Llasat et al. (2016) Trends in flash flood events versus convective precipitation in the Mediterranean region: The case of Catalonia

Identification

• Journal: Journal of Hydrology
• Year: 2016
• Date: 2016-05-28
• Authors: María Carmen Llasat, Raül Marcos-Matamoros, Marco Turco, Joan Gilabert, Montserrat Llasat-Botija
• DOI: 10.1016/j.jhydrol.2016.05.040

Research Groups

• Department of Astronomy and Meteorology, University of Barcelona, Barcelona, Spain
• Barcelona Supercomputing Center – Centro Nacional de Supercomputación (BSC-CNS), Barcelona, Spain

Short Summary

This paper analyzes the relationship and trends between flash flood events and convective precipitation in Catalonia, revealing an increase in flash floods partially explained by an increase in less torrential convective precipitation during summer, despite no detected trends in daily extreme precipitation.

Objective

• To analyze the potential relationship between flash flood events and convective precipitation in Catalonia.
• To identify and analyze trends in flash flood events and convective precipitation in Catalonia.
• To characterize flash flood events based on the convective contribution to rainfall using the 'b parameter'.

Study Configuration

• Spatial Scale: Catalonia (north-eastern Iberian Peninsula), focusing on small catchment areas (typically less than 1000 square kilometers).
• Temporal Scale:
  • Long-term precipitation series: Since 1928 (Fabra Observatory, 1-minute precipitation).
  • Shorter, more extensive precipitation series: 1996–2011 (43 rain gauges, 5-minute precipitation).
  • Flash flood event data: Period for trend analysis (not explicitly stated start date).

Methodology and Data

• Models used: The 'b parameter' was introduced as a metric:
  • b parameter: Ratio between convective precipitation and total precipitation in any period, used to characterize the degree of convective contribution to rainfall.
• Data sources:
  • Precipitation data:
    • Fabra Observatory: 1-minute precipitation series (since 1928).
    • Network of 43 rain gauges: 5-minute precipitation series (1996–2011).
  • Flood event data: INUNGAMA database (a flood database created by the GAMA team), based on damage information.
  • Extreme precipitation indices: ETCCDI (Expert Team on Climate Change Detection and Indices) extreme index.

Main Results

• An increase in flash flood events was detected in Catalonia.
• No significant trends were detected in terms of extreme values of precipitation on a daily scale, nor in the associated ETCCDI extreme index.
• The summer increase in convective precipitation was concentrated in less torrential events, which partially explains the positive trend observed in flash flood events.
• The 'b parameter' effectively characterizes flash flood events based on precipitation features:
  • Highest 'b' values (typically above 0.5 daily) correspond to short and local events.
  • The minimum threshold of daily 'b' for catastrophic flash floods was identified as 0.31.

Contributions

• Provides a detailed analysis of the relationship and trends between flash floods and convective precipitation in Catalonia, a region highly prone to such events.
• Introduces and applies the 'b parameter' as a novel metric to characterize the convective contribution to rainfall and classify flash flood events.
• Offers insights into potential drivers of increasing flash flood trends, suggesting that changes in less torrential convective precipitation, vulnerability, exposure, or land use might be more significant than changes in daily extreme precipitation.
• Utilizes long-term, high-resolution precipitation data (1-minute and 5-minute) for a comprehensive analysis.

Funding

• Not explicitly mentioned in the provided text.

Citation

@article{Llasat2016Trends,
  author = {Llasat, María Carmen and Marcos-Matamoros, Raül and Turco, Marco and Gilabert, Joan and Llasat-Botija, Montserrat},
  title = {Trends in flash flood events versus convective precipitation in the Mediterranean region: The case of Catalonia},
  journal = {Journal of Hydrology},
  year = {2016},
  doi = {10.1016/j.jhydrol.2016.05.040},
  url = {https://doi.org/10.1016/j.jhydrol.2016.05.040}
}