NATURE OF PROJECT: GEOLOGICAL & GEOHAZARDS ASSESSMENT
CLIENT: PROJEK LINTASAN SUNGAI BESI – ULU KELANG SDN BHD
DURATION: MARCH 2019 – JULY 2019
INTRODUCTION
SUKE is a 24.4km, three-lane, dual-carriageway, elevated expressway running from Sri Petaling to Ulu Kelang. It has 14 interchanges and reaches out to over 60 residential areas as well as connects to major highways and roads in Kuala Lumpur. Initial assessment on 2018 proved that there is a need to conduct a detailed study on the landslide-prone area along the designated package due to the proximity to the residential houses as well as considering the potential hazard to the highway itself. Thus, GMT has conducted LiDAR survey to detect potential landslide additionally sources from outside the ROW of the highway.
LiDAR data acquisition was done along the designated package of the SUKE highway stretch on 11th April 2019. Several products from LiDAR were generated such as Georeferenced Orthomosaic model, classified point cloud, Digital Surface Model (DSM), Digital Terrain Model (DTM) and Contour Map. Interpretations were made based on aerial imagery (orthomosaic) and LiDAR DTM data. Several factors were identified based on the published methodology, with conceptual model generated for geohazards within the designated study area.
Guidelines for Natural Terrain Hazard Studies by Ho and Roberts (2016) were used to analyzed the parameter such as i) Catchment characteristics, ii) Surface Geology, iii) Bedrock Geology, iv) Landslide Scars and Slope Features, v) Anthropogenic Features, vi) Erosion and vii) land use.
RESULT
The assessments are focused on three main type of geohazards, namely landslide, debris flow and rock fall.
Recent landslides, dormant landslides, flow-path of potential debris flow as well as the potential rock fall area are identified. From the assessment, there are 19 locations identified to potentially of geohazard occurrences where six (6) locations for landslides, nine (9) locations for debris flow and four (4) locations for rock fall. Figure 1 shows some of the identified geohazard locations that are tabulated in the Geohazard Risk Register Map. Apart from the assessment, proposed mitigation measure also suggested to overcome the potential problem.
Figure 1: Some of the identified geohazard at the designated package of the highway. Potential landslide is labelled as L, debris flow as DF while rockfall as RF.
CONCLUSION
LiDAR data is a useful method in geohazard study. The data that capture wide area in limited time useful especially for any project area that are inaccessible and have time constraint. However, there are also some limitation of the technology especially for the area with very thick vegetation cover and forest canopy. The interpretation of geohazard shall be conducted by the Professional Geologist (P.Geol) or geologist under direct supervision of the Professional Geologist.
