Mangrove as Flood Protection
Wednesday, 14. May 2008, 17:43:36
No doubt large-scale destruction of protective mangroves along the coasts of Myanmar aggravated the devastation wreaked by the tropical cyclone Nargis. Mangrove provide significant flood protection in low coastal areas, but never the less Mangrove forests are one of the world’s most threatened tropical ecosystems. In January 2008, the UN Food and Agriculture Organization warned that Asia is fast losing its coastal mangroves, with more than 1.9 million hectares being destroyed each year. Mangroves are only suitable for planting on coastal mud-flats and lagoons, but such mud-flats and lagoons cover about 25% of the continental coastline of the Bay of Bengal.
The protective benefits were clearly demonstrated when the Boxing Day Tsunami on 26 December 2004 flooded the coasts of the Indian Ocean. In regions with lesser tsunami intensity areas with coastal tree vegetation were markedly less damaged than areas without. A study published in Science of 28 October 2005 titled The Asian Tsunami: A Protective Role for Coastal Vegetation describe how Cuddalore District in Tamil Nadu, India, provided a unique experimental setting to test the benefits of coastal tree vegetation in reducing coastal destruction by tsunamis (and other flooding events). Cuddalore has a relatively straight shoreline, a fairly uniform beach profile, and a homogenous continental slope. Moreover, the shoreline comprises vegetated as well as non-vegetated areas and was documented by cloud-free pre- and post-tsunami satellite images.
Salt-marshes, mangroves and other forested wetlands act as the front-line defence against incoming storms. They help minimise the impact of storms by reducing wind action, wave action and currents, while the roots of the plants help to hold the sediment in place. The Government of Bangladesh has invested considerable sums of money in re-planting mangroves in previously storm flooded areas to assist in storm protection.
Mangroves are also important for fisheries. Furthermore I must confess that I have had some of my best bird watching experiences in mangrove areas, which may though be of less economic importance.
Predicted effects of climate change over the next 50-100 years will place both coastal and inland wetlands in some parts of the world under a great deal of pressure through increased prevalence of tropical storms, changing patterns of precipitation, and sea level rise.
The protective benefits were clearly demonstrated when the Boxing Day Tsunami on 26 December 2004 flooded the coasts of the Indian Ocean. In regions with lesser tsunami intensity areas with coastal tree vegetation were markedly less damaged than areas without. A study published in Science of 28 October 2005 titled The Asian Tsunami: A Protective Role for Coastal Vegetation describe how Cuddalore District in Tamil Nadu, India, provided a unique experimental setting to test the benefits of coastal tree vegetation in reducing coastal destruction by tsunamis (and other flooding events). Cuddalore has a relatively straight shoreline, a fairly uniform beach profile, and a homogenous continental slope. Moreover, the shoreline comprises vegetated as well as non-vegetated areas and was documented by cloud-free pre- and post-tsunami satellite images.
Salt-marshes, mangroves and other forested wetlands act as the front-line defence against incoming storms. They help minimise the impact of storms by reducing wind action, wave action and currents, while the roots of the plants help to hold the sediment in place. The Government of Bangladesh has invested considerable sums of money in re-planting mangroves in previously storm flooded areas to assist in storm protection.
Mangroves are also important for fisheries. Furthermore I must confess that I have had some of my best bird watching experiences in mangrove areas, which may though be of less economic importance.
Predicted effects of climate change over the next 50-100 years will place both coastal and inland wetlands in some parts of the world under a great deal of pressure through increased prevalence of tropical storms, changing patterns of precipitation, and sea level rise.
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Do you know what are the main reasons of mangroves destruction in Myanmar ?
By galanga, # 16. May 2008, 07:56:42
Here are some links to news I hadn’t yet seen when I wrote my post. They just confirm the problem. Thr one from Mongabay gives a good overview.
http://news.mongabay.com/2008/0513-hance_mangroves.html
http://afp.google.com/article/ALeqM5h04OPSU9fV0L33AI7oMdAEbv3hkA
http://www.terradaily.com/reports/Myanmar_cyclone_damage_worsened_by_loss_of_mangroves_FAO_999.html
Ole
By nielsol, # 16. May 2008, 15:54:32
It is horrible to see that decisions made one or two centuries ahead could progressively, with consecutive some other greed and madness, could lead to such a disaster.
By galanga, # 16. May 2008, 22:08:07