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The environmental damage caused by the tsunami and the earthquake had not been fully assessed by early 2005 when this publication went to press. It is known to include groundwater contamination from salt intrusion, soil salinization and erosion, damage to biodiversity rich ecosystems such as coral reefs, mangroves, seagrass meadows and estuaries (Figure 2), and damage to forests, woodlands, and protected areas.

Figure 2: Damage in the Nicobar Islands, India

The island of Trinkat appears to have been cut in half by the tsunami with a new channel of water approximately five km long stretching from the settlement of Tapiyang to a point on the opposite coast just west of Ol Ol Chuaka. Another channel has possibly been opened up to the south-east of Takasem separating the large mangrove swamp area from the inhabited northern end of the island. The mangrove appears to be relatively intact though several inlets have been created in the east.

The extensive coral reefs visible along the west and east coasts of Trinkat before the tsunami are largely obscured by large plumes of sediments presumably washed from the land. In the later image the coastline has retreated along the east coast enlarging the lagoon. This scouring of terrestrial matter into the lagoon and onto the reefs could have serious consequences for shallow water habitats if sediments settle for longer periods.

Source: UNOSAT

Cement factory along the tsunami-battered coast of Banda Aceh.
Source: Choo Youn-Kong/Reuters/South

Coral reefs and mangroves, which act as buffers against large waves and prevent coastal erosion, are likely to have suffered considerable damage. There are preliminary reports of these ecosystems absorbing the impact of the tsunami in some areas. For instance, according to the MS Swaminathan Research Institute in India, the mangrove forests in Pitchavaram and Muthupet regions of south India acted like a shield and bore the brunt of the tsunami (Venkataramani 2004). The coral reefs around the Surin Island chain on the west coast of Thailand have also been attributed with saving lives by reducing the impact of the waves (Browne 2004).

Besides direct damage from the tsunami, marine ecosystems will also be affected by the resulting sedimentation and debris. Scientists point out that while the coastal beaches and land areas devastated by the tsunami could be restored within a few years, the most severely impacted marine ecosystems could take centuries to fully recover. Debris that ended up in the shallow marine environment, when caught up in strong waves and current, can easily 'bulldoze' corals and marine life, or entangle and drown protected marine mammals. It could also contain hazardous and toxic chemicals, which cause stress to marine ecosystems and disease in corals, algae, fish and other invertebrates. These impacts could be long-lived and may not become apparent to researchers for months or even years (NOAA 2005).

Hazardous or toxic debris and waste, particularly from damaged industrial sites and waste facilities, could also pose a threat. In the Maldives, for example, part of the island that contained the island's waste facilities was washed away. The amount of waste deposited in the ocean as a result has not been established, but a remaining stretch with a two-metre deep layer of waste now extends approximately 30 metres into the water (UNOCHA 2004b).

The tsunami is also likely to have caused damage to coastal forests and protected areas. The infrastructure and management systems of protected areas such as Yala National Park in Sri Lanka and Gunung Leuser National Park in Aceh could also be affected (BirdLife International 2005).

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