Two Fishery Harbours in Sri Lanka

Hambantota Bay Client: Ministry of Fisheries/Sri Lanka Construction Costs: 12 million US$ Service: Feasibility study, design, contracting, construction supervision Period: May 2004 May 2007 Cooperation: NIRAS a/s (Denmark) Lanka Hydraulic Institute (Sri Lanka)

As part of the Asia Development Bank financed Coastal Resources Management Project (CRMP) the fishery infrastructure of Sri Lanka shall be improved. This includes the construction of two fishery harbours, namely Ambalangoda at the south-west coast and Hanbantota at the south-east coast. The objectives are to provide at each side sheltered area for the fishing boats, quay wall for fish landing and supply of boats and a terminal area for harbour operation by private entities.

A British consultant has developed harbour concepts which finally proved to be not feasible (not economically viable due to excessive costs).

NIRAS Portconsult a/s (Denmark), Lanka Hydraulic Institute (Sri Lanka) and Sellhorn Ingenieurgesellschaft, the group is the design consultant for the coastal stabilisation component of the CRMP, have been entrusted to review the concepts and cut the works to a feasible level considering engineering sound civil designs and providing sufficient capacity within the allocated project budget.

The nearshore wave climate has been reviewed at both sites and a criteria for sufficient shelter during the annual monsoon periods and extreme storm events defined. The wave conditions at the harbour entrances and within the harbours have been modelled with the well known hydronumerical model package MIKE 21®. The average wave conditions along the wharfs have been analysed considering different reflection properties of the quay wall. Figure 2 shows a typical result of the modelling for Ambalangoda harbour, the nearfield modelling and the harbour wave conditions.

The rubble mound breakwaters have been designed based on physical model studies considering stability and overtopping.

Considering the soil conditions, the costs and availability of construction material and lifetime of structures (corrosion) a sheet pile quay solution has been found as most appropriate.

The quay wall alignment was optimised to avoid rock dredging, to balance dredging and reclamation works and to avoid unfavourable exposure to the waves.

The works have been tendered through international competitive bidding process and the award to the lowest bidder has been recommended by the consultant. The lowest bid was lower than the Engineer's Estimate and within the project budget.