Replacing vegetation that has been damaged by tsunamis – especially mangrove forests that protect the coastline
The term mangrove refers to a diverse group of salt tolerant trees and other plant species that are found along sheltered tropical and sub-tropical shores and estuaries.
Mangroves prevent costal erosion and act as a barrier against typhoons, cyclones, hurricanes and tsunamis and protect against damage to property and life. Mangrove tree species that inhabit lower tidal zones can block or buffer wave action with their stems. The trees shield the land from the wind and trap sediment in their roots. This maintains a shallow slope on the seabed that absorbs the energy of tidal surges.
Whether mangroves functions as buffers against tsunamis is a topic of research that has been debated hotly despite the popular belief that they are effective in managing against natural hazards such as Tsunamis. Mangroves often modify coastlines through their ability to weaken the effect of wave action, capture sediments and build soils. According to a project conducted by the University of Cambridge in conjunction with The Nature Conservancy Cooperation. Hundreds of meters width of mangroves are needed to reduce tsunami flood depth by 15%. Open channels and lagoons allow free passage of water through after a tsunami while dense roots systems obstruct flow. Smaller trees and shrubs may be overtopped by tsunamis. Large tsunamis (more than 4 metres in depth) can damage mangroves since the highest waves are often taller than the mangrove trees. Despite this limitation, mangroves can still have a modest mitigating effect on tsunamis. Mangroves also trap floating debris and provide resources such as wood that may be scarce after the Tsunami. In terms of deciding whether mangroves are effective in protection against tsunamis, consideration must also be given to the size of the tsunami. Clearly the size of the tsunami has a major effect on the mangrove's ability to provide protection. So, to some extent mangroves provide protection from small tsunamis but if a very large tsunami arrives with little warning, it will be highly destructive to the mangrove system.
Revegetation of certain plants won’t be as effective.
The MFF (Mangroves for the future), is a conservation group that aims to promote sustainably livelihoods for costal communities and build resilience against natural disasters. For example, in Gujarat, MFF aims to increase the extent of mangrove vegetation in the area to allow protection against costal natural disasters.