Project

Building with Nature along a tropical muddy coast in Indonesia: innovation in mangrove restoration

While mangrove restoration and mitigation has become very popular worldwide as a method to restore coastal resilience and ecosystem functioning, high failure rates are typical. In most cases involving actual planting, the wrong species are planted in unsuitable areas. In fact, recent work has shown that given the right conditions, mangrove recovery actually works best without planting at all.

Photo right: Young mangroves testing the ground. Naturally recruited Avicennia marina. No planting involved. (Photo: Wetlands International)

A Dutch consortium of coastal engineering concerns, NGOs and maritime knowledge institutes (Witteveen+Bos, Deltares, EcoShape, Wetlands International, Wageningen University and IMARES) together with the Indonesian government and Indonesian partners recently developed an innovative approach to mangrove restoration near the city of Semarang, northern Java island. With the initiative the partners aim to enhance coastal resilience for 70,000 vulnerability people in Central Java by avoiding further coastal flooding and erosion and by providing them with a long term perspective for sustainable economic development through revitalization of aquaculture ponds for crab and shrimp farming. We do this by integrating mangrove restoration, small scale engineering and sustainable land use (Building with Nature).

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The approach was borrowed from a method already used for centuries to grow land in the muddy Dutch Wadden Sea. In this method, semi-permeable dams are built from wooden poles packed with branches to dampen wave action and allow fine sediment to settle and build up and consolidate behind the dams. Based on the restored sediment dynamics and sediment build-up, mangroves in many cases will recruit and start growing by themselves or can be effectively planted if the right species are placed in the right areas.

Mangrove destruction has set the way for coastal erosion, flooding and loss of property and livelihood
Mangrove destruction has set the way for coastal erosion, flooding and loss of property and livelihood

This is one key aspect of this larger project to which experts from IMARES are contributing by means of their practical knowledge and experience in tropical habitat restoration. Many hundreds of meters of semi-permeable dams have been constructed and together with Deltares, UNDIP and Wetlands International, experimental trials will be started to evaluate and assess various approaches and species to be used for mangrove recovery. Soon the team expects to bring out a new implementation guide based on the lessons learnt.

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The partners aim for replication and scaling up of the Building with Mangroves approach to other rural and urban areas in Indonesia and other vulnerable muddy coastlines in the world, including through capacity building, knowledge exchange and embedding in policies and planning.

For whom we do it all: Children of Timbulsloko village. (Photo: Dolfi Debrot)
For whom we do it all: Children of Timbulsloko village. (Photo: Dolfi Debrot)