The Effects of Flexible Vegetation on Forces with a Keulegan- Carpenter Number in Relation to Structures Due to Long Waves

Extreme coastal events require careful prediction of wave forces. Recent tsunamis have resulted in extensive damage of coastal structures. Such scenarios are the result of the action of long waves on structures. In this paper, the efficiency of vegetation as a buffer system in attenuating the incident ocean waves was studied through a well controlled experimental program. The study focused on the measurement of forces resulting from cnoidal waves on a model building mounted over a slope in the presence and absence of vegetation. The vegetative parameters, along with the width of the green belt, its position from the reference line, the diameter of the individual stems as well as the spacing between them, and their rigidity are varied so as to obtain a holistic view of the wave-vegetation interaction problem. The effect of vegetation on variations of dimensional forces with a Keulegan-Carpenter number （KC） was discussed in this paper. It has been shown that when vegetal patches are present in front of structure, the forces could be limited to within F＊≤I, by a percentile of 92%, 90%, 55%, and 96%, respectively for gap ratios of 0.0, 0.5, 1.0, and 1.5. The force is at its maximum for the gap ratio of 1.0 and beyond which the forces start to diminish.

Numerical investigation on tsunami wave mitigation on forest sloping beach

An explicit one-dimensional model based on the shallow water equations(SWEs) was established in this work to simulate tsunami wave propagation on a vegetated beach. This model adopted the finite-volume method(FVM)for maintaining the mass balance of these equations. The resistance force caused by vegetation was taken into account as a source term in the momentum equation. The Harten–Lax–van Leer(HLL) approximate Riemann solver was applied to evaluate the interface fluxes for tracing the wet/dry transition boundary. This proposed model was used to simulate solitary wave run-up and long-periodic wave propagation on a sloping beach. The calibration process suitably compared the calculated results with the measured data. The tsunami waves were also simulated to discuss the water depth, tsunami force, as well as the current speed in absence of and in presence of forest domain. The results indicated that forest growth at the beach reduced wave energy loss caused by tsunamis. A series of sensitivity analyses were conducted with respect to variable parameters(such as vegetation densities, wave heights, wave periods, bed resistance, and beach slopes) to identify important influences on mitigating tsunami damage on coastal forest beach.

Origins of Terrestrial Organic Matter in Surface Sediments of the East China Sea Shelf

Terrestrial organic matter(TOM) is an important component of marine sedimentary OM, and revealing the origins and transport mechanisms of TOM to the East China Sea(ECS) is important for understanding regional carbon cycle. A novel approach combining molecular proxies and compound-specific carbon isotopes is used to quantitatively constrain the origins and transport mechanisms of TOM in surface sediments from the ECS shelf. The content of terrestrial biomarkers of(C_(27)+C_(29)+C_(31)) n-alkanes(52 to 580 ng g^(-1)) revealed a seaward decreasing trend, the δ^(13)CTOC values(-20.6‰ to-22.7‰) were more negative near the coast, and the TMBR(terrestrial and marine biomarker ratio) values(0.06 to 0.40) also revealed a seaward decreasing trend. These proxies all indicated more TOM(up to 48%) deposition in the coastal areas. The Alkane Index, the ratio of C_(29)/(C_(29)+C_(31)) n-alkanes indicated a higher proportion of grass vegetation in the coastal area; While the δ13C values of C_(29) n-alkane(-_(29).3‰ to-33.8‰) indicated that terrestrial plant in the sediments of the ECS shelf were mainly derived from C_3 plants. Cluster analysis afforded detailed estimates of different-sourced TOM contributions and transport mechanisms. TOM in the Zhejiang-Fujian coastal area was mostly delivered by the Changjiang River, and characterized by higher %TOM(up to 48%), higher %C_3 plant OM(68%-85%) and higher grass plant OM(56%-61%); TOM in the mid-shelf area was mostly transported by aerosols, and characterized by low %TOM(less than 17%), slightly lower C_3 plant OM(56%-72%) and lower grass plant OM(49%-55%).

Floristic survey of traditional herbal medicinal plants for treatments of various diseases from coastal diversity in Pudhukkottai District,Tamilnadu,India

Objective:To conduct ethno medicinal survey in coastal plant species in Pudhukkottai district and collect information on medicinal plants used for the treatment of various diseases such as pneumonia,asthma,rheumatism,piles,diarrhea,skin diseases,spleen diseases and several other ailments.Methods:The study was conducted during November 2012 to April 2013 by visiting regularly fishery communities and local peoples with the help of interviews.Traditional herbal medicine information was collected as per the described methods.Results:A total of 52 plant species,28 were herbs,8 trees,8 climbers,7 shrubs and one species of aquatic creeper.Conclusions:The study revealed that local communities and fishery communities have a great species representing 31 families have been reported.Of the 52 plant faith in the traditional healing system and they rely on medicinal plants for treatment of various diseases.Now,the coastal plants have been extensively modified by human activity.Further studies on phytochemistry,pharmacology and pharmacognosy on these species may lead to the invention of novel bioactive compounds to treat pathogenic diseases.Due to continuous loss of coastal vegetation,the associated indigenous knowledge is also gradually disappearing.So,it is imperative to protect and restore the coastal vegetation,as an immediate priority.