Geospatial Detection of Hidden Lithologies along Taiping to Ipoh Stretch of the Highway Using Medium Resolution Satellite Imagery in Malaysia

Abstract

A highway that is an essential link to major cities is prone to different geological hazards. The first step to tackling this problem is identifying the type of lithologies underneath the region’s bedrock. Detecting lithologies in a tropical rainforest area such as Malaysia may be a difficult task and logistically intricate due to inaccessibility to some areas. To overcome this challenge, band rationing was performed on the surface reflectance band of Landsat 8 OLI in the GIS environment regarding Malaysian locales. Four different band ratios were generated along with composite bands. The band ratios used for this study are 6/5 7/6 4/7, 5/4 6/5 7/6, 6/7 4/2 5/4, and 6/5 6/7 4/2. The band ratio 4/2 is used to map iron oxides due to their absorption capability in the blue region and high reflectance capability in the red region. The band ratio 6/7 is used for the lithological mapping of clay minerals and kaolinite due to the high and low reflectance in bands 6 and 7, respectively. While band ratio 5/4 is used for Alteration minerals, and ratio 6/5 is used for ferrous minerals. The generated outcome shows the lithological combination as granites, limestones, phyllites, and metasandstones. The metasediments and limestones region are also well discriminated within small areas of the study area. The best band ratio of 5/4 6/5 7/6 illustrates the most distinct spectral reflectance and absorption capability bringing out the weathered medium-grained granites. A new up-to-date lithologic map of the Taiping to Ipoh area is proposed based on the interpretation of image results and field verification work. Results show that the proposed methods have great potential for lithological mapping of tropical regions. Thus, this technique is recommended for mapping different types of granitic rocks, which is the most abundant rock underlying the study area along the highway.