Nature Based Solution for Repairation and Coastal Erosion Control
What is the problem?
Flash floods and extreme flood events are becoming more frequent as a result of climate changeLoss of land and good quality soils in flood plains Increasing sedimentation and pollution impacting on inshore marine environment. Fagalii Bay is experiencing increased sedimentation from 2 main streams, river bank erosion affecting coral reef health and fisheries
Biolog filter
The BIOLOG filter was devised for the purpose of preserving the Okinawa coral reef by reducing the turbidity of river water discharged to the sea. The BIOLOG filter has proved to be highly effective in Okinawa as well as other parts of Japan, and is believed to be an effective measure for turbid water treatment in Samoa.
What is the Biolog Filter?Â
- Material manufactured by forming recyclable coconut fibers into a cylinder shape, and wrapping/reinforcing the cylinder with nets of the same material. originally used as plant beds on the riverbank.Â
- The filter absorbs soil particles and water, and promotes the growth of plants, and will eventually decompose naturally after five to eight years.is effective in absorbing soil particles and is used to filter turbid water discharged from civil engineering works throughout Japan, including Okinawa.Â
- But now has effective benefits for riverbank stabilization and river outlet filtration for the Fagalii River in Samoa.
Key Outstanding Criteria
- Green solution and made of 100% natural materials – safe for environment and recyclableRetains water and does not change natural river flow patterns
- Stabilizes soil erosion and riverbanks
- Controls pollution by retaining debris and filtering sedimentation flowing into the marine environment – high filtering effect of fibresInstallation is easy and has little impact on the environment during construction – simple construction method
- Allows for the growth of natural vegetation – promotes riparian revegetationIt slowly builds back riverbanks and does not take up much space
How was it implemented in Samoa?
- Community surveys and consultations – local knowledge of the areaSurveyed the priority vulnerable areas affected by erosion (site selection)
- Monitored the water flow, water levels and any species of concernCarried out the detailed designs and drawingsÂ
- Obtained village chief council and community approval Compiled an Environment and Social Management Plan
- Secured Development Consent approval from the Ministry of Works, Infrastructure and Transport
- Procured a local contractor Installation and training Launching and public awareness (media, universities, schools, communities etc.) Monitoring of impacts and maintenance
Key Successes
- Riverbank erosion and the loss of family lands due to flooding have been controlled through a nature based solution instead of a hard infrastructureÂ
- Much of the riverbank was retained ie, very little disturbance during construction
- Additional benefit of filtration and blocking of debris from polluting the reef and receiving watersÂ
- Revival of the riparian environment is being realizedÂ
- Forming a good habitat/ecosystem for biodiversity
- Community is still able to access the riverÂ
Scalability and Replicability
- Minimal environmental impacts vs. High environmental benefits
- Has national applicability beyond riverbank stabilization:
- Water supply intakes – resolve turbidity issuesÂ
- Construction and infrastructure development – drainages, road side runoff and dust/erosion control
- Replicate it to mangrove areas – protect boardwalks and maintaining flow of water within mangrove areas. Â
- Low cost
- Installation training by JICAÂ
- Business case to manufacture the biologs in the PacificÂ
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