Trends in flash flood events versus convective precipitation in the Mediterranean region: The case of Catalonia

Maria Carmen Llasat, Raul Marcos, Marco Turco, Joan Gilabert, Montserrat Llasat-Botija

ABSTRACT

The aim of this paper is to analyse the potential relationship between flash flood events and convective precipitation in Catalonia, as well as any related trends. The paper starts with an overview of flash floods and their trends in the Mediterranean region, along with their associated factors, followed by the definition of, identification of, and trends in convective precipitation. After this introduction the paper focuses on the north-eastern Iberian Peninsula, for which there is a long-term precipitation series (since 1928) of 1-min precipitation from the Fabra Observatory, as well as a shorter (1996–2011) but more extensive precipitation series (43 rain gauges) of 5-min precipitation. Both series have been used to characterise the degree of convective contribution to rainfall, introducing the β parameter as the ratio between convective precipitation versus total precipitation in any period. Information about flood events was obtained from the INUNGAMA database (a flood database created by the GAMA team), with the aim of finding any potential links to convective precipitation. These flood data were gathered using information on damage where flood is treated as a multifactorial risk, and where any trend or anomaly might have been caused by one or more factors affecting hazard, vulnerability or exposure. Trend analysis has shown an increase in flash flood events. The fact that no trends were detected in terms of extreme values of precipitation on a daily scale, nor on the associated ETCCDI (Expert Team on Climate Change Detection and Indices) extreme index, could point to an increase in vulnerability, an increase in exposure, or changes in land use. However, the summer increase in convective precipitation was concentrated in less torrential events, which could partially explain this positive trend in flash flood events. The β parameter has been also used to characterise the type of flood event according to the features of the precipitation. The highest values correspond to short and local events, usually with daily β values above 0.5, while the minimum threshold of daily β for catastrophic flash floods is 0.31

Keywords

  • Flash floods;
  • Convective precipitation;
  • β parameter;
  • Trend analysis;
  • Mediterranean

You can download here: http://www.sciencedirect.com/science/article/pii/S0022169416303079

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9th HyMeX Workshop 21-25 September 2015, Mykonos, Greece

General information

The 9th HyMeX workshop will take place from 21 to 25 September 2015, in Mykonos Island, Greece. It will be organized by the National Observatory of Athens at Saint-John hotel.

Objectives

The general objectives of the HyMeX workshops are to strengthen the links and knowledge exchange, as well as to foster collaborations within the HyMeX research community. The 9th HyMeX workshop will occur at midterm of the programme. It will be the opportunity to assess the achievements of the programme, both in terms of data collected and science results, against the original objectives of the HyMeX Science Plan (http://www.hymex.org/public/documents/HyMeX_Science_Plan.pdf). Running over 5 days, the programme will consist of plenary sessions with review solicited talks and Science Teams oral and poster sessions with an open call for contributions to present and discuss recent scientific progresses regarding the Mediterranean water cycle. Leer más de esta entrada

Les Programmes d’Actions et de Prévention des Inondations (PAPI) : Expériences, bilans et perspectives

11ème Rencontre GÉORISQUE
27 & 28 Janvier 2015 – MONTPELLIER

Les inondations représentent près des deux tiers des arrêtés catastrophes naturelles sur le territoire français. En 2011, on estime à près de 6 millions le nombre de personnes susceptibles d’être impactées par une inondation. La gestion de ce risque reste donc une priorité.

Dans le cadre d’une politique de gestion de l’aléa et de réduction de la vulnérabilité des personnes et des territoires, les Programmes d’Actions de Prévention des Inondations (PAPI) ont été lancés en 2002. Ils ont vocation à coordonner à l’échelle du bassin versant les politiques de gestion du risque inondation entre les acteurs locaux et les services de l’Etat.

Après un bilan de la première génération de PAPI 2003-2009, les règles ont été affermies en 2011 et les PAPI sont devenus des outils majeurs de la prévention des inondations en France.

La seconde génération doit se positionner dans le cadre de la Directive européenne Inondation (DI) de 2007 et présente donc un certain nombre de nouveautés.  Leer más de esta entrada

GEORISK 2014 “IMPROVING GEOPHYSICAL RISK ASSESSMENT, FORECASTING, AND MANAGEMENT”

Organization: IUGG Commission on Geophysical Risk and Sustainability

Date and place: November 18-21, 2014, Madrid, Spain

Deadlines: October 15

Registration here!

The goal of the conference


We propose the theme of IMPROVING GEOPHYSICAL RISK ASSESSMENT, FORECASTING, AND MANAGEMENT as the main goal of the conference. What is the essential knowledge-based on Geophysical Risks that scientist, administrators, politicians, economists, emergency managers, citizens, require for sustainable development and for preparedness and emergency management in future crises? There is a growing need to combine natural risks forecasting and assessment techniques to improve the information that officials involved with early warning and management of crises require in order to answer efficiently when they face an emergency. Modern society is making a considerable effort to improve our knowledge of the dynamics of natural systems and their associated hazards, as well as on promoting technological development addressed to early warning and monitoring of natural disasters. However, the integration of scientific and technological achievements into products with a direct applicability to Society has not always been reached. Moreover, natural disasters have been treated separately not only for what concerns to their dynamics, but also with regard to their corresponding forecasting and assessing technologies, when most of them are common or show significant similarities. Therefore, it is easy to assume that a comparison between the scientific and technological research carried out on the different natural hazards, as well as a joint effort of the scientists and technologists who work on assessment and mitigation of natural disasters, would imply considerable social benefits. Consequently, accurate assessment and mitigation programmes, as well as the development of effective tools for management of crisis are necessary to reduce risk and to promote sustainable development.

The conference will analyse the state of the art of relevant aspects in geophysical risk assessment and management, such as modelling and monitoring of hazardous phenomena, hazard assessment methods, quantification of uncertainty in forecasting geophysical hazards, decision making models, communication protocols among the different stakeholders involved in managing geophysical risks, vulnerability assessment methodologies, or education about geophysical risk.

ALL INFORMATION: http://www.georisk2014.com/Home.html

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PhD fellow position in Geomorphology/ Paleoclimatology

Contrato predoctoral (4 años) para la formación de doctores en Geomorfología/Paleoclimatología

Fluvalps-Iberia Project: Multi-proxy analysis of palaeofloods in mountain regions. Driving factors and impacts in the past, present and future (CGL2013-43716-R)

The Fluvalps-Iberia project aims to generate from a multidisciplinary approach, that includes alluvial sedimentary archives, long reference time series of paleofloods in the Eastern Betic Range, the Swiss Alps and the Northeastern Iberian Peninsula (comparative study area). The detailed analysis of these geoarchives will enlarge the flood series to record low-frequency extreme events. Furthermore, the trends, clusters and gaps detected in the instrumental and documentary time series can be interpreted in the context of millennia and centennial climate changes and variability. In addition, the project investigates the driving factors and effects in the past, present and future. The novelty is the reconstruction of long time series generated not from lake records of small watersheds, but from high-resolution floodplain sediments from interdistributary basins, which reproduce the fluvial dynamic and environment of a medium size basin (between 250 and 600 km2), providing a regional signal that could be influenced by the global climate variability. The robustness of the flood series come from the calibration of different proxies to each other: natural archives (sedimentary, geochemical, pollen, lichen), documentary sources (descriptions of floods, historical buildings and maps) and instrumental (flow, precipitation, temperature), cataloging atmospheric synoptic types from grids and correlations with climate reference records. This approach aims to identify more precisely the cyclic pattern, mechanisms and driving forces (orbital, solar, climate, volcanic and land use) by statistical processing of the generated time series and also of paleoclimatic reference records. Leer más de esta entrada

Flash flood evolution in North-Western Mediterranean

Abstract

The present paper shows an in-depth analysis of the evolution of floods and precipitation in Catalonia for the period 1981–2010. In order to have homogeneous information, and having in mind that not gauge data was available for all the events, neither for all the rivers and stream flows, daily press from a specific newspaper has been systematically analysed for this period. Furthermore a comparison with a longer period starting in 1900 has been done. 219 flood events (mainly flash flood events) have been identified for the period of 30 years (375 starting in 1900), 79 of them were ordinary, 117 of them were extraordinary and 23 of them were catastrophic, being autumn and summer the seasons with the maxima values. 19% of the events caused a total of 110 casualties. 60% of them died when they tried to cross the street or the stream. Factors like the evolution of precipitation, population density and other socio-economical aspects have been considered. The trend analysis shows an increase of 1 flood/decade that probably has been mainly due to inter-annual and intra-annual changes in population density and in land-use and land-cover.

Authors: Maria Carmen Llasat, Raül Marcos, Montserrat Llasat-Botijaa, Joan Gilabert, Marco Turco i Pere Quintana-Seguí.

Podéis descargar el artículo de forma gratuita hasta el 31 de agosto. LINK:  http://authors.elsevier.com/a/1PLdgcd3RmlUW

Floods in the north-western Mediterranean region: presentation of the HYMEX database and comparison with pre-existing global databases

Authors: M. Carmen LLASAT, Montserrat LLASAT-BOTIJA, Olga PETRUCCI, Angela Aurora PASQUA, Joan ROSSELLO, Freddy VINET, Laurent BOISSIER

Abstract:

The contribution presents the database on floods (1981-2010) that is being developed in the framework of HYMEX project and the preliminary results obtained for the NW sector of Mediterranean region. This database contains data on damages and the main hydrometeorological features of each reported event. The study is included in one of the objectives of the Working Group 5, which is a transversal group of the HYMEX project dealing with all the aspects related to societal and ecological impacts of hydrometeorological extremes, as well as their perception and communication processes. One of the main points of the WG5 is the creation of a common database on floods and their societal impact, for the Mediterranean region, as well as its analysis. Although some databases already exist and are frequently consulted, they are mainly focused on “major” catastrophic events. But the Mediterranean region experiences every year a high number of minor flash-floods that, considered in their totality, produce important losses and disruptions of the everyday life. This contribution is focused on North-Eastern Spain, South of Italy and South-East of France and the objective is to include all the floods that have produced damages, although they are not considered as “major” disasters.

Key-words: floods, flash-floods, societal impact, damages, Mediterranean Region.

Link: http://www.shf-lhb.org/articles/lhb/abs/2013/01/lhb2013001/lhb2013001.html