30 Jun 2021
30 Jun 2021
Status: a revised version of this preprint is currently under review for the journal NHESS.

Spatial variability in the relation between fire weather and burned area: patterns and drivers in Portugal

Tomás Calheiros1, Akli Benali2, João Neves Silva2, Mário Pereira3,4, and João Pedro Nunes1,5 Tomás Calheiros et al.
  • 1cE3c: centre for Ecology, Evolution and Environmental changes, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
  • 2Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
  • 3Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas (CITAB), Universidade de Trás-os-Montes e Alto Douro, Vila Real, Portugal
  • 4IDL, Universidade de Lisboa, Lisboa, Portugal
  • 5Soil Physics and Land Management group, Wageningen University and Research, Wageningen, Netherlands

Abstract. Fire weather indices are used to assess the effect of weather conditions on wildfire behaviour and the high Daily Severity Rating percentile (DSRp) is strongly related to the total burned area (BA) in Portugal. The aims of this study were to: 1) assess if the 90th DSRp (DSR90p) threshold is adequate for Portugal; 2) identify and characterize regional variations of the DSRp threshold that justifies the bulk of BA; and, 3) analyse if vegetation cover can explain the DSRp spatial variability. We used wildfire data, weather reanalysis data from ERA5, for the 2001–2019 period, and the land use map for Portugal. DSRp were computed for an extended summer period and combined with individual large wildfires. Cluster analysis was performed using the relationship between DSRp and BA, in each municipality. Results revealed that the DSR90p is an adequate threshold for Portugal and well related to large BA. However, at the municipality scale, differences appear between the DSRp linked to the majority of accumulated BA. Cluster analysis revealed that municipalities where large wildfires occur in high DSRp present higher BA in forests and are located in coastal areas. In contrast, clusters with lower DSRp present greater BA in shrublands and are situated in eastern regions. These findings can support better prevention and fire suppression planning.

Tomás Calheiros et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2021-173', Anonymous Referee #1, 04 Aug 2021
  • RC2: 'Comment on nhess-2021-173', Anonymous Referee #2, 28 Oct 2021

Tomás Calheiros et al.

Tomás Calheiros et al.


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Short summary
Fire weather indices are used to assess the effect of weather on wildfires and are strongly related to burnt area in Portugal. Fire weather risk was computed and combined with large wildfires. Results revealed the influence of vegetation cover: municipalities with prevalence of shrublands, located in eastern parts, burnt with less extreme conditions than those with higher forested areas, situated in coastal regions. These findings can support better prevention and fire suppression planning.