Building with Nature in Indonesia: Restoring an Eroding Coastline and Inspiring Action at Scale
Indonesia has become a pioneer in embracing Building with Nature, an approach to infrastructure and environmental management that aims to work with the forces of nature, rather than opposing them. This publication summarises the insights and lessons from a landscape scale implementation of the Building with Nature approach between 2015 and 2021 in Demak. Demak is a coastal district in Central Java province that has been plagued by erosion, flooding and devastating land loss that in places has extended for several kilometres inland. The Building with Nature approach was undertaken by a unique public private partnership under the leadership of the Indonesian government, Wetlands International and Ecoshape after the construction of “hard” infrastructure such as sea walls and the planting of mangroves failed to stop the loss of land. This publication gives a voice to the many different partners involved in the project.
The knowledge, approaches and mechanisms used and lessons learned in Demak can support sound replication along the entire northern coast of Java, where millions of people are facing the loss of productive land from erosion, flooding, and other disasters. Beyond that, we hope that our work inspires and helps enable the recovery of mangroves to protect communities and enhance local livelihoods for other Indonesian islands and for coastlines more widely in South and East Asia and globally.
This weADAPT article is an abridged version of the original text, which can be downloaded from the right-hand column. Please access the original text for more detail, research purposes, full references, or to quote text.
Building with Nature Indonesia is led by Wetlands International, Ecoshape, the Indonesian Ministry of Marine Affairs and Fisheries (MMAF)and the Indonesian Ministry of Public Work and Housing (PU) in partnership with Witteveen + Bos, TU Delft, Wageningen University & Research, UNESCO-IHE, Blue Forests, Kota Kita, Von Lieberman, the Diponegoro University, and local communities in Demak.
Methods: Mangroves and Sustainable Aquaculture for Coastal Resilience
The Building with Nature approach adopted in Demak has been based on research showing that even narrow strips of mangroves along shores reduce wave heights, moderate storm surges and trap sediment. A 100-metre strip reduces wave heights by between 13 and 66 per cent, for instance. So their loss has been traumatic. Years of mangrove removal to create ponds for aquaculture had by 2015 reduced their presence along the shore of Demak to a few scattered patches. As the seas invaded, local communities realised the predicament they had created, and tried to turn the tide by planting new mangroves. But this usually failed. The water was by now too deep and the waves too strong. Planted seedlings were washed away. Still, mangroves are remarkably robust and opportunistic species, and seeds are ever present in these coastal waters. So successful natural restoration is possible, if the conditions are mild enough for mud to accumulate and capture passing seeds. We set out to create those conditions and applied two measures: permeable structures and converted ponds.
One novel technology has been the placement of 9km of mud-trapping semi-permeable structures along the seaward edge to prevent further erosion of the 20km coastline. The structures, made from local brushwood and bamboo attached to poles, slow down waves and allow mud to settle inside the grid. Once the nearshore bed level rises enough, mangroves can regenerate naturally to protect the hinterland from further erosion. The structures were largely built by communities. Besides providing their labour, they have become ever more involved in planning. In 2018, the communities formally took ownership of the grids.
Converting Ponds to Mangroves
Severe land subsidence demonstrated how important it is to restore mangroves in landward direction from the shoreline wherever possible, especially in the face of sea level rise. The project supported farmers in the desired coastal greenbelt zone to convert some of their abandoned and mostly unproductive aquaculture ponds into mangroves. Sometimes they did this in exchange for financial and other assistance to rent ponds outside the green-belt area or start alternative livelihoods. Sediment was allowed to enter the basins, along with water containing mangrove seeds. In some places specific mangrove species were replanted, but otherwise we allowed natural regeneration.
Associated Mangrove Aquaculture Systems
Along rivers and creeks, farmers were introduced to the novel ‘Associated Mangrove Aquaculture’ system, a more sustainable alternative to the conventional silvo-fisheries system. Part of the pond is given up to make space for the natural recruitment of riverine mangroves to protect earthen sea walls along rivers and ponds, reduce maintenance costs, and enhance fisheries and water quality.
Historically, a typical response to declining aquaculture yields was to maintain income by converting yet more mangroves to ponds, exacerbating the problems. In the past decades the aquaculture sector in Demak lost 60-80% of its income due to erosion, flooding and pollution. We proposed that restored mangroves become a key part of the solution. Mangroves can protect the fish ponds from waves, filter sea-borne toxins, deliver firewood and fertiliser, and provide nursery and feeding grounds for wild fish. So, rather than being competing land uses, mangroves and aquaculture can be complementary. In ponds further land inward, we introduced sustainable aquaculture practices that use less chemicals and provide space for mangrove restoration. This enables communities and the economy to prosper and increase hazard resilience. Communities were supported by field facilitators who lived in the district throughout the landscape restoration process.
Through the innovative Bio-rights incentive mechanism, communities received financial and technical support to adopt sustainable aquaculture practices and other livelihoods in return for ecosystem restoration activities.
The flagship supported upscaling in Indonesia through training, knowledge exchange and institutional embedding. Communities participated in coastal and village planning which already resulted in enhanced government funding for the maintenance of permeable structures, mangrove rehabilitation and improved aquaculture.
Coastal erosion halted
We built permeable structures along more than nine kilometers of the Demak coastline. The idea was for mangroves to take root and grow in the newly trapped sediment behind the permeable structures and eventually replace them. In some places that happened, with mangroves reaching about 1 metre in height.While some have been abandoned and the structures need frequent maintenance, the grids have captured mud and locally stopped coastal erosion, delaying marine invasion and land loss. That is a big gain for the villagers and promising for other communities that live along other eroding coastlines.
Unfortunately, land subsidence due to unsustainable groundwater extraction has limited seaward mangrove restoration close to Semarang. New mangroves were disappearing, and monitoring poles in the water were becoming submerged.Mangroves may not return on the scale anticipated until land subsidence is substantially reduced. The structures may need to be maintained in place for longer than once thought. If subsidence can be stopped, lost ground can also be recovered to push out the coastline to where it used to be. But if it continues, the structures can only reduce the land loss temporarily.
Communities maintain the structures, with local-government finance. The role of the project partners is now restricted to providing advice and funding maintenance. We see this successful transfer as being of equal value to the technical innovation, providing a social and institutional model that can be replicated elsewhere.
Permeable structure approach mainstreamed across Indonesia
The Indonesian Ministry of Marine Affairs and Fisheries mainstreamed the approach and already installed 23,5 kmof its own structures to halt coastal erosion in 13 districts of Java, Lombok and Sulawesi, worth ~2.5 mln EUR.
Conversion of degraded ponds to mangroves
Among the ten community groups involved in Building with Nature, more than two dozen farmers gave up almost 80 hectares of ponds to green-belt recovery. This exceeded the programme target. For these efforts of mangrove restoration to really pay off and connect to other parts of the mangrove belt, more farmers, investment and guidance is needed.
Successful introduction of sustainable aquaculture practices
Our coastal protection efforts were integrated with the introduction of aquaculture practices that support mangrove restoration instead of damaging the ecosystem and that boosted the local economy. The programme organised Coastal Field Schools in which 277 farmerswere trained with more sustainable aquaculture practices and on the importance of mangrove greenbelts. These practices were adopted by 80 percent of the farmers in 464 ha of pondswhich, compared to the baseline, tripled their shrimp yields. This motivated farmers to give up (part of their) ponds for mangrove restoration.
In Demak we demonstrated that through Associated Mangrove Aquaculture (AMA) systems, aquaculture productivity and local incomes can be boosted while increasing hazard resilience. The success rate of mangrove recovery was ~75% and farmers experienced improvements in yields, especially when applying techniques learned at coastal field schools (CFS), in which they learnt practices that preserve and restore the mangrove and require less chemicals.
To the community groups engaged in mangrove restoration, we provided Bio-rights funds to support required investments for improving aquaculture or in creating alternative livelihoods. Some bought equipment to make fish food or fertiliser for their ponds from organic waste such as straw and leaves. Others created vegetable gardens, produced flour from crab shell, harvested non-timber forest products to make handicrafts and honey, or explored ways to cultivate green mussels on the permeable structures.
More than 80 percent of fishers report better near-shore catches, with incomes now as good as those from aquaculture. A recent study confirmed a clear recovery in fish populations and rapid increases in fish catches. We also supported farmers with equipment to harvest wild fish from in and around the resurgent mangroves.
An assessment of non-timber forest products that used Demak as an example, found that mangroves provided products ranging from medicines to textiles and firewood to foods such as leaf chips, chutneys and fruit drinks. They were a major but largely untapped business opportunity for local communities.
Thanks to one Bio-rights investment, the regent of Demak opened a 350-metreboardwalk through new mangroves in Bedono, for enjoyment by tourists, for educational purpose and local meetings.
During the programme community groups gained the knowledge, skills and authority to engage in policy dialogues on coastal and spatial planning in their villages and at district levels. Village development plans and associated land-use regulations incorporating Building with Nature have been adopted by communities and formalised within local government of the 9 villages involved. These developments have received government support and resulted it enhanced funding for the maintenance of permeable structures, mangrove rehabilitation and improved aquaculture.
There were many takeaways from the project. Some of the key ones were:
- Seawalls and levies do not work for long coastlines with irregular shapes, are generally too expensive to construct and maintain. They are also likely to increase erosion in other areas, because they stop the waves, and hence mud transport, altogether.
- The success rate of mangrove restoration ranges between 15-20% as a result of inadequate planting techniques and failure to resolve socio-economic and institutional barriers. We recommend to move away from traditional mass planting, especially seaward of the shoreline, towards creating the right ecological and socio-economic conditions for mangroves to settle naturally. This provides a more resilient and functional forest at a lower cost.
- Mangrove restoration with permeable structures and through pond conversion is low-tech, but requires a sophisticated design based on comprehensive understanding of biophysical and socioeconomic processes, and adaptive management. A key lesson for replication is not to do it blindly: learn general lessons, but recognise that every environment and community is different.
- Permeable structures are a temporary measure to allow mangroves to recolonise and require regular maintenance until mangroves behind the grids are sufficiently developed to take over their function. Under conditions of significant land subsidence or reduced sediment input, their effectiveness decreases. Community ownership is essential, as permeable structures need continuous maintenance in the face of storms and other wear and tear.
- Sustainable solutions require technical and socio-economic measures that address the root causes of the problem. Although the interrelatedness of measures challenge the design process, the outcome is more resilient. The key to success is collaboration across disciplines and sectors and with communities.
- Mangrove and brackish water aquaculture can be complementary when managed sustainably. When a wide greenbelt is restored, ponds can be revitalised behind mangroves and deliver essential ecosystem services for aquaculture.
- Coastal field schools were critical to both mangrove restoration and increasing aquaculture production and was cost-efficient. Trained villagers passed on their insights, became creative in adapting to change and were empowered in policy dialogues.
- Active community engagement is the way to create a local social-economic structure to facilitate an integrated landscape transition. Improved aquaculture productivity realised through coastal field schools provided the push for farmers to dedicate areas for greenbelt restoration. The Bio-Rights finance mechanism enabled the transition from traditional to sustainable aquaculture as well as restoration and protection of mangroves.
- Achieving gender balance can be a challenge due to local customs. A gender strategy should be an integral part of programme design and be developed in the early stages.
- Co-benefits do not necessarily translate into revenue streams. And if they do, additional efforts and new methods beyond traditional financial accounting are needed to revenues such as from carbon, ecotourism and fisheries into the project structure.
- For NbS innovative procurement models (short term versus long term, performance-based) and multi-party integrated delivery agreements may apply to share risks. Pilots allow learning and further development of such models.
- Continuous monitoring and research increases technology and system understanding which allows to respond to natural dynamics with innovations in design and changes to budget allocations. Consultants and the science community can support with tools for adaptive management practices to reduce uncertainty and risks.
- Policies and plans at different levels can enable NbS and long-term budget allocations for measures on the ground. To be effective in the long-term, mangrove restoration needs to be part of integrated coastal management and be supported by policy, long-term integrated planning and strong local governance.
The Building with Nature approach can be mainstreamed in other types of landscapes. Check out the Building with Nature Asia initiative which aims to accelerate upscaling of Building with Nature in Asia.
There is a Building with Nature solution for every setting, combining green and grey in an optimal mix alongside other measures for risk reduction. Discover more on the Building with Nature platform (EcoShape) and learn about all Building with Nature concepts piloted thus far.
All publications, technical reports and scientific articles, blogs and news about Building with Nature Indonesia can be found on the pilot webpage.
Finally, the project also produced five technical briefs, which can be found below:
- Technical Guidelines ‘Building with Nature approach’
- Technical Guidelines ‘Systems Understanding’ for Nature-inclusive Coastal Infrastructure design
- Technical Guidelines ‘Permeable Structures’
- Technical Guidelines ‘Associated Mangrove Aquaculture Farms’
- Technical Guideline ‘Building Sustainable Aquaculture through Coastal Field Schools’
Tonneijck, F., Van der Goot, F., Pearce, F. Building with Nature in Indonesia. Restoring an eroding coastline and inspiring action at scale. Wetlands International and Ecoshape Foundation. February 2022