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Rehabilitation of a mangrove-mud coast in Timbul Sloko - Java, Indonesia

 

Location: Demak District (near Timbul Sloko), Northern Java, Indonesia
Date: 2015 - 2020
Involved parties: Building with Nature in Indonesia is a programme from Ecoshape, Wetlands International, the Indonesian Ministry of Marine Affairs and Fisheries (MMAF), the Indonesian Ministry of Public Works and Housing (PUPR), Witteveen+Bos, Deltares, Wageningen University & Research, UNESCO-IHE, TU Delft, Von Lieberman, Blue Forests, Kota Kita, Diponegoro University, and local communities.; Supported by Dutch Sustainable Water Fund, The German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) as part of the International Climate Initiative (IKI), Waterloo Foundation, Otter Foundation, Topconsortia for Knowledge and Innovation Mangroves for the Future, and with contributions by all partners.

Technology Readiness Level: 7 System being tested in actual conditions at relevant location
Environment: Tropical shores
Keywords: coastline, mangrove, restoration, muddy shore, erosion, community, resilience, aquaculture, multi stakeholder approach, land subsidence, sustainable aquaculture, permeable structures, self-supportive

 

Building with Nature designTraditional design


A sustainable solution for a safe and productive coastline.


Using the “Building with Nature” approach, green (nature-based) solutions, such as mangrove restoration, are combined with grey (hard-engineering) techniques such as permeable structures. In this way use is made of the power (services) of nature instead of fighting against it. With this innovative approach stable (restored) mangrove coastlines are built that reduce flood risk, erosion and saline intrusion and can adapt to sea level rise. Simultaneously a multi-stakeholder approach is taken for the introduction of sustainable multi-functional land uses (in particular sustainable aquaculture), that enables inclusive economic growth once the coastline is stable.


Dams and sea walls as a single solution, are ineffective in muddy coasts. Hard structures like dams and sea walls have proven to be ineffective as a single solution along rural mud-coasts and often exacerbate erosion. They also tend to be expensive and unstable as they are incapable of adapting to climate change. Furthermore, they fail to provide the vital economic, environmental and social services that healthy mangrove belts provide.

 

Abstract

Communities in Northern Java are suffering from coastal erosion affecting hundreds of kilometres of coastline. In the district of Demak more than 3 kilometres of land including entire villages have already been swallowed up by the sea. Next video shows the situation of the coastline as per 2013.


Should nothing have been undertaken, unfortunately ‘business as usual’ at that time, the result around 2030 would be a fully flooded area with evacuated villages and land loss due to unsustainable groundwater extraction, mangrove loss and expected sea level rise, affecting over 70,000 people and 6000 hectares of aquaculture ponds. In the long run 30 million people in Northern Java may be affected by coastal erosion.




Instead of fighting nature with dams and dikes, Building with Nature solutions work with and along the dynamics of nature. For example, by restoring ecosystems so that they once more provide protection against extreme events and offer valuable ‘natural capital’ (shell-fish, timber or recreational opportunities for example).


In the Building with Nature programme in Demak, stable (restored) mangrove coastlines are built that reduce flood risk, erosion and saline intrusion and can adapt to sea level rise. Local stakeholders – including communities – are involved in design, construction and maintenance of measures. Simultaneously a multi-stakeholder approach is taken for the introduction of sustainable multi-functional land uses that enables inclusive economic growth once the coastline is stable. Through its policy trajectories, the Building with Nature measures are supported through village development plans and regulations on land use rights, protected areas and coastal zone management and Demak district and Central Java Provincial policies, as well as adaptation and disaster risk management.


This altogether leads to a so-called ‘dream scenario’ by 2030.



Three objectives of the program have been defined:

  1. Rehabilitation of mangrove coastal protection system.
    The mangrove coastline has deteriorated due to erosion, aggravated by less effective control measures, leading to loss of valuable land and aquaculture ponds. The objective is to restore the coastal system, by building stable (restored) mangrove coastlines that reduce flood risk, erosion and saline intrusion and can adapt to sea level rise. Moreover, organic litter from mangroves enrich the water and may improve water quality, and mangrove roots absorb heavy metals. This all can be achieved through a holistic and stakeholder inclusive approach with local communities, governments, ecologists, socio-economists and engineers.
  2. Revitalisation of aquaculture ponds.
    Once a stable coastline has been restored, aquaculture ponds can be revitalised, and new ones can be created. Thus, a model is introduced for sustainable aquaculture and alternative livelihoods that provides space for mangrove restoration and enhances the prosperity of local communities so that they can sustain the mangrove greenbelt
  3. Training of local inhabitants for self-supportiveness.
    The above objectives shall be attained and maintained by the local people. In this way they become ‘owner’ of the re-development, bringing the Building with Nature approach into mainstream coastal zone management, in particular into regional master plans for sustainable coastal zone management and development and risk reduction in Northern Java


This project page describes the activities to achieve the three objectives separately, as if they were three projects. In reality, actions for one objective will always be connected to interference with the other objectives. 



Rehabilitation of mangrove coastal protection system using permeable structures (Objective 1)


Initiation for mangrove coast rehabilitation using permeable structures

Strongly eroded coastline in Northern Java


Communities in Northern Java are suffering from coastal erosion affecting hundreds of kilometres of coastline. In the district of Demak more than 3 kilometres of land including entire villages have already been swallowed by the sea.


It is expected that further sea level rise will by 2100  result in flooding 6 kilometres inland, affecting over 70,000 people and 6000 hectares of aquaculture ponds. In the long run 30 million people may be affected by coastal erosion.


Furthermore, subsidence of coastal land, for a good part caused by groundwater extraction, makes coastal erosion issues more severe and complicates the protective measures provided by mangrove restoration.


In the initiation phase a physical understanding of the coastal system has been obtained, with focus on the problem of coastal erosion and its root causes, with basic information on bathymetry, soil and oceanographic conditions.


Vision


To fight this coastal erosion in a sustainable manner, a ‘vision’ (or ‘dream’) has been developed.


The principal objective is to build a stable coastline with reduced erosion by stimulating the rehabilitation of mangroves of the most vulnerable parts of 20 kilometres of affected coastline in Demak District. The restored coastline should be able to adapt to sea level rise to some extent. A stable coastline will enable a revitalisation of the aquaculture in  the communities in Demak, which will provide income for the inhabitants. Part of the income earned shall then be reinvested in maintaining and further strengthening of the mangrove coastline, thus obtaining a sustainable development cycle. Thereto this inspiring Building with Nature pilot is initiated, in which a paradigm shift towards water infrastructure solutions is triggered, aligning coastal protection with the interest of economic development and care for the environment. The alternative, Business as Usual scenario, shows a fully flooded area with evacuated villages and land loss due to land subsidence and erosion. 

Read more

 

Planning and design for mangrove coast rehabilitation using permeable structures


In 2012 the Indonesian government asked for support to address the severe coastal erosion in Northern Java. Hard infrastructures like dams and sea walls had proven to be ineffective along the rural mud-coast, exacerbating erosion and being unstable and expensive. Furthermore, they failed to deliver the vital economic, environmental and social services that the mangrove belt, the original natural coastal protection, provided. A Building with Nature approach was proposed and jointly a small but inspirational pilot started in Timbul Sloko village to restore the mangrove coast, engaging communities, government agencies and knowledge institutes.


Planning and design studies for coastal rehabilitation focused on:

  • Addressing the root causes of erosion
  • The effect of mangrove belts on wave heights 
  • Mangrove rehabilitation using permeable structures


 Read more


Implementation for mangrove coast rehabilitation using permeable structures

Mangrove rehabilitation using permeable structures


Permeable structures have been built from poles and brushwood to dampen the waves and capture sediment. Once the near shore bed level rises to around average sea level, mangroves will regenerate naturally, developing a natural defence that will protect the hinterland from further erosion.


Natural mangrove restoration supports the development of mangrove forests with different species. This is because not all species can equally withstand the submerged conditions, wave exposure and salinity occurring at the seafront. Natural mangrove succession starts with pioneer species that facilitate colonization by many other species and results in a great variety in root types, tree sizes, foliage and fruits, fulfilling different functions and attracting diverse (fish) fauna. This in turn results in the provisioning of multiple goods (timber, fodder, honey, fruits, and fish) and services (enhanced coastal protection, carbon storage, water purification, fisheries enhancement). Ecologically restored forests are also likely to be more resilient to change because of this. For more information see the brochure: ‘Mangrove restoration: to plant or not to plant ’, which has been developed by the Building with Nature Indonesia consortium.

Where the coastline has not yet been eroded, the conversion of ponds into mangrove forests in close collaboration with local communities is encouraged.



The construction of a permeable structure is low-tech. It can be built by the local community with minimal tools or machines. At many locations where permeable structures should be constructed, it is difficult to bring mechanical equipment due to limited water depth and soft sea bed material. Machines can also more easily damage the material. In Demak one team of 6 to 8 workers can build 4m of permeable structure during a working day of 8 hours.


More information on construction of permeable structures can be found in Technical Guidelines #4: Building with nature to restore eroding tropical muddy coasts: permeable structures (in preparation).


Mud Nourishment


Since 2015 the project has investigated several sediment nourishment options, notably offshore agitation dredging (to bring in additional sediment into the near-shore system) and infilling of (abandoned) ponds. However, the preliminary conclusion is that there is currently still sufficient sediment naturally available in the nearshore system to ensure natural infilling and (costly) mud nourishment is not required.


Operation and maintenance for mangrove coast rehabilitation using permeable structures


Monitoring and evaluation methods

 

Over the course of the project monitoring of the individual structures will be done to assess the durability of the permeable structures and implement gained information and further planning to increase the efficiency of the construction. Monitoring of the permeable structures is required at several stages and regarding different aspects.

 

BwN Indonesia is using a variety of methods to measure biophysical and socio-economic effects such as coastal risk reduction, land and water quality improvements, mangrove re-establishment and livelihood gains. This includes: physical field observations and measurements on variables such as sediment availability, salinity, water quality, mangrove extent and composition; satellite technologies to assess coastline change and erosion/deposition areas; drone images to assess on-the-ground mangrove recovery; and household surveys and community consultations to provide information about changes in local livelihood status and ecological condition.


Coastline development and performance of permeable structures 


Coastline development

At the locations where permeable structures are built the coastal erosion was halted. In addition to that the first measurements in the first year showed 0.45 m of sedimentation. And mangroves settled once elevation was above mean sea level. This happened behind several structures within a year. However, in 2017 in many areas elevation lowered again and mangroves disappeared. In addition, monitoring poles and structures disappeared below sea level within a couple of years. Subsidence (having several causes, among which unsustainable groundwater extraction) seems a lot more severe in this rural area than initially thought.


Permeable structures

The permeable structures function well when they are well maintained. The brushwood dampens the wave energy and sediment settles in the shelter of the structures. When the structures get damaged, by shipworm that eats wood and bamboo, compaction of the fill material or lack of maintenance the waves pass through the structures and erode the settled sediment. The design of the structures was updated, the vertical poles are changed to PVC filled with concrete and the bamboo is protected with wrapping. Also different types of materials are tested. Next to the update of the design the maintenance was intensified to keep sufficient fill material within the poles.


Maintenance of permeable structures  

 

Permeable structures need continuous maintenance. Without maintenance the fill material lowers and decreases, and wave attenuation reduces, with the result that the structure can no longer perform. The material is also eaten by shipworm which reduces the lifetime of the structures. Tests are done with wrapping of bamboo and wood and the use of PVC poles to increase the lifetime. Also alternative fill materials are tested like the replacement of the brushwood by horizontal bamboo beams tied to the vertical poles.

 

Maintenance of the structures needs to follow the monitoring outcome and needs to be executed directly after monitoring shows it is required. If stormy conditions occur more often, the monitoring and maintenance frequency should be increased. This also implies that at the start of the project a life cycle cost analysis has to be made and budgets for the entire lifetime need to be allocated.

 

More information on monitoring and maintenance of permeable structures can be found in Technical Guidelines #4: Building with nature to restore eroding tropical muddy coasts: permeable structures (in preparation)



Revitalisation of aquaculture ponds (Objective 2)


Initiation (aquaculture)


Decline in well-being of communities


Over the last decade, income from aquaculture has decreased by 60-80% and 25-50% for shrimp farmers and fishermen respectively as it collapsed in a few years’ time due to disease and pollution. As natural resources were destroyed for the creation of new ponds close to the coastline, fishermen are no longer able to sustainably exploit the marine environment. Therefore, besides technical measures, the project needs to invest in socio-economic measures to promote sustainable land-use including development and introduction of sustainable aquaculture and livelihoods diversification. These measures need to be rooted in community development plans, law and funding mechanisms and integral government master planning.
In the initiation phase of the project, a first overview of the organisation of the villages and aquacultures has been developed as well as an overview of local and district-level regulations. Possible alternatives were developed for addressing the low productivity in the aquaculture ponds.


Planning & Design (aquaculture)


The project develops and introduces sustainable aquaculture and livelihoods diversification (crab & shrimp farming). 10 community groups are supported through coastal (farmer) field schools and by providing resources (financial support) to initiate new aquaculture management practices and livelihood diversification. These improved practices aim to revitalize 300 ha of land for 300 households (based on a conservative estimate of 1 ha per household), and increasing average aquaculture productivity with 50%, by adjusting pond lay-out and management, by reducing fertilizer and pesticide inputs, by making optimal use of mangrove services like water purification and by diversifying livelihoods activities. The measures will be controlled using community bylaws and will be rooted in community development plans and government master planning for sustainable development.


Altogether productivity of the ponds is expected to go up with at least 50% as a result. The project directly supports sustainable revitalization of 300 ha of aquaculture ponds along a 20 km shoreline.


Implementation (aquaculture)


The project directly supports sustainable revitalization of 300 ha of aquaculture ponds along a 20 km shoreline. A model was put into place for sustainable aquaculture that provides space for mangrove restoration and requires less use of chemicals, in order to enable vulnerable communities and economic sectors to prosper, to be more self-reliant and to increase their hazard resilience. The project develops and introduces sustainable aquaculture and livelihoods diversification (crab & mussels & shrimp farming).

In the project area, farmers in Demak are trained through Coastal Field Schools (CFS). This is an existing method, which the Building with Nature Consortium has adjusted with a focus on shrimp farming and mangrove belt recovery. Farmers learn critical adaptive thinking to develop, test and implement best practices such as generating farm inputs locally to reduce cost and in an ecologically sound way. The trained villagers pass on their insights through new trainings in other villages with the help of government programs.


Also the pond lay-out and management are adjusted to enhance water quality. The ponds will include a filter pond, and fertilizer and pesticide inputs will be decreased. Further, poly-culture systems is introduced, in which farmers stock multiple species which stimulates nutrient recycling, limits pollution and enhances resilience. 


All communities have agreed to convert some ponds into mangroves to avoid further erosion, which shows their commitment towards a sustainable future and that they can be effectively engaged in coastal restoration and aquaculture revitalisation to safeguard their own future. The ponds are being relocated behind the restored mangrove belt, instead of right in front of the coast or directly bordering the rivers where they induce erosion. In this way the ponds can make optimal use of mangrove services like water purification


In total 10 community groups are supported through coastal field schools and by providing resources (financial support) to initiate new aquaculture management practices and livelihood diversification.


These improved practices directly revitalize 300 ha of land for 300 households, increasing average aquaculture productivity by adjusting pond lay-out and management, by reducing fertilizer and pesticide inputs, by making optimal use of mangrove services like water purification and by diversifying livelihoods activities.


The measures are rooted in community development plans and government master planning for sustainable development.


Best aquaculture practices introduced through Coastal Field Schools have been very successful and significantly increase aquaculture productivity and income. This boosts farmers’ support for the approach, already spurring them to convince others. 


Operation and Maintenance (aquaculture)


Farmers formally entered the Biorights program, and are implementing best aquaculture practices in no less than 422 hectare of ponds. The project leveraged the allocation of 70 ha of (degraded) ponds for rehabilitation into coastal and riverine mangrove. Although they may not all be suitable for mangrove recovery, it shows how communities start valuing mangroves.


The best aquaculture practices that were introduced to traditional farmers increased aquaculture productivity and tripled income, boosting farmers’ support and already spurring them to convince others.

  • To make space for mangrove restoration, the project works with villagers to move ponds at the shoreline backwards. So far 70 hectares (degraded) aquaculture ponds have been allocated for rehabilitation into coastal and riverine mangrove as part of the biorights mechanism; hence communities are giving up land for mangrove restoration. 
  • The project introduced the innovative mixed mangrove-aquaculture system for the first time in Indonesia. In this system 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.



Training of local inhabitants for self-supportiveness (Objective 3) 

 

Initiation (training)


In Indonesia most farmers learned aquaculture through trial and error. Knowledge transfer by services was limited and not always based on facts, in particular when advice was given by salesmen. This is one of the factors explaining the low and volatile yields of the coastal brackish water ponds (tambak) and contributing to the near disappearance of mangroves.

 

It is estimated that in Northern Java more than 30 million people are subjected to increased coastal vulnerability due to unsustainable land use practice. Therefore, the flagship project in Demak also serves to inform and inspire coastal zone managers from government and private sector and help them include the Building with Nature approach in their urban and rural development programmes. This contributes to replication and scaling up of Building with Nature across Indonesia. For this the project aims for BwN solutions to be embedded in policies and plans for sustainable development and coastal security in Demak, Central java and the national level. In the initiation phase an overview of these policies and plans has been developed. 


Planning & Design (training)


Using the field school approach, the Building with Nature Initiative intends to stimulate meaningful stakeholder participation to ensure the long-term success, and to build farmer's capacity to make aquaculture beneficial and ecologically sound. The so-called Coastal field schools (CFS) are extensive year-long learning programmes that enable communities to advance their livelihoods by sustainably managing their coastlines and its natural resources. Such programmes can be implemented by public and or private parties.


In the case of Building with Nature Indonesia project, the CFS compares organic low external input sustainable aquaculture (LEISA) with a traditionally managed pond. Gradually the CFS participants will learn to: manage their pond and its surrounding agro-ecosystem, use critical thinking skills at both pond and community level, engage in mangrove' restoration for coastal protection and biodiversity, and discover new opportunities or solutions to new local problems. After the training, farmers can enhance their income from milkfish and shrimp aquaculture to underpin efforts to restore mangroves for coastal safety.


Implementation (training)


CFS Key Characteristics

 

A CFS consists of regular group meetings at agreed intervals during a full cropping season and is field based. The primary learning material is the farming system. The training principle is not teaching, but facilitation of hands-on and discovery-based learning that enable farmers to be active learners and expert of their own field. The integrated and participant-defined curriculum which cover the full cycle of production.

Read more


Bio-rights incentive mechanism for community engagements


The engagement of local people is managed on basis of the financial incentive mechanism called Bio-rights, which reconciles economic productivity with environmental conservation and restoration measures. In return for active engagement in conservation and restoration measures, communities receive (financial) support to develop sustainable livelihoods that will generate income. So, the communities were not paid for their labour in erecting the permeable barriers.  Instead, they received loans for development projects using coastal resources, such as improving the productivity of their fish ponds and providing facilities for tourists.


In the case of Demak this translates into coastal safety measures on the one hand and sustainable aquaculture on the other hand. In 2017 Bio-rights contracts were negotiated with 10 community groups, representing 300 villagers. Legal contractual agreements are set up with community groups, rather than with individuals, and are witnessed by the village government. All communities have agreed to convert some ponds into mangroves to avoid further erosion, which was previously deemed impossible.

 

Operation and Maintenance (training)


Community engagement


'Involvement of local people managed on basis of bio-rights mechanism' 

Bio-rights is a financial incentive mechanism that reconciles economic productivity with environmental conservation and restoration measures. In return for active engagement in conservation and restoration measures, communities receive (financial) support to develop sustainable livelihoods that will generate income.


The Demak District Government has allocated budget to support the local government financially for the maintenance of permeable structures for the coming 3 years to be carried out by community groups nearby the structures. Budget has also been allocated by district and village governments for mangrove rehabilitation and aquaculture revitalisation.


The 10 Demak community groups, which have supported BwN measures are now organised in an ocean management forum called Bintoro (see photo of meeting above). This allows networking with the government and is a mechanism to receive funding to ensure sustainability of Building with Nature interventions.

 

Capacity building


One of the key initiatives of the programme is to support the development of an Indonesian Building with Nature Forum in which the government, knowledge institutes, private sector, NGO´s and communities collaborate to build up and share Building with Nature knowledge and experience in Indonesia. The Forum is already providing helpdesk facilities, offering trainings, hosting learning events and organising field visits and exchange visits.


A training programme, addressing Building with Nature measures has been developed and executed, reaching local governmental agents, coastal managers at different regional levels and local trainers such as universities and research institutes


A new training and awareness programme in collaboration with 10 knowledge institutes and universities, has been established to integrate Building with Nature in their curricula will help build the necessary capacity to implement Building with Nature at scale. In January 2020 the last training of trainers took place, accompanied by signing of a Memorandum of Agreement with several institutes.

 

Embedding in policies and planning


Works have been initiated to integrate BwN approaches and practices in policies and planning, on national, regional, district and village level.

Read more

 

Connecting, Replication and Up-scaling 


Building with Nature is innovative and site specific and it operates in areas where the understanding of systems is limited and where changes are dynamic. Therefore, a strategy of learning-by-doing has been adopted, and knowledge and lessons learned are shared widely to support the sound replication of the chosen approach. This is done through capacity building, knowledge exchange and embedding in policies and planning.

Read more

 

Lesson Learned


Since start of the project early 2015 every autumn permeable structures are constructed by the local community and a lot is learned by doing that and monitoring the construction and the effects afterwards. As natural materials are used, they degrade due to species and rotting. Frequent inspection and maintenance are required. The structures dampen wave energy, they are not strong enough to act as breakwaters. Large land subsidence is a threat to this solution as it creates a continuous setback. The Indonesian ministry of Marine Affairs and Fisheries is active in replicating this measure at other locations in Indonesia. This requires close contact with them to select suitable locations and develop adjustments to the design.

The Building with Nature measures implemented have in principle been successful.

 

The challenges in Demak emphasize the need for holistic solutions like Building with Nature, in combination with integrated water resources and coastal zone management.

Hence, the project will increase efforts regarding mainstreaming Building with Nature across Indonesia, including through capacity building and training.

In phases, 9 kilometres of permeable structures have been built, of which 4,4 km by government partner MMAF, preventing further erosion of the heavily subsiding area. The ownership as well as the maintenance of the permeable structures were officially transferred to the communities.


Best practices have been introduced to revitalise aquaculture productivity, boosting productivity and tripling income. Best practices are implemented by farmers in no less than 422 hectares of ponds. Through the biorights financial incentive mechanism the allocation of 70 ha (degraded) ponds for rehabilitation into coastal and riverine mangrove has been leveraged.


For the first time in Indonesia the innovative mixed mangrove-aquaculture system was introduced, in which part of the pond is given up to make space for riverine mangroves. In this system the aquaculture productivity is optimal, while the surrounding mangroves purify water and enhance fisheries.

Field studies indicate that fisheries are recovering along with mangrove recovery in the area, providing an extra source of income.


Village development plans and regulations on land use rights, protected areas and coastal zone management were developed and adopted by 10 communities and formalised with local government. It has already resulted in enhanced government support and district/village budget allocation for maintenance of permeable structures, mangrove rehabilitation and aquaculture.


References


 Weblinks

 Publications (reports and articles)

 Magazine articles

 Technical Guidelines (in preparation)

 

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