Abstract
Abstract. In this study, the recently launched Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2 (ALOS-2), remote sensing data were used to map geologic structural and topographical features in the Kelantan river basin for identification of high potential risk and susceptible zones for landslides and flooding areas. A ScanSAR and two fine mode dual polarization level 3.1 images cover Kelantan state were processed for comprehensive analysis of major geological structures and detailed characterizations of lineaments, drainage patterns and lithology at both regional and district scales. Red-Green-Blue (RGB) colour-composite was applied to different polarization channels of PALSAR-2 data to extract variety of geological information. Directional convolution filters were applied to the data for identifying linear features in particular directions and edge enhancement in the spatial domain. Results derived from ScanSAR image indicate that lineament occurrence at regional scale was mainly linked to the N-S trending of the Bentong-Raub Suture Zone (BRSZ) in the west and Lebir Fault Zone in the east of the Kelantan state. Combination of different polarization channels produced image maps contain important information related to water bodies, wetlands and lithological units for the Kelantan state using fine mode observation data. The N-S, NE-SW and NNE-SSW lineament trends were identified in the study area using directional filtering. Dendritic, sub-dendritic and rectangular drainage patterns were detected in the Kelantan river basin. The analysis of field investigations data indicate that many of flooded areas were associated with high potential risk zones for hydro-geological hazards such as wetlands, urban areas, floodplain scroll, meander bend, dendritic and sub-dendritic drainage patterns, which are located in flat topograghy regions. Numerous landslide points were located in rectangular drainage system that associated with topographic slope of metamorphic and Quaternary rock units. Some large landslides were associated with N-S, NNE-SSW and NE-SW trending fault zones. Consequently, structural and topographical geology maps were produced for Kelantan river basin using PALSAR-2 data, which could be broadly applicable for landslide hazard mapping and identification of high potential risk zone for hydro-geological hazards.
Highlights
Structural field mapping is often difficult in heavily vegetated Terrain
A wide-swath ScanSAR observation mode of PALSAR-2 was used for comprehensive analysis of major geological structures, which shows mega-geomorphology and mega-lineaments in the Kelantan state
Results of this investigation indicate that the PALSAR-2 onboard the Advanced Land Observing Satellite-2 (ALOS-2) has proven to be successful advanced remote sensing satellite data for disasters monitoring in tropical environments
Summary
Structural field mapping is often difficult in heavily vegetated Terrain. This is the case with the study area where dense vegetation cover, deep weathering and scarcity of bedrock exposure hampers geological structure mapping over a long distance. The presence of linear tectonic structures is one of the important factors in geological hazard occurrences (Bannert, 2000a,b). Lineaments are represented by faults (linear features), lithological contacts between rock units and drainage patterns in any area (van der Pluijm and Marshak, 1997). Observation from satellite images (Landsat Thematic Mapper) in the Himalayan Mountains of Nepal and China revealed a clear connection between of active faults, associated with earthquakes and the occurrence of large landslides (Bannert, 2000a,b)
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