EGU22-6389
https://doi.org/10.5194/egusphere-egu22-6389
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Empirical rainfall thresholds for landslide activity based on long-term Portuguese meteorological stations

Teresa Vaz1,2 and José Luís Zêzere1,2
Teresa Vaz and José Luís Zêzere
  • 1Centre for Geographical Studies, Institute of Geography and Spatial Planning, Universidade de Lisboa, Lisbon, Portugal (tvaz@campus.ul.pt)
  • 2Associated Laboratory TERRA

In this research the occurrence of landslides triggered by rainfall is investigated through the assessment of rainfall thresholds for three regions in Portugal: Lisbon, Oporto, and Coimbra. An historical landslide inventory is used, based on newspapers published between 1865 and 2010, associated with daily precipitation databases from three long-term meteorological stations. An empirical approach based on antecedent rainfall is applied to define the rainfall thresholds for landslides occurrence. The analysis is focused on each single rain gauge, for which the spatial representativeness is evaluated. The daily rainfall data is analysed using the Gumbel probability distribution for different durations. The critical rainfall combinations (cumulated rainfall duration) with the highest return period are associated with the landslide occurrence.

For the three regions, rainfall thresholds are defined from regression (linear and potential), extreme values (upper and lower) and probability (probability of a rainfall event resulting in a landslide event when the threshold is exceeded), and the results are assessed and calibrated using the receiver operating characteristic (ROC) metrics. The thresholds comparation reveal regional patterns in rainfall thresholds. The differences in regional critical rainfall conditions for landslide occurrence between regions are associated with geological, geomorphological, and climatic features.

 

This work is part of the project BeSafeSlide (BSS) - Landslide Early Warning soft technology prototype to improve community resilience and adaptation to environmental change [PTDC/GES-AMB/30052/2017]. JL Zêzere was supported by the RiskCoast project - Development of tools to prevent and manage geological risks on the coast linked to climate change, Interreg SUDOE [SOE3/P4/EO868]

How to cite: Vaz, T. and Zêzere, J. L.: Empirical rainfall thresholds for landslide activity based on long-term Portuguese meteorological stations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6389, https://doi.org/10.5194/egusphere-egu22-6389, 2022.