BUILDING WITH NATURE: RESTORING MANGROVE COAST

Abstract

Communities in Northern Java, Indonesia are suffering from coastal erosion affecting hundreds of kilometres of coastline. At the north coast of the province of Central Java in the district of Demak more than 3 kilometres of land including entire villages has already been swallowed up by the sea. The main causes of the problem are the removal of mangrove belts for aquaculture development, the construction of coastal infrastructure impacting sediment build-up from offshore sources, river canalisation and land subsidence caused by groundwater extraction. The Building with Nature (BwN) approach was introduced in Demak to address these root causes and mitigate their effects. The approach integrates mangrove and river restoration, small-scale engineering and sustainable land use. Permeable brushwood and bamboo structures have been built to dampen the waves and capture sediment. Once the near shore bed level had risen enough, mangrove seedlings will start to regenerate naturally. Local communities build and maintain these permeable structures through a Bio-rights approach. They are also trained to practice sustainable mixed mangrove-aquaculture, working with probiotics and local food sources. A strategy of learning-by-doing was adopted, where sharing the knowledge and the lessons learnt is supporting sound replication of the BwN approach through capacity building, knowledge exchange and embedding in policies and planning. A lesson learnt is that the land subsidence is more severe than expected which affects the net sedimentation rate behind the permeable structures and slows down the recolonization by mangroves. This lesson is communicated to the communities and policy makers.