scholarly journals Physical and Numerical Modelling of Tsunami Run-up on Seawall at Sloping Beach

2019 ◽  
Vol 5 (2) ◽  
pp. 139
Author(s):  
Ma'ruf Hadi Sutanto
Keyword(s):  
Numerical Model ◽  
Water Depth ◽  
Tsunami Wave ◽  
Peak Height ◽  
Initial Water ◽  
Tsunami Mitigation ◽  
Run Up ◽  
Tsunami Run Up ◽  
Sloping Beach ◽  
Reduction Percentage

Tsunami run-up on land has a large destructive power. Further studies are deemed necessary to understand the process and characteristics of tsunami run-up in coastal areas. Seawall structures can reduce the run-up of a tsunami depending on the height of the seawall crest. Physical modeling shows that seawall may significantly reduce run-up (𝑅) and inundation (𝑋𝑖). The highest reduction up to 55% where the seawall peak height is 7 cm and the water depth is 15 cm. With the same scenario in numerical modeling, the percentage reduction is 67.53%. The highest inundation (Xi) in the scenario without seawall structure is 6.081 m when the initial water depth (d0) equals to 30 cm. The result of the numerical model for the same scenario is 6.970 m. Seawall as tsunami mitigation structure is only effective when the tsunami wave is relatively low compared to the seawall height (H/ sw). Reduction percentage > 25%, with conditions that H/ sw is < 0.856 (physical model) and < 0.802 (numerical model).

scholarly journals Numerical Investigations of Tsunami Run-Up and Flow Structure on Coastal Vegetated Beaches

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1776 ◽  
Author(s):  
Hongxing Zhang ◽  
Mingliang Zhang ◽  
Tianping Xu ◽  
Jun Tang
Keyword(s):  
Wave Propagation ◽  
Numerical Model ◽  
Peak Flow ◽  
Tsunami Wave ◽  
Coastal Vegetation ◽  
Coastal Forest ◽  
Governing Equations ◽  
Tsunami Waves ◽  
Run Up ◽  
Sloping Beach

Tsunami waves become hazardous when they reach the coast. In South and Southeast Asian countries, coastal forest is widely utilized as a natural approach to mitigate tsunami damage. In this study, a depth-integrated numerical model was established to simulate wave propagation in a coastal region with and without forest cover. This numerical model was based on a finite volume Roe-type scheme, and was developed to solve the governing equations with the option of treating either a wet or dry wave front boundary. The governing equations were modified by adding a drag force term caused by vegetation. First, the model was validated for the case of solitary wave (breaking and non-breaking) run-up and run-down on a sloping beach, and long periodic wave propagation was investigated on a partially vegetated beach. The simulated results agree well with the measured data. Further, tsunami wave propagation on an actual-scale slope covered by coastal forest Pandanus odoratissimus (P. odoratissimus) and Casuarina equisetifolia (C. equisetifolia) was simulated to elucidate the influence of vegetation on tsunami mitigation with a different forest open gap. The numerical results revealed that coastal vegetation on sloping beach has significant potential to mitigate the impacts from tsunami waves by acting as a buffer zone. Coastal vegetation with open gaps causes the peak flow velocity at the exit of the gap to increase, and reduces the peak flow velocity behind the forest. Compared to a forest with open gaps in a linear arrangement, specific arrangements of gaps in the forest can increase the energy attenuation from tsunami wave. The results also showed that different cost-effective natural strategies in varying forest parameters including vegetation collocations, densities, and growth stages had significant impacts in reducing the severity of tsunami damage.

An Experimental Study of the Run-Up Process of Breaking Bores Generated by Dam-Break Under Dry- and Wet-Bed Conditions

2018 ◽  
Vol 12 (02) ◽  
pp. 1840005 ◽  
Author(s):  
Senxun Lu ◽  
Haijiang Liu ◽  
Xiaohu Deng
Keyword(s):  
Water Depth ◽  
Laboratory Experiments ◽  
Bottom Friction ◽  
Dam Break ◽  
Hydrodynamic Characteristics ◽  
Initial Water ◽  
Water Head ◽  
Run Up ◽  
Front Profile ◽  
Two Stages

In this study, a series of dam-break laboratory experiments were carried out to investigate the run-up process of breaking bores under dry- and wet-bed conditions. Detailed measurements were conducted to reveal differences in the run-up hydrodynamic characteristics under these two conditions, e.g. the bore front profile, the maximum run-up height and duration, and the instantaneous bore front velocity. Two successive bores were observed under the wet-bed run-up process, while multiple bores (three bores in general) were generated during the dry-bed run-up process due to the significant bottom friction effect. A linear relationship with the uniform gradient is found between the maximum run-up height and the initial water head for both dry- and wet-bed conditions, indicating that difference in the maximum run-up height between the dry- and specified wet-bed cases or among various wet-bed cases is not sensitive to the initial water head. Under the same initial water head, although the dry-bed run-up process takes a longer duration than that of wet-bed cases, the maximum run-up height is smallest for the dry-bed case and gradually increases with the increase of the initial downstream water depth for wet-bed cases. Under the wet-bed conditions, temporal variation of the bore front run-up velocity can be classified into two stages, i.e. the acceleration stage induced by the relatively large incident bore front water depth (large onshore hydrostatic pressure gradient) and the deceleration stage governed by the offshore-directed gravity force and bottom friction. Nevertheless, due to the small incident bore front water depth, run-up process under the dry-bed conditions does not show the acceleration stage.

scholarly journals The Implementation of Combined Roughness and Reflected Model (CRRM) in Tsunami Run-up Simulation through Coastal Vegetation

2018 ◽  
Vol 4 (3) ◽  
pp. 201
Author(s):  
Benazir B. Iska ◽  
Radianta Triatmadja ◽  
Adam Pamudji Rahardjo ◽  
Nur Yuwono
Keyword(s):  
Numerical Model ◽  
Numerical Method ◽  
Physical Model ◽  
Physical Process ◽  
Experimental Work ◽  
Coastal Vegetation ◽  
Vegetation Models ◽  
Run Up ◽  
Tsunami Run Up ◽  
Inertia Forces

Hydraulics resistance is commonly used to simulate or replace drag and inertia forces due to vegetation when modeling tsunami run-up. A new numerical method was proposed which was named Combined Roughness and Reflected Model (CRRM). This method accommodates the reflection process of tsunami flow by tree surfaces. A series of experimental work was performed in laboratory to verify the numerical results. The physical process of laboratory work was discussed to explain the interaction between tsunami and vegetation models. The relation of some notable parameters was reviewed for both models. The physical model verified that the deviations between the physical and the numerical model were below 20%. With such numerical method, more challenging forest layout such as zigzag arrangement can be studied more accurately. It is concluded that the zigzag arrangement of trees layout and higher density of trees were capable of reducing tsunami run-up on land significantly. 

scholarly journals Design of a Facility for Tsunami Run up Generation to Study Tsunami and Seawall Interaction

2019 ◽  
Vol 5 (1) ◽  
pp. 9
Author(s):  
Warniyati Warniyati ◽  
Radianta Triatmadja ◽  
Nur Yuwono ◽  
David S. V. L Bangguna
Keyword(s):  
Numerical Simulation ◽  
Tsunami Wave ◽  
Wave Generator ◽  
Control Discharge ◽  
Run Up ◽  
Tsunami Run Up ◽  
Experimental Researches

Experimental researches on the tsunami in the laboratory have been conducted using various methods. The use and techniques of tsunami wave generator depend on the objective of the tsunami observation to be conducted. When the objective is the scouring at the downstream of a seawall, the use of a short flume with control discharge seems to be appropriate. A valve with a mechanic controller was equipped to control the discharge from a reservoir into the flume. A numerical simulation of discharge into the flume and the overflow above the seawall was conducted to determine the dimension of the tsunami flume and its generator before construction. The experiments were conducted to simulate the hydrograph of tsunami overflow above the seawall model. The numerical hydrograph is found to be comparable with the experimental hydrograph. This indicates that the tsunami wave generator is capable of simulating tsunami hydrograph and ready for further use of simulations.

scholarly journals Review Study on Location Plan of Temporary Shelter for Tsunami Disaster in Kuta Bay of Central Lombok

2018 ◽  
Vol 4 (3) ◽  
pp. 243
Author(s):  
Adi Mawardin
Keyword(s):  
Wave Propagation ◽  
Arrival Time ◽  
Tsunami Wave ◽  
Historical Record ◽  
Tectonic Activity ◽  
Evacuation Simulation ◽  
Tsunami Disaster ◽  
Magnitude Variation ◽  
Run Up ◽  
Tsunami Run Up

Historical record showed in 1977, tsunami attacked Lombok and caused extensive damages due to tectonic activity. Kuta Bay located in the southern area of Lombok has a high risk of earthquake and tsunami, thus mitigation plan on tsunami attack is very important. This study aimed to determine the arrival time, run-up height of tsunami and the coverage areas, so it could be used to determine the temporary shelter location (Tempat Evakuasi Sementara-TES). Simulation of the tsunami wave propagation used the TUNAMI modified (beta version) program with three scenarios of earthquake magnitude variation (Mw), namely 7.7, 8.1, 8.3, and 7.9 (based on the Sumba earthquake event in 1977). Field surveys, questionnaire distributions, and interviews were used in determining input parameters of Tsunami Evacuation Simulation (Simulasi Evakuasi Tsunami-SET) by using 2011 EVACUWARE 1.0 version. Tsunami wave propagation simulation showed the tsunami arrival time on Kuta Bay ranged between 21 - 38 minutes. Tsunami run-up height was about 1.01 - 8.71 meters along Kuta Bay, with the farthest distance of inundation was 860 meters from the seashore. The percentage of survivors based on SET results in scenario 1 and 2 for 20 minutes of evacuation time were respectively, 63.62% and 93.27%.

Standing edge waves reinvestigated: A comparison between two different bathymetries

2019 ◽  
Vol 234 (1) ◽  
pp. 108-126
Author(s):  
Dong Shao ◽  
Gang Jiang ◽  
Zirui Zheng ◽  
Yun Xing
Keyword(s):  
Water Depth ◽  
Water Surface ◽  
Initial Position ◽  
Trapped Modes ◽  
Edge Waves ◽  
Wave Refraction ◽  
Theoretical Predictions ◽  
Run Up ◽  
Sloping Beach ◽  
Standing Edge Waves

As a result of wave refraction caused by variable water depth within enclosed or semi-enclosed nearshore areas like harbors and bays, standing edge waves play an important part in the circulation patterns. The bathymetries of these areas may fall into two categories as follows: one is a reflective beach with a moving shoreline where the waves run up and down and the other has a certain water depth at a fixed backwall. A comparison of the standing edge waves trapped on these two types of bathymetries is made. Analytical investigations show that the trapped modes may behave dissimilarly on each type of bathymetry, especially for relatively high modes when the bathymetry is not simply a constantly sloping beach but a piecewise one. Wave patterns induced by water surface disturbances of the numerical simulations are analyzed with wavelet spectra. Frequencies of different components of the standing edge waves are compared with theoretical predictions. The results of the bathymetry with a reflective backwall are consistent with the findings of previous studies. For the case with a moving shoreline, several very low modes of the standing edge waves can survive and persist into a steady state, whereas higher modes may suffer from a quick attenuation. The occurrence of the trapped modes is revealed sensitive to the initial position of the water surface agitations in this case.

Numerical Model for Tsunami Run-Up

1970 ◽  
Vol 96 (3) ◽  
pp. 701-719
Author(s):  
Kenneth L. Heitner ◽  
George W. Housner
Keyword(s):  
Numerical Model ◽  
Run Up ◽  
Tsunami Run Up

scholarly journals Erratum for “Numerical Model for Tsunami Run-Up”

1971 ◽  
Vol 97 (4) ◽  
pp. 766-766
Author(s):  
Kenneth L. Heitner ◽  
George W. Housner
Keyword(s):  
Numerical Model ◽  
Run Up ◽  
Tsunami Run Up

Two-Layer Non-Hydrostatic Scheme for Simulations of Wave Runup

2019 ◽  
Vol 13 (05n06) ◽  
pp. 1941004 ◽  
Author(s):  
M. A. Ginting ◽  
S. R. Pudjaprasetya ◽  
D. Adytia
Keyword(s):  
Wave Propagation ◽  
Solitary Wave ◽  
Water Waves ◽  
Tsunami Wave ◽  
Harmonic Wave ◽  
Laboratory Data ◽  
Analytical Formula ◽  
Wave Simulation ◽  
Run Up ◽  
Sloping Beach

There are indisputable research supporting scientific argument that propagation of (tsunami) wave from intermediate depth towards shallower coastal area needs dispersive wave model. For tsunami wave simulation, efficiency of the numerical scheme is an important issue. In this paper, the two-layer non-hydrostatic model as developed previously in Pudjaprasetya et al. [2017] “A non-hydrostatic two-layer staggered scheme for transient waves due to anti-symmetric seabed thrust,” J. Earthquake Tsunami  11, 1–17, to study tsunami generation and propagation, is adopted. Restricting to 1+1 dimension, here, we focus on the performance of the scheme in simulating wave propagation in coastal areas, in particular predicting the run-up height. First, we conducted a simulation of harmonic wave over a sloping beach to conform the analytical shoreline motion by Carrier and Greenspan [1958] “Water waves of finite amplitude on a sloping beach,” J. Fluid Mech.  4, 97–109. The ability of the scheme in accommodating dispersion and non-linearity were shown via simulation of a solitary wave that propagates over a flat bottom. This solitary wave simulation provides an evaluation of the convergence aspect of the model. Further, several benchmark tests were conducted; a solitary wave over a sloping beach to mimic the experimental data by Synolakis [1986] “The run-up of solitary waves,” J. Fluid Mech.  185, 523–545, as well as solitary wave over a composite beach. Good agreement with laboratory data was obtained in terms of wave signal, whereas for relatively low amplitude, the solitary run-up height conforms the analytical formula. Moreover, the scheme is tested for simulating the Beji–Battjes experiment Beji, S. and Battjes, J. A. [1993] “Experimental investigation of wave propagation over a bar,” Coast. Eng.  19, 151–162. As well as wave focusing experiment by Kurnia et al. [2015] “Simulations for design and reconstruction of breaking waves in a wavetank,” Proc. ASME 2015 34th Int. Conf. Ocean, Offshore and Arctic Engineering, Newfoundland, Canada, 31 May–5 June 2015, pp. 2–7.

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