Tsunami mitigation by combination of coastal vegetation and a backward-facing step

Pasha, Ghufran Ahmed; Tanaka, Norio; Yagisawa, Junji; Achmad, Fuadi Noor

doi:10.1080/21664250.2018.1437014

Cited by 34 publications

(15 citation statements)

References 40 publications

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“…Currently, ecological, natural methods are widely considered in many developed and underdeveloped countries [19][20][21][22][23]. Ecosystem degradation is a major cause of increasing water resources management challenges [24][25][26][27][28]. In the floodplain of rivers, vegetation may increase the hydraulic resistance by dragging and turbulence to safeguard the ecosystem [26].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the above-mentioned solutions, the hybrid or compound defense system were also studied by different researchers. Various studies consist of the energy dissipation through a compound defense system of vegetation [28], combined effects of sea embankment and coastal forest [4,29], a moat with/without a forest [30] and a double embankment system [31]. Furthermore, Zaha (2019) conducted a series of experiments to investigate a hybrid defense system consisting of a forest, a moat (depression) and an embankment under unsteady flow conditions, considering the dike as unbreakable [32].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

Ahmed

Ghumman

2019

Water

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In this study, a series of laboratory experiments were conducted to investigate the energy loss through the hybrid defense system (HDS) in the order of dike, moat, and emergent vegetation in steady subcritical flow conditions. The results of HDS were compared with a single defense system (SDS) comprising only vegetation (OV). The dimensions of dike were kept constant while two different shapes (trapezoidal and rectangular) of moat were considered. The impacts of vegetation of variable thickness and density were investigated. Two combinations of HDS were investigated including the combination of dike and vegetation (DV) and the combination of dike, moat, and vegetation (DMV). The effect of backwater rise due to the vegetation, hydraulic jump formation and the impact of the arrival time of floodwater on energy dissipation were investigated. It was observed that on the upstream side of obstructions, the backwater depth increased by increasing the Froude number in both the SDS and HDS. The hydraulic jump observed in HDS was classified and the energy dissipation due to it was calculated. Under various conditions investigated in this paper, the maximum average energy dissipation was 32% in SDS and 46% in HDS. The trapezoidal moat performed better than rectangular moat as energy dissipater. The delay time was also greater with trapezoidal moat as compared to that in rectangular one. The maximum delay time was 140 s in the case of HDS. Hence, the hybrid defense system offered maximum resistance to the flow of water, thus causing a significant energy loss. For each case of SDS and HDS, empirical equations were developed by regression analysis to estimate the energy dissipation amounts.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

Ahmed

Ghumman

2019

Water

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“…and Fini (2011), Grote et al (2016), Livesley et al (2016), Maher et al (2013), Mori et al (2016), Pasha et al (2018), Potgieter (2019), Rahman et al (2017), Rey et al (2019), Shanahan et al (2015), Shackleton et al (2015), Tanaka and Onai (2017), Xiao et al (2017), and Weissert et al (2017). c Cavender and Donnelly (2019), Carrus et al (2015), Clément (2004), Fischer and Lindenmayer (2002), Hofmann et al (2018), Luck et al (2011), and Lumsden and Bennett (2005).…”

Section: Benefits Of Trees: Strengthsmentioning

confidence: 99%

“…In general, from the environmental point of view, plant benefits include climatic regulation; uptake/reduction of CO 2 and other greenhouse gases and pollutants; shading, which reduces urban heat island effects and is a general cooling factor, also intercepting incoming precipitations and avoiding dangerous water run-off while enriching water-table capacity (Alexandri and Jones, 2008;Edmondson et al, 2012;Maher et al, 2013;Livesley et al, 2016;Mori et al, 2016;Berland et al, 2017;Dobbs et al, 2017;Rahman et al, 2017;Weissert et al, 2017;Andoni and Wonorahardjo, 2018). Plants in densely urbanized areas also contribute to environmental protection from several hazards like strong winds, soil and slope erosion, torrential floods, landslides (Tanaka and Onai, 2017;Xiao et al, 2017;Pasha et al, 2018;Rey et al, 2019), and reduce traffic noise (Carrus et al, 2015;Shackleton et al, 2015). According to several results reviewed by Donovan (2017), benefits provided by plants (note: the author specifically refers to trees) change relative to their location within the urbanized area.…”

Section: Plants In Urban Environment: Multiple Ecological Functions Amentioning

confidence: 99%

A Survey of Multiple Interactions Between Plants and the Urban Environment

Fineschi¹,

Loreto²

2020

Front. For. Glob. Change

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It is well-acknowledged that plants in urban areas provide multiple ecosystem services. They contribute improving ambient quality and mitigating negative impacts of human presence, beautifying the anthropic environment, and promoting place identity and cultural heritage. However, the existence of plants in general, and trees in particular, cannot be considered independent on urban activities and infrastructures. Release of plant volatile compounds is profoundly affected in urban environments, in turn modifying plant relationships with other living organisms, both plants and animals, and affecting air chemistry and quality. Plants also interfere with stone artifacts, cultural and historical heritage. Plant-human coexistence requires precise and adequate managing measures, which have often been ignored in cities' government and planning. Plants and humans (and human infrastructures) are frequently considered as independent from each other and plant requirements are often disregarded, thus causing difficult or erroneous management and/or environmental damage. We review some of the most important ecosystem services provided by plants in urban environment, and also focus on possible negative effects of plants that may become relevant if urban vegetation is improperly managed and unintegrated in proper city planning, both of historical centers and of new towns or suburbs. Keywords: ecosystem services, global change, green area typologies in cities, green urban planning and management, positive (negative) plant-human interactions, urban trees

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“…Experimental work was performed and observed that two rows Vegetation device more driftwood even in sparse case than the single row Vegetation. When aspect ratio is increased it results in devising more driftwood [19].Numerical model was presented by considering the tsunami events of 1975 and 1755 of Portugal and resulted tsunami evacuation maps consisting of safe and quick route, located on high ground to save community [20]. Laboratory experiments were conducted to study the overtopping and its effects on height of inundation behind the structure [22].…”

Section: Introductionmentioning

confidence: 99%

Investigating Role of Vegetation in Protection of Houses during Floods

et al. 2019

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Flood flows have the potential to cause substantial damage to infrastructure, mankind, livestock and agricultural land which all stacks up to greatly affect the financial condition of the region. During 2010 Pakistan floods, more than two million houses were damaged partly or totally [1]. To minimize these types of destructions, inland vegetation can be considered a natural barrier to dissipate the energy of flood flow and limits widespread inundation. This study involves volume of fluid (VOF) modelling approach to figure out the role of vegetation of finite width in energy reduction of flood flow, in front of houses, against: vegetation of varying Aspect Ratio (A/R width-length ratio) and distance between vegetation & houses (Lr). Channel domain was built in ANSYS workbench toolkit and meshing was done in meshing building toolkit. For the postprocessing and simulation, FLUENT was used. Various contour plots & profiles of cross stream-wise velocities and water level measurements are presented in this paper. The simulation results of cross stream-wise velocities and water level measurements were identical with experimental data. At vegetation upstream and downstream, velocity reduction observed in higher A/R (2.40) compared to vegetation of A/R-1. Whereas, outside the vegetation and near the walls of channel domain flow velocities were high. The water level was raised on the upstream side of the vegetation due to resistance offered by vegetation. On the upstream side of vegetation, the rise in backwater depth increased by increasing A/R. Contrarily, on the downstream side of vegetation, an undular hydraulic jump was observed in between vegetation and a house. By increasing A/R, the energy loss increases under constant vegetation conditions (G/d = 0.24, Fro = 0.70; G = spacing of each cylinder in cross-stream direction and d= diameter of cylinder and Fro = initial Froude number) and increase in house distance from 1W to 2W, the energy reduction increased from 2.40% to 3.15% which was further increased to 5.04% for another 5W increase in house distance, where W is the vegetation width. Simulation results also shown that with increasing Froude no from 0.60 to 0.70 water level depth has also an incremental pattern which ultimately results in increase in energy dissipation along the varying building distance (1W, 2W & 5W). Thus, to minimize the structural damage, a structure must be located at a safe distance away from the vegetation where flow becomes sub-critical.

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Tsunami mitigation by combination of coastal vegetation and a backward-facing step

Cited by 34 publications

References 40 publications

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

A Survey of Multiple Interactions Between Plants and the Urban Environment

Investigating Role of Vegetation in Protection of Houses during Floods

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