Sinkhole susceptibility mapping in the Kuala Lumpur and the need for a buried karst database

One of the deliverables for the Newton Ungku Omar funded project: Disaster Resilient Cities: Forecasting local level climate extremes and physical hazards for Kuala Lumpur, awarded in 2016, was the development of a sinkhole susceptibility map for Kuala Lumpur. The purpose of the map was to contribute to the examination atmospheric and physical hazards in the context of climate extremes. At the commencement of the project there was no sinkhole database available to either inform or validate the mapping. The geology of the Kuala Lumpur area comprises a flat, alluvial plain underlain by a bedrock inlier of Cambrian Dinding Schist, Ordovician Hawthornden Schist and metamorphosed Silurian Kuala Lumpur Limestone, capped to the west by the Kenny Hill Formation (Carboniferous to Permian quartzite and phyllite) and bounded on the east and west by Triassic granitic hills. The structural geology is complex and the depth of weathered bedrock extends to 40 metres or more. Alluvial tin, derived from the granite ranges was trapped between karst pinnacles where they remained exposed. Consequently the Silurian limestone is largely buried by a range of sediment types, including the Kenny Hill Formation, placer deposits and alluvium associated with the Klang Valley. In order to generate the sinkhole susceptibility map, a comprehensive literature review of karst landforms and reports of sinkholes was used to better characterise karst processes in the Kuala Lumpur region. Processes with the potential to affect karst susceptibility were translated into “rules” for GIS hosted karst susceptibility mapping. For example, geological boundaries such as the juxtaposition of the schists and the limestone. The compilation of the literature based data highlighted the benefits that might be realized in the generation of a buried karst feature database