Dossier pedagógico sobre los riesgos de las inundaciones y las tormentas

Podeu consultar la versió catalana a http://hdl.handle.net/2445/8610 i la versió anglesa a http://hdl.handle.net/2445/8611 Este trabajo se ha realizado gracias al apoyo de: "Grupo de Análisis de situaciones Meteorológicas Adversas (GAMA)-Universitat de Barcelona; Proyecto EDRINA-06 (FECYT. Ministerio de Educación y Ciencia); Proyecto europeo FLASH (FP6-2005-Global-4) no. 036852Dosier pedagógico compuesto por fichas sobre inundaciones, tormentas y aspectos de prevención. Partes: Observación de la atmosfera (conceptos generales, meteorología, métodos de pronóstico); Inundaciones y Tormentas; Ecología de las inundacionesEste trabajo se ha realizado gracias al apoyo de: "Grupo de Análisis de situaciones Meteorológicas Adversas (GAMA)-Universitat de Barcelona; Proyecto EDRINA-06 (FECYT. Ministerio de Educación y Ciencia); Proyecto europeo FLASH (FP6-2005-Global-4) no. 03685

Flash-floods in Catalonia: the social perception in a context of changing vulnerability

In assessing a flood event two risk components need to be considered: the intrinsic hazard of the hydrome- teorological event causing the flood and the vulnerability of the area where the precipitation has been registered. In the present study four flood events selected by the FLASH Eu- ropean project have been classified according to the charac- teristics of the meteorological event (classification according to hazard) and according to the physical and economic dam- ages caused (classification according to vulnerability). The social impact of these events is analysed taking into account the growth of the population. An increase in the number of extraordinary flash-floods was detected in the areas with a major growth of the population, as a consequence of an in- creased vulnerability of these areas, both from a physical per- spective (exposure of infrastructures) and from an economic perspective (more goods exposed). In addition, the numer- ous non-native inhabitants of the region are not aware of the meteorological risks characteristic of the area, and this con- tributes to increased social vulnerabilit

Evolving flood patterns in a Mediterranean region (1301-2012) and climatic factors - the case of Catalonia

Data on flood occurrence and flood impacts for the last seven centuries in the northeastern Iberian Peninsula have been analysed in order to characterise long-term trends, anomalous periods and their relationship with different climatic factors such as precipitation, general circulation and solar activity. Catastrophic floods (those that produce complete or partial destruction of infrastructure close to the river, and major damages in the overflowed area, including some zones away from the channels) do not present a statistically significant trend, whereas extraordinary floods (the channel is overflowed and some punctual severe damages can be produced in the infrastructures placed in the rivercourse or near it, but usually damages are slight) have seen a significant rise, especially from 1850 on, and were responsible for the total increase in flooding in the region. This rise can be mainly attributed to small coastal catchments, which have experienced a marked increase in developed land and population, resulting in changes in land use and greater vulnerability. Changes in precipitation alone cannot explain the variation in flood patterns, although a certain increase was shown in late summer-early autumn, when extraordinary floods are most frequently recorded. The relationship between the North Atlantic circulation and floods is not as strong, due to the important role of mesoscale factors in heavy precipitation in the northwest of the Mediterranean region. However, it can explain the variance to some extent, mainly in relation to the catastrophic floods experienced during the autumn. Solar activity has some impact on changes in catastrophic floods, with cycles related to the quasi-biennial oscillation (QBO) and the Gleissberg solar cycle. In addition, anomalous periods of high flood frequency in autumn generally occurred during periods of increased solar activity. The physical influence of the latter in general circulation patterns, the high troposphere and the stratosphere, has been analysed in order to ascertain its role in causing floods

Characteristics of 2D convective structures in Catalonia (NE Spain): an analysis using radar data and GIS

Flood simulation studies use spatial-temporal rainfall data input into distributed hydrological models. A correct description of rainfall in space and in time contributes to improvements on hydrological modelling and design. This work is focused on the analysis of 2-D convective structures (rain cells), whose contribution is especially significant in most flood events. The objective of this paper is to provide statistical descriptors and distribution functions for convective structure characteristics of precipitation systems producing floods in Catalonia (NE Spain). To achieve this purpose heavy rainfall events recorded between 1996 and 2000 have been analysed. By means of weather radar, and applying 2-D radar algorithms a distinction between convective and stratiform precipitation is made. These data are introduced and analyzed with a GIS. In a first step different groups of connected pixels with convective precipitation are identified. Only convective structures with an area greater than 32 km2 are selected. Then, geometric characteristics (area, perimeter, orientation and dimensions of the ellipse), and rainfall statistics (maximum, mean, minimum, range, standard deviation, and sum) of these structures are obtained and stored in a database. Finally, descriptive statistics for selected characteristics are calculated and statistical distributions are fitted to the observed frequency distributions. Statistical analyses reveal that the Generalized Pareto distribution for the area and the Generalized Extreme Value distribution for the perimeter, dimensions, orientation and mean areal precipitation are the statistical distributions that best fit the observed ones of these parameters. The statistical descriptors and the probability distribution functions obtained are of direct use as an input in spatial rainfall generators

The Results of Applying Different Methodologies to 10 Years of Quantitative Precipitation Estimation in Catalonia Using Weather Radar

The single polarization C-Band weather radar network of the Meteorological Service of Catalonia covers the entire region (32,000 km2), which allows it to apply a series of corrections that improve preliminary estimations of the rainfall field (hourly and daily). In addition, an automatic re-processing using automatic weather stations helps to incorporate ground-based information. The last process of the quantitative precipitation estimation (QPE) is running the end-product again eight days later, when the data have been reviewed and corrected in the case of detecting anomalies in the radar or gauge data. These corrections are applied operationally, with the fields generated and stored automatically. The QPE fields are generated in the GeoTIFF format, allowing easy use with multiple applications and simplifying processes such as quality control. In this way, the analysis of a 10 year period of GeoTIFF QPE daily data compared with ground rainfall values is introduced. The results help to understand different points regarding the functioning of the network such as the dependance on the type of precipitation and the seasonality. In addition, the description of a heavy rainfall episode (22 October 2019) shows the variations and improvements in the different products. The main conclusions refer to how using GeoTIFF combined with point data (rain gauges), it is possible to ensure simple but effective quality control of an operational radar network

Nota sobre la distribución de gotas de aire frío en Europa y su vecindad

[EN]Cold air pools over Europe and surrounding seas during the years 1974 to 1983 are briefly analysed as regards their initial location, the seasonal variation of the place of birth and their motion.[ES]Se analizan brevemente las gotas de aire frío halladas en el período 1974 a 1983 en relación con sus posiciones iniciales y la variación de éstas así como su movimiento

Aplicación del método de los análogos a Cataluña

Ponencia presentada en: I Congreso de la Asociación Española de Climatología “La climatología española en los albores del siglo XXI”, celebrado en Barcelona del 1 al 3 de diciembre de 1999.[ES]El objetivo del estudio que a continuación se presenta pretende la mejora de la previsión cuantitativa de la precipitación diaria en Cataluña a partir de la técnica de los análogos. En este caso se han utilizado los campos meteorológicos a 700 hPa, 1000 hPa y 70011000 hPa. Posteriormente también se ha incluido información a escala local proporcionada por los radiosondeos de Palma de Mallorca.[EN]The objective of this study pretends to show the improvement of the quantitative forecasting of daily rainfall in Catalonia from analogous technique. In this case fields to 700 hPa, 1000 hPa and 700/1000 hPa have been used. Subsequently also we have included it locale scale information proportionate for Palma of Majorca radiosoundings