Development of a risk assessment methodologyfor landslides in Sri Lanka

Abstract

The central hilly areas of Sri Lanka underlaid by highly folded and fractured metamorphic rocks of different grades of weatheringhave a high probability for landslides. Intense precipitation is a major factor contributing to the landslides . Despite repeatedoccurrences of landslides in Sri Lanka inflicting losses in terms of life and property, very little has been done towards introducingscientific practices for delineating the degrees of hazard, identifying elements at risk, and landslide risk assessment. A National Building Research Organisation (NBRO) has already commenced production of landslide hazard zonation maps (1 : 10, 000) coveringthe areas prone to landslides. The proposed methodology for risk assessment in this paper will facilitate determination of riskthrough scientific analysis of landslide hazards in future. The demonstration of method was based on a case study carried out at Yatiyantota in Kegalle district. The expected annual total risk cost due to landslide disaster at specific site and/or annual risk coston specific element at risk (property or person) could be calculated through the given methodology. It may assist in the designingof cost effective solutions and mitigation actions for the area It is also expected to help non-technical decision-makers to assessthe situation before taking appropriate futuristic measure. This methodology may be used for assessment of the risk at any specificsite in landslide-prone areas in Sri Lanka. Assessment of risk before commencement of major infrastructure development projectsand establishment of human settlements in landslide-prone areas based on the risk criterion will be essential for sustainabledevelopment of the central hills of Sri Lanka.