A Study on the Rainfall and Landslides Along Sarawak Road Using the Antecedent Rainfall Analysis

Abstract

Sarawak is a state known for its high percentage of clayey soil which is overlaid with "weak" strata. The state has experienced many cases of severe landslides which even resulted to deaths. This study aims to address the correlation between rainfall intensity and landslide occurrences along roads in Sarawak. By using the antecedent rainfall analysis, this study emphasizes on more than 50 cases of landslides which occurred along Sarawak roads in the early 2009. Where, during the month of January marks the most amount of rainfall experienced by the state in that year. Many landslide cases were reported, especially along the stretch of Sarawak roads, leading to injuries and road repair cost. The hyetograph drawn in this analysis provides probability of days of antecedent rainfall that induces landslides as well as the total amount of rainfall during the antecedent period that would lead to landslide occurrence. The intensity of rainfall on the day of landslides itself as well as the highest intensity of rainfall during the antecedent period is also analyzed to establish whether it is a factor leading to the landslide occurrence. The observations and forecasts present in this paper will provide warning system for the members of public as well as the state's civil defense authority before the occurrence of rainfall-induced landslide.