Coastal protection at west coast of Sri Lanka

Detached breakwater with beach fill Client: Ministry of Fisheries and Ocean Resources - Sri Lanka Construction Costs: approx. 40 mill. US$ Services: Conceptual planning of coastal stabilisation, detailed engineering planning, tendering awarding, construction supervision Period: 2001 - 2005 Cooperation: NIRAS Portconsult a/s, Denmark Lanka Hydraulic Institute, Sri Lanka

Sri Lanka is located at the southern tip of the Indian Subcontinent and has a coastline of about 1,700 km length. 50 % of the coastline is threatened by erosion, which is in particular significant at the south-west and west coast. On average the annual retreat is in the range between 0.2 and 1.0 m, but there are coastal stretches with an annual maximum retreat of 30 m. The coastal zone is densely populated and coastline retreat causes damage to houses, roads and other infrastructures. Various economic activities like fisheries and tourism are affected.

The local authorities react with emergency measures and construction of revetments. Usually these measures will be implemented after erosion have caused severe damages and losses, but in most cases the problem will be only shifted to the adjacent coastal stretches by these measures.

Insufficient general planning and lack of funds have prevented the implementation of large scale stabilisation concepts, which have been designed with bilateral technical assistance.
As part of the Asian Development Bank (ADB) funded Coastal Resources Management Project large scale coastal stabilising schemes have been planned at 7 sites and are currently implemented. Through these interventions a 250 km long coastal sector shall be stabilised.

The individual concepts incorporate different structural measures like revetments, groins and coastal breakwaters to create coastal fix points (artificial headlands). In addition sand is dredged offshore and pumped in between of these headlands creating stable beaches. In addition large scale beach nourishment (in total 2.5 mill. m³) is being implemented for the first time in Sri Lanka.

Figure 1 shows a coastal stretch with a detached breakwater and the newly created beach as result of artificial beach fill.

The pre-qualification, tendering and award procedures followed the ADB regulations, which are based on FIDIC documents. The evaluation had to satisfy ADB and the Government of Sri Lanka conditions. The consultant's recommendation passed without amendments the Sri Lanka Technical Committee and Cabinet Appointed Tender Board and has been endorsed by the ADB. The lowest bid was 5 % lower than the Engineer's Estimate.

Sellhorn has been responsible for development of stabilisation concepts based on assessment of coastal processes and provided the Team Leader.