Assessing the influence of anthropogenic causal factors on landslide susceptibility in Bukit Antarabangsa

Abstract

The purpose of this study is to assess the influence of landslide causal factors related to anthropogenic activities on landslide occurrence in Bukit Antarabangsa, a township northeast of Kuala Lumpur in Ampang Jaya Municipal Council. Landslide disasters are a widespread phenomenon in Malaysia’s Selangor region; with the study area being the site of numerous incidents that are frequently attributed to human-induced causes. The study implements a data-driven weight of evidence model to identify landslide causal factors that are most predictive of landslide occurrence based on an inventory of 20 landslides, and attempts to evaluate the extent to which these factors are driven by urban development. A total of 18 landslide causal factors are selected for analysis, 17 of which are used in the final analysis. The causal factors are categorized on four main groups, namely geological, geomorphological, hydro-tographical, and anthropogenic factors. Dichotomies between anthropogenic and non-anthropogenic factors are also made to understand the contribution of human-related factors on slope failures. The landslide causal factors, represented spatially as a set of factor maps were processed to determine factor classes for each landslide causal parameter, after which data was entered into a Bayesian weight of evidence statistical model to determine the contrast values for each factor class. The contrast values reflected the extent to which each causal factor class was predictive of landslide occurrences. These values were used to create weight maps for each factor class, which were combined to derive the landslide susceptibility index (LSI). The LSI values enabled visualization of the spatial distribution of landslide susceptibility across the study area based on a given combination of causal factors. Susceptibility maps were prepared for factor combinations including 1) only non-anthropogenic parameters and 2) all landslide causal parameters. Comparisons were made between these two combinations to determine the influence of human-induced factors on overall susceptibility, as well as analyses to determine the incremental effect that individual anthropogenic causal factors had on cumulative landslide susceptibility. The results indicated that collectively, the selected anthropogenic factors had a marginal influence on landslide susceptibility. However, within the anthropogenic factor group, land use land cover appeared to weigh significantly on landslide susceptibility, especially within the zone of the highest LSI values. This was followed closely by the influence of one distance to road factor class (147-218). Among the non-anthropogenic factors, lineament density, distance to lineament, slope, terrain ruggedness index (TRI), flow direction, aspect and terrain surface texture (TST) displayed the highest spatial correlation with landslide occurrence.