Fundamental Study on the Development of a Tsunami Hazard Map for Moored Vessels in a Port

2016 ◽  
Author(s):  
Koichi Masuda ◽  
Tomoki Ikoma ◽  
Satoshi Hoshino
Keyword(s):  
Depth Map ◽  
Maximum Flow ◽  
Tsunami Hazard ◽  
Hazard Map ◽  
Tsunami Height ◽  
Promising Candidate ◽  
Fundamental Study ◽  
Inundation Depth ◽  
Maximum Tsunami Height ◽  
Maximum Flow Velocity

The Great East Japan Earthquake in 2011 revealed the vulnerability of modern ports to damage caused by drifting vessels as a result of a tsunami. The goal of the present study is to develop a tsunami hazard map for moored vessels in order to evaluate the potential for damage caused by drifting vessels that were previously moored at a port. The proposed map consists of four components: a maximum tsunami-height map, a maximum inundation depth map, a maximum flow velocity map, and an evaluation map of maximum mooring tension. The proposed tsunami hazard map for mooring vessels can be used to reduce the number of possible mooring locations and to obtain information for selecting a promising candidate mooring location. Furthermore, information on the tsunami force on moored vessels and on the grounding of vessels by a tsunami can be obtained, and information required for the development of preemptive measures for tsunami relief can be obtained using the proposed hazard map. In the present study, the suitability of mooring locations at Kisarazu port was analyzed, and the results are presented in the form of a map.

scholarly journals Probabilistic Tsunami Hazard Analysis of Inundated Buildings Following a Subaqueous Volcanic Explosion Based on the 1716 Tsunami Scenario in Taal Lake, Philippines

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 92
Author(s):  
Kwanchai Pakoksung ◽  
Anawat Suppasri ◽  
Fumihiko Imamura
Keyword(s):  
Hazard Analysis ◽  
Active Volcano ◽  
The Philippines ◽  
Tsunami Hazard ◽  
Initial Water ◽  
Volcanic Explosion ◽  
Inundation Depth ◽  
Tsunami Mitigation ◽  
Probabilistic Tsunami Hazard Analysis ◽  
Tunami N2

A probabilistic hazard analysis of a tsunami generated by a subaqueous volcanic explosion was performed for Taal Lake in the Philippines. The Taal volcano at Taal Lake is an active volcano on Luzon Island in the Philippines, and its eruption would potentially generate tsunamis in the lake. This study aimed to analyze a probabilistic tsunami hazard of inundated buildings for tsunami mitigation in future scenarios. To determine the probabilistic tsunami hazard, different explosion diameters were used to generate tsunamis of different magnitudes in the TUNAMI-N2 model. The initial water level in the tsunami model was estimated based on the explosion energy. The tsunami-induced inundation from the TUNAMI-N2 model was overlaid on the distribution of buildings. The tsunami hazard analysis of inundated buildings was performed by using the maximum inundation depth in each explosion case. These products were used to calculate the probability of the inundated building given the occurrence of a subaqueous explosion. The results from this study can be used for future tsunami mitigation if a tsunami is generated by a subaqueous volcanic explosion.

scholarly journals Spatio-Temporal Variations in Phytoplankton Communities in Sediment and Surface Water as Reservoir Drawdown—A Case Study of Pengxi River in Three Gorges Reservoir, China

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 340
Author(s):  
Wenjuan Ouyang ◽  
Zhe Li ◽  
Jixiang Yang ◽  
Lunhui Lu ◽  
Jinsong Guo
Keyword(s):  
Surface Water ◽  
Algal Blooms ◽  
Maximum Flow ◽  
Total Carbon ◽  
Hydrodynamic Conditions ◽  
Reservoir Drawdown ◽  
River Reservoir ◽  
Reservoir Systems ◽  
Spatio Temporal ◽  
Maximum Flow Velocity

The resting stages of phytoplankton are usually regarded as the seed bank and source of harmful algal blooms because of the recruitment of phytoplankton from sediment to the water column under suitable environmental conditions. Information about resting stages of phytoplankton is abundant in shallow lakes and littoral sea; yet, studies on river–reservoir systems are rare. The river–reservoir continuum shows a unique structuring of longitudinal gradients of hydrological and hydrodynamic conditions. We hypothesized that the seed bank and algal blooms in reservoirs are influenced by the hydrodynamic conditions of each reservoir. We used Illumina Miseq sequencing to examine the spatio-temporal variation in the phytoplankton community in the sediment as reservoir drawdown and in surface water during algal blooms in Pengxi River, a tributary of China’s Three Gorges Reservoir. The results show that the cyanobacteria community in sediment is significantly influenced by temperature, total carbon, maximum flow velocity, and total phosphorous, the eukaryotic phytoplankton community in sediment is significantly influenced by total phosphorous, temperature, total carbon, maximum flow velocity, and total nitrogen. Additionally, the dominant species in sediment is significantly different from that in surface water during algal blooms. Our results suggest that the dominant species in surface water during algal blooms is more influenced by the environmental factors and hydrodynamic conditions in the water column than the seeds in the sediment. These findings are fundamental for further research on the influence of hydrodynamic conditions on algal blooms in artificially regulated river-reservoir systems.

scholarly journals Design of a Tsunami Hazard Map on the Sea to Reduce Fishing Boat User's Damage

2007 ◽  
Vol 54 ◽  
pp. 1351-1355 ◽  
Author(s):  
Taro OHASHI ◽  
Shunichi KOSHIMURA ◽  
Fumihiko IMAMURA
Keyword(s):  
Tsunami Hazard ◽  
Hazard Map ◽  
Fishing Boat

scholarly journals The mechanical origin of snow avalanche dynamics and flow regime transitions

2020 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Flow Velocity ◽  
Alpha Angle ◽  
Maximum Flow ◽  
Flow Regimes ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Deposition Zone ◽  
Avalanche Dynamics ◽  
Maximum Flow Velocity ◽  
Deposit Height

Abstract. Snow avalanches cause fatalities and economic damages. Key to their mitigation entails the understanding of snow avalanche dynamics. This study investigates the dynamic behaviors of snow avalanches, using the Material Point Method (MPM) and an elastoplastic constitutive law for porous cohesive materials. By virtue of the hybrid Eulerian-Lagrangian nature of MPM, we can handle processes involving large deformations, collisions and fractures. Meanwhile, the elastoplastic model enables us to capture the mixed-mode failure of snow, including tensile, shear and compressive failure. Using the proposed numerical approach, distinct behaviors of snow avalanches, from fluid-like to solid-like, are examined with varied snow mechanical properties. In particular, four flow regimes reported from real observations are identified, namely, cold dense, warm shear, warm plug and sliding slab regimes. Moreover, notable surges and roll-waves are observed peculiarly for flows in transition from cold dense to warm shear regimes. Each of the flow regimes shows unique flow characteristics in terms of the evolution of the avalanche front, the free surface shape, and the vertical velocity profile. We further explore the influence of slope geometry on the behaviors of snow avalanches, including the effect of slope angle and path length on the maximum flow velocity, the $\\alpha$ angle and the deposit height. Unified trends are obtained between the normalized maximum flow velocity and the scaled $\\alpha$ angle as well as the scaled deposit height, reflecting analogous rules with different geometry conditions of the slope. It is found the maximum flow velocity is mainly controlled by the friction between the bed and the flow, the geometry of the slope, and the snow properties. In addition to the flow behavior before reaching the deposition zone, which has long been regarded as the key factor governing the $\\alpha$ angle, we reveal the crucial effect of the stopping behavior in the deposition zone. Furthermore, our MPM model is benchmarked with simulations of real snow avalanches. The evolution of the avalanche front position and velocity from the MPM modeling shows reasonable agreement with the measurement data from literature. The MPM approach serves as a novel and promising tool to offer systematic and quantitative analysis for mitigation of gravitational hazards like snow avalanches.

Comparative study of transcranial color duplex sonography and transcranial Doppler sonography in adults

1993 ◽  
Vol 78 (5) ◽  
pp. 776-784 ◽  
Author(s):  
Martin Schöoning ◽  
Reiner Buchholz ◽  
Jochen Walter
Keyword(s):  
Flow Velocity ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Maximum Flow ◽  
Duplex Sonography ◽  
Color Duplex Sonography ◽  
Content Type ◽  
Maximum Flow Velocity ◽  
Fine Print ◽  
Flow Velocities

✓ To determine whether the frequency shift recorded in basal cerebral arteries corresponds to “true” flow velocities, a prospective comparative study of transcranial color duplex sonography (TCCD) and transcranial Doppler sonography (TCD) was performed. A 2.0-MHz transducer of a computerized TCCD system and a TCD device were used. The middle cerebral artery (MCA) and anterior cerebral artery (ACA) were examined by TCCD in 49 healthy volunteers (mean age 35 ± 12 years). In 45 of the same volunteers a comparative TCD examination was possible. The studies were carried out blindly by different examiners at separate appointments. Peak systolic flow velocity, end-diastolic maximum flow velocity, time-averaged maximum flow velocity, and the pulsatility index were measured by both techniques. Additionally, for TCCD, time-averaged flow velocity was assessed, the resistance index and a spectral broadening index were calculated, and the energy output required for reliable measurement was analyzed. The TCCD signals were recorded in 98% of both MCA's and ACA's; with TCD, signals were recorded in 98% of MCA's and 87% of ACA's. Although in both vessels the angle-corrected peak systolic and time-averaged maximum velocities were approximately 10% to 15% higher in TCCD than in TCD measurements, correlation of flow velocities between both techniques was significant (p < 0.0001); differences between sides and age-dependency of flow velocities corresponded as well. In a reproducibility study, TCCD was repeated in 27 subjects by a third examiner with significant correlation (p < 0.0001) of both TCCD examinations. It is concluded that the advantage of TCCD is associated more with a qualitative aspect than a quantitative one. The additional visual dimension of TCCD can open new diagnostic possibilities in cerebrovascular disorders.

Debris flow hazard mapping considering the effect of mitigation structure – a case study in Taiwan based on numerical simulation

2020 ◽  
Author(s):  
Chih-Hao Hsu ◽  
Chuan-Yi Huang ◽  
Ting-Chi Tsao ◽  
Hsiao-Yuan Yin ◽  
Hsiao-Yu Huang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Water Conservation ◽  
Large Scale ◽  
Mass Movement ◽  
Hazard Mapping ◽  
Hazard Map ◽  
Inundation Depth ◽  
Central Taiwan ◽  
Debris Flow Hazard ◽  
Typhoon Herb

&lt;p&gt;This study added the dams and retain basin according to their dimensions measured with UAV onto the original 5m-resolition DEM to compare the effect of mitigation structures to debris flow hazard. The original and the modified DEMs were both applied to simulate the consequences by using RAMMS::Debris Flow (RApid Mass Movement Simulation) model.&lt;/p&gt;&lt;p&gt;Hazard map is the best tool to provide the information of debris flow hazard in Taiwan. It has an important role to play in evacuating the residents within the affected zone during typhoon season. For the reason, debris flow hazard maps become a useful tool for local government to execute the evacuation. As the mitigation structure is constructed, the intensity of debris flow hazard reduces.&lt;/p&gt;&lt;p&gt;The Nantou DF190 debris flow potential torrent is located in central Taiwan. In 1996 when Typhoon Herb stroke, 470,000 cubic-meter of debris were washed out and deposited in 91,200 square-meter area (Yu et al., 2006), and the event caused the destruction of 10 residential houses with 2 fatalities. After the event the Soil and Water Conservation Bureau constructed a 100-meter long sabo dam and sediment retain basin with capacity of 60,000 cubic-meters. In order to compare the difference of affected zone before and after the construction of mitigation structures, the study applies RAMMS to simulate the above-mentioned event.&lt;/p&gt;&lt;p&gt;The result shows when large-scale debris flow occurs, most of the sediments still overflow and deposit on the fan with shape similar to the 1996 Typhoon Herb event. However, the intensity has reduced significantly with 50% less in area, several meters less in inundation depth and 50% less in flow velocity approximately. The comparison shows the effect of mitigation structures and could provide valuable information for debris flow hazard mapping.&lt;/p&gt;&lt;p&gt;Key Words: Debris flow, RAMMS, Hazard map, Mitigation, Taiwan&lt;/p&gt;

scholarly journals Two-dimensional computational simulation flow of exhaust gases passing inside an electrostatic precipitator

2016 ◽  
Vol 10 (1) ◽  
pp. 106-112
Author(s):  
Giorgos Kouropoulos
Keyword(s):  
Fluid Mechanics ◽  
Flow Velocity ◽  
Electrostatic Precipitator ◽  
Computational Simulation ◽  
Flow Simulation ◽  
Maximum Flow ◽  
Theoretical Background ◽  
Two Dimensional ◽  
Exhaust Gases ◽  
Maximum Flow Velocity

In the present study the two-dimensional computational simulation flow of hot exhaust gases which are passed inside an electrostatic precipitator will be carried out. Initially, the theoretical background and necessary equations from fluid mechanics will be described. These equations will be used by software for flow simulation. Furthermore, are presented the design of precipitator through which the exhaust gases are passed. In the next step follows the declaration of various parameters of simulation on the software and finally the necessary images of the computational simulation for two case studies will be extracted. The general conclusions that arise are that the maximum flow velocity of exhaust gases prevails only at the beginning of the entrance of the precipitation element. There are different velocities in all other parts of precipitation element. When the exhaust gases approach the collecting electrodes within the element, their velocity is decreased.

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