Permeable structure that traps sediment to stabilise the coastline at Bogorame Timbulsloko village, Java.
The Indonesian government is adopting the same approach to provide protection for dozens of other coastal com- munities across the country, says Abdul Muhari, formerly of the Ministry of Maritime Affairs, a project partner, and now head of early warning at the government’s National Disaster Management Authority. So far, permeable brush- wood barriers have been erected along 23.5 kilometres of flood-threatened coast in Java, Lombok and Sulawesi. We worked in 2019 with the ministry and the government’s Geospatial Information Agency to develop national man- grove maps to boost conservation and restoration. But it has become clear that around Semarang subsidence is flooding land and limiting mangrove restoration. The future of the entire coastline and its millions of inhabitants can only be secured if the mangrove restoration is comple- mented by ending land subsidence. So in 2019 we worked with a design team, ONE Resilient Semarang, to draft a wider strategy for coastal protection in and around the city. Its centrepieces are restoring a man- grove “green belt” along the coast, and ending the ground- water pumping by providing new water sources. The aim is to incorporate the ideas into future regional infrastructure planning. We hope to integrate a 2000-hectare mangrove and fishing park into the government’s existing plan for a coastal road on a sea wall that, depending on its design, could help mangrove recovery or kill it by cutting the green belt off from the ocean.
Along the adjacent coast, the story is the same. The land is sinking because of Semarang’s pumping, and with man- groves replaced by prawn ponds in rural areas, the sea is swamping the land. “We’ve lost 500 metres to the sea in the last ten years,” said Maskur, a teacher in Wedung village, as our boat headed past the submerged banks of former prawn ponds and out into a bay unmarked on any maps. Nearby Timbulsloko village is now almost an island, connected to the mainland by a five-kilometre causeway. In the past five years, Wetlands International and Dutch water engineers have been working with the inhabitants of nine villages east of Semarang, and local experts, in an innovative project to erect offshore brushwood barriers that capture silt, stabilising the coastline and allowing man- groves to re-establish themselves. The labour of commu- nity groups was exchanged for our support for local eco- nomic activities such as improved aquaculture and tourist developments. We have since been working on developing village regulations to protect the restored mangroves. This strategy of “Building with Nature” appears to be work- ing, with sediment accumulating behind the barriers and mangroves starting to emerge, with ecological as well as coastal defences and community benefits. The new and restored mangroves and adjacent mud flats in Wedung and elsewhere were in 2019 also being occupied by new bird life, including night herons and great and little egrets which community groups are now protecting.
Sinking land and the conversion of the mangroves to fish ponds has created a crisis along Java’s northern shore. The ocean has invaded several kilometres inland, obliterating whole villages.
One of the animals that take advantage of the mangroves are crabs.
Wetlands Annual Review 2019
Wetlands Annual Review 2019
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