Riscos meteorològics, ens hem de preocupar o ocupar?

Conferència realitzada el Dissabte, 22 de Febrer de 2020La conferència constarà de tres parts. La primera presentarà que són els riscos meteorològics, quina relació tenen amb la física i quin impacte tenen al món. En segon lloc es parlarà dels riscos meteorològics que afecten Catalunya i de la seva evolució passada i futura. La darrera part es centrarà en veure com poder afrontar aquests riscos i mitigar els seus impactes

Por qué el creciente impacto de las inundaciones no se debe solo al cambio climático

Las imágenes que vimos hace poco de Benicàssim tras unas lluvias que acumularon más de 200 l/m² en pocas horas, el vídeo viral en las redes del metro inundado en China, las trágicas inundaciones que asolaron pueblos alemanes a principios de verano, las lluvias torrenciales en el Sahel

Convective precipitation trends in the Spanish Mediterranean region

This paper aims to analyse the distribution and temporal evolution of convective precipitation in the Mediterranean region of Spain. To accomplish this goal, we used 148 sets of 5-min rainfall rate data from the 1989–2015 period. The selected regions were the Júcar Hydrographic Confederation (CHJ) and the Internal Basins of Catalonia (CIC), which cover most of the autonomous communities of Catalonia and the Valencian Community (east Spain). The average 5-min intensity threshold of 35 mm/h and the β parameter, defined as the ratio between convective precipitation versus total precipitation in any period, were used to characterise convective precipitation. Convective episodes were categorised as “very convective”, “moderately convective”, and “slightly convective” based on the β value. After quality control, the series of 129 stations were clustered into homogeneous precipitation zones that also include β as one of the variables of characterisation. The results show that convective precipitation can contribute to total annual precipitation by up to 16% on average, but it is generated by a very small percentage of convective events (between 3% and 6% across all the stations) in comparison with the total number of rainfall episodes. In this sense, moderately convective events are the most common, with a predominantly unimodal monthly distribution of β, with summer the most convective season. Trends show a significant increase in precipitation, convective precipitation, and convective episodes in the CHJ. On the other hand, a positive trend of convective events is predominant in the CIC region, despite an overall precipitation decrease in the analysed period. These results are relevant given that extreme daily rainfall does not show a positive or significant trend, and they are in line with the impact of climate change on increased atmospheric instability and water vapour in the atmosphere. They highlight the need to work with sub-daily precipitation series in the case of the Mediterranean, which is mainly affected by flash floods.This work has been done in the framework of the M-CostAdapt (CTM2017-83655-C2-2-R) research project, funded by the Spanish Ministry of Economy and Competitiveness (MINECO/AEI/FEDER, UE), and the PIRAGUA project EFA210/16 funded by INTERREG/POCTEFA

Towards a better understanding of the evolution of the flood risk in Mediterranean urban areas: the case of Barcelona

This contribution explores the evolution of the flood risk in the Metropolitan Area of Barcelona (MAB; Northeast Spain) from 1981 to 2015, and how it has been affected by changes in land use, population and precipitation. To complete this study, we analysed PRESSGAMA and INUNGAMA databases to look for all the information related to the floods and flash floods that have affected the chosen region. The ''Consorcio de Compensación de Seguros'', a state insurance company for extraordinary risks, provided data on economic damage. The extreme precipitation trend was analysed by the Fabra Observatory and El Prat-Airport Observatory, and daily precipitation data were provided by the State Meteorological Agency of Spain (AEMET) and the Meteorological Service of Catalonia (SMC). Population data were obtained from the Statistical Institute of Catalonia (IDESCAT). Changes in land use were estimated from the land use maps for Catalonia corresponding to 1956, 1993, 2000, 2005 and 2009. Prevention measures like rainwater tanks and improvements to the drainage system were also been considered. The specific case of Barcelona is presented, a city recognised by United Nations International Strategy for Disaster Reduction as a model city for urban resilience to floods. The evolution of flood events in the MAB does not show any significant trend for this period. We argue that the evolution in floods can be explained, at least in part, by the lack of trend in extreme precipitation indices, and also by the improvements in flood prevention measures

Changes in meteo-hydrological extremes in Spain at different levels of global warming

Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018.This work assesses changes in the extremes of precipitation and streamflow in Spain assuming global warming scenarios of 1.5, 2, and 3 degrees Celsius from pre-industrial levels. We consider an ensemble of seven regional climate model simulations spanning the period 1970-2099 to evaluate precipitation changes and to drive a distributed hydrological model and thus to derive streamflow statistics under present and future climates. The climate simulations were performed under the umbrella of the EURO-CORDEX project, thus covering Europe with a spatial resolution of 0.11 degree both in latitude and longitude, the finest so far in this type of climatological multimodel and multi-scenario experiments. Preliminary results suggest that constraining global warming well below 2°C, as sought in the Paris Agreement, reduces the probability of increasing drought related indices.This work has been supported by the Spanish Projects HOPE (CGL2014-52571-R) and M-CostAdapt (CTM2017-83655-C2-2-R) of the Ministry of Economy, Industry and Competitiveness, as well as the EFA 210/216 PIRAGUA project financed by the INTERREG V A (POCTEFA) and FEDER

Abating heat waves in a coastal Mediterranean city : What can cool roofs and vegetation contribute?

Unidad de excelencia María de Maeztu CEX2019-000940-MAltres ajuts: Acord transformatiu CRUE-CSICThe frequency and intensity of heat waves (HW) in cities are on the rise due to climate change as well as urban fabric materials and anthropogenic activities that affect heat accumulation. The efficacy of HW mitigation strategies depends on a city's specific and unique morphology, land use, building materials, climate and geography. In this study, we show the effectiveness of cool roofs and vegetation in reducing temperature in the Metropolitan Area of Barcelona (AMB). We use the Weather and Research Forecasting (WRF) model with the urban scheme BEP+BEM, including11 urban classes to simulate a HW that occurred in August 2015. We find that cool roofs reduce temperature best during the day (0.67 °C average and 2.22 °C maximum reductions), while additional green areas moderate temperatures to a lesser degree but also more evenly during the day and at night (average reductions of 0.15 °C and 0.17 °C, respectively). However, when irrigation is increased, the temperature reduction during the day is intensified due to the cooling effect of more evapotranspiration. The thermal regulation of combining the two strategies is the most evenly distributed over the AMB and has the highest impact, with an average and maximum reduction of 1.26 °C and 4.73 °C at 13:00UTC

Trend analysis for daily rainfall series of Barcelona

Frequency analysis of hydrological series is a key point to acquire an in-depth understanding of the behaviour of hydrologic events. The occurrence of extreme hydrologic events in an area may imply great social and economical impacts. A good understanding of hazardous events improves the planning of human activities.Peer ReviewedPostprint (published version

Large wood debris that clogged bridges followed by a sudden release: the 2019 flash flood in Catalonia

The aim is the reconstruction of the October 2019 flash flood, that was documented through extensive field work: rainfall (300 mm in just a few hours), flood marks, times of flood passage and witnesses' snapshots and reports, channel changes, log drift (20,000 trees) and woody debris at bridges, as well as large damage and six fatalities. The methods are: hydrological model built for the rainfall-runoff in the basin and the flood routing in the river, use of hydraulic principles such as flow at waterfalls, flow against obstacles (trees), etc. and finally 1D/2D free surface numerical models. The uppermost 100 km2 produced discharges of 700 m3/s (up to 50 m3/s/km2, locally). Three bridges failed, but their cascading failure (when one failure triggers the next one downstream) was not proved. The main channel widened more than 10 times, dragging away soil and vegetation like a bulldozer. The resulting large wood debris that clogged two bridges worsened the inundation. An anomalous flow downstream, probably a surge of around 1090 m3/s, due to the failure of a woody jam at a narrow bridge, took two lives. Water Authority is now warning flood planners that vegetated, torrential basins may cause catastrophic floods in the valley towns, if their narrow bridges are sensitive to woody debris.Catalan Water Authority and its Tarragona officers, Meteoprades and Fons Signatus, Joan March and a number of witnesses. The UPC's contribution was funded by the contract CTN2000029 of the “Agència Catalana de l′Aigua”. The UB's contribution has been developed within the framework of the AGORA project, funded by the "Agència Catalana de l′Aigua". Our thanks to the "Museu de la Vida Rural", in l′Espluga de Francolí, and all the citizens who contributed to the return of experience. The UIB's research has been supported by the Ministerio de Ciencia, Innovación y Universidades (CGL2017-82868-R and PID2020-113036RB-I00/AEI/10.13039/501100011033 research projects, which are partially supported by the European Regional Development Funds).Peer ReviewedPostprint (published version

Application of Severe Weather Nowcasting to Case Studies in Air Traffic Management

Effective and time-efficient aircraft assistance and guidance in severe weather environments remains a challenge for air traffic control. Air navigation service providers around the globe could greatly benefit from specific and adapted meteorological information for the controller position, helping to reduce the increased workload induced by adverse weather. The present work proposes a radar-based nowcasting algorithm providing compact meteorological information on convective weather near airports for introduction into the algorithms intended to assist in air-traffic management. The use of vertically integrated liquid density enables extremely rapid identification and short-term prediction of convective regions that should not be traversed by aircraft, which is an essential requirement for use in tactical controller support systems. The proposed tracking and nowcasting method facilitates the anticipation of the meteorological situation around an airport. Nowcasts of centroid locations of various approaching thunderstorms were compared with corresponding radar data, and centroid distances between nowcasted and observed storms were computed. The results were analyzed with Method for the Object-Based Evaluation from the Model Evaluation tools software (MET-10.0.1, Developmental Testbed Center, Boulder, CO, US) and later integrated into an assistance arrival manager software, showing the potential of this approach for automatic air traffic assistance in adverse weather scenarios