08. EFFECTS OF MANGROVE DENSITIES AND WIDTH ON WAVE TRANSMISSIONS BY OPEN-SOURCE MODELS

Tóm tắt

The Mekong deltaic coasts have suffered from erosion and mangrove losses due to many relative threats in human activities, bringing to coastal instabilities. The massive and large number of constructions, such as sea dikes, revetments, and sea walls, tend to break the equilibrium in multiple locations along the coasts. As a result, a significant reduction of mangroves comes along in qualitative and quantitative variations, for example, the number of trees in one location and the healthy width of mangroves. An observation from Google Imagine Engine in multiple sites along the Mekong Deltal coasts shows an average width retreated from 2006 to 2016 was about 60 m. In this study, open-source models, SWAN and SWASH - Developed by Delft University of Technology, are implemented to assess the effect of density and width on wave transmission in Nhat Mat ward, Bac Lieu province, Vietnam. The present results show a significant influence of density on wave transmission, while the larger width of mangroves creates more damping space for waves. Moreover, wave reduction rates (Kt = Ht/Hi, where Hi and Ht are the incoming and transmission wave heights) are related to densities by the power fit. From these results, it is hypothesized that wave height reduction can be predicted via the density of mangroves.