Landslide mapping and characterization for agriculturally intensive mountainous region of Cameron Highlands, Malaysia

Abstract

Relatively cool tropical climate with high annual rainfall experienced in mountainous tropical region creates favorable agricultural areas where intensive agricultural practices often correlate with increasing landslide events. While it has long been associated with landslides, agricultural practice in such areas especially in Cameron Highlands, Malaysia continues to flourish with minimal regard to environmental sustainability and safety. Therefore, this study aims to confirm the relationship between human activities and landslide occurrences and identify human practices that directly or indirectly cause landslides. Aerial photograph was used to identify landslides and anthropogenic features while other remotely sensed data including Interferometric Synthetic Aperture Radar (IFSAR) were used to establish the geomorphology of study area. A total of 207 landslides were identified in a 25 km2 area from remote sensing study and field mapping. They were superimposed over several potential contributing factors including geology, slope gradient and human activities. This study found that landslides are more likely to occur in areas greater than 15° of slope angle. The main factor, however, is the human factor where 164 landslides (79.22% of total identified landslides) were located in agricultural lands. Poorly planned and engineered agricultural farms were identified as the main causal factors for landslide occurrences at the study area, either directly or indirectly. These issues were observed through remote sensing study using aerial photograph which were then verified through site observations. New district development plan called for a stricter regulations in new tourism and agricultural developments. Improvements should also be implemented on existing agricultural activities where most of these landslides were located at this area. Therefore, in addition to controlling new developments, improving of existing agricultural practices in Cameron Highlands shall be a major focus in ensuring slope safety and their sustainability.