Integrating spatial and temporal probabilities for the annual landslide hazard maps in Shihmen watershed, Taiwan
Abstract. Landslide spatial probability, temporal probability, and landslide size probability were employed to perform landslide hazard assessment in this study. Following a screening process, landslide susceptibility-related factors included eleven intrinsic geomorphological factors and two extrinsic rainfall factors, which were evaluated as effective factors because of the higher correlation with the landslide distribution. Landslide area analysis was first employed to establish the power law relationship between landslide area and noncumulative number, and a probability density function was then used to convert this relationship to cumulative probability of landslide area. The exceedance probability of rainfall with different recurrence intervals was used to determine the temporal probability of those events. Finally, the landslide spatial probability, landslide area probability, and exceedance probability were integrated to estimate the annual probability of each slope-unit with a landslide area exceeding a certain threshold in a watershed. The slope-units with high landslide probability were concentrated in Taigang River watershed, which should be the leading target of future management efforts.