Like mangroves, bamboos are a local solution to coastal erosion
It is well-known for its ability to protect river banks and degraded soils from erosion – but in Thailand, bamboo is also a key material for coastal protection.
Samut Songkhram is a central Thai province which is leading the way to show how bamboo can decelerate erosion and increase sediment in coastal areas. Like much of Thailand, the province is subject to severe erosion along its coastlines and tidal flats. There are many causes, but the decline in protective mangrove forests, which once covered the country, is certainly a major one. The loss of mangrove coverage means that strong waves pound the tidal areas, dislodging much sediment and eroding the soft soil.
For some local communities, like the villagers in Krabi province, bamboo barriers are the natural solution. By plunging bamboo poles into soft sediment off the coast, residents have created thick barriers – of about 35 poles per metre – which decrease wave strength and height, and help build up sediment. Bamboo poles can last several years underwater. The windbreak and thick sediment layer which forms behind such barriers creates the perfect environment for mangroves to grow.
This old technique has recently attracted the attention of the Department of Marine and Coastal Resources (DMCR). Curious Ministry officials and specialists created thick fences of bamboo across several sites in Samut Songkhram. Their preliminary findings seem to support local wisdom. Between November 2010 and March 2013, the Ministry found that between 23 to 55 cm sediment accumulated behind bamboo canes – according to local estimates, an impressive increase.
As well as the buildup of sediment, bamboo barriers had a noticeable impact on the strength and height of waves. At Pak Klong Bang Bo, Samut Songkhram, bamboo revetment decreased wave amplitude by 70%. This impressive reduction in wave energy can help decelerate coastline erosion, as it diffuses the impact of waves hitting the shore.
Overall, the Ministry concluded that bamboo revetment “helps decelerating coastal erosion and supports nursey ground [mangrove stocks] to increase.” They also noted bamboo’s cheapness and ready availability for local communities. This programme has now expanded to 6 locations in 5 provinces of Thailand, with tens of kilometers of similar bamboo fencing in the sea.
More work needs to be done. There is little consensus or formal research done on the age, length or type of bamboo which works best in barriers, and creatures such as shipworm can compromise the quality of submerged poles. This lack of research makes it more difficult to scale up the use of bamboo fencing. Despite this, bamboo’s huge potential to help mangrove growth, and slow coastal erosion, offers an exciting prospect for many of INBAR’s Member states.
This piece was written for the UN’s International Day for the Conservation of the Mangrove Ecosystem.
INBAR does a lot of work with bamboo to restore degraded landscapes. To see how bamboo can help restore severely degraded land, watch our video ‘Greening Red Earth’ here. You can also read about how bamboo is dramatically improving landscapes in Ethiopia and Chishui, China.