Performance of Mangrove Forests in Coastal Protection

Abstract

The importance of mangrove forest as a natural protection system has been a focused interest especially after the 2004 tsunami. It was reported that human deaths and property losses were reduced in areas of dense mangrove forests. Devastating incidents in recent years due to extreme environmental and catastrophic conditions that lead to various degrees of damages in the coastal areas have significantly increased awareness on the role of mangrove forests as eco-engineering approach to coastal stability and defense. With the recent urge for mangroves protection and replanting, a sound basis for a more optimum strategy in maintaining mangroves as coastal protection buffer is inevitably required. Hence, this study is aimed to quantify the reduction of wave height by 10 years old mangroves with various densities and tree arrangements. The laboratory experiments were conducted in a narrow wave flume using artificial mangrove models. The results showed that wave height reduction in areas of 100 m width of 10 years old mangroves was 2.5 times more effective as compared to areas without mangroves. Earlier investigation revealed that for areas with 20 years old mangroves was able to dissipate waves four times greater compared to areas without mangroves. For areas with 200 m width of 10 years old mangroves, a density of 0.11 trees/m2 is sufficient to reduce wave height over 77 %. With a difference of less than 3%, the investigation also revealed no significant difference of wave reduction between tandem and staggered arrangements when the mangroves are of 10 years old.