LANDSLIDE MAPPING AND DEBRIS FLOW RECONSTRUCTION USING IMAGE INTERPRETATION AND MODELING METHODS: HONGCHUN CATCHMENT, SOUTHWEST, CHINA

Abstract

Landslide mapping and debris flow reconstruction was carried out in the Hongchun catchment South West, China. The research put into perspective the concept of multi-hazard assessments. Image interpretation was used to map the landslides while the debris flow was model using Flo-2D model. The result of the research was validated by data obtained from fieldwork and back analysis of previous event. The result from the image interpretation revealed a total of 38 landslides which was further characterized according to scarp and body respectively. The field mapping result, supported by historical knowledge gathered through interviews revealed that the co-seismic landslides were the potential source of debris flows in the catchment. The Flo-2D model reconstructed the debris flow volume of 171,350 m3 representing 80.7% of the total debris flow volume. Other parameters determined for the catchment are viz: maximum flow velocity of 2.9m/s, area extent of 975000 km2, average flow depth of 11.2 m and impact force of 4,559 N/m2. This paper, therefore, presents a multi-hazard assessment approach to map landslides (inventories) and model debris flow within the Hongchun catchment. These multi-hazard assessment methods can detects landslides and model debris flow relatively quickly, and hence has the potential to aid risk analysis, disaster management and decision making processes in the aftermath of an earthquake or an extreme rainfall event.