Improving Existing Landslide Hazard Zonation Map in KMC Area, Sri Lanka

Potuhera, Oshadee Lasitha; Primali, Vithanage; Weerasinghe, Anuruddhika

Improving Existing Landslide Hazard Zonation Map in KMC Area, Sri Lanka

2015

Potuhera, Oshadee Lasitha | Primali, Vithanage | Weerasinghe, Anuruddhika

In Sri Lanka, presently used landslide hazard zonation (LHZ) map which was developed by National Building and Research Organization (NBRO) is based entirely on geological, geomorphological and hydrological factors. As development expands into unstable hill slope areas under the pressures of increasing population and urbanization, human activities such as deforestation or excavation of slopes for road cuts and building sites, etc., have become important triggers for landslide occurrence. The present study was undertaken in highly urbanized Kandy Municipal Council (KMC) area in Sri Lanka. Main objective of the study was to validate the existing LHZ map with current active landslides and the improvement of the LHZ map for further use for management purposes. Validation of the existing LHZ map shows lowest percentage of landslide occurrence in the landslides most likely to occur zone and highest in the landslides are to be expected zone. To evaluate this situation building density and transport lines were used. The relationship between building density and landslide occurrence was 97.1% and the relationship between distance from transport lines and landslide occurrence was 88.3% till 50 m. An improved LHZ map was developed including the effect of building density and distance from transport lines using frequency ratio method and improved LHZ map has an accuracy of 98.5%.

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