Preemptive Restoration Saves Mangrove by Correcting Hydrology – Case study from Trang, Thailand
“Preemptive
restoration”, as termed by Robin Lewis, the Mangrove Action Project’s, Expert Technical
Advisor, is the process where stressed mangroves are detected and saved prior
to death. It can be included within the Community-based Ecological Mangrove
Restoration (CBEMR) method as it intervenes in mangrove degradation before
total death and loss of mangroves and their ecological functions.
restoration”, as termed by Robin Lewis, the Mangrove Action Project’s, Expert Technical
Advisor, is the process where stressed mangroves are detected and saved prior
to death. It can be included within the Community-based Ecological Mangrove
Restoration (CBEMR) method as it intervenes in mangrove degradation before
total death and loss of mangroves and their ecological functions.
A case study of
this preventive technique was undertaken by Mangrove Action Project (MAP) in
Trang province in September 2013. Near the Bang Khao Village CBEMR site where
MAP has been working a road was illegally built through the mangroves by a private
individual who wanted to gain access his oil palm plantation. MAP was alerted about
the road construction problem by the villagers that worked with them at the Ban
Bang Khao site. After observation and assessment of the situation, MAP staff
determined that the road was acting like a dike as there were not enough
culverts placed underneath the road to allow normal tidal exchange. It also
appeared that one culvert had collapsed. This poor construction was causing
high stress on the mangroves due to the slow water drainage and was also
causing the water to flow over the road during spring tide as the culverts
could not handle the high water volume. Standing water at low tide indicated improper
drainage. Dying Ceriops tagal, which
seemed to be suffering the most due to their preference for higher drier sites
and their inability to deal with the flooding, was observed in the area. Rhizophora apiculata were faring better
to the flooding stress.
this preventive technique was undertaken by Mangrove Action Project (MAP) in
Trang province in September 2013. Near the Bang Khao Village CBEMR site where
MAP has been working a road was illegally built through the mangroves by a private
individual who wanted to gain access his oil palm plantation. MAP was alerted about
the road construction problem by the villagers that worked with them at the Ban
Bang Khao site. After observation and assessment of the situation, MAP staff
determined that the road was acting like a dike as there were not enough
culverts placed underneath the road to allow normal tidal exchange. It also
appeared that one culvert had collapsed. This poor construction was causing
high stress on the mangroves due to the slow water drainage and was also
causing the water to flow over the road during spring tide as the culverts
could not handle the high water volume. Standing water at low tide indicated improper
drainage. Dying Ceriops tagal, which
seemed to be suffering the most due to their preference for higher drier sites
and their inability to deal with the flooding, was observed in the area. Rhizophora apiculata were faring better
to the flooding stress.
Illegal road built through the mangroves
Water flowing on the road during Spring tide
Dying Ceriops tagal due to flooding
Drown mangroves and wood taken by locals for firewood
MAP decided to take action and solve the problem by using the backhoe that they had working near the village on the CBEMR site in order to install two new large culverts under the road. This was done fairly quickly and on a low budget costing just over $300. The cost only entailed the backhoe operation time as the culverts were provided free. The site was visited about month later and MAP reports that the problem seems to have been solved. Future visits will be carried out in order to monitor the hydrological situation and the state of the mangroves.
Large culverts being brought to the site
The culverts being installed
State of the site once the culverts were installed
This case study shows that although CBEMR is not a substitute of proper management and protection of existing mangroves, it can also be used to prevent the loss of mangroves and a much more costly restoration intervention. It is a good example of the importance of preventive action and community involvement.
This hydrological correction work was completed under MAP’s “Mangrove Restoration and Reforestation in Asia, a Project for Knowledge Exchange and Action to Protect Climate change, Forest and Biodiversity” project supported by the Global Nature Fund, the Ministry for Economic Cooperation and Development (BMZ) (Germany) and the Foundation Ursula Merz.
