Bowing
The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Long term readers of this blog will know that I have a deep passion for understanding the patterns of fatal landslides in time and space. Some of my own work has focused on this research, from a global and regional perspective, but over the years I have also highlighted other interesting studies from around the world.
China is heavily impacted by landslides, but the challenges of language and the nature of reporting has made collation of data difficult for researchers from outside of the country. So, it is really welcome to see a paper published in the journal Landslides that provides detail on patterns of fatal landslides there. The work (Li et al. 2024) examines non-seismic fatal landslides from 2010 to 2022. The analysis is fascinating.
During the study period of 13 years, Li et al. (2024) recorded 710 fatal landslides, generating 5,1578 fatalities. The landslides occurred across the nation, but with a particular concentration in the central subtropical humid region. The temporal pattern was found to be strongly seasonal, with a peak in July across most of China, reflecting the monsoonal pattern of rainfall, as expected.
However, the most interesting aspect of this study is the longer term trend in annual fatalities. The graph below, from the paper, shows this data:-
As always with these datasets, the least noisy data in the number of fatal landslides (the fatalities data tends to be heavily affected by occasional landslides with a large number of deaths). Li et al. (2024) postulate that the data shows a cyclic pattern, with landslide peaks approximately every four years (e.g. in 2013, 2016 and 2020). But within this, they suggest that there is a net declining trend in the number of fatal landslides. Now, it should be highlighted that this is not analysed statistically, and that a thirteen year dataset is perhaps too short to be able to conclude definitively that this is correct. We need to increase the length of the dataset to do this, which is a project for another day.
They authors suggest that the cyclic pattern might be associated with El Nino events, but again this probably needs a more detailed (statistical) analysis. It is an intriguing possibility. The possible net declining trend in the number of fatalities, is potentially really important. Li et al. (2024) have this observation about the postulated trend:-
This may be attributed to the response of disaster prevention policies, the increase of investment in disaster prevention, and the strengthening of public awareness of disaster prevention.
If so, this is a major achievement. There is no doubt that there has been a huge increase in landslide research in China over the last two decades (the most recent complete edition of the journal Landslides has 20 articles, of which 12 have Chinese first authors – this feels to be typical now), and we’d hope that this would translate into reduced impacts of landslides, even as climate change is potentially increasing the underlying hazard. In addition, focused attempts to reduce risk and to increase awareness in China are likely to be having an impact.
The authors conclude the paper by highlighting their ambition to extend the analysis over a longer time period. This is very welcome – the research is undoubtedly contributing to a better understanding of landslide impacts in one of the most heavily impacted countries.
Reference
Li, Z., et al. 2024. Spatiotemporal patterns of non-seismic fatal landslides in China from 2010 to 2022. Landslides (2024). https://doi.org/10.1007/s10346-024-02362-1.
