Big steps forward on coastal restoration by Building with Nature consortium in Demak, Indonesia
Last year the Dutch-Indonesian consortium working on the Building with Nature project made big steps forward. A major achievement for the consortium that is responsible for the restoration of the coastline of Northern Java, was the signing of ten bio-rights contracts with local communities. These communities, representing 300 villagers in Demak, are now converting some of their pounds into mangroves to put an halt to the erosion.
On the website the consortium reviewed their major achievements in 2017.Aerial view of Bedono village with two of the permeable dams (left) that catch sediment.
Bamboo sediment traps
In 2017 the consortium placed a 1.7 kilometres of semi-permeable bamboo barrier, on top of the 3.5 kilometres that were built and maintained in 2015 and 2016.
The Indonesian Ministry of Marine Affairs and Fisheries has in total placed 11 kilometres of structures to trap sediment in 12 districts of Northern Java.
A ship worm is affecting the structures and limits the lifetime to two years. To keep the shipworms out, PVC poles have been placed, filled with concrete on the front row and bamboo covered with wrapping at the back row.Bamboo sediment traps protected against ship worm with PVC in Bedono.
The consortium organised monthly meetings in the field to discuss matters and solve them early.
These meetings also help to raise understanding among villagers how the semi-permeable barriers help to restore their mangrove belt, protecting their village, and how this intervention also leads to the return of oysters and green mussels (kerang hijau) which supports them economically.
Shrimp yield tripled
Community groups that gave up part of their ponds to make space for a mangrove belt, have been assisted by Coastal Field Schools (CFS) to develop new socio-economic activities.
The first monitoring results show that these trainings helped the farmers to triple their shrimp yield and double their income.Coastal Field School to train the villagers in critical thinking skills to develop aquaculture practices.
Mixed mangrove-aquaculture system
The introduction of the innovative mixed mangrove-aquaculture system is very exciting. This system is different from the traditional silvofisheries system where mangroves are planted on pond bunds or inside ponds and as such are not connected to open water.
In the mixed mangrove-aquaculture system mangroves and aquaculture ponds are separated. Due to this separation, the aquaculture productivity is optimal, while the surrounding mangroves reduce the spread of disease agents, purify water and maintain their coastal safety and fisheries enhancement functions.
More severe land subsidence
Last year the consortium observed that the problems with land subsidence are much more severe than previously thought.
Ultimately, sedimentation rates may not keep up with such high levels of subsidence, and in some places a threshold shall be reached soon where coastal restoration and aquaculture revitalisation may no longer be feasible.
Roll out of Building with Nature concept
The consortium created a secretariat in Indonesia, facilitated by the Ministry of Marine Affairs and Fisheries, to disseminate the Building with Nature concept across Indonesia, by providing practical design guidelines, training and policy recommendations.
A help desk facility can provide on-the-job guidance on all aspects of the project life cycle of existing and future BwN projects.
A high-level network of champions will be created to facilitate outreach in media, policy fora, and working groups for wider uptake of BwN in Indonesia.
This news item is based on a blog on the website of Building with Nature Indonesia.
Read also on this website
● Dutch-Indonesian support for Javanese communities to restore their coast line, 20 October 2017
● Wetlands International reports first sediment build-up behind permeable coastal dam on Java, Indonesia, 3 March 2016
● Project: Mangrove restoration Java - Building with nature
● Country: Indonesia
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Building with Nature: restoring mangrove coast with semipermeable dams (English subtitles)