Environmental impact assessment for the coastal protection of Reethi Beach, B. Fonimagoodhoo

Abstract

1. The present report is the Environmental Impact Assessment (EIA) regarding the construction of a breakwater, implementation of revetment and headland, and the replenishment of the beach on Fonimagoodhoo Island in Baa Atoll. The report has been developed in compliance with the Environmental Protection and Preservation Act of Maldives (Law No. 4/93, article 5a) and the Environmental Impact Assessment Regulation 2012 requiring such an assessment study before implementation of any activity that may have a significant impact on the environment. The assessment exposes the solutions and preferred alternatives as well as mitigation measures to minimize any negative impacts whilst trying to derive the maximum positive impacts from the project. 2. Reethi Beach Resort is threatened by erosion, particularly on its east side. The management of the resort has been taking different measures to prevent erosion around the island. The protection actions that have been already implemented on the northeast and southeast side consist of structures that are parallel and perpendicular to the shore, resulting in a poor aesthetic aspect to the beach. Moreover, a structural sand leak has been noticed during the NE monsoon and is being exacerbated by the existing structure. Consequently, the planned works are designed to remedy this situation in the following ways: 1) Large submerged geo-tubes will be laid on the rock bed in the northeast and southeast of the island in order to break the waves before they reach the shoreline. 2) Three other geo-tubes will be implemented on the north beach as revetments to prevent direct erosion. 3) Building groynes in the east and southeast to impede the sand movement and to seal off the sand leak. 4) Pumping sand from the lagoon in order to replenish the beach and cover the previous unasthetic coastal structures. 3. The proposed structure will be secured using sand filled containers known as geo-tubes. These are deployed on a rocky base and filled in situ. The designs have taken into account the bathymetry of the area in order for the top of the bag to reach the highest tide level. 4. Fonimagoodhoo is located on the east of Baa Atoll. It is mostly susceptible to the oceanic swell and to the wind waves modulated by the monsoon, generating sand transport and geomorphologic changes between the windward and the leeward sides. This is most apparent in three particular directions, one in the northeast sector, another one in the south and one in the west sector are clear of any direct obstacles, enabling higher energy swells and wind waves to reach the reef system. 5. 10 photographic transects were used to assess the benthic cover of 10 sites. Each picture is analyzed using 25 point grids to obtain quantitative substrate cover data of morphological xii characteristics of the reef community. Living corals represent9.32±2.46% of the whole area surveyed comprising mostly of massive and sub-massive species (4.36±1.47% and 2.73±1.09% respectively). Surprisingly, Acropora sp. represents only 0.76% of the substrate. This low abundance may be due to the high seawater temperatures (> 30°C) measured around Fonimaagoodhoo engendering coral with bleaching which affects mainly Acropora sp. From 2006 to 2012, the coral cover has stayed constant (10.16±1.77% to 10.30±1.77% respectively). The sand movement around the island may avoid recruit settlement hindering development of the coral reef. 6. For the fish community survey, data was collected using the methodology outlined by FishWatch Maldives, where 3 x 15 minute fish counts were carried out at each site. Surveyed area is a band of 2.5m on either side of the recorder and 5m up the water column. Surveys were carried out at 2 different depths (5 and 10 meters) on 6 sites. 42 of the 76 FishWatch target species were recorded among 14 families. Lutjanus gibbus (38.10%), Caranx melampygus (7.47%) and Zanclus cornutus (7.14%) showed the greatest densities. The significant presence of the predator Caranx melamgypus is an indicator of a healthy fish community. The weak density of Chaetodontidae (9.20%) may be related to the generally poor coral cover. Acanthuridae were very poorly represented (1.19%) and this is in contradiction with the fact that the substrate is mainly rocky with a cover of turf algae which should normally support a healthy herbivorous community. This may be due to the fact that the 5 species counted in this protocol are rare compared to other more common Acanthuridae such as Ctenochaetus striatus or Acanthurus leucosternon. 7. The main potential environmental impacts identified associated with the new developments are construction impacts, in relation to the use of machinery (smell and noise disturbances, oil spillage risks, green house gas emission) and with the construction works themselves (temporary rise in turbidity and modification or damages to the seabed through direct physical damage), as well as permanent modification of the hydrodynamic regime of the whole area. 8. The pros and cons of alternative options are considered as well as mitigation for the impacts highlighted. Given that the present configuration of the coastline is the result of different ad-hoc initiatives, it is expected that the works will improve the coastal protection of the islands and promote rationality in dealing with this issue. 9. A monitoring plan has been proposed in order to assess the impact of the works over the years and long term changes to the environmental conditions. The plan will aid in implementing mitigation measures during construction and operation of the project.