Nouméa: Stone barriers and mangrove planting to strengthen coastal resilience

In response to sea level rise and coastal erosion, the Kiwa PEBACC+ project is implementing a nature-based solution in Nouméa aimed at restoring mangroves and strengthening shoreline protection.

The initiative involves installing stone barriers made of basalt blocks and planting carefully selected mangrove propagules within them. The basalt blocks used for this work are remnants of coastal filling operations carried out in the 1990s. They were gathered as part of a work-integration project led by the City of Nouméa, while the planting of propagules is being carried out with the support of the Caledoclean association.

This approach was inspired by traditional practices from fishers in the tribe of Touho, who used coral stones naturally rolled by waves across the reef flat to stabilize certain coastal areas. Although coral is less dense than basalt, these structures, once properly installed, can effectively withstand marine conditions.

One year after the first direct planting of propagules, around one-third have survived and are growing well, demonstrating the potential of this simple and cost-effective method. Since collecting propagules requires very limited resources, theoperation remains remarkably inexpensive while delivering significant ecological benefits