Research Achievements - Original paper -

INVESTIGATION OF QUANTITATIVE SANDBAR MONITORING USING UAV AND SEDIMENT ANALYSIS AT BABAMEGAWA RIVER

Yoshitaka JIKEN,Kazuya WATANBE and Noritoshi SAITO

International Journal of GEOMATE     2024.12  [Refereed]

Research paper (journal)   Domestic Co-author

STUDY ON COLLISIONS BETWEEN OFFSHORE WIND POWER GENERATION EQUIPMENT AND TSUNAMI DRIFTING DEBRIS

SAITO Noritoshi, WATANABE Kazuya

Japanese Journal of JSCE ( Japan Society of Civil Engineers )  79 ( 18 ) n/a   2023.10  [Refereed]

Research paper (journal)  

<p> Akita Port is one of the most important ports on the Sea of Japan side, playing an important role as a logistics hub in Akita Prefecture. In 2023, thirteen landing-type offshore power generators were installed in the port. However, the power generation facilities are located around breakwaters, which are relatively close to container groups and anchored vessels in the port. In this study, a hydraulic model experiment was conducted to investigate the speed and load of drifting debris impacting the offshore wind turbines. As a result, the behavior of the drifting object model was different for the first wave and the second and subsequent waves of the assumed tsunami. The maximum load on the structure model tended to increase as the difference between the storage depth and the inundation depth increased, but this was not the case for the drifting object model.</p>

DOI CiNii Research

Study on sediment analysis and quantitative sandbar monitoring of UAV at Babamegawa river

Yoshitaka JIKEN,Kazuya WATANBE and Noritoshi SAITO

proceedings of the eleventh international conference – GEOMATE 2023 GEOTECHNIQUE, CONSTRUCTION MATERIALS AND ENVIRONMENT     2023.09  [Refereed]

Research paper (journal)   Domestic Co-author

HYDRAULIC MODEL EXPERIMENTAL STUDY ON BARK STRIPPING PROCESS USING DRIFTWOOD MODEL

Kazuya Watanabe, Noritoshi Saito and Yoshitaka Jiken

International Journal of GEOMATE     2023.08  [Refereed]

Research paper (journal)   Domestic Co-author

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STUDY ON SEDIMENT GRAIN-SIZE MEASUREMENT AND CALUCULATION AT MULTIPLE POINTS ON THE SANDBAR IN CLASS B RIVER

Yoshitaka Jiken, Kazuya Watanabe and Noritoshi Saito

International Journal of GEOMATE ( International Journal of GEOMATE )  24 ( 104 ) 93 - 100   2023.04  [Refereed]

Research paper (journal)   Domestic Co-author

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EXAMINATION OF GRAIN-SIZE OF SEDIMENT AT MULTIPLE POINTS ON THE SANDBAR IN CLASS B RIVER

Yoshitaka Jiken, Kazuya Watanabe and Noritoshi Saito

Proceedings of 7th Int. Conf. on Structure, Engineering & Environment (SEE)     168 - 173   2022.11  [Refereed]

Research paper (journal)   Domestic Co-author

A NUMERICAL ANALYSIS ABOUT SUSPENDED SEDIMENT DEPOSITION AROUND FILTER UNIT

Terumichi Hagiwara, Shunsuke Aita, Kazuya Watanabe, So Kazama

Proceedings of IAHR Congress     2022.06  [Refereed]

Research paper (journal)   Domestic Co-author

INVESTIGATIONON THE RELATIONSHIP BETWEEN THE CHANGE OF RIVER MOUTH SANDBAR AND RIVER DISCHARGE AND OCEAN WAVE ENERGY AT OMONO RIVER

Junya Taniguchi, Kazuya Watanabe, Noritoshi Saito

International Journal of GEOMATE   22 ( 88 ) 113 - 120   2021.12  [Refereed]

Research paper (journal)   Domestic Co-author

STUDY ON THE INFLUENCE OF STRUCTURES ON THE SEDIMENT TRANSPORT DUE TO THE TSUNAMI RUN-UP TO RIVER

KAMATAKI Takanobu, KODACHI Syunya, SAITO Noritoshi, WATANABE Kazuya

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) ( Japan Society of Civil Engineers )  77 ( 2 ) I_277 - I_282   2021.11  [Refereed]

Research paper (journal)   Domestic Co-author

<p> The sediments within the tsunami inundation flow increases their density. In addition, it is known that the horizontal and vertical forces of the tsunami inundation flow increase accordingly. Thus, it is important to consider sediments when we studied flume experiments of tsunami run-up to river. In this study, we simulated the tsunami run-up to river using two types of sediment, such as fine and coarse sands, and studied a flume experiments on the effect of the tsunami on structure and sediment transport. As a result of this study, we have clarified the following three points. The tsunami inundation flow scours the sediments around the structure. In addition, due to the influence of the structure, almost no sand is deposited behind the structure. The density of tsunami inundation flow is higher under the condition that fine sand is on the sea side and coarse sand is on the river side. The wave force that hits in front of the structure increases when fine sand is on the sea side and coarse sand is on the river side.</p>

DOI

RELATIONSHIP BETWEEN DYNAMICS OF RIVER MOUTH SANDBAR AND RIVER DISCHARGE AND WAVE AT OMONO RIVER

TANIGUCHI Junya, WATANABE Kazuya, SAITO Noritoshi

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) ( Japan Society of Civil Engineers )  77 ( 2 ) I_529 - I_534   2021.11  [Refereed]

Research paper (journal)   Domestic Co-author

<p> River mouth sandbar grows in Omono River in Akita prefecture. River mouth sandbar topography was affected by combined forces, such as river discharge, ocean waves. River mouth sandbar interrupts salt and wave intrusion and affects the navigation of cruisers and fishing vessels. Therefore, study on sandbar on Omono River was carried out. However, field investigation was conducted more frequently to understand the change of sandbar in detail. In this study, field investigation using UAV was conducted. Then, sandbar change process was analyzed calculating sandbar area and river mouth width from reconstructed topography by the SfM technique. Furthermore, the investigation of relationship between sandbar area and river mouth width and river discharge, cross-shore, and longshore waves was carried out.</p><p> As a result, the following results were found out from this study. The relationship between sandbar area and river mouth width and river discharge, cross-shore, and longshore waves were cleared. The seasonal cycle was discovered. Moreover, recovery of sandbar was cleared partly. It was found out that sandbar area was changed -500-+400 m² per day and river mouth width was changed -2-+2 m per day.</p>

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STUDY ON THE RELATIONSHIP BETWEEN THE CHANGE OF RIVER MOUTH SANDBAR AND RIVER DISCHARGE AND OCEAN WAVE AT THE OMONO RIVER

Junya Taniguchi, Kazuya Watanabe, Noritoshi Saito

proceedings of the eleventh international conference – GEOMATE 2021 GEOTECHNIQUE, CONSTRUCTION MATERIALS AND ENVIRONMENT   11   436 - 441   2021.11  [Refereed]

Research paper (journal)   Domestic Co-author

STUDY ON WAVE FORCE OF DRITING OBJECTS USING PRESSURE SENSOR

SAITO Noritoshi, WATANABE Kazuya, ISIZUKA Daichi

Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) ( Japan Society of Civil Engineers )  77 ( 2 ) I_103 - I_108   2021.06  [Refereed]

Research paper (journal)   Domestic Co-author

<p> The 2011 Great East Japan Earthquake and Tsunami attacked Japan on a scale far beyond conventional expectations. Buildings, automobiles, and ships were swept away, and a large amount of drifted debris caused catastrophic damage. In the event of a tsunami, evacuation methods using floating tsunami evacuation shelters have been proposed, and the behavior and wave forces of shelter models installed on buildings have been investigated. In this paper, we propose a method of evacuation using a floating tsunami shelter. In this study, a pressure sensor was attached to a drifting object model and a tsunami impact experiment was conducted to examination the wave force in the drifting condition. For this results, the maximum value of the wave force and the behavior of the model differed depending on the inundation conditions. Furthermore, it was found that the wave force was overestimated by fixing the model.</p>

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INVESTIGATION ON TSUNAMI RUN-UP AND SEDIMENTS IN SMALL RIVERS AROUND THE AKITA REGION IN 1983

WATANBE Kazuya, TANIGUCHI Jyunya, SAITO Noritoshi, HAYASHI Naoyuki, KAMATAKI Takanobu

Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) ( Japan Society of Civil Engineers )  77 ( 2 ) I_91 - I_96   2021.06  [Refereed]

Research paper (journal)   Domestic Co-author

<p> The tsunami which run-up in river over the embankment affected serious damage in coastal area at the 2011 Tohoku earthquake and tsunami. Therefore the measures to river run-up of the tsunami were important in thinking about the tsunami disaster prevention in the coastal area. On the other hand, there were few records of the tsunami data, though active faults were near the land on the Sea of Japan side and time to tsunami arrival from an earthquake occurrence tends to be short. Therefore it was simulated based on 1983 Japan Sea Earthquake to perform the comparison with the measured value with Sea of Japan side particularly.</p><p> The following things were confirmed from a calculation result and measured. It is thought that the tsunami sediment in this area is of the sea origin at Takogawa River. (1) The tsunami run over the beach bank, (2) The tsunami flowed into the small river, (3) The flow to return to the sea from the east side in the right bank the small river was confirmed at Shirayukigawa River</p>

DOI

STUDY ON THE BEHAVIOR OF SANDBAR IN A RIVER CHANNEL AT THE BABAMEGAWA RIVER

Taniguchi J., Watanabe k. and Saito N.

International Journal of GEOMATE ( International Journal of GEOMATE )  20 ( 78 ) 115 - 120   2021.02  [Refereed]

Research paper (journal)   Domestic Co-author

DOI

STUDY ON SALINITY INTRUSION IN ESTUARY OF KOYOSHI RIVER

WATANABE Kazuya, TANIGUCHI Junya, SAITO Noritoshi, KOBAYASHI Ryoma, KONAKA Akiho

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) ( Japan Society of Civil Engineers )  76 ( 2 ) I_79 - I_84   2020.11  [Refereed]

Research paper (journal)   Domestic Co-author

<p> Supply of water use as the agriculture water was formed mainly in the Koyoshi River. The Honjo plain field was known as production area creationg high quality rice. In addition, there were fewer rations than agriculture, but is used as water service and water for industrial use elsewhere. However, salinity intrusion was occurred by drought in the Koyoshi River. Distanve of salinity intrusion was from the river mouth to nearly 10 km. It cannot pump up water at Yurihonjo City Koyoshi distinct by salinity intrusion. Therefore, it was grasping to the situation about going up of the salt water and it is very important to examine a condition of the going up.</p><p> In the study, it was examined salt going up and relations with external force such as river discharge, the wave height, etc., for the Koyoshi River. Koyoshi River was first-grade river in Akita Prefecture. As a result, it was able to confirm that salinity intrusion was frequent in the Koyoshi a clear relationship was not seen about wave height and the salinity intrusion.</p>

DOI

STUDY ON THE BEHAVIOR OF SANDBAR IN A RIVER CHANNEL AT THE BABAMEGAWA RIVE

Junya Taniguchi, Kazuya Watanabe, Noritoshi Saito and Naoya Fujisawa

Proceedings of 6th Int. Conf. on Structure, Engineering & Environment (SEE)     149 - 154   2020.09  [Refereed]

Research paper (journal)   Domestic Co-author

CHARACTERISTICS OF BOTTOM SHEAR STRESS VARIATION UNDER SHOALING SOLITARY WAVE

TANAKA Hitoshi, TINH Nguyen Xuan, NISHIWAKI Ryo, WATANABE Kazuya

Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) ( Japan Society of Civil Engineers )  76 ( 2 ) I_150 - I_155   2020.06  [Refereed]

Research paper (journal)   Domestic Co-author

<p> In the coastal environments, detailed understanding of current or wave-induced bottom shear stresses, which are often associated to the steady friction law and wave friction law respectively, is essential to evaluate quantitatively the sediment transport and coastal morphological changes. Many previous studies have indicated that there was an influence of unsteady characteristics in the boundary layer beneath a long-period wave. Therefore, the bottom shear stress under shoaling tsunami should be considered the unsteady wave-like effects. A new correction approach has been proposed by comparing the wave friction factor to the steady friction factor. The current study aims to implement the new correction method for assessing the bed shear stress to the conventional model for tsunami. Application for a solitary wave, which propagates from the tsunami source to the shore, shows that bottom shear stress by the new method is ten times larger than the conventional method in a deep water and become smaller in shallow area. In addition, the location of the critical Shields parameter of 0.05 by the new method is situated in deeper water than the conventional method.</p>

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INVESTIGATION OF WAVE FORCE ACTING ON FLOATING TYPE TSUNAMI EVACUATION SHELTER AT TSUNAMI CONSIDERING INUNDATION DEPTH

WATANABE Kazuya, SAITO Noritoshi, MAKANAE Jun, KUNII Yuta

Journal of Japan Society of Civil Engineers, Ser. B3 (Ocean Engineering) ( Japan Society of Civil Engineers )  76 ( 2 ) I_1079 - I_1084   2020.06  [Refereed]

Research paper (journal)   Domestic Co-author

<p> It was received tsunami damage in The Great East Japan Earthquake, tsunami wave height of two levels were sets by Central Disaster Prevention Council. "The tsunami of the greatest class where the outbreak frequency brings the damage that is serious although it is extremely low" was tsunami more than assumptions conventionally. Then, it was only high place refuge and it may not protect human life. So, it became important that establish the measures to the tsunami more than evacuation sites. There was the tsunami refuge that utilized a floating type of tsunami evacuation shelter as tsunami measures after the high place refuge. However, it may not become clear about the characteristics of floating type of tsunami evacuation shelter.</p><p> In this study, the motion of shelter examined using wave force and Froude number at the tsunami. As a result, angle of the water to hit the shelter influenced it by difference in inundation depth, and it turned out that was greatly different in wave force.</p>

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EXAMINATION ABOUT THE FORMATION OF RIVER MOUTH SANDBAR BY THE INFLUENCE OF RIVER DISCHARGE AND OCEAN WAVES AT YONESHIRO RIVER MOUTH

WATANABE Kazuya, HORII Yusuke

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) ( Japan Society of Civil Engineers )  75 ( 2 ) I_193 - I_198   2019.11  [Refereed]

Research paper (journal)   Domestic Co-author

<p> Frequent occurrence of water level rise caused with increase in abnormal weather such as the local torrential rain by the influence of the global warming. Therefore, apprehensive the saline water intrusion was generated at the tidal area due to water level rising and the river mouth topography change in recent years. Saline water intrusion was generated to go up upstream by the ocean waves during winter at the Sea of Japan side river mouth especially. Hence, riverine environment was affected from saline water intrusion. It was in particular thought river mouth shape have a high impact on tidal discharge and saline water intrusion. However, it was not understood in sufficient elucidation of the mechanism of the increase of tidal discharge saline water intrusion. For this reason, it was very important to examine the long-run effect of river shape on tidal discharge and saline water intrusion.</p><p> In this study, it was investigated about the hydraulic characteristics by the field observation and data analysis target at Yoneshiro river where the extension of the sandbar was remarkable. As a result, the amount of change of the river mouth width ΔB grows large more than up to approximately 20m from a previous week. It was revealed that river-mouth closure up to approximately around 10m occurred by the reverse case. Saline water intrusion was not confirmed in Yoneshiro River which was developed of the sandbar. It was thought to cause the river-mouth closure by the development of the sandbar. Furthermore, discharge of wave set-up was about 70m³/s from calculation of the tidal discharge.In addition, it became clear from river mouth width rate of change α that there were many changes of the river mouth width in 500m³/s or less river discharge in Yoneshiro River.</p>

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ONE-DIMENSIONAL NUMERICAL SIMULATION OF TSUNAMI PROPAGATION CONSIDERING TRANSITION OF A FRICTION FACTOR

TINH Nguyen Xuan, TANAKA Hitoshi, NISHIWAKI Ryo, WATANABE Kazuya

Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) ( Japan Society of Civil Engineers )  75 ( 2 ) I_697 - I_702   2019.11  [Refereed]

Research paper (journal)   Domestic Co-author

<p> In most of current conventional tsunami numerical models, the steady flow friction law is usually used for accessing the tsunami-induced bottom shear stress. However, we have been theoretically proved that the the steady flow friction law was not valid in almost the entire model domain from the tsunami source, it was the wave friction law instead. Therefore, the estimated bottom shear stress by steady friction law is inaccurated. We have proposed a new correction method for the steady tsunami-induced bottom shear stress. In this study, A numericall implementation of this correction method into the one-dimensional shallow water equation model of tsunami propagation is presented. The new correction method is called as the Method 1 and the traditional method is the Method 2 in this study. The Method 1 is calculated by the iteration process. As a result, the comparison results indicate that the simulated maximum tsunami wave height and tsunami-induced velocity by the Method 1 and Method 2 were had almost similar results. However, the bottom shear stress estimated by the Method 1 was obtained about 10 times higher than the Method 2 at the tunami source area and the difference decreases as the water depth decreases. Two methods are coincided from the location of water depth around 6m to the shoreline.</p>

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