Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 17, 1091-1109, 2017
https://doi.org/10.5194/nhess-17-1091-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
10 Jul 2017
Combination of statistical and physically based methods to assess shallow slide susceptibility at the basin scale
Sérgio C. Oliveira, José L. Zêzere, Sara Lajas, and Raquel Melo Centre for Geographical Studies, IGOT (Institute of Geography and Spatial Planning), Universidade de Lisboa, Edifício IGOT, Rua Branca Edmée Marques, 1600-276 Lisbon, Portugal
Abstract. Approaches used to assess shallow slide susceptibility at the basin scale are conceptually different depending on the use of statistical or physically based methods. The former are based on the assumption that the same causes are more likely to produce the same effects, whereas the latter are based on the comparison between forces which tend to promote movement along the slope and the counteracting forces that are resistant to motion. Within this general framework, this work tests two hypotheses: (i) although conceptually and methodologically distinct, the statistical and deterministic methods generate similar shallow slide susceptibility results regarding the model's predictive capacity and spatial agreement; and (ii) the combination of shallow slide susceptibility maps obtained with statistical and physically based methods, for the same study area, generate a more reliable susceptibility model for shallow slide occurrence. These hypotheses were tested at a small test site (13.9 km2) located north of Lisbon (Portugal), using a statistical method (the information value method, IV) and a physically based method (the infinite slope method, IS). The landslide susceptibility maps produced with the statistical and deterministic methods were combined into a new landslide susceptibility map. The latter was based on a set of integration rules defined by the cross tabulation of the susceptibility classes of both maps and analysis of the corresponding contingency tables. The results demonstrate a higher predictive capacity of the new shallow slide susceptibility map, which combines the independent results obtained with statistical and physically based models. Moreover, the combination of the two models allowed the identification of areas where the results of the information value and the infinite slope methods are contradictory. Thus, these areas were classified as uncertain and deserve additional investigation at a more detailed scale.

Citation: Oliveira, S. C., Zêzere, J. L., Lajas, S., and Melo, R.: Combination of statistical and physically based methods to assess shallow slide susceptibility at the basin scale, Nat. Hazards Earth Syst. Sci., 17, 1091-1109, https://doi.org/10.5194/nhess-17-1091-2017, 2017.
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Short summary
Approaches to assess shallow slide susceptibility at the basin scale are conceptually different depending on the use of statistical or physically based methods. Two hypotheses are tested: (i) both methods generate similar shallow slide susceptibility results and (ii) the combination of both susceptibility maps generates a more reliable susceptibility model. Model combinations registered a higher predictive capacity and the identification of areas where the results from both models are uncertain.
Approaches to assess shallow slide susceptibility at the basin scale are conceptually different...
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