Abstract

Improving the landslide hazard zonation map to risk zonation map
Track: Disaster and Emergency Management
Authors: Oshadee Potuhera, Primali Weerasinghe

The existing landslide hazard zonation (LHZ) map for Kandy Municipal Council area is entirely based on geomorphological and hydrological factors. Validation of this map shows low accuracy as building density and transport lines have increased landslide incidents. The relationship of landslide occurrence with building density and distance from transport lines was 97.1% and 88.3% respectively. An improved LHZ map was developed including above two factors using frequency ratio method. The improved LHZ map shows 98.5% accuracy.

Improved LHZ was used to develop the landslide risk zonation (LRZ) map. It depicts the level of risk combining the improved LHZ map with population density, building density and transport line density as high risk, moderate risk, low risk and safe zones.

Due to handling of large amount of spatial data ArcGIS was a very efficient tool to analyze the data wherever necessary and to produce very meaningful maps.