Environmental impact assessment report harbor restoration works Hirilandhoo, Thaa atoll

Abstract

This Environmental Impact Assessment (EIA) report is to fulfill the regulatory requirement under the environmental preservation act of Maldives prior to the proposed harbor development at Hirilandhoo in Th. Atoll. The proposed repair and reconstruction works for this EIA is part of the project for infrastructure repair works in the atolls as a result of 2004 Tsunami. This project is executed by Ministry of Housing and Environment, financed by Ministry of Finance and Treasury. Major component of the proposed development is deepening of the existing harbor basin to the standard depth of -3m MSL, replacement of the existing damaged quay walls by pre cast L shaped concrete elements and a breakwater section adjoining northern side quay wall of harbor basin. Breakwater section will be constructed using imported granite rock boulders. Sediment excavated to deepen the harbor basin and demolished concrete from the existing quay walls would be used as core material for the new quay walls and as backfill. Hirilandhoo is located on the south western side of Thaa Atoll on the northern end of a long peripheral reef. Several lag0onal depressions are associated with the reef where the harbor basin is open ended to this. An entrance has been cleared for access to the deep lagoon across the reef flat at the western side. This report provides the results of the fieldwork carried out at Hirilandhoo in January 2010 and associated public and community consultations that followed. The environmental impacts arising from the proposed developments are predicted based on the findings of the fieldwork along with the activities that cause these impacts during the construction and operation phase. Existing environment was examined to identify significant environmental components that would be affected and to establish a baseline condition of the site. Available and relevant literature on environmental impacts associated with similar projects was evaluated to identify possible impacts. Oceanographic data and information on local hydrodynamics were qualitatively assessed to determine the current pattern around the island which was based on monsoonal wind patterns, wind generated waves, tidal flushing, geographic setting, the topography of the lagoon and shape of the shoreline. The impact area in terms of marine environment is largely a sandy lagoon. The substrate of the lagoon is mostly abiotic with isolated patched of corals As the area to be dredged is already modified and form the existing harbor basin, there is no new area that is prone to alteration It is important to note that the most significant impact associated with the project would be impact on the marine environment from sedimentation. Dredging and excavation often carry heavy load of sediments increasing sediment load in the water column causing discoloration (due to suspended sediments) of the of the impact area for a prolonged period. Environmental impact matrix in chapter 7 identified key components of the natural and socioeconomic environment; the likely impacts on each component based on the criteria used for impact prediction. The proposed development will have direct impact on the benthos in all excavated areas. However, there is no established coral community that would be directly affected except perhaps few isolated coral colonies. Environmental impacts associated with the proposed project are considered minor to moderate. The significant environmental components that are likely to be affected are the coral community established on the reef flat and changes to littoral drift and near-shore coastal hydrodynamics. Impact on the coral community from sedimentation as a result of excavation is inevitable. It is also important to note that the coral community in the immediate impact area is rather sparse and coral rubble and sand dominates the reef substrate. Mitigation measures were provided in the report for impacts that were categorized minor to moderate. Impact mitigation measures and monitoring is carried out to compare predicted and actual impacts occurring from project activities to determine the efficiency of the mitigation measures. The environmental monitoring proposed here is to determine the effectiveness of the mitigation measures and long term change to the benthic community (especially coral community) where the baseline information was collected. In addition to this additional monitoring station would be established at the reef slope (channel entrance) to determine the changes to this habitat by sediment deposition transported through the reef access channel. With due consideration to main environmental components identified and the magnitude of impacts on these components from the proposed developments, the consultant concludes that the project components and designs are feasible and appropriate mitigation measures are given to correct and minimize unfavorable environmental consequences. Furthermore the public and community consultation responses were in favor of the project due to the socio-economic benefits.