structural:summarization
Environmental impact

Beyond the heavy toll on human lives, the Indian Ocean earthquake caused an enormous environmental impact that affected the region for many years. Severe damage was inflicted on ecosystems such as mangroves, coral reefs, forests, coastal wetlands, vegetation, sand dunes and rock formations, animal and plant biodiversity and groundwater. Also, the spread of solid and liquid waste and industrial chemicals, water pollution and the destruction of sewage collectors and treatment plants threatened the environment even further. The environmental impact took a long time and significant resources to assess.

The main effect was caused by poisoning of the freshwater supplies and of the soil by saltwater infiltration and a deposit of a salt layer over arable land. In the Maldives, 16 to 17 coral reef atolls that were overcome by sea waves are without fresh water and could be rendered uninhabitable for decades. Uncountable wells that served communities were invaded by sea, sand, and earth, and aquifers were invaded through porous rock. On the island's east coast, the tsunami contaminated wells on which many villagers relied for drinking water.

The Colombo-based International Water Management Institute monitored the effects of saltwater and concluded that the wells recovered to pre-tsunami drinking water quality one-and-a-half years after the event. The IWMI developed protocols for cleaning wells contaminated by saltwater; these were subsequently officially endorsed by the World Health Organization as part of its series of Emergency Guidelines.

Salted-over soil becomes sterile, and it is difficult and costly to restore for agriculture. It also causes the death of plants and important soil micro-organisms. Thousands of rice, mango, and banana plantations in Sri Lanka were destroyed almost entirely and will take years to recover.

In addition to other forms of aid, the Australian government sent ecological experts to help develop strategies for reef-monitoring and rehabilitation of marine environments and coral reefs in the Maldives, Seychelles and other areas. Scientists had developed significant ecological expertise from work with the Great Barrier Reef, in Australia's northeastern waters.

In response to the unprecedented situation, the United Nations Environment Programme (UNEP) worked with governments in the region to determine the severity of the ecological impact and how to address it. UNEP established an emergency fund, set up a Task Force to respond to requests for assistance from countries affected by the tsunami, and was able to mobilize and distribute approximately US$9.3 million for environmental recovery and disaster risk reduction between 2004 and 2007. Funding came from other international agencies and from countries including Finland, Norway, Spain, Sweden and the United Kingdom.

Evidence suggested that the presence of mangroves in coastal areas had provided some protection, when compared to areas that had been cleared for aquaculture or development. As a result, mangrove restoration become a focus of a number of projects, with varied success. Such approaches to ecosystem-based disaster risk reduction appear to be most successful when local communities are closely involved as stakeholders throughout the process, and when careful attention is paid to the physical conditions of chosen sites to ensure that mangroves can thrive there.