Tsunami Disaster: Opportunity for Change?

This rise will have two effects on low-lying coastal regions: first any structures located below the resulting level of the sea will be flooded and, second, the rise in sea-level may lead to coastal erosion that can further threaten coastal structures. As a “rule-of-thumb” (the “Bruun rule”) a sandy shoreline retreats about 100 metres for every metre rise in sea-level or at a ratio of 100:1.

Coastal planners in Australia and overseas are beginning to plan development in a way which allows for the projected sea-level rise during the life of the structure (i.e. by prescribing minimum heights of foundations and minimum setbacks from the high water mark). It is important that these new planning practices are applied to the reconstruction that follows the tsunami in the Indian Ocean.

Throughout tsunami reconstruction planning there should be two basic precautionary measures:

1. The foundations of structures should be located at a height that is the highest sea-level ever recorded in that region, and takes into account the projected rise in mean sea-level over the expected life of the structure. Considering the IPCC projections, a 100-year lifetime needs to accommodate up to 88 centimetres of sea-level rise.
2. For foundations on erodible material (for example sand) then, in addition to the above recommendation, the structure should be set back from the present extreme high water mark (as indicated by the limit of vegetation or by an erosion scarp) by an appropriate distance which allows for the retreat of the shoreline due to sea-level rise. For a sandy shoreline, this distance would be around 100 times the projected sea-level rise, or about 100 metres.

For some countries shoreline protection is already considered in planning regulation: the Indian government has had in place a Coastal Zone Region (pdf file 76KB) since 1998 which prohibits construction within 500 metres of the high tide mark and coastal protection groups are seeking to expand and tighten this regulation.

Step Two: Conserve and regenerate natural barriers

Enhancing coastal areas’ natural protection using “low-tech” community initiatives is the best strategy for reducing risk from natural disasters. Community leaders and environmentalists worldwide say that mangroves and coral reefs provide essential protection against tsunamis and storm surges because they buffer the impact of waves.

According to a Wall Street Journal report (December 31, 2004), "The ring of coral in crystal waters around the Surin Island chain off Thailand's west coast forms a sturdy defence against the sea. So when the tsunami struck on Sunday it punched a few holes in the reef, but the structure mostly held firm. The reef, says Thai marine environmentalist Thon Thamrongnavasawadi, may have saved many lives. Only a handful of people on the islands are known to have perished - most scrambled to safety as the first wave exploded against the coral."
 
M.S. Swaminathan, Chairman of the M.S. Swaminathan Research Foundation (MSSRF) in Chennai, India says, "The dense mangrove forests stood like a wall to save coastal communities living behind them ... It is now found that wherever the mangroves have been regenerated, especially in the Orissa coast, the damage due to tsunami is minimal".

In another report by the Science and Development Network in India (December 30, 2004), "When the tsunami struck India's southern state of Tamil Nadu on 26 December, areas in Pichavaram and Muthupet with dense mangroves suffered fewer human casualties and less damage to property compared to areas without mangroves".

On Penang Island, the worst affected area in Malaysia, representatives of the Penang Inshore Fishermen Welfare Association observed that in areas where the mangrove forests were intact, there was reduced property damage and less impact on the coast.

The World Conservation Union (IUCN), releasing an early report on the damage of tsunami to the environment notes:

It seems clear that areas with healthier ecosystems have been less affected. For example, the coastal destruction is very patchy in some severely affected areas of Sri Lanka, with less altered and more vegetated parts of the sea-land interface withstanding the tsunami to a much larger extent than areas where vegetation has been removed or the shoreline changed or encroached on. Structures in more obviously vulnerable locations, including many hotels and residential areas built too close to the sea or in coastal reservation areas, have fared worse, and artificial canals that connect lagoons with the sea appear to have aggravated the damage by funnelling water inland, resulting in flash floods in urban and sub-urban areas, as seen e.g. in Hambanthota town in Southern Sri Lanka.

Where affected nations are already acting to protect the natural protection of coastal zones though protecting coral reefs and mangrove zones, such as in India via the Coastal Regulation Zone (CRZ), this should be strongly encouraged and supported. Other nations recovering from the devastation of the tsunami should be strongly encouraged to implement coastal regeneration zones in their reconstruction plans as an investment in future disaster mitigation.

As rebuilding will soon begin in the tsunami stricken regions, the world needs to recognise that the impact of climate change is likely to pose similar problems to the current tsunami crisis, through incremental sea-level rise and rapid non-linear events as currently under scientific investigation. In fact it has been going on relatively ignored by western nations for years. In 1997 Tuvalu, Nauru, Kiribati, Niue, and the Cook Island governments issued a joint statement that sea-level rise was a daily issue to them, and the most serious threat to Pacific nations.

In this respect, planning reconstruction to protect the coastal zone and avoid its danger is long overdue and absolutely necessary future risk management. In reconstructing the tsunami disaster region, Australia and other western nations must learn lessons for their own coastal development, and contribute the necessary legislative, technological and financial help to make it possible. The lessons for protecting our invaluable coastline should not be lost to local planning and policy makers: we will all be affected eventually.