytolite content) within MIS 2 (20 ± 2 ka BP – 17, Ministerio de Economía y Competitividad (MINECO)/FEDER, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

A sedimentary sequence covering the entire last glacial cycle (period between Terminations I and II) outcrops along the south-eastern coast of Formentera Island. A detailed geomorphological, geological and sedimentological study, supported by geochemical, soil and soil-morphology analyses, magnetic susceptibility, phytolite content and luminescence dating (TL, OSL) allowed to reconstruct the environmental evolution of this coastal setting, and to frame it within the evolutionary pattern of the North Atlantic climate variability. Three highstands of sea level are identified in this island for MIS 5e, and a fourth one is attributed to MIS5a. MIS5 – MIS4 transition is characterized by soil development under a moist-warm climate and a descending sea level scenario. Aeolian units (72 ± 7 ka BP) developed during MIS4 under prevailing northerly winds that persisted until the beginning of MIS3, when new aeolian dunes (54 ± 5 ka BP) developed after a major sea-level lowstand. A sudden shift in prevailing winds occur within MIS3, when aeolian units (51 ± 4 ka BP) grew under the influence of S-SW winds and moister climate, evidenced by a dense root bioturbation. The greater influence of northerly winds is attributed to the weakening of Atlantic Meridional Overturning Current (AMOC) in North Atlantic, and enhancement of westerlies in NW Europe during colder periods. Periods of prevailing southerly winds and moister climate correlate well with warm Greenland Interstadials, and reinforcement of AMOC. Between 50 and 40ka, alluvial/colluvial sedimentary units punctuated by soil and calcrete development, witness the climatic variability recorded along this period in the North Atlantic. A sedimentary hiatus with erosion and calcrete development characterizes the transit between MIS3 and MIS2. Finally, a reddish alluvial sedimentary unit records a short span of humid and warm climate (soil development, peak in magnetic susceptibility, phytolite content) within MIS 2 (20 ± 2 ka BP – 17

Glacier outburstfloods are a major hazard in glacierized catchments. Global analyses have shownreduced frequency of glacierfloods over recent decades but there is limited longer-term data on eventmagnitude and frequency. Here, we present a Holocene palaeoflood record from the Río Baker (ChileanPatagonia), quantifying the discharge and timing of glacierfloods over millennial timescales. A cata-strophicflood of 110,000 m3/s (0.11 Sv) occurred at 9.6±0.8 ka, duringfinal stages of the Late GlacialInterglacial Transition, followed byfiveflood-phases coeval or post-dating Holocene neoglacials. Highestflood frequencies occurred at 4.3e4.4 ka, with 26floods of minimum discharges of 10,000e11,000 m3/s,and 0.6 ka with 10floods exceeding 4600e5700 m3/s. The largest modern outburstflood recordedsurpassed ~3810 m3/s. Thus glacierflood magnitude declines from the order of 0.1 to 0.01 Sv over theEarly to Mid Holocene, and to 0.001 Sv in the instrumental record.

Current climate modelling frameworks present significant uncertainties when it comes to quantifying flood quantiles in the context of climate change, calling for new information and strategies in hazard assessments. Here, state-of-the-art methods on hydraulic and statistical modelling are applied to historical and contemporaneous flood records to evaluate flood hazards beyond natural climate cycles. A comprehensive flood record of the Duero River in Zamora (Spain) was compiled from documentary sources, early water-level readings and continuous gauge records spanning the last 500 years. Documentary evidence of flood events includes minute books (municipal and ecclesiastic), narrative descriptions, epigraphic marks, newspapers and technical reports. We identified 69 flood events over the period 1250 to 1871, of which 15 were classified as catastrophic floods, 16 as extraordinary floods and 38 as ordinary floods. Subsequently, a two-dimensional hydraulic model was implemented to relate flood stages (flood marks and inundated areas) to discharges. The historical flood records show the largest floods over the last 500 years occurred in 1860 (3450 m3 s−1), 1597 (3200 m3 s−1) and 1739 (2700 m3 s−1). Moreover, at least 24 floods exceeded the perception threshold of 1900 m3 s−1 during the period (1500–1871). Annual maximum flood records were completed with gauged water-level readings (pre-instrumental dataset, PRE: 1872–1919) and systematic gauge records (systematic dataset, SYS: 1920–2018). The flood frequency analyses were based on (1) the expected moments algorithm (EMA) and (2) the maximum likelihood estimator (MLE) method, using five datasets with different temporal frameworks (historic dataset, HISTO: 1511–2018; PRE–SYS: 1872–2018; full systematic record, ALLSYS: 1920–2018; SYS1: 1920–1969; and SYS2: 1970–2018). The most consistent results were obtained using the HISTO dataset, even for high quantiles (0.001 % annual exceedance probability, AEP). PRE–SYS was robust for

This paper provides a new methodological approach to analyse secular patterns of flooding (magnitude and frequency) from sedimentary evidence (palaeofloods), taking into account changes in channel geometry, and their links to historical environmental changes and the inherent social and demographic evolution within the catchment. A case study analysis was focused in Rambla de la Viuda (drainage area of 1500 km2) whose stream flow is related to extreme rainfalls. A 500 years sedimentary archive was reconstructed from eight stratigraphic profiles comprising continuous sequences of slackwater flood deposits interbedded with episodic colluvial and edaphic horizons. Discharge estimates associated to sedimentary flood evidences were obtained from one-dimensional hydraulic modelling. The stratigraphic units were sampled to characterise their geochemical and paleobotanical (phytoliths) contents. Palaeoflood chronology was obtained from radiocarbon and luminescence (OSL) dating, supported by documentary data (written historical documents). A high frequency and high magnitude palaeoflood period took place during the 15th-middle 16th century, which seem to correlate in time with general wetter conditions. Three short-term environment stability conditions (land use and climatic) also made possible the development of three paleosols. The lowest flood magnitude and discharges in the sedimentary record was found between the mid-17th to mid-18th centuries, under prevailing drier environmental conditions. Episodic high magnitude flooding took place at late 18th century, correlating in time with palaeovegetation and geochemical evidences of important changes on land use (deforestation and grazing). Poorer developed soils were found at upper stratigraphic sequences (19th century) characterised by thick units of colluvium deposits, usually culminating sequences of short-lived continuous slackwater flood units. Despite of the potential human influence (land-use) on soil hydrology, the lo, Ministerio de Economía y Competitividad (MINECO), CSIC PIE Intramural, Fundación Biodiversidad (MAPAMA), Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

Received 17 March 2010 / Available online 22 February 2011. © 2011 University of Washington. Published by Elsevier Inc. All rights reserved. Green Open Access., A long-term flood record from the Buffels River, the largest ephemeral river of NW South Africa (9250 km2 ), was reconstructed based on interpretation of palaeoflood, documentary and instrumental rainfall data. Palaeoflood data were obtained at three study reaches, with preserved sedimentary evidence indicating at least 25 large floods during the last 700 yr. Geochronological control for the palaeoflood record was provided by radiocarbon and optically stimulated luminescence (OSL) dating. Annual resolution was obtained since the 19th century using the overlapping documentary and instrumental records. Large floods coincided in the past within three main hydroclimatic settings: (1) periods of regular large flood occurrence (1 large flood/~30 yr) under wetter and cooler prevailing climatic conditions (AD 1600–1800), (2) decreasing occurrence of large floods (1 large flood/~100 yr) during warmer conditions (e.g., AD 1425–1600 and after 1925), and (3) periods of high frequency of large floods (~4–5 large floods in 20–30 yr) coinciding with wetter conditions of decadal duration, namely at AD 1390–1425, 1800–1825 and 1915–1925. These decadal-scale periods of the highest flood frequency seem to correspond in time with changes in atmospheric circulation patterns, as inferred when comparing their onset and distribution with temperature proxies in southern Africa., Comisión Europea, Depto. de Geodinámica, Estratigrafía y Paleontología, Fac. de Ciencias Geológicas, TRUE, pub

La cubierta ecológica es un tipo de cubierta vegetal con un substrato de poco espesor y una capa vegetal con plantas de bajo porte. Las ventajas de este tipo de cubierta, abarcan aspectos arquitectónicos, constructivos, medioambientales y estéticos. Para realizar estudios a través de modelos de ordenador con cubiertas ecológicas, primero se determinó el valor de conductividad térmica equivalente del substrato y capa vegetal, utilizando las ecuaciones de balance térmico, lo cual fue comprobado con un ensayo de laboratorio y, con estos resultados, se realizaron simulaciones térmicas en los espacios con cubiertas ecológicas comparándolos con sistemas constructivos de cubiertas utilizados en las dos zonas de estudio: Maracaibo y Madrid. Para el estudio se establecieron cinco alternativas de cubiertas, analizándose de cuatro maneras diferentes: 1) cerrada durante las 24 horas. 2) cerrada durante el día y abierta en la noche ; 3) abierta las 24 horas ; 4) abierta durante el día y cerrada en la noche. La herramienta utilizada para el estudio fue el Cálculo de Evolución de Temperaturas Interiores, desarrollada por Javier Neila. Los resultados obtenidos muestran que la cubierta ecológica disminuye la transferencia de calor en épocas calurosas, ya que actúa como aislamiento exterior.