Environmental impact assessment for the proposed shore protection project at Hoarafushi, Haa Alifu Atoll, Maldives

Abstract

This report discusses the findings of an environmental impact study under the shore protection project proposed for Hoarafushi in Haa Alifu Atoll. The project is proposed by Ministry of Environment and Energy. The project comprises of the protection of the eroding area on either sides of the harbour. A 570m long rock boulder revetment on the northwest of the harbour and 230m breakwater on the southeast of the harbour has been proposed. The project also involves backfill of the proposed revetment areas using an estimated total of 17,000cbm of sand. The sand is proposed to be taken from the lagoon on the north of Hoarafushi. The project will be undertaken as part of the ongoing harbour project and is estimated to take about 180 days with a manpower requirement estimated at 27 and involving heavy machinery including excavator, dump truck, loader and crane. A number of alternatives to the proposed project components have been identified in this document. Of these, the preferred alternative is a groyne field with a smaller revetment adjoining the harbour. The cost of the preferred alternative is similar or slightly less but provides beach in these areas and better protection to downdrift locations, if the structures are designed properly. Other alternatives include a groyne field with a semi-submerged breakwater or just a groyne field or a semi-submerged breakwater only. Rock boulders is the preferred material for the proposed shore protection while geotextile bags or geotextile tubes may be used as a cheaper alternative but would not be as effective as rock boulders. Sand is available from the large span of lagoon on the north of Hoarafushi including the three options considered by the Contractor. The shallow channel between Ungulufinolhu on the south and Hoarafushi is also an alternative that will help to minimize the magnitude of flow between these two islands since Kudafinolhu on the northwest of Hoarafushi is now naturally connected with Hoarafushi. Even when the island on the north was not connected with Hoarafushi, there was severe erosion on the south of Hoarafushi, as identified in the EIA report. Therefore, deepening this channel would help to ease the erosion on the southern end of Hoarafushi. This area is more feasible for the fill behind the proposed revetment on the south of the harbour. The harbour is also an option, however, may not have material suitable for beach fill. Environmental impacts were assessed for both the construction and operational phases of the project. Most of the direct, negative environmental impacts identified for the construction phase of the project were minor negative; the main impact being sedimentation during the filling of the proposed fill areas. However, these impacts are of low significance while the benefits of the proposed project outweigh the negative impacts including the protection to the area, which has been eroded mainly as a result of constructing the harbour. In fact, these shore protection measures should have been proposed as mitigation measures within the EIA for the harbour project. However, the measures could have been avoided at that time due to budgetary constraints. Since there are a few impacts, there are no specific mitigation measures for the proposed project except to keep the borrow areas at least 50m from shore, as per the requirements of the Dredging and Reclamation Regulation. However, in order to mitigate the impacts on the aesthetics of the beach area due to the revetment, it is recommended to minimize the revetment and consider groyne field or offshore structure as proposed in the alternatives. However, the proposed revetments may provide better protection to the areas under consideration. Therefore, it is a choice that the Proponent can make in consultation with the Engineers and other stakeholders. General mitigation measures, involving appropriate construction management such as working during low-tide as much as possible and rigorous supervision during project implementation are recommended. Since monitoring has not been undertaken in the past for the harbour project, it is recommended to carry out monitoring for this project. This project has linkages with the harbour project and therefore the recommended mitigation measures and monitoring programmes in the EIA for the harbour project shall be undertaken in conjunction with the proposed shore protection project. Therefore, a holistic monitoring programme has been recommended for the eastern shoreline of the island under this project. In conclusion, it appears justified, from a technical and environmental point of view, to carry out the proposed shore protection project. Since alternatives have not been considered or discussed with the relevant stakeholders including the Council, it is recommended to consider all potential alternatives to shore protection, including those identified by the EIA Consultants, before proceeding with the project.