Mangroves as a coastal protection from waves in the Tong King delta, Vietnam

The wave reduction (wave period; 5–8 sec.) was investigated in amangrove reforestation area (Kandelia candel) close toaquaculture ponds in the Tong King delta, Vietnam.On one site where only young mangrove trees grew, the wavereduction due to the drag force on the trees was hardlyeffective. On the other site where mangrove trees weresufficiently tall, the rate of wave reduction per 100 m was aslarge as 20%. Due to the high density of vegetation distributedthroughout the whole water depth, the effect of wave reductionwas large even when the water depth increased. These resultsdemonstrate the usefulness of mangrove reforestation for coastalprotection.