The Bangkok Metropolitan Administration (BMA) has managed to plant 50 rai of mangrove forest to stem coastal erosion in Bang Khunthian district, according to Bangkok governor Aswin Kwanmuang.
The planting was carried out over the past 10 months, he said, admitting that initially about 50% of the trees died because BMA workers failed to protect the trees properly.
Many of the mangrove trees were wiped out by rapid coastal erosion which ate into about 10 metres of the district's 20-kilometre stretch of coastline over the course of a year.
To stem the erosion, the BMA erected bamboo and concrete poles to act as permanent barriers, Pol Gen Aswin said.
The barriers were built in and around areas where the mangrove trees were planted. Concrete poles were put up forming an outer wall. Three inner walls were made from bamboo poles.
After the walls were erected, damage to the newly planted mangrove trees was reduced significantly.
Apart from rapid erosion, some mangrove trees died because they were not properly planted. Also, barnacles attached themselves to the plants and ate the stems, prompting the BMA to hire local residents to scrape them off.
Pol Gen Aswin said the Metropolitan Electricity Authority (MEA) donated 1,300 unused concrete power poles, of which 1,100 were used to build the outer anti-tidal walls. The MEA is in the midst of delivering another 4,000 poles.
The Provincial Electricity Authority has pledged to donate 5,000 power poles for the cause. The BMA estimates it will need about 20,000 poles to construct walls along the district's entire erosion-affected coastline.
The city governor said that in the walled area, destruction has not only stopped but 40cm of shoreline has returned.
For the mangrove reforestation, Pol Gen Aswin said the BMA has set a target of planting some 400 rai of trees this year. If successful, up to 50cm of eroded shoreline would return, he claimed.
The ecology was gradually improving with spawning areas for shellfish becoming larger behind the protective walls.
"What we have seen since the beginning of the planting project is that much marine life, including mud skippers, has increased. Most are sheltered behind the anti-erosion walls," the Bangkok governor said.
Many large companies contributed to the mangrove reforestation effort in Bang Khunthian. They include Thai Beverage, Bangkok Mass Transit System Public Company Limited, the Central Group and the PTT Public Company Limited.