Award for innovative engineering solution

The mangrove project, located northeast of Semarang, Java, was recently recognised with a Dutch annual award for innovative engineering solutions (‘Vernufteling’). Originally there was a mangrove greenbelt along the coast that served as a coastal defence, since the roots of the trees trap the sediment. However, many trees were cut when the local community needed more fish ponds to expand aquaculture operations. This resulted in coastal erosion, with the coast moving inland by several kilometres at some locations.

A Dutch consortium consisting of Witteveen+Bos, Deltares, Ecoshape, Wetlands International, Wageningen University & Research Centre and Imares developed an ingenious solution in accordance with the ‘Building with Nature’ principle: permeable dams of bamboo poles and brushwood fill. This solution enhances coastal resilience for local residents by preventing further coastal flooding and erosion. Along the most heavily eroded sections of the Demak coastline, the programme is building permeable dams to attenuate the waves and trap the sediment. This brings the massive coastal erosion to a halt and promotes the natural regrowth of the mangrove greenbelt.

The mangrove forest should take over the role of the dams and attenuate the waves and keep the sediment in place. In addition, coastal protection by mangrove greenbelts will restore the ecological value of the area. This ‘Building with Nature’ project not only involves the construction of permeable dams, but also provides residents with a long-term perspective for sustainable economic development through sustainable aquaculture.

The local population is closely involved in the construction and maintenance of the dams and aquaculture ponds. The potential for replication is considerable, since many mangrove areas in Indonesia and the rest of the world are threatened by logging and coastal erosion.