The role of mangroves and other vegetation in
protecting against tsunamis and tidal surges
Mr Ong Jin Eong, Malaysia
Mr Ong explained the role of coastal vegetation in protecting against tsunamis and tidal surges with a specific focus on mangroves. He emphasized that the idea that mangroves protect coastal areas from tsunamis and erosion is a myth! Mangroves are usually found on low-impact coastlines with limited rates of erosion (mangrove propagules can not root in high-impact areas or areas with high erosion rates). The ability of mangroves to reduce the impact of a wave is determined by the Manning roughness coefficient of the forest as a whole – in general, this effect is negligible with the kind of forces involved with a tsunami. With regards to rehabilitation, he indicated that mangroves are fully capable of regenerating themselves in most cases. The only reason that this would not occur is if there is not a sufficient supply of propagules in the area that needs to be rehabilitated or there is too much (human) disturbance of the area. The best way of (naturally) rehabilitating degraded areas is to restore the hydrodynamics of the area to be rehabilitated (i.e. remove barriers to tidal movements). If human intervention is necessary for rehabilitation, then the following elements need to be considered:
Mr Ong indicated that he was all for the preservation of mangrove ecosystems but for the right reasons, not the wrong ones.
A question was raised concerning the role of mangroves in protecting mud-flats. Mr Ong replied that mud-flats are not suitable for planting mangroves.
Another question was asked about an effective way to rehabilitate the areas that had been converted for development activities (e.g. shrimp ponds) by restoring mangroves or recovering hydrodynamics. Mr Ong mentioned that a relatively easy and effective way would be to re-establish the free flow of water and normal tidal flows.
Integrated approaches to coastal zone management
Mr Simon Funge-Smith, FAO Regional Office for Asia and the Pacific
Mr Funge-Smith described integrated approaches to coastal zone management with a specific emphasis on the complexities of coastal livelihoods that depend on fisheries, aquaculture, tourism and forestry. He mentioned that longer term rehabilitation work should focus on creating sustainable livelihoods and restoring productive use of coastal resources. He highlighted the need to balance ecological, social, cultural, governance and economic considerations and the importance of community participation. He also emphasized the need for inter-sectoral cooperation (forestry, fisheries, aquaculture, agriculture, tourism, and infrastructure) and for appropriate policy and strategic planning mechanisms to balance trade-offs between different interests. He concluded by outlining the challenges in integrated coastal area management, which included land title, equitable recovery and collaboration among organizations and between different sectors.
A clarification was requested regarding the reason land titles are an issue in fisheries. Mr Funge-Smith replied that it is an issue of critical importance in fisheries-related rehabilitation, as fishing communities live on coastal areas where land titles have not been clearly defined and conflicts are already occurring over land ownership in coastal areas.
A comment was made with regard to the difficulties in establishing an inter-sectoral mechanism to collectively manage coastal zones. Mr Funge-Smith mentioned that bringing all the stakeholders from different sectors around the table would be difficult at the national level but that it would be possible at the local level.
Assessment of the impacts of the tsunami on coastal vegetation in the region
Ms Sundari Ramakrishna, Wetlands International and Mr Faizal Parish, Global Environmental Centre
Ms Ramakrishna gave an overview of the assessment of impacts of the tsunami on coastal vegetation in the region. By referring to assessments conducted by M. S. Swaminathan Research Foundation (MSSRF) as well as Wetlands International, she introduced the findings pertaining to the magnitude of damage to coastal areas and the role of mangroves and other coastal vegetation in mitigating damage. She mentioned that the buffering effect depended on the width and strength of mangrove belts. Mr Parish explained how and to what extent mangroves and other coastal vegetation mitigated the impacts of the tsunami on the coastal zones in the region. He referred to the analysis that concluded that coastal forests provided significant protection where there was a sufficient width of intact forest, while degraded forest or widely spaced trees provided little protection.This provides strong justification for rehabilitating and protecting remaining coastal forests. He also introduced recommendations for rehabilitation, which include the enhancement of natural coastal defenses through greenbelts, the exploration of eco-engineering techniques, and the development of modalities for community-based rehabilitation and management of coastal forests.
A clarification was sought concerning where the figure of the mangrove area affected by the tsunami in Indonesia came from. Ms Ramakrishna mentioned that the figure was taken from the report produced by the National Planning Agency of Indonesia (BAPPENAS).
A comment was made that the extent greenbelts can protect coastal areas depends on various factors. Mr Parish made a clarification that it depends on various factors including the nature, size, width, and range of greenbelts.
Assessment of wood use and needs in the region for reconstruction: a case study from Aceh
Mr Nazamuddin Basyah Said, Greenomics
Mr Said mentioned that the aims of the assessment were to estimate the volume of logs needed in the emergency response and rehabilitation phases in Aceh and to identify their sources. He gave the estimates of wood needed for the construction of houses (1.2 – 3.4 million m3 of sawn timber depending on the type of housing), offices and houses of worship (101 756 to 135 675 m3 of sawn timber), and fishing fleet (14 774 to 18 468 m3 of sawn timber), totaling 1.6 – 3.2 m3 of sawn timber or 4 – 8 million m3 of logs. He highlighted the need for importing timber for the reconstruction in Aceh and presented the proposal of establishing a timber importation mechanism.
A clarification was sought about whether the imports are from other provinces of Indonesia or other countries. Mr Said replied that the proposal for a timber importation mechanism is for overseas sources, while transporting wood from other provinces is ongoing.
A question was asked about the durability of wood imported from other countries if used for house construction in a tropical country like Indonesia. The chairman acknowledged the importance of this issue and suggested it requires further investigation.
A question was raised about local alternatives for house construction such as bamboo. Greenomics mentioned that around 55 percent of those surveyed by Greenomics had replied that they use other woods for house construction. Mangrove Action Project referred to the findings from a meeting in India on earthquake-resistant bamboo housing and mentioned that bamboo is a feasible alternative to regular wood for building houses as they are durable and can be managed sustainably by local communities.
Mr Heruela asked a question regarding demand for wood fuels in tsunami-affected areas in Aceh. Mr Said replied that the demands for woods for fuel purposes are not significant in Aceh.
A question was raised concerning approaches for promoting the establishment of greenbelts. Mr Parish (Global Environment Centre) emphasized the importance of creating greenbelts without excluding local communities, and highlighted the need for instituting laws/regulations and guidelines for promoting greenbelts. Mr Kashio (FAO) mentioned that the current greenbelts are not designed to protect against tsunamis, although they happened to perform such a role in the recent tsunami incidence, and thus highlighted the need for renewed efforts in establishing greenbelts for specifically protecting against tidal surges.
A question was asked regarding the effectiveness of coastal plantations, especially that of Casuarina. Response was given by a Malaysian representative that plantations are useful to the extent they reduce the energy of tidal surges but such effects depend on the width, range and nature of plantations. A representative from India added that involving local communities in planting and management (such as under the Joint Forest Management scheme in India) is important for success. A Malaysian representative referred to the difficulties Malaysia had experienced in involving communities in planting large areas and suggested private-community partnerships as a potential solution.
Mr Parish mentioned that the Global Environment Centre, in collaboration with various partners such as the Port and Airport Research Institute and Disaster Reduction Research Institute from Japan, has started assembling models to assess the effectiveness of greenbelts in protecting against tsunamis, and developing guidelines for establishing or strengthening greenbelts.
UNESCO raised a concern about timeliness of assistance for reconstruction and rehabilitation as there is a possibility that people would start using wood from nearby areas before timber is imported from outside.
M. S. Swaminathan Research Foundation highlighted the need for disseminating reliable data on the contribution of coastal vegetation to livelihoods and integrated coastal management, especially in local languages.
Mangrove Action Project emphasized the importance of hydrological assessments in planning mangrove rehabilitation efforts.
An Indonesian representative made a comment that demand for wood can be reduced because the Government plans to build about 120 000 houses, instead of 500 000 as estimated by Greenomics, and also because houses are designed to use less wood and more of alternative materials.
