Extreme flash floods in Barcelona County

In this paper the catastrophic and extraordinary floods occurring in Barcelona County (Catalonia, NE Spain) are studied, in order to characterise the temporal evolution of extreme flash floods in that area and their main features. These events usually cause economical losses and major problems for undertaking daily activity in Barcelona city. This kind of floods is a very common feature in the North-east of Spain and they are recorded every year in some point of Catalonia. This contribution also shows the frequency of those events, within the framework of all the floods that have occurred in Barcelona since the 14th century, but also describes the flooded area, urban evolution, impacts and the weather conditions for any of most severe events. The evolution of flood occurrence shows the existence of oscillations in the earlier and later modern age periods that can be attributed to climatic variability, evolution of the perception threshold and changes in vulnerability. A great increase of vulnerability can be assumed for the period 1850-1900. The analysis of the time evolution for the Barcelona rainfall series (1854-2000) shows that no trend exists, although, due to the changes in urban planning, flash-floods impact has changed over this time. The number of catastrophic flash floods has diminished, although the extraordinary ones have increased

Estimation of extreme flash flood evolution in Barcelona County from 1351 to 2005

International audienceEvery year, flash floods cause economic losses and major problems for undertaking daily activity in the Catalonia region (NE Spain). Sometimes catastrophic damage and casualties occur. When a long term analysis of floods is undertaken, a question arises regarding the changing role of the vulnerability and the hazard in risk evolution. This paper sets out to give some information to deal with this question, on the basis of analysis of all the floods that have occurred in Barcelona county (Catalonia) since the 14th century, as well as the flooded area, urban evolution, impacts and the weather conditions for any of most severe events. With this objective, the identification and classification of historical floods, and characterisation of flash-floods among these, have been undertaken. Besides this, the main meteorological factors associated with recent flash floods in this city and neighbouring regions are well-known. On the other hand, the identification of rainfall trends that could explain the historical evolution of flood hazard occurrence in this city has been analysed. Finally, identification of the influence of urban development on the vulnerability to floods has been carried out. Barcelona city has been selected thanks to its long continuous data series (daily rainfall data series, since 1854; one of the longest rainfall rate series of Europe, since 1921) and for the accurate historical archive information that is available (since the Roman Empire for the urban evolution). The evolution of flood occurrence shows the existence of oscillations in the earlier and later modern-age periods that can be attributed to climatic variability, evolution of the perception threshold and changes in vulnerability. A great increase of vulnerability can be assumed for the period 1850?1900. The analysis of the time evolution for the Barcelona rainfall series (1854?2000) shows that no trend exists, although, due to changes in urban planning, flash-floods impact has altered over this time. The number of catastrophic flash floods has diminished, although the extraordinary ones have increased

Western Mediterranean precipitation over the last 300 years from instrumental observations

The paper reports the results of the analysis of the 14 longest precipitation instrumental series, covering the last 300 years, that have been recovered in six subareas of the Western Mediterranean basin, i.e., Portugal, Northern and Southern Spain, Southern France, Northern and Southern Italy. This study extends back by one century our knowledge about the instrumental precipitation over theWestern Mediterranean, and by two centuries in some specific subareas. All the time series show repeated swings. No specific trends have been found over the whole period, except in a few cases, but with modest time changes and sometimes having opposite tendency. The same can be said for the most recent decades although with some more marked departures from the average. The correlation between the various Mediterranean subareas is generally not significant, or almost uncorrelated. The Wavelet Spectral Analysis applied to the precipitation identifies only a minor 56-year cycle in autumn, i.e., the same return period that has been found in literature for the Sea Surface Temperature over North Atlantic. A comparison with a gridded dataset reconstruction based on mixed multiproxy and instrumental observations, shows that the grid reconstruction is in good agreement with the observed data for the period after 1900, less for the previous period

A shift in the spatial pattern of Iberian droughts during the 17th century

In this paper, series of drought occurrence and drought extension in the Iberian Peninsula are constructed for the 1600–1750 period from seven rogation series. These rogation ceremony records come from Bilbao, Catalonia, Zamora, Zaragoza, Toledo, Murcia and Seville. They are distributed across the Peninsula and include the areas with the most characteristic Iberian climate types, influenced by the Atlantic and the Mediterranean conditions, described from modern data. A seasonal division of the series shows that spring is a critical season for rogation series in most of Iberia, being Bilbao the only site were the highest number of rogations is detected for a different season. The annual analysis of the series shows a dramatic difference between the first half of the 17th century when droughts are characterized by its local character; and the rest of the period, when they affect to broader regions or even to the whole Peninsula. The analysis of spring series confirms the existence of the two periods detected in the annual analysis. Finally, secondary documentary sources are used to further characterise the two most extended droughts in the period, 1664 and 1680, and to verify the extension of the areas affected by droughts recorded through rogation series

Stationarity analysis of historical flood series in France and Spain (14th–20th centuries)

International audienceInterdisciplinary frameworks for studying natural hazards and their temporal trends have an important potential in data generation for risk assessment, land use planning, and therefore the sustainable management of resources. This paper focuses on the adjustments required because of the wide variety of scientific fields involved in the reconstruction and characterisation of flood events for the past 1000 years. The aim of this paper is to describe various methodological aspects of the study of flood events in their historical dimension, including the critical evaluation of old documentary and instrumental sources, flood-event classification and hydraulic modelling, and homogeneity and quality control tests. Standardized criteria for flood classification have been defined and applied to the Isère and Drac floods in France, from 1600 to 1950, and to the Ter, the Llobregat and the Segre floods, in Spain, from 1300 to 1980. The analysis on the Drac and Isère data series from 1600 to the present day showed that extraordinary and catastrophic floods were not distributed uniformly in time. However, the largest floods (general catastrophic floods) were homogeneously distributed in time within the period 1600–1900. No major flood occurred during the 20th century in these rivers. From 1300 to the present day, no homogeneous behaviour was observed for extraordinary floods in the Spanish rivers. The largest floods were uniformly distributed in time within the period 1300–1900, for the Segre and Ter rivers

La sequía de mediados del siglo XVII en el valle del Ebro. Características climáticas e impacto social del evento

En este trabajo se analizan las sequías de mediados del siglo XVII en las tierras centrales del valle del Ebro y su impacto en la demografía. Mediante la recopilación de ceremonias de rogativas «ad petendam pluviam» y reconstrucciones dendroclimáticas, se ha elaborado un índice de sequía y precipitación de todo el siglo y se ha relacionado con los datos demográficos de varias localidades del interior del valle. Los resultados muestran la existencia de un acusado y largo periodo seco a mitad del siglo, prácticamente desde 1641 a 1654, interrumpido por algunos intensos temporales causantes de grandes riadas, como la que sufrió el río Ebro en febrero de 1643. La prolongada sequía se corresponde con el descenso de la natalidad y un fuerte incremento de la mortalidad.Droughts of the mid XVII century in the Central lands of the Ebro Valley and its impact on demography are analyzed in this paper. Through the collecting of rogations ceremonies «ad petendam pluviam» and dendroclimatic reconstructions, an index of drought and precipitation has been developed. In addition, it has been linked with demographic data from various locations inside the Valley. The results show the existence of a pronounced and long dry period in the middle of the century, practically from 1641 to 1654, interrupted by some intense tempests causing big floods: For instance, the flood in the Ebro River in February 1643. The prolonged drought corresponds to the decline in the birth rate and a strong increase in mortality.Este estudio se ha realizado en el marco del proyecto de investigación CGL2011-28255, financiado por el Ministerio de Economía y Competitividad del Gobierno de España, y el programa de Grupos de Investigación Consolidados «Clima, Agua y Cambio Global» del Gobierno de Aragón y Fondos FEDER. Además, Ernesto Tejedor disfruta de una beca predoctoral de investigación concedida por el Gobierno de Aragón 2012-2016

The importance of ship log data: reconstructing North Atlantic, European and Mediterranean sea level pressure fields back to 1750

Local to regional climate anomalies are to a large extent determined by the state of the atmospheric circulation. The knowledge of large-scale sea level pressure (SLP) variations in former times is therefore crucial when addressing past climate changes across Europe and the Mediterranean. However, currently available SLP reconstructions lack data from the ocean, particularly in the pre-1850 period. Here we present a new statistically-derived 5°×5° resolved gridded seasonal SLP dataset covering the eastern North Atlantic, Europe and the Mediterranean area (40°W-50°E; 20°N-70°N) back to 1750 using terrestrial instrumental pressure series and marine wind information from ship logbooks. For the period 1750-1850, the new SLP reconstruction provides a more accurate representation of the strength of the winter westerlies as well as the location and variability of the Azores High than currently available multiproxy pressure field reconstructions. These findings strongly support the potential of ship logbooks as an important source to determine past circulation variations especially for the pre-1850 period. This new dataset can be further used for dynamical studies relating large-scale atmospheric circulation to temperature and precipitation variability over the Mediterranean and Eurasia, for the comparison with outputs from GCMs as well as for detection and attribution studie

Extreme Floods in Small Mediterranean Catchments: Long-Term Response to Climate Variability and Change

Climate change implies changes in the frequency and magnitude of flood events. The influence of climate variability on flooding was evaluated by an analysis of sedimentary (palaeofloods) and documentary archives. A 500-year palaeoflood record at Montilea River (657 km(2) in catchment area), eastern Spain, revealed up to 31 palaeofloods with a range of discharges of 20-950 m(3) s(-1), and with at least five floods exceeding 740-950 m(3) s(-1). This information contrasts with the available gauged flood registers (since year 1971) with an annual maximum daily discharge of 129 m(3) s(-1). Our palaeoflood dataset indicates flood cluster episodes at (1) 1570-1620, (2) 1775-1795, (3) 1850-1890, and (4) 1920-1969. Flood rich periods 1 and 3 corresponded to cooler than usual (about 0.3 degrees C and 0.2 degrees C) climate oscillations, whereas 2 and 4 were characterised by higher inter-annual climatic variability (floods and droughts). This high inter-annual rainfall variability increased over the last 150 years, leading to a reduction of annual maximum flow. Flood quantiles (>50 years) calculated from palaeoflood+gauged data showed 30%-40% higher peak discharges than those using only instrumental records, whereas when increasing the catchment area (1500 km(2)) the discharge estimation variance decreased to-15%. The results reflect the higher sensitivity of small catchments to changes on flood magnitude and frequency due to climate variability whereas a larger catchment buffers the response due to the limited extent of convective storms. Our findings show that extended flood records provide robust knowledge about hazardous flooding that can assist in the prioritization of low-regret actions for flood-risk adaptation to climate change

Climatic drivers of the historical variations in cereal prices in the northeast of the Iberian peninsula in the 17th century

The 17th century knew in Spain several periods of agricultural crisis producing shortages in staple foods and a rising in grain prices. The fluctuations of the prices of wheat, barley and rye are relatively well documented in several areas of the country, however, the knowledge about the influence of climatic and environmental factors on these variations is still limited. In this work, we present the historical records of grain prices of four cities of different geographical areas in northeastern Iberian Peninsula during period 1630-1660, and they are compared with drought indices, reconstructed from documentary and dendroclimatic proxies. We observed that prices variations coincide with regional anomalies in spring-summer drought. Direct correlations between them are low (0.435), however, if analysis is focused on extreme values, the climatic influence is higher: prices are high during dry periods and lower during wet periods. This correspondence is higher in previous and following years to the Guerra dels Segadors, showing that the exchange of goods and the coherence of data were controlled by sociopolitical and environmental factors, being the latter more influential in peacetime. ©2021 José M. Cuadrat, Francisco J. Alfaro Pérez, Ernesto Tejedor Vargas, Mariano Barriendos, Roberto Serrano-Notivoli, Miguel Á. Saz Sánche

Avances en la reconstrucción plurisecular del clima en el noreste de España: nuevas bases de datos y resultados

En el marco de los proyectos CGL2011-28255 y CGL2015-69985 se ha generado una base de datos multiproxy e instrumental con el objetivo de analizar la evolución, tendencia, variabilidad y los fenómenos extremos de las temperaturas y la precipitación en el Noreste de España a lo largo de los últimos 400 años. En esta comunicación presentamos la base de datos creada, así como los primeros resultados referentes al estudio de la variabilidad de las sequías. La información multiproxy está formada por documentos históricos procedentes de 16 archivos de las Comunidades de Aragón, la Rioja y Cataluña, y por series dendrocronológicas de 23 áreas localizadas en los Pirineos, el Sistema Ibérico y el valle del Ebro. Los datos han sido calibrados con toda la red de estaciones meteorológicas de temperatura y precipitación del Noreste de España. Con ellos se ha realizado la reconstrucción de los periodos de sequía desde el siglo XVII que permiten contextualizar el clima actual en un ámbito temporal más amplio, y ayudan a validar los escenarios climáticos futuros.In the framework of the projects CGL2011-28255 and CGL2015-69985 a multiproxy and instrumental database has been generated with the aim of analyzing the evolution, trends, variability and extreme events of temperature and precipitation in the northeast of Spain over the last 400 years. In this paper, we present a novel database that integrates multiproxy and instrumental data as well as the first results concerning the evolution of drought variability. Multiproxy data is composed of 16 historical documents located in Aragon, La Rioja and Catalonia and by 23 dendrochronological series located in the Pyrenees, the Iberian Range and the Ebro Valley. Multiproxy data is calibrated with all the network of stations of temperature and precipitation in the northeast of Spain. The database has led to develop a reconstruction of drought periods since the XVII century which serve not only to contextualize the current climate in a temporal scale, but also to validate future climate change scenarios.Este estudio se ha realizado gracias a siguiente financiación: proyectos de investigación CGL2011-28255 y CGL2015-69985 del Ministerio de Economía y Competitividad del Gobierno de España y FEDER. Programa de Grupos de Investigación Consolidados “Clima, Agua y Cambio Global” del Gobierno de Aragón y Fondos FEDER. Además, Ernesto Tejedor disfruta de una beca predoctoral de investigación concedida por el Gobierno de Aragón 2012-2016