National Building Research Organisation

Landslides attract increasing attention in many countries in the world as a natural disaster. They cause substantial damage to life, farmlands, communication systems; engineering constructions, forest growth, infrastructure such as educational facilities, domestic and industrial supply systems, roads, railway lines, etc., and therefore the economic development of many countries are threatened by landslides.

In Sri Lanka, most of the landslides, rock and cutting failures occur in the central highland of the country. The central region of Sri Lanka is hilly and mountainous with highly fractured and folded basement rock overlain by residual soil and colluvium. The elevation of the hilly region of the country ranges from 185m to 2717m above mean sea level. It is about 20% of the total land area and is occupied by 30% of the total population of the country. Landslides, slope failures and rock falls are frequent phenomena in these areas causing severe damages to life and property. Therefore, occurrence of frequent Landslides and slope failures could be considered as the most significant natural disaster in Sri Lanka. They are likely to have a greater economic impact in the urban and semi urban environment when there is a possibility of damages and losses to the investments on various development projects, infrastructure facilities and more importantly to lives. The total extent of loss of forest cover, wild life and damage to the eco-system by landslides cannot be estimated and will probably remain unknown.

In the case of occurrences of Landslides in Sri Lanka, ten major districts have been identified as Landslide prone areas. Those are Badulla, Nuwara-Eliya, Rathnapura, Kegalle, Kandy, Matale, Matara, Galle, Hambanthota and Kalutara. More than 12,500 Km² of highly prone area to Landslides are spread over these ten districts. During the last rainy season, hilly areas belonging to Matara, Galle and Hambanthota districts were severely affected by large-scale Landslides and slope failures. Major Landslides that occurred during the past two decades have taken thousands of lives and about 175,000 people became homeless.