Attenuation of waves from boat wakes in mixed mangrove forest of rhizophora and bruguiera species in matang perak

Abstract

In Malaysia, there are several small rivers and estuaries which are frequented by fishing boats. The wave action due to the movement of boats impact the coastal morphology of the area. In this paper, we have studied the wave reduction in mixed mangrove forest of Rhizosphere and Bruguiera species based on field observations of waves from boat wakes in Sg. Sangga Kecil of Matang forest reserve, west coast of Peninsular Malaysia. The unique physical characteristics of Bruguiera sp. and Rhizophora sp. such as the intricate knee root and numerous pneumatophores, respectively, impact the wave amplitudes in the mangrove forest. The reduction of wave amplitudes in a 15 m long transect of mixed mangrove forest at a given study site has been analysed in the present study. It is found that the wave reduction for each 5-m distance from the vegetation edge ranged from 47.4% to 9.6%. However, on a cumulative basis the wave reduction inside the mixed mangrove forest ranged between 47.4% to 72.8%, with an average of 63%. As far as the vertical trend is concerned the wave reduction in (0-10cm) level was 88.7% while in (10-20cm) level it was found to be 61.2%. INTRODUCTIONMangroves are coastal forests that are found in sheltered estuaries and along river banks and lagoons in the tropics and subtropics. Mangroves worldwide cover an approximate area of 240 000 km2 of sheltered coastlines in the tropics and subtropics [1]. They are distributed within the tropics and subtropics, reaching their maximum development between 25o N and 25o S. The first attempt to estimate total mangrove area worldwide was undertaken as part of the Food and Agriculture Organization of the United Nations (FAO) and United Nations Environment Programme (UNEP) Tropical Forest Resource Assessment in 1980 [2].Mangrove forest ecosystems fulfil many important functions and provide a wide range of services at the local and national levels. Mangroves support the conservation of biological diversity by providing habitats, spawning grounds, nurseries and nutrients for many animals. Mangrove ecosystem is also used for aquaculture, both as open-water estuarine maricultural and as pond culture. The physical importance of mangrove is to act as a wave buffer. The December 2004 tsunami highlighted the physical importance of mangroves.The study about the physical processes in mangrove forest is still poorly understood due to the lack of extensive research on the subject. As stated in a research, it is only a short time since the studies of the physical processes in mangrove areas have been initiated [3,4]. Some researcher has studied some tidal periodic phenomena in mangrove areas along rivers or estuaries protected from the open sea [5][6][7][8][9].In the present study, we have analysed the reduction in the amplitude of waves produced by the passage of fishing boats in an estuary as these waves travel through the Matang mangrove forest area of Perak. The paper focuses on the mixed mangrove forest of Rhizophora and Bruguiera species which was chosen because they are ...

Application of Computer Identification and Location Algorithm in Small far Infrared Target Recognition of Ship Under Surge Interference

“…The experiment uses Matlab 7 simulation design, supposing that the point distribution model of ship far small infrared targets is composed of the uniform line array which is composed of 14 array elements. The array element spacing is 0.25 times of minimum wavelength [31,32] is a coefficient responding spectrum width. According to the simulation environment and parameter settings, the searching results of the power spectrum of the ship's far small infrared target position estimation is obtained in surge interference are shown in Fig.…”

Engineering With Nature : the role of mangroves in coastal protection

“…Trung et al (2015) andThuy et al (2017) measured ship wake attenuation by riverine mangroves in Vietnam and found significant wave height reduction within moderate cross-shore distances Trung et al (2015). reported wave height reductions of 44% -56% and 70% -84% within 4 m and 10 m, respectively, whileThuy et al (2017) supplemented field results with a twodimensional Boussinesq numerical modeling and estimated that 200 m long timber piling combined with a 20 m wide mangrove fringe reduced runup and forces by 61% and 95%, respectively Ismail et al (2017). measured reduction of wave amplitudes in a mixed mangrove forest and reported average reduction of wave amplitude by 63% over a 15 m transect.…”

Dynamic Characteristics of Magnetic Coupling in Horizontal Axis Wave Energy Device

“…Accord ing to t he measured pa ra meters, [19][20][21][22]. Table 2 shows the indexes of the dynamic characteristics.…”