Probability of Landslide Occurrence Mapping using Probability Density Function in Nam Li Watershed of Thailand

Abstract

The study offers local probability density function (PDF) analysis to estimate spatial probability failure index (PFI) which was applied to mapping probability of landslide occurrence of the Nam Li watershed, Uttaradit, Thailand, where big event of landslide occurred in 2007. The PDF analysis required landslide susceptibility indexes (LSIs) as input. They were derived from slope stability model involving ranges of engineering properties and varying slopes of each rock unit. Critical PFI layer of each rock unit was cell-based estimated from one of the candidate LSIs which provided the biggest ratio of landslide scars and PFI equal 1. Critical PFIs of all rock units were divided into 4 classes, namely low, moderate, high, and very high to represent the probability of landslide occurrence of the area in terms of scar-class area ratio as 0.038, 0.051, 0.054, and 0.112, respectively.