On the Indonesian island of Java, advancing sea water is putting tens of millions of people at risk. With the aid of the Sustainable Water Fund (Fonds Duurzaam Water, FDW), a unique public-private partnership in the Netherlands and Indonesia is working on a solution. Small dams are being constructed to ensure the return of mangrove forests, offering coastal defences which are as natural as they are effective. The initial results are already evident.
Mangrove forests form natural coastal defences. With their roots in the water, they offer natural protection against high waves. They help to soften storms and capture silt. However, the coastal residents of Java felt that they were taking up too much room. As a result, they cut down the forests to grow rice and later to breed shrimp and other species of fish. Nature then hit back hard. Without the mangrove forests, the sea is free to take its toll on the coastline.
Natural coastal protection
Kilometres of coast have already been washed away. Some 30 million Javanese people remain in danger unless something is done to restore the coastal defences in the near future. "Your first thought might be a substantial dike", says Femke Tonneijck from the NGO Wetlands International. "But this has little chance of success on the soft, muddy sea bed. We would rather develop new mangrove forests in a more natural way."
Wetlands International joined forces with other parties to set up a mangrove restoration project. Ecoshape is one of the main partners. "We are a consortium of government bodies, dredgers, NGOs, consulting firms and knowledge institutions", says programme manager Fokko van der Goot. "We put the concept of Building With Nature into practice and are applying it on an international basis. The idea? To put nature to work in civil engineering projects, creating opportunities for the economy, society and nature at the same time. On Java, we are constructing small dams which let water through. These capture the silt in the sea water, creating fertile ground for mangroves."
Training for growers
However, the project goes far beyond just building dams. Tonneijck: "We also involve the local communities and authorities. To stop them cutting down the mangrove forests again, we are also making the shrimp breeders more productive. One of the project partners is the Indonesian NGO Blue Forest. They organise so-called coastal field schools. These are practical training courses for teaching breeders more sustainable breeding methods which also increase their returns."
According to Tonneijck, the involvement of the Indonesian government is very important. "The protection of mangroves and the Building with Nature concept must be embedded within the policy", says Tonneijck. "Thankfully, the Ministries of Maritime Affairs and Fisheries and Infrastructure and Housing (public partners in the project, ed.) are 100% behind the project. They are keen to learn from our method, and we are keen to learn from their experience. They are co-investors and have even built small dams of their own. This will allow them to continue the work once our project comes to an end."
"The Building with Nature project involves many different parties. The collaboration does not just include Ecoshape, the NGOs Wetlands International and Blue Forest and the Indonesian government. The knowledge institute Deltares and Witteveen + Bos are designing and constructing the small dams. Wageningen University is contributing knowledge of sustainable aquaculture and UNESCO-IHE is setting up training in order to make our approach more widely embedded in Indonesia. The project therefore has broad-based support, leading to a successful FDW grant application."
Surface water changes (1985-2016): Green and blue colors represent areas where surface water changes occured during the last 30 years. Green pixels show where surface water has been turned into land (accretion, land reclamation, droughts). Blue pixels show where land has been changed into surface water (erosion, reservoir construction). Results dec 2016: Constructed: 0.7 km coastline defense; Maintained: 1.04 km. Sedimentation rates are good, and mangroves are recovering.
"The project is mainly intended to get something new off the ground", says Van der Goot. "At various locations along the 20 kilometres of coastline, we want to demonstrate that the dams work. And that a new, sustainable way of breeding fish and shrimp is effective. We hope that Indonesia will then embrace this method."
Although the project will continue until 2019, results are already evident. "Just look at the dozens of centimetres of silt which have been deposited behind the dams. This shows that the concept is working. The first mangrove plants are expected to germinate very soon."
The signs are already equally favourable further inland, says Tonneijck. "We have completed 5 coastal field schools. Thanks to the training, the breeders have already doubled their yield on 116 hectares of breeding ponds. They are using compost, carrying out their own tests and seeing that the shrimp in their ponds are larger than they were before. Seeing is believing. In the end, we want to expand the pilot to 300 hectares."
A working concept
Van der Goot emphasises that the project is also promising outside Indonesia. "We can see that the Building with Nature concept works along these kinds of muddy coastlines. It is just a question of time before the mangrove starts growing there. This is relevant for dredgers. Silt and fine sediment are often removed during harbour maintenance, for example, and these products are regarded as useless. This project shows that damaged mangrove coasts can be restored using this material. We also aim to start applying this concept in other tropical locations. The social aspects of the project are also interesting. After all, contractors are increasingly becoming responsible for communication with people who live near construction projects. In Indonesia, we work with various sectors and local communities. It is particularly educational."
Read more about the Sustainable Water Fund