Coastal protection forest

ENTRY DATE: 25.12.2014 | LAST UPDATE: 26.12.2014

CATEGORIES:

  • Disaster Prevention
  • Coastal disaster (Hard measures)

TECHNOLOGIES MATURITY:

Applicable immediately

Technology Owners:

Each prefecture

Needs Address

The need to reduce damage from storm surges, tsunamis, etc., by utilizing natural ecosystems 

Adaptation effects

In addition to its function of disaster reduction by blocking blown sand, blocking wind, and preventing salt damage, this technology provides a variety of other functions, including biodiversity conservation. 

Overview and Features

  • The coastal protection forest is protection forest planted with the purpose of protecting the human living environment further inland, including residential areas and farmland, from damage caused by blown sand, briny wind, tsunamis and storm surges. Japanese black pine is the main tree species used for this purpose (in Japan). 
  • The functions of a coastal protection forest are listed below.
    • Sand break: Coastal sandy areas are planted with trees to prevent sand from being picked up by the wind and blown further inland.
    • Wind break: Tree trunks, branches and leaves slow the wind speed, to prevent damage caused by strong winds.
    • Tidal damage protection: Tree trunks, branches and leaves capture the brine contained in ocean winds, to block it from being blow further inland In addition, tree trunks reduce the energy of tsunamis and storm surges, reducing damage. They also have a delaying effect on the arrival of a tsunami.
    • Another role they play is to hold back flotsam in the event of a disaster
    Figure: Illustration of Sendai Bay coastal protection forest
    Source: "Efforts to restore coastal protection forests in Miyagi Prefecture"

Cost

  • Costs depend on scale of operation and type of trees, etc. 
  • Besides installation costs, maintenance costs need to be considered. 

Ease of maintenance

Maintenance work requires not only managers but also cooperation from local residents and volunteer organizations. Tasks are varied and include replanting to replace seedlings that have died, repair of associated facilities such as sand-stabilization fences (which weaken the wind and prevent sand from blowing, and protect trees planted inside the fenced areas), etc., as well as removal of pests/insects/disease, and management of tree spacing or density.

Considerations

  • Proper management is required. Without proper management, pest damage and disease damage can spread, resulting in a larger number of vulnerable trees (leaning and falling trunks, partially broken branches, etc.). 
  • In many cases, trees from coastal protection forests damaged by tsunami or storm surge can be carried by waves out of the forest and cause further damage. To prevent this, care is needed to grow healthy forests. 

Co-benefit, suitability for developing countries

The coastal protection forest does not rely on hard infrastructure technology such as seawalls, but rather serves as a disaster prevention and disaster reduction approach that utilizes natural ecosystems, and its environmental impacts are lower. 

Information Resources

  • Miyagi Prefecture, Forest Maintenance Division (2012), "Survey report on species suitable for tree planting in coastal protection forests" (in Japanese).
    http://www.pref.miyagi.jp/soshiki/sinrin/chousahoukokusho.html
  • Miyagi Prefecture, Agriculture, Forestry and Fisheries Department, "Efforts to restore coastal protection forests in Miyagi Prefecture: Discussions about species selection for tree planting" (in Japanese)
    http://www.pref.miyagi.jp/uploaded/life/204992_255858_misc.pdf