FACTBOX-Warnings, reefs lessen tsunamis, storms impact

March 11 Fri Mar 11, 2011 1:44pm GMT

March 11 (Reuters) - Early warning systems and a drive to protect mangroves and coral reefs as buffers to waves are among ways to safeguard coasts at risk from tsunamis and storm surges, U.N. studies show.

Japan's devastating tsunami on Friday was caused by a quake beyond human control but efforts to limit impacts from more powerful cyclones or a rise in world sea levels, blamed on human emissions of greenhouse gases, can also help lessen damage.

The U.N. panel of climate change scientists said in its latest 2007 report that lessons from seismic events such as the Indian Ocean tsunami in 2004 or weather disasters including Hurricane Katrina which stuck New Orleans in 2005 include: 1) Early warning and response can curb death tolls and destruction 2) Teaching people about the hazards can enable communities to work to adapt 3) Many factors reduce the ability or willingness of people to flee. Those include the warning time, exit routes and "their perceived need to protect property, pets and possessions." 4) Natural coastal barriers -- coral reefs, islands and wetlands such as mangroves and marshes -- are a first line of defence against storm surges and floods. Safeguarding such natural systems can help limit the damage. 5) Repeated events such as storm surges caused by hurricanes reduce the effectiveness of defences. 6) The trauma of extreme events can lead to mental health problems. 7) Uncoordinated and poorly regulated construction along many coasts has aggravated the risks. 8) Effective disaster prevention and response rely on strong institutions, as well as adequate public preparedness. ----

Nick Nuttall, spokesman of the U.N. Environment Programme, said many countries have already worked to lessen the impact of disasters.

-- Bangladesh, for instance, has built shelters that have cut death tolls from cyclones after about 300,000 people died in cyclone Bhola in 1970.

-- Mosques survived the 2004 Indian Ocean tsunami better than many other buildings, apparently due to wide doors and open spaces that helped absorb the shock of waves.

-- In Sri Lanka, some coastal parks with sand dunes and natural vegetation were little affected by the tsunami. Many countries are now trying to restore natural vegetation such as mangroves as buffers.

-- One big problem after the 2004 tsunami was contamination of wells by salt water and other pollution uprooted from trash dumps. Flooding of latrines also spread disease.

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(Editing by Matthew Jones)