MAPPING OF HAZARD-PRONE AREAS IN SINGAPORE

Abstract

Due to its location, Singapore is free of most major natural hazards except floods and landslides. These hazards arise from a combination of factors. The geology, landforms and drainage combine to provide a physical environment susceptible to floods and landslides on a local scale. Rainfall is often the mechanism which triggers off slides and causes floods. The process of urbanization has significantly altered the physical environment. Housing development, establishment of industrial estates and road constructions are occupying an increasing area of the island. These have the effect of increasing the frequency and magnitude of both floods and landslides by altering the surface and subsurface hydrological and soil conditions. Both hazards have fairly distinct temporal and spatial distributions, allowing the pattern of areas prone to these hazards to be mapped, which is perhaps the most important contribution of this exercise. However, the information available for these two hazards differs, as does people's perception of floods and landslides. Adjustments to both hazards in Singapore are mainly structural in nature. Non-structural adjustments are not practiced. Case studies of selected sites highlight the different causes of floods and landslides and the different measures taken to mitigate these hazards. Several types of mapping were done. The flood and landslide-prone areas for the whole of Singapore Island and those of selected sites were mapped. For flood hazard, areas prone to flooding were identified. In landslide-prone areas, work centered on the mapping of landuse, areas of slope repair and updating of areas which experience repeated slope failures.