Development of an empirical model for rainfall-induced hillside vulnerability assessment: a case study on Chen-Yu-Lan watershed, Nantou, Taiwan

• Published in: Natural hazards (Dordrecht) Vol. 74; no. 2; pp. 341 - 373
• Main Authors: Lei, Tsu-Chiang, Huang, Yi-Min, Lee, Bing-Jean, Hsieh, Meng-Hsun, Lin, Kuan-Ting
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2014; Springer; Springer Nature B.V
• Subjects: Civil Engineering; Damage; Debris flow; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Empirical analysis; Engineering and environment geology. Geothermics; Environmental Management; Exact sciences and technology; Geological hazards; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Hydrologic data; Landslides; Landslides & mudslides; Mathematical models; Natural Hazards; Natural hazards: prediction, damages, etc; Numerical analysis; Original Paper; Rain; Rainfall; Rainfall intensity; Remote sensing; Risk assessment; Typhoons; Vegetation; Watersheds; Far East; Asia; Taiwan; Landslide; Maximum likelihood method; Risk management; Hazard analysis; damage; models; rainfall; Spot; kriging; probability; topography; debris flows; remote sensing; vegetation; slopes; classification; duration; drainage basins; management; numerical analysis; landslides; maximum likelihood; standard deviation
• ISSN: 0921-030X; 1573-0840
• DOI: 10.1007/s11069-014-1219-z

In Taiwan, the hillside is about 70 % of total area. These areas also have steep topography and geological vulnerability. When an event of torrential rain comes during a typhoon, the landslide disasters usually occur at these areas due to the long duration and high intensity of rainfall. Therefore, a design which considers the potential landslide has become an important issue in Taiwan. In this study, a temporal characteristic of landslide fragility curve (LFC) was developed, based on the geomorphological and vegetation factors using landslides at the Chen-Yu-Lan watershed in Taiwan, during Typhoon Sinlaku (September 2008) and Typhoon Morakot (August 2009). This study addressed an effective landslide hazard assessment process, linking together the post-landslide damage and post-rainfall data for LFC model. The Kriging method was used to interpolate the rainfall indices ( R 0 , R , I ) for numerical analysis. Remote sensing data from SPOT images were applied to analyze the landslide ratio and vegetation conditions. The 40-m digital elevation model was used for slope variation analysis in the watershed, and the maximum likelihood estimate was conducted to determine the mean and standard deviation parameters of the proposed empirical LFC model. This empirical model can express the probability of exceeding a damage state for a certain classification (or conditions) of landslides by considering a specific hazard index for a given event. Finally, the vulnerability functions can be used to assess the loss from landslides, and, in the future, to manage the risk of debris flow in the watershed.