dc.description.abstract | An event-based landslide susceptibility model is constructed based upon an event landslide inventory, topographic factors, geological factors and triggering factors. If an extreme rainfall, typhoon, or a major earthquake happened before a modeling event, the characteristics of landslide distribution may be different with undisturbed conditions. In the present study, an independent event is defined as the event without a prior-event which exceeds the rainfall threshold of the region within 6 months or more. In the Zengwen reservoir catchment area, this study chooses nine independent events, including Herb typhoon, Toraji typhoon, Mindulle typhoon, 20050615 rainfall, 20060609 rainfall, Morakot typhoon, 20110718 rainfall, 20120610 rainfall, and 20150523 rainfall, to establish nine event-based landslide susceptibility models. These models are then cross-validated. The results are good between rainfall events. Due to good performance of slope factor and triggering factors, Mindulle model is the most stable event-based landslide susceptibility model for typhoon events. It shows that AUC of the prediction curve for landslide induced by Morakot typhoon is 0.673; AUCs of prediction curve for other events are more than 0.710.
Compare the landslide susceptibility model built by multi-temporal landslide inventories, via traditional approach without triggering factors, to the nine basic susceptibility maps built by each event, a similar trend of susceptibility distribution among them can be observed. This study chooses the multi-temporal landslide susceptibility map as representative basic susceptibility of the region. The events are divieded into extreme events and common events. In each susceptibility bin and each rainfall bin, the average of probability of landslide failure is calculated from every events landslide inventory of same type, and then a relationship among landslide susceptibility, probability of failure, and rainfall intensity or total rainfall is completed. Utilizing the correlation coefficient between two rainfall factors, this study combines the two relationships to calculate the probability of failure of different susceptibility values in rainfall event. Comparing the result of landslide area predicted by the relationship and each event inventory shows that the relationship underestimate landslide area of Toraji typhoon, and overestimate landslide area of Herb typhoon, Mindulle typhoom and rainfall events. Predicted landslide area of Morakot typhoon is approximate to actual landslide area. | en_US |