Environment - ތިމާވެށި
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Item Environmental impact assessment for coastal protection and erosion control on west of runway 18, Malé International Airport, Hulhulé, Kaafu Atoll, Maldives(2010-04-05) SandcaysThis report addresses the environmental concerns of the proposed quaywall strengthening and erosion control of western coast of Runway 18, Malé International Airport, Hulhulé, Kaafu Atoll. The primary objective of the project is to enhance the safety of the airstrip at the turning pad area, which is prone to flooding during rough weather due to wave overtopping from existing sheetpile structure. As a result there is scour behind the sheetpile wall increasing the threat of subsidence or structural weakening of the western edge of the turning pad area. Therefore, there is an immediate need to protect this area by strengthening existing sheetpile quaywall with additional protection measures. Hence, different options for the coastal protection have been evaluated and the most practicable options not entailing excessive costs have been recommended. Since this is an immediate and temporary measure, minimal protection has been proposed, which is the protection of the immediate area behind the turning pad where sheetpile structure has been placed. The length of protection is about 100m. The other areas with concrete gravity seawalls have not been considered for protection as these areas are not severely affected and the entire area, including the 100m coastline which is proposed for immediate protection, would be reclaimed in the near future, as per the Airport Master Plan. The different options for the protection of the proposed 100m coastline immediately behind the turning pad area include revetments along the coastline or offshore breakwaters covering a length of about 250m on the dead reef flat at about 100m from the sheetpile coastline. Two types of materials have been considered for the revetments: single layer Core-Loc armour units and 2.5m3 geotextile containers filled with sand. The Core-Loc units have very high permeability (50-60% voids) to absorb wave energy while the geotextile containers have no voids when placed together. Therefore, the design using geotextile containers have been revised to incorporate about 15% voids, thereby improving the wave energy absorption capacity. Based on the costs and wave energy absorption potential of each type of material, it is recommended to use the Core-Loc units. However, these units are not readily available in the Maldives, therefore, geotextile containers have been recommended due to the urgency of the project. In both cases, the revetments have been designed to provide adequate wave runup to minimize the force of the wave. Additional protection would not be required. For the breakwater also, the above two types of materials have been considered and submerged breakwaters as well as emerged breakwaters have been considered. The breakwater option is expensive given the length of the breakwater. Also, the distance between the potential breakwater location and the shore area to be protected is about 100m, which makes it less effective as wind-generated waves will reoccur inside the lee of the breakwater. Other options such as groynes have not been considered because the lagoon on this side has been dredged. Imported rock boulders could also be used for both the revetment option and the breakwater option. However, the cost of boulders and the time to deliver to site makes it impracticable and has not been considered. Moreover, a structure with rock boulders would be less permeable (about 30-40%) than the proposed Core-Loc armour units. Hence, cost was the deciding factor in choosing the Core-Loc units and geotextile containers over rock boulders. The reef flat at the area in which the proposed offshore breakwater would be constructed is almost entirely dead with high levels of sediment resuspended in the water column. This is due to the increased sediment level from dredging that had taken place in the area. There is also the cumulative effect of sediment resuspension resulting from the Hulhumalé reclamation, but this is expected to be small. The reef slope and edge in this area would not be severely affected as no machinery would be used in or closer to these areas during the implementation of the proposed project activities. All machinery would be used on the shallow reef flat area, which consists of bedrock and a few dead coral porites. Given the level of dredging, reclamation and coastal protection works that have been carried out in the area, the cumulative impacts of the proposed project would be negligible. Therefore, this project is not considered to have adverse environmental or social impacts but there would be economic impacts that would be positive in that the dangers of potential subsidence of the airstrip turning pad is minimized with greater flood control and protection afforded by the proposed temporary coastal protection structures. However, mitigation measures to minimize any damage to reef will be in place and the project components will be well planned considering minimal aesthetic impact although this area is not aesthetically sensitive. Environmental monitoring is not recommended for the project under consideration except monitoring of the effectiveness of the structures for at least one year after construction. However, it is recommended that the Maldives Airports Company in association with other operators in Hulhulé initiate and conduct an island-wide environmental monitoring programme which would cover the environmental monitoring needs of all projects undertaken on the island.Item Environmental impact assessment : coastal protection at Paradise Island Resort, Kaafu Atoll, Maldives(2010-08-01) SandcaysThis report addresses the environmental concerns of the proposed coastal protection at Paradise Island Resort located on Lankanfinolhu in North Malé Atoll. The primary objective of the project is to protect the coastal infrastructure of Paradise Island Resort and also enhance the natural environmental of Paradise and to improve the services offered to guests thereby minimizing operational and environmental costs. As such the project encompasses the replenishment of approximately 200m of beach at the arrival jetty and swimming pool area on the western side and about 300m of shoreline on the eastern side at the base of the water villas jetty. Paradise Island is surrounded by a large expanse of lagoon or reef flat on the eastern side and similar but not so great expanse of reef flat and lagoon on the western side. The western side beach is, therefore, much more prone to wave attack than the eastern side. The western side is exposed to wind generated waves during the southwest monsoon while the eastern side is exposed to wind generated waves during the northeast monsoon as well as swells during both monsoons. The eastern side reef flat has recently been subjected to anthropogenic changes during the construction of water villas which were destroyed by the tsunami of 2004 as a result of which the erosion of the eastern beaches at the foot of the water villa jetty has been severed. However, the western side beaches have been a victim of wave-induced erosion during the southwest monsoon for as long as the island existed. Therefore, regular beach nourishment by pumping sand from nearshore areas has helped to keep the beaches intact to some extent. Such frequent beach nourishment creates more sediment suspension and resuspension in the water column causing deterioration of the quality of the main product, which is the natural environment. Continuous beach nourishment would also provide little protection to these eroding areas without structural protection. Shore protection measures have, therefore, been evaluated and most practicable option(s) chosen to protect the eroding areas and minimize the frequency of beach nourishment. The proposed coastal protection structure is a breakwater that would be submerged at high tide. Such a breakwater is expected to provide adequate protection from wave induced erosion on both sides, which is the cause for concern at present. The overall environmental impacts of the project have been assessed using appropriate matrices and the results indicated that the proposed project has a net positive impact. That is, the project has no major adverse impacts on the environment as far as current knowledge is concerned. Given that the project has major socio-economic benefits and some environmental benefits, it is advisable to allow the project to proceed as proposed. It is also recommended to continue to monitor the impacts of the proposed project by regular monitoring of shorelines and nearshore currents for at least two years and communicate and feed the data into the EIA system in the country.