Added value of regional landslide susceptibility analysis: the western branch of the East African Rift
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Authors
Depicker, A.
Jacobs, L.
Delvaux, D.
Havbenith, H.-B.
Maki-Maeteso, J.-C.
Govers, G.
Dewitte, O.
Discipline
Earth and related Environmental sciences
Subject
Geodynamics and mineral resources
Natural hazards
Audience
Scientific
Date
2019Metadata
Show full item recordDescription
Landslides have a strong impact on environments and societies in many regions worldwide. Nonetheless, for most  of these regions, landslide susceptibility has not been assessed in detail, so that susceptibility assessments necessarily  rely on relatively coarse global/continental models. The regional accuracy and/or geomorphological plausibility  of these global/continental models can be questioned due to several reasons: (1) they have not been calibrated and  validated for the region under consideration (2) they rely on few and simple covariates, and (3) when they are datadriven,  they are calibrated using a global rather than a local dataset. Therefore, we investigated whether there is an  added value of regional models that justifies the construction efforts and costs and whether these efforts should be  focused on compiling the regional landslide inventory or on the quality of spatial covariates such as slope steepness  and lithology. More specifically, we performed a regional susceptibility assessment in a tropical data-scarce environment  (the western branch of the East African Rift, with an approximate extent of 100,000 km2) and assessed its  added value compared to recent continental and global assessments in terms of model performance. First, we constructed  three data-driven regional models using a historical inventory ( > 6000 occurrences) compiled in Google  Earth. Second, we quantified the cost of making such an inventory, by looking at how the model quality was  impacted by (1) the inventory size, and (2) the use of more accurate regional peak ground acceleration and geolithology  covariates. Third, we compared the predictive power and geomorphological plausibility of the regional  and global/continental models. Despite the fact that global/continental models are useful in terms of identifying  landslide-prone areas, we observed that they were considerably outperformed by the regional models in terms of  predictive power ( AUC > 15%) and plausibility. We also showed that the differences in model performance are  linked to differences in the size and quality of the landslide inventory, rather than the use of more accurate, regional  covariates. Within our study area, high-quality models can be obtained with inventories of  500 landslides, i.e.  15% of the total inventory: a further increase in inventory size did not lead to better predictions. In conclusion,  we demonstrated that regional susceptibility assessments do lead to a better understanding of spatial patterns in  landslide susceptibility and are characterized by significant improvements in performance, compared to global and  continental products. For our study area, we showed that the construction of representative local inventories plays  a determinative role in these improvements.
Citation
Depicker, A.; Jacobs, L.; Delvaux, D.; Havbenith, H.-B.; Maki-Maeteso, J.-C.; Govers, G.; Dewitte, O. (2019). Added value of regional landslide susceptibility analysis: the western branch of the East African Rift. , European Geoscience Union, Vienna, 23-28 April 2019, Vol. Geophysical Research Abstracts Vol. 21, EGU2019-18367,Identifiers
Type
Conference
Peer-Review
No
Language
eng
