Benarkah Mangrove Berperan Sebagai Penghalang Tsunami?

Semarang - KeSEMaTBLOG. Bapak Abdul Ghofar, salah seorang Rekan kami yang adalah dosen dari Jurusan Perikanan Universitas Diponegoro (UNDIP) telah merekomendasikan dua buah artikel mengenai mangrove dan tsunami yang ditulis oleh Papri Sri Raman dan T. V. Padma untuk dipublikasikan di KeSEMaTONLINE.

Dalam emailnya kepada kami, beliau mengatakan hal sebagai berikut, “Many thanks. Here is the article that Mas Sapto (KeSEMaTERS) and I discussed. Although it isn't very recent as a Science Development Network material (Jan ‘09), the issue is perhaps still relevant to KeSEMaT current interest, as it is indeed to Indonesia, generally. Hope it is of any use, but please let me know should there be anything I can do help. Do keep up with good work!”

Pada intinya, dalam artikel yang direkomendasikan oleh Bapak Ghofar ini, terdapat pernyataan bahwa mangrove bukanlah satu-satunya faktor penghalang utama yang menyebabkan amannya rumah-rumah penduduk yang ada di belakangnya, dari terjangan gelombang tsunami. Namun demikian, menurut hemat kami, masih dibutuhkan sebuah penelitian dan studi lanjutan yang lebih banyak dan representatif lagi, hingga didapatkan sebuah kesimpulan yang “meyakinkan” atas pernyataan di atas.

Dan, berikut ini adalah dua buah artikel yang direkomendasikan oleh beliau, tersebut. Selamat membaca dan mencermati. Semoga bisa menambah pengetahuan dan pemahaman kita, terhadap fungsi ekosistem mangrove yang kita cintai bersama ini, sebagai “penghalang” tsunami.

Mangroves 'do not protect against tsunamis'
By Papri Sri Raman
Science Development Network, 14 January 2009 | EN

[CHENNAI] Claims that coastal forests can protect communities from the impact of tsunamis have been dismissed in a new report.

Researchers analysed the pattern of damage that occurred during the 2004 Indian Ocean tsunami and say that there is no compelling evidence that coastal forests - such as mangroves - can act as 'bioshields' to adequately protect against tsunamis or cyclone storm surges. The full report is soon to be published by the UN Environment Programme.

They go on to say that it would be "extremely dangerous" to rely on tree-planting alone to protect coastal communities.

Other factors, such as the height of a village above sea level and its distance from the shore need to be incorporated into an extensive, statistically sound analysis of which factors determine the impact of tsunamis.

Following the 2004 tsunami, studies claimed there was less damage to communities where there was a tree or vegetation barrier. Naluvedapathy - a coastal village in the state of Tamil Nadu - hit the headlines as a village that was saved by its bank of 60,000 casuarina and eucalyptus trees.

Bioshields have now become part of India's National Disaster Management Plan and official policy, and many organisations have established programmes in the country.

In 2005, 254,464 trees were planted in a single day in Vedaranyam, Tamil Nadu, and state forest departments have been funded by the World Bank's Emergency Tsunami Reconstruction Project to plant trees.

The M.S. Swaminathan Research Foundation (MSSRF) has also spent more than six million Indian rupees (about US$120,000) on bioshield research.

"Increasing green cover in any area is not waste of money … [The study] needs to be ignored," V. Selvam, programme director of Coastal Systems Research at MSSRF, told SciDev.Net.

"Enough field-based and laboratory-oriented studies have been conducted to provide proof that bioshields can mitigate the impact of tsunamis. This conclusion is accepted by many global organisations," he said.

But Andrew Baird of the ARC Centre of Excellence for Coral Reef Studies and James Cook University, Australia, who led the study, says in a press release: "In my own visits to the tsunami-ravaged areas, I saw places where quite heavy vegetation had provided absolutely no protection at all against the force of the ocean."

Mangrove forests 'can reduce impact of tsunamis'
By T. V. Padma
30 December 2004 | EN

[NEW DELHI] Dense mangrove forests growing along the coasts of tropical and sub-tropical countries can help reduce the devastating impact of tsunamis and coastal storms by absorbing some of the waves' energy, say scientists.

When the tsunami struck India's southern state of Tamil Nadu on 26 December, for example, areas in Pichavaram and Muthupet with dense mangroves suffered fewer human casualties and less damage to property compared to areas without mangroves.

But the scientists also warn that the unique coastal tropical forests are among the most threatened habitats in the world. This is due to population growth and unsustainable economic development including deliberate land reclamation for urban and industrial development, widespread shrimp farming, and chemical pollution.

"We have observed that mangroves often served as a barrier to the fury of water," says M. S. Swaminathan, so-called father of India’s 'green revolution', and head of the M. S. Swaminathan Research Foundation (MSSRF) in Chennai, India.

MSSRF scientists found, for example, that in October 1999, mangrove forests reduced the impact of a 'super-cyclone' that struck Orissa on India’s east coast, killing at least 10,000 people and making 7.5 million homeless.

More than 15 years ago, MSSRF launched a programme to restore India's vanishing mangrove forests. One success story is the Joint Mangrove Management project, supported by the India-Canada Environment Facility with funding from the Canadian International Development Agency.

Implemented in six mangrove areas along the east coast of southern India between 1996 and 2003, the project helped restore 1,447 hectares of degraded mangrove forest.

The foundation adopted a three-pronged strategy. The first goal was to conserve and regenerate mangroves along India's east coast. The second involved identifying and transferring salt tolerance genes from mangroves species to crops like rice and mustard growing in coastal areas. Thirdly, the foundation has been raising awareness among local communities about impending storms and about safe fishing zones and days.

Jeff McNeely, chief scientist of the Switzerland-based World Conservation Union (IUCN), also voiced concern this week about rapidly disappearing mangrove forests that offer protection against events like tsunamis.

McNeely told the Agence France Press news agency that over the past several decades, many mangroves have been cleared to grow shrimp ponds by, among others, outsiders granted concessions from governments to set up shrimp farms, who lacked the long-term knowledge of why the forests should have been saved.

According to the US-based Earth Island Institute's Mangrove Action Project, mangrove forests once covered three-quarters of the coastlines of tropical and sub-tropical countries, but only half of that area remains intact today.

The Mangrove Action Project says vast tracts of mangroves have been cleared to make way for shrimp farms in developing countries, and that national governments have been unable to adequately regulate the industry. Multilateral agencies are also supporting shrimp farming projects without paying attention to social and ecological security, says the organisation.

Shrimp farming alone caused a loss of 65,000 hectares of mangroves in Thailand, according to a 2002 paper by V. P. Upadhyay and colleagues in the journal Current Science. In Indonesia, Java has lost 70 per cent of its mangrove area, Sulawesi 49 per cent, Sumatra 36 per cent. Globally the rate of decline in mangrove forest cover is 2-8 per cent each year, said the paper.

In India, large stretches of mangrove forest have been severely degraded in almost all areas where they are found.

As well as acting as a barrier against tsunamis, cyclones and hurricanes, mangrove forests provide society with a range of other 'ecological services'. These include preventing coastal erosion, protecting coral reefs from silting up, and providing a source of timber, food and traditional medicines.