Mangrove-based coastal defense strategies
Wetlands International is committed to reducing the knowledge gaps on mangrove functions and values. Our aim is to maximise the utilisation of ecosystem-based solutions for coastal defense.
Mangrove forests are at the front line of natural defense systems which is of great significance to disaster risk reduction. As a terrestrial natural defense system, mangroves are capable of sheltering coasts from a range of possible hazards coming from the sea, such as tidal waves, hurricane, storms, and even tsunami.
This knowledge is yet inaccessible and underrated. To date, coastal defense strategies are mainly based on infrastructure-based solutions which are costly to build, require high maintenance costs and only provide restricted protection against extreme and unpredictable events. There is an urgent need for in-depth researches and pilot activities to the contribution of mangrove- based coastal defense strategies.
We are committed to reducing the knowledge gaps on mangrove functions and values. We aim to maximise the utilisation of ecosystem-based solutions for coastal defense. Together with partner organisations from the engineering sector, we are currently exploring innovative coastal defense solutions that combine nature and infrastructure. This integrated approach is called hybrid-engineering. In Indonesia, for example, we are exploring how erosion can be halted by establishing mangrove belts in grids of small permeable bunds made of branches and bamboes. When implemented jointly, these measures allow for maximum capture of sediment, while minimising the eroding forces. Another example of hybrid-engineering is the salt marsh works; as part of this approach, salt marshes are constructed along sea dikes to mitigate the power of incoming waves before they reach the dyke.
This represents a fundamentally different way of working. Rather than fighting natural processes through infrastructure, hybrid-engineering enables engineers to work alongside natural processes. In other words, the protective services provided by nature are optimally used and complement those that are provided by infrastructure. Another advantage is that the approach sustains a range of other natural values, such as carbon storage, fisheries provision or opportunities for ecotourism. This renders the approach more sustainable and often more cost-effective than conventional hard-infrastructure approaches. Hybrid engineering approaches are often highly adaptive: by capturing sediment and storing organic matter in the soil, salt marshes and mangroves, for example, are to a certain extent able to ‘grow’ along with the sea and thereby cope with rising sea levels. This flexibility is highly relevant in times where climate change makes it very hard to predict future changes in the occurrence and intensity of coastal hazards.
These methodologies will be tested in the field through key pilot activities.
- The Netherlands-based knowledge institute on water issues, Deltares: development of new approaches for coastal defense through restoration of mangroves and sediment dynamics.
- Wageningen University: studies on the economic values of different land-use scenarios in (former) mangrove areas.
- The global NGO The Nature Conservancy: literature reviews on mangrove services.
- The Indonesian government service BPDAS-PB of the Ministry of Forestry: to coordinate the engagement of government agencies in data gathering, fieldwork and policy dialogues.
- The Indonesian Government Centre for Marine Resource Survey: detailed mapping of mangrove status and distribution in Indonesia.