Adopting the I 3 –R 24 rainfall index and landslide susceptibility for the establishment of an early warning model for rainfall-induced shallow landslides

Rainfall-induced landslides number among the most devastating natural hazards in the world and early warning models are urgently needed to reduce losses and fatalities. Most landslide early warning systems are based on rainfall thresholds defined on the regional scale, regardless of the different la...

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Bibliographic Details
Published in:Natural hazards and earth system sciences 2018-06, Vol.18 (6), p.1717-1733
Main Authors: Wei, Lun-Wei, Huang, Chuen-Ming, Chen, Hongey, Lee, Chyi-Tyi, Chi, Chun-Chi, Chiu, Chen-Lung
Format: Article
Language:English
Subjects:
Duration
Early warning systems
Field investigations
Hazards
Landslides
Landslides & mudslides
Local government
Rain
Rainfall
Rainfall index
Rainfall intensity
Rainfall patterns
Regression analysis
Slope
Thresholds
Warning systems
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Summary:Rainfall-induced landslides number among the most devastating natural hazards in the world and early warning models are urgently needed to reduce losses and fatalities. Most landslide early warning systems are based on rainfall thresholds defined on the regional scale, regardless of the different landslide susceptibilities of various slopes. Here we divided slope units in southern Taiwan into three categories (high, moderate and low) according to their susceptibility. For each category, we established separate rainfall thresholds so as to provide differentiated thresholds for different degrees of susceptibility. Logistic regression (LR) analysis was performed to evaluate landslide susceptibility by using event-based landslide inventories and predisposing factors. Analysis of rainfall patterns of 941 landslide cases gathered from field investigation led to the recognition that 3 h mean rainfall intensity (I3) is a key rainfall index for rainfall of short duration but high intensity; in contrast, 24 h accumulated rainfall (R24) was recognized as a key rainfall index for rainfall of long duration but low intensity. Thus, the I3–R24 rainfall index was used to establish rainfall thresholds in this study. Finally, an early warning model is proposed by setting alert levels including yellow (advisory), orange (watch) and red (warning) according to a hazard matrix. These differentiated thresholds and alert levels can provide essential information for local governments to use in deciding whether to evacuate residents.
ISSN:1684-9981
1561-8633
1684-9981
DOI:10.5194/nhess-18-1717-2018